(19)
(11)EP 3 657 661 B1

(12)EUROPEAN PATENT SPECIFICATION

(45)Mention of the grant of the patent:
03.08.2022 Bulletin 2022/31

(21)Application number: 18843954.1

(22)Date of filing:  10.08.2018
(51)International Patent Classification (IPC): 
H02M 7/483(2007.01)
H02M 1/00(2006.01)
(52)Cooperative Patent Classification (CPC):
H02J 3/38; H02M 7/483; Y02B 70/10; Y02E 10/56; H02M 1/0058; H02M 1/0095; H02M 7/4837
(86)International application number:
PCT/CN2018/099926
(87)International publication number:
WO 2019/029694 (14.02.2019 Gazette  2019/07)

(54)

CONVERSION CIRCUIT, CONTROL METHOD, AND POWER SUPPLY DEVICE

WANDLUNGSSCHALTUNG, STEUERVERFAHREN UND ENERGIEVERSORGUNGSVORRICHTUNG

CIRCUIT DE CONVERSION, PROCÉDÉ DE COMMANDE, ET DISPOSITIF D'ALIMENTATION ÉLECTRIQUE


(84)Designated Contracting States:
AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

(30)Priority: 11.08.2017 CN 201710686021

(43)Date of publication of application:
27.05.2020 Bulletin 2020/22

(73)Proprietor: Huawei Digital Power Technologies Co., Ltd.
Shenzhen, 518043 (CN)

(72)Inventors:
  • WANG, Zhaohui
    Shenzhen Guangdong 518129 (CN)
  • SHI, Lei
    Shenzhen Guangdong 518129 (CN)
  • FU, Dianbo
    Shenzhen Guangdong 518129 (CN)

(74)Representative: Epping - Hermann - Fischer 
Patentanwaltsgesellschaft mbH Schloßschmidstraße 5
80639 München
80639 München (DE)


(56)References cited: : 
EP-A1- 2 590 312
CN-A- 102 664 548
CN-A- 107 317 508
US-A1- 2013 154 716
WO-A1-2017/201373
CN-A- 103 236 796
US-A1- 2012 218 795
US-A1- 2015 333 522
  
  • XIAOMING YUAN ET AL: "Investigation on the clamping voltage self-balancing of the three-level capacitor clamping inverter", POWER ELECTRONICS SPECIALISTS CONFERENCE, 1999. PESC 99. 30TH ANNUAL I EEE CHARLESTON, SC, USA 27 JUNE-1 JULY 1999, PISCATAWAY, NJ, USA,IEEE, US, vol. 2, 27 June 1999 (1999-06-27), pages 1059-1064, XP010346808, DOI: 10.1109/PESC.1999.785642 ISBN: 978-0-7803-5421-0
  
Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention).


Description

TECHNICAL FIELD



[0001] This application relates to the field of photovoltaic power generation technologies, and in particular, to a conversion circuit, a control method, and a power supply device.

BACKGROUND



[0002] In a photovoltaic power generation system, an inverter as a core device directly determines a system architecture and reliable operation of a photovoltaic power station. A high-efficiency inverter can increase electric energy production of the photovoltaic power generation system, reduce a weight and a size of a converter, facilitate installation and maintenance, and improve product cost performance and enhance product market competitiveness. As a core part of a photovoltaic inverter, an inverter circuit has a crucial effect on overall performance of the inverter.

[0003] To implement high-efficiency electric energy conversion, deep exploration and research are performed on inverter circuits in industry and academia. Currently, commonly used inverter circuits mainly include a two-level inverter circuit and a three-level inverter circuit. As shown in FIG. 1, FIG. 1a shows a conventional bridge-type two-level inverter circuit, and FIG. 1b shows a diode neutral point clamped (neutral point clamped, NPC) three-level inverter circuit. The conventional two-level inverter circuit and the NPC three-level inverter circuit have different loss characteristics. When total losses of the two circuits are close to each other, the two-level inverter circuit has a lower conduction loss than the three-level inverter circuit, while the NPC three-level inverter circuit has a lower switching loss than the two-level inverter circuit. This is because in the three-level inverter circuit, low-voltage semiconductor switching devices may be used, and the low-voltage devices have excellent switching characteristics and low switching losses. However, these devices need to be connected in series to reach a voltage grade of the two-level circuit, and series connection of these devices causes a relatively high forward conduction voltage drop. The curves shown in FIG. 2 indicate that when forward currents of devices are the same, a conduction voltage drop (VI) of a 1200 V IGBT is obviously lower than a conduction voltage drop (V2) of two 650 V IGBTs connected in series. Therefore, the two-level circuit can achieve a lower conduction loss.

[0004] In conclusion, the two-level inverter circuit has a low conduction loss, while a multilevel inverter circuit has a low switching loss. Therefore, to further reduce a loss of a converter and increase power density and product competitiveness of the converter, advantages of the two types of inverter circuits can be comprehensively used in an inverter, to improve converter performance.

[0005] However, in a circuit obtained by combining a two-level inverter circuit with an NPC three-level inverter circuit, there are a large quantity of semiconductor devices, a commutation loop is complex, and a power circuit layout is affected. In addition, in a topology of the combined circuit, capacitors with large capacity need to be used to divide direct current bus voltage to generate a midpoint voltage. However, serious voltage fluctuation occurs on the midpoint voltage, and the voltage fluctuation leads to an increase in an amplitude value of a current ripple of a bus capacitor, causing the bus capacitor to generate heat, reducing a service life of the capacitor, and affecting long-term reliable working of the converter.

[0006] EP 2 590 312 A1 relates to a Voltage Source Converter (VSC) with Neutral-Point-Clamped (NPC) topology with one or more phases, comprising: an intermediate DC circuit having at least a first and a second capacitance connected in series between a positive terminal and a negative terminal, providing a central tap terminal between both capacitances, and at least one sub-circuit for generating one phase of an alternating voltage, each sub-circuit comprising: an AC terminal for supplying a pulsed voltage; a circuit arrangement of the form of a conventional neutral-point-clamped converter, with a first series connection of at least two switches between said AC terminal and said positive terminal, a second series connection of at least two switches between said AC terminal said negative terminal, and switchable connections from said central tap terminal to the centers of both two-switch series connections; and additional first and second auxiliary switches being assigned to said two-switch series connections.

[0007] Further prior art is provided by US2013/154716 A1.

SUMMARY



[0008] The present invention is defined by the appended claims. In the following, parts of the description and drawings referring to embodiments which are not covered by the claims are not presented as embodiments of the invention, but as examples useful for understanding the invention. This application provides a conversion circuit, where the circuit belongs to a mixed type three-level inverter circuit topology. Based on this, this application further provides a control method matching the circuit, so as to reduce a loss of a converter and improve converter performance.

[0009] According to a first aspect, this application provides a conversion circuit, where the circuit includes an input terminal, an output terminal, a control module, and a first switch unit and a second switch unit that are formed by semiconductor switching devices; the input terminal includes a positive direct current bus terminal and a negative direct current bus terminal, and the output terminal includes an alternating current output end; the first switch unit includes a flying clamping capacitor and a first converter bridge arm that is formed by connecting a first switch, a second switch, a third switch, and a fourth switch in series, where two ends of the first converter bridge arm are respectively connected to the positive direct current bus terminal and the negative direct current bus terminal, a first end of the flying clamping capacitor is connected to a series connection point between the first switch and the second switch, a second end of the flying clamping capacitor is connected to a series connection point between the third switch and the fourth switch, and a series connection point between the second switch and the third switch forms an output end of the first switch unit; the flying clamping capacitor is configured to implement voltage clamping of the second switch and the third switch, to avoid overvoltage damage of the switch devices; the second switch unit includes a second converter bridge arm that includes a fifth switch and a sixth switch, two ends of the second converter bridge arm are respectively connected to the positive direct current bus terminal and the negative direct current bus terminal, and a series connection point between the fifth switch and the sixth switch is connected to the alternating current output end; and the first switch unit and the second switch unit are connected to the control module; and switch under control of the control module, so that the conversion circuit converts between a direct current voltage and an alternating current voltage.

[0010] With reference to the first aspect, in an implementation of the first aspect, the circuit further includes a filtering module, configured to filter out a ripple of a voltage of the output end of the first switch unit and the second switch unit, where one end of the filtering module is connected to the output end of the first switch unit and the second switch unit, and the other end of the filtering module is connected to the alternating current output end. Optionally, the filtering module includes a filter circuit such as an inductor.

[0011] With reference to the first aspect, in another implementation of the first aspect, the first switch, the second switch, the third switch, the fourth switch, the fifth switch, and the sixth switch each include a semiconductor switching device such as an IGBT or a MOSFET device, and the IGBT includes an anti-parallel diode.

[0012] With reference to the first aspect, in still another implementation of the first aspect, the first switch, the second switch, the third switch, and the fourth switch each include an IGBT and an anti-parallel diode, and the fifth switch and the sixth switch each include a semiconductor switching device such as an IGBT or a MOSFET.

[0013] With reference to the first aspect, in still another implementation of the first aspect, the circuit may be a part of a single-phase circuit, a three-phase circuit, or a multiphase circuit.

[0014] With reference to the first aspect, in still another implementation of the first aspect, the circuit is a part of a rectifying circuit or an inverter circuit.

[0015] With reference to the first aspect, in still another implementation of the first aspect, a steady state voltage of the flying clamping capacitor is usually controlled at 1/2 of a direct current bus voltage, that is, Vbus/2, and based on driving logic, output levels of the output end OUT of the first switch unit and the second switch unit relative to a direct current bus midpoint M are +Vbus/2, 0, and -Vbus/2.

[0016] According to a second aspect, this application further provides a control method, used to control the conversion circuit described in the first aspect, where the conversion circuit includes an input terminal, an output terminal, a control module, and a first switch unit and a second switch unit that are formed by semiconductor switching devices; the input terminal includes a positive direct current bus terminal and a negative direct current bus terminal, and the output terminal includes an alternating current output end; the first switch unit includes a flying clamping capacitor and a first converter bridge arm that is formed by connecting a first switch, a second switch, a third switch, and a fourth switch in series, where two ends of the first converter bridge arm are respectively connected to the positive direct current bus terminal and the negative direct current bus terminal, a first end of the flying clamping capacitor is connected to a series connection point between the first switch and the second switch, a second end of the flying clamping capacitor is connected to a series connection point between the third switch and the fourth switch, and a series connection point between the second switch and the third switch forms an output end of the first switch unit; the second switch unit includes a second converter bridge arm that includes a fifth switch and a sixth switch, two ends of the second converter bridge arm are respectively connected to the positive direct current bus terminal and the negative direct current bus terminal, and a series connection point between the fifth switch and the sixth switch is connected to an output end of the second switch unit; the output end of the first switch unit and the second switch unit are connected to the alternating current output end; the control module is connected to the first switch unit and the second switch unit, is configured to control switch-on or switch-off of each switch device in the switch units to implement power conversion between a direct current voltage and an alternating current voltage; the circuit control method includes: controlling, by the control module within a time in which both the first switch and the second switch are on, the fifth switch to be on for at least a period of time, to reduce a conduction voltage drop of a path of the first switch and the second switch; and controlling, by the control module within a time in which both the third switch and the fourth switch are on, the sixth switch to be on for at least a period of time, to reduce a conduction voltage drop of a path of the third switch and the fourth switch.

[0017] In the control method provided in this aspect, because an on-state voltage drop of the fifth switch is lower than a voltage drop obtained after the first switch and the second switch are connected in series, and an on-state voltage drop of the sixth switch is lower than a voltage drop obtained after the third switch and the fourth switch are connected in series, switch-on of the fifth switch and the sixth switch may cause a decrease in a conduction voltage drop in a current flowing loop, thereby reducing a conduction loss of a converter.

[0018] With reference to the second aspect, in an implementation of the second aspect, a switching frequency of each of the four switches in the first switch unit is a high frequency, and the first switch and the fourth switch are complementary switches; the second switch and the third switch are complementary switches; switching cycles of the four switches in the first switch unit are the same; and the fifth switch and the sixth switch are complementary switches.

[0019] With reference to the second aspect, in another implementation of the second aspect, the first switch and the second switch in the first switch unit are switched on/off with a phase shift of 180°, and the third switch and the fourth switch are switched on/off with a phase shift of 180°. With reference to the second aspect, the controlling, by the control module within a time in which both the first switch and the second switch are on, the fifth switch to be on for at least a period of time includes: when the first switch is off and the second switch is on, when the first switch is switched on, controlling, by the control module, the fifth switch to be switched on a time interval Td1 later than a switch-on moment of the first switch, so as to implement zero voltage switch-on of the fifth switch, so that the fifth switch has no switching-on loss; when both the first switch and the second switch are on, when the second switch is to be switched off, controlling, by the control module, the fifth switch to be switched off a time interval Td2 earlier than a switch-off moment of the second switch, where the second switch is used to implement switching-off commutation and implement zero voltage switch-off of the fifth switch, so that the fifth switch has no switching-off loss; when the first switch is on and the second switch is off, when the second switch is switched on, controlling, by the control module, the fifth switch to be switched on a time interval Td3 later than a switch-on moment of the second switch, where the second switch is used to implement switching-on commutation and implement zero voltage switch-on of the fifth switch, so that the fifth switch has no switching-on loss; and when both the first switch and the second switch are on, when the first switch is to be switched off, controlling, by the control module, the fifth switch to be switched off a time interval Td4 earlier than a switch-off moment of the first switch, where the first switch is used to implement switching-off commutation and implement zero voltage switch-off of the fifth switch, so that the fifth switch has no switching-off loss.

[0020] With reference to the second aspect, the controlling, by the control module within a time in which both the third switch and the fourth switch are on, the sixth switch to be on for at least a period of time includes: when the third switch is on and the fourth switch is off, when the fourth switch is switched on, controlling, by the control module, the sixth switch to be switched on a time interval Td5 later than a switch-on moment of the fourth switch, where the fourth switch is used to implement switching-on commutation and implement zero voltage switch-on of the sixth switch, so that the sixth switch has no switching-on loss; when both the third switch and the fourth switch are on, when the third switch is to be switched off, controlling, by the control module, the sixth switch to be switched off a time interval Td6 earlier than a switch-off moment of the third switch, where the third switch is used to implement switching-off commutation and implement zero voltage switch-off of the sixth switch, so that the sixth switch has no switching-off loss; when the third switch is off and the fourth switch is on, when the third switch is switched on, controlling, by the control module, the sixth switch to be switched on a time interval Td7 later than a switch-on moment of the third switch, where the third switch is used to implement switching-on commutation and implement zero voltage switch-on of the sixth switch, so that the sixth switch has no switching-on loss; when both the third switch and the fourth switch are on, when the fourth switch is to be switched off, controlling, by the control module, the sixth switch to be switched off a time interval Td8 earlier than a switch-off moment of the fourth switch, where the fourth switch is used to implement switching-off commutation and implement zero voltage switch-off of the sixth switch, so that the sixth switch has no switching-off loss.

[0021] With reference to the second aspect, in still another implementation of the second aspect, the method further includes: determining, by the control module, the time intervals based on switching characteristics of the switch devices in the first switch unit and the second switch unit, where the time interval is between 0 ns and 10 µs.

[0022] With reference to the second aspect, in another implementation of the second aspect, the method further includes: setting, by the control module, the time intervals solely, where the time interval is between 0 ns and 10 µs.

[0023] With reference to the second aspect, in another implementation of the second aspect, the circuit further includes a filtering module; one end of the filtering module is connected to the output end of the first switch unit and the second switch unit, and the other end of the filtering module is connected to the alternating current output end; and the filtering module is configured to filter out a ripple of a voltage of the output end of the first switch unit and the second switch unit. According to a third aspect, this application further provides a power supply device, and the power supply device includes the conversion circuit described in the first aspect, and is configured to implement power conversion between a direct current voltage and an alternating current voltage. Further, the power supply device includes a converter, for example, an AC/DC converter and a DC/AC converter.

[0024] With reference to the third aspect, in an implementation of the third aspect, the device includes a processor and a memory, where the processor is configured to control switch-on or switch-off of each switch device in the conversion circuit, to implement power conversion between a direct current voltage and an alternating current voltage, and output a required alternating current voltage. The memory may store a program, and the program is used to perform the circuit control method in various implementations of the second aspect of this application. According to a fourth aspect, this application further provides a photovoltaic power generation system, where the system includes a photovoltaic cell, a photovoltaic inverter, and an alternating current power grid; the photovoltaic inverter includes an input end, an output end, and the conversion circuit described in the foregoing first aspect or various implementations of the first aspect; the input end of the photovoltaic inverter is connected to the photovoltaic cell, and the output end of the photovoltaic inverter is connected to the alternating current power grid; and the conversion circuit is configured to convert voltages at the input end and the output end of the photovoltaic inverter. Optionally, the photovoltaic inverter is the power supply device described in the foregoing third aspect.

[0025] Compared with a mixed type NPC three-level inverter circuit or a mixed type ANPC three-level inverter circuit, the conversion circuit provided in this application implements electric energy conversion between a direct current and an alternating current by using a flying capacitor three-level circuit, to replace some diodes. This reduces a quantity of semiconductors, and simplifies a circuit structure is simplified, facilitating power module layout. In addition, due to use of the flying capacitor, a direct current bus does not need to use a large capacity capacitor for voltage division to generate a midpoint voltage, and therefore there is no problem of midpoint voltage fluctuation, a direct current bus capacitor structure is simplified, and a bus capacitor is saved.

[0026] In the circuit control method provided in this application, each switch of the first switch unit and the second switch unit is controlled to be switched on or off, so that the output end of the first switch unit and the second switch unit is alternately connected to the positive direct current bus terminal and the negative direct current bus terminal according to a preset switch-on/off time sequence, and commutation is implemented through switch-on or switch-off of the four switches in the first switch unit, and switch-on of the fifth switch and the sixth switch in the second switch unit causes a decrease in the conduction voltage drop of the current flowing loop, thereby reducing a conduction loss of the converter.

BRIEF DESCRIPTION OF DRAWINGS



[0027] 

FIG. 1a is a schematic structural diagram of a conventional bridge-type two-level inverter circuit;

FIG. 1b is a schematic structural diagram of a diode neutral point clamped three-level inverter circuit;

FIG. 2 is a schematic diagram of comparison between forward on-state voltage drops of IGBTs connected in series and a high voltage IGBT;

FIG. 3 is a schematic diagram of an application scenario of a converter in a UPS power supply system according to this application;

FIG. 4 is a schematic diagram of an application scenario of a converter in a grid-connected photovoltaic power generation system according to this application;

FIG. 5 is a topological diagram of a mixed type NPC three-level inverter circuit;

FIG. 6a is a schematic structural diagram of a conversion circuit according to this application;

FIG. 6b is a schematic structural diagram of another conversion circuit according to this application;

FIG. 6c is a schematic structural diagram of still another conversion circuit according to this application;

FIG. 7 is a topological diagram of a circuit in which a direct current bus uses capacitors connected in series to virtualize a reference potential according to this application;

FIG. 8 is a topological diagram of a circuit in which a direct current bus capacitor uses a single capacitor according to this application;

FIG. 9 is a time sequence diagram of driving logic of switch devices in a conversion circuit according to this application;

FIG. 10 is a schematic structural diagram of another conversion circuit according to this application; and

FIG. 11 is a schematic structural diagram of a three-phase inverter circuit based on a conversion circuit according to this application.


DESCRIPTION OF EMBODIMENTS



[0028] To make a person skilled in the art understand the technical solutions in the embodiments of the present invention better, and make the objectives, features, and advantages of the embodiments of the present invention clearer, the following further describes the technical solutions in the embodiments of the present invention in detail with reference to the accompanying drawings.

[0029] The present invention is intended to implement high-efficiency electric energy conversion between an alternating current (alternating current, AC) and a direct current (direct current, DC). Before the technical solutions of the embodiments of the present invention are described, application scenarios of the embodiments of the present invention are first described with reference to the accompanying drawings. Common application scenarios are uninterruptible power supply (uninterrupted power supply, UPS), photovoltaic power generation, and the like. FIG. 3 is a schematic diagram of an application scenario of a converter in a UPS power supply system. In a normal case, power is directly supplied to a load through mains power, and industrial frequency alternating-current mains power can be converted to a direct current from an alternating current through an AC/DC converter, and a battery is charged through a DC/DC converter; and when a fault occurs on mains supply, a direct current in the battery is converted to an alternating current through the DC/DC converter and the DC/AC converter, to supply power to the load. FIG. 4 shows a grid-connected photovoltaic power generation system. A direct current output by a photovoltaic panel is converted to an alternating current through a DC/AC converter, so as to implement grid-connected power generation of the photovoltaic panel.

[0030] To further reduce a loss of a converter, and increase power density and product competitiveness of the converter, advantages of a two-level inverter circuit and an NPC three-level inverter circuit can be comprehensively used in an inverter, to improve converter performance.

Embodiment 1



[0031] FIG. 5 is a topological diagram of a mixed type NPC three-level inverter circuit. A switch network in a topology of the circuit includes two parts, a left half part is an NPC three-level inverter circuit, and a right half part is a two-level inverter circuit. In the topology of the circuit, a low conduction loss characteristic of a conventional two-level inverter circuit and a low switching loss characteristic of an NPC three-level inverter circuit can be comprehensively used, so as to reduce an overall loss of a converter and improve converter performance.

[0032] FIG. 6a to FIG. 6c are schematic structural diagrams of a conversion circuit according to this embodiment of the present invention. The circuit includes an input terminal, an output terminal, a control module, and a switch network formed by semiconductor switching devices. The switch network includes a first switch unit and a second switch unit.

[0033] As shown in FIG. 6b or FIG. 6c, the input terminal includes a positive direct current bus terminal and a negative direct current bus terminal, and the output terminal includes an alternating current output end; the first switch unit includes a first switch S1, a second switch S2, a third switch S3, a fourth switch S4, and a flying clamping capacitor Cc; further, the first switch S1, the second switch S2, the third switch S3, the fourth switch S4 are connected in series to form a first converter bridge arm, where two ends of the first converter bridge arm are respectively connected to the positive direct current bus terminal P and the negative direct current bus terminal N, a first end of the flying clamping capacitor Cc is connected to a series connection point SP between the first switch S1 and the second switch S2, a second end of the flying clamping capacitor Cc is connected to a series connection point SN between the third switch S3 and the fourth switch S4, and a series connection point between the second switch S2 and the third switch S3 forms an output end of the first switch unit.

[0034] Specifically, a first end of the first switch S1 is connected to the positive direct current bus terminal P; the other end of the first switch S1 is connected to one end of the second switch S2; and a junction point is SP. The other end of the second switch S2 is connected to one end of the third switch S3, and a junction point is an output end OUT of the switch network. The other end of the third switch S3 is connected to one end of the fourth switch S4, and a junction point is SN. The other end of the fourth switch S4 is connected to the negative direct current bus terminal N, and the first end of the flying clamping capacitor Cc is connected to SP and the other end of the flying clamping capacitor Cc is connected to SN. In this way, voltage clamping of the switch devices S2 and S3 is implemented. The flying clamping capacitor Cc is configured to implement voltage clamping of the switch devices S2 and S3, to avoid overvoltage damage of the foregoing devices.

[0035] The second switch unit includes a fifth switch S5 and a sixth switch S6, where the fifth switch S5 and the sixth switch S6 form a second converter bridge arm; two ends of the second converter bridge arm are respectively connected to the positive direct current bus terminal P and the negative direct current bus terminal N, and a series connection point between the fifth switch S5 and the sixth switch S6 is connected to an output end of the second switch unit.

[0036] The output end OUT of the first switch unit and the second switch unit is connected to the alternating current output end Vac.

[0037] The first switch unit and the second switch unit are connected to the control module, and perform power conversion between a direct current voltage and an alternating current voltage under control of the control module, and the switch devices are controlled by the control module according to a preset time sequence, so as to implement electric energy conversion between a direct current and an alternating current.

[0038] In the circuit provided in this embodiment, to implement voltage balancing of the switch devices in the first switch unit and optimal control of converter performance, a steady-state voltage of the flying clamping capacitor is usually controlled at 1/2 of a direct current bus voltage, that is, Vbus/2. In this case, based on driving logic, output levels of the output end OUT of the first switch unit and the second switch unit relative to a direct current bus midpoint M are +Vbus/2, 0, and -Vbus/2.

[0039] Optionally, during an actual control process, the control module may perform fine adjustment on the steady-state voltage of the flying clamping capacitor based on an actual application situation. In addition, the control module includes a control circuit, a controller, or the like. Optionally, based on a direct current input voltage Vbus, a withstand voltage value of each switch device (for example, the first switch S1 to the fourth switch S4) in the first switch unit is not smaller than Vbus/2, and a withstand voltage value of each switch device (for example, the fifth switch S5 and the sixth switch S6) in the second switch unit is not smaller than Vbus.

[0040] For a converter application in which a maximum direct current input voltage Vbus is 1 kV, optionally, a selectable withstand voltage value of each of the switch devices S1 to S4 in the first switch unit is 600 V or 650 V, and a selectable withstand voltage value of each of the fifth switch S5 and the sixth switch S6 in the second switch unit is 1200 V.

[0041] The circuit provided in this embodiment can comprehensively use a low conduction loss of a two-level inverter circuit and a low switching loss of a multilevel inverter circuit, and can significantly reduce a loss of a converter by controlling switch-on/off time sequences of the switch devices in the first switch unit and the switch devices in the first switch unit. Specifically, within a time in which both the first switch S1 and the second switch S2 are on, that is, when the output end OUT of the first switch unit and the second switch unit is connected to the positive direct current bus terminal P, the fifth switch S5 is controlled to be on for at least a period of time; and within a time in which both the third switch S3 and the fourth switch S4 are on, that is, when the output end OUT is connected to the negative direct current bus terminal N, the sixth switch S6 is controlled to be on for at least a period of time. Because an on-state voltage drop of the fifth switch S5 is lower than a voltage drop obtained after the first switch S1 and the second switch S2 are connected in series, and an on-state voltage drop of the sixth switch S6 is lower than a voltage drop obtained after the third switch S3 and the fourth switch S4 are connected in series, switch-on of the fifth switch S5 and the sixth switch S6 may cause a decrease in a conduction loss of the converter.

[0042] In addition, the control module controls a switch on/off moment of a switch device in the second switch unit to be later than or earlier than a switch on/off moment of a switch device in the first switch unit, so as to implement transient commutation in power conversion by using the first switch unit. Because S1 to S4 are low-voltage devices and have excellent switching characteristics and low switching losses, switch-on/off commutation implemented by using S1 to S4 can cause a decrease in a switching loss of the converter, and implement zero voltage switch-on and switch-off of the switch devices in the second switch unit.

[0043] Optionally, the circuit further includes a filtering module, configured to filter out a ripple in a voltage of the output end OUT of the first switch unit and the second switch unit, one end of the filtering module is connected to the output end OUT, and the other end of the filtering module is connected to the alternating current output end. The filtering module includes a filter circuit, and the filter circuit may be an inductor L.

[0044] Optionally, the fifth switch S5 and the sixth switch S6 have no switching loss. Therefore, to reduce the conduction loss of the converter, S5 and S6 may be switch devices with low conduction voltage drops in an actual application.

[0045] Optionally, switching cycles of the four switches (S1 to S4) in the first switch unit are the same, and a switching frequency of each of the four switches is a high frequency; the first switch S1 and the fourth switch S4 are complementary switches; and the second switch S2 and the third switch S3 are complementary switches. The high frequency means that a switching frequency is at a kHz (kilohertz) level, for example, several kHz, dozens of kHz, or hundreds of kHz. A value of a switching frequency of each switch is not specifically limited in this embodiment.

[0046] Further, the first switch S1 and the second switch S2 in the first switch unit are switched on/off with a phase shift of 180°, and the third switch S3 and the fourth switch S4 are switched on/off with a phase shift of 180°. In an actual application, to implement steady-state voltage control of the flying clamping capacitor, the phase shift angle between the first switch and the second switch and the phase shift angle between the third switch and the fourth switch are not strictly fixed at 180°, but fluctuate near 180°.

[0047] It should be noted that, each switch in the first switch unit and the second switch unit may be one switch, and may alternatively include a switch device formed by a plurality of switches. In this embodiment, the switches (including S1 to S6) in the switch units each include an insulated gate bipolar transistor (insulated gate bipolar transistor, IGBT) (T1 to T6) and an anti-parallel diode (D1 to D6) of the IGBT. In addition, the first switch, the second switch, the third switch, the fourth switch, the fifth switch, and the sixth switch may alternatively be metal-oxide semiconductor field-effect transistor (metal-oxide semiconductor field-effect transistor, MOSFET) devices.

[0048] As shown in FIG. 7 and FIG. 8, a topology of the circuit includes a switch network, a direct current bus capacitor, a flying clamping capacitor, an output filter inductor, and a control module. The switch network includes two switch units: a first switch unit and a second switch unit. The first switch unit includes a first switch (T1&D1), a second switch (T2&D2), a third switch (T3&D3), a fourth switch (T4&D4), and the flying clamping capacitor Cc, and the second switch unit includes a fifth switch (T5&D6) and a sixth switch (T6&D6).

[0049] In the first switch unit, the first switch, the second switch, the third switch, and the fourth switch are connected in series to form a first converter bridge arm; a first end of the first switch is connected to a positive direct current bus terminal P, the other end of the first switch is connected to the second switch, and a junction point is SP. A junction point of the second switch and the third switch forms an output end of the first switch unit, the other end of the third switch is connected to one end of the fourth switch, and a junction point is SN. The other end of the fourth switch is connected to a negative direct current bus terminal N, and a first end of the flying clamping capacitor is connected to SP and the other end of the flying clamping capacitor is connected to SN. In the second switch unit, the fifth switch and the sixth switch are connected in series to form a second converter bridge arm; a first end of the fifth switch is connected to the positive direct current bus terminal P, the other end of the fifth switch is connected to one end of the sixth switch, and a junction point is an output end of the second switch unit; and the other end of the sixth switch is connected to the negative direct current bus terminal N.

[0050] The direct current bus capacitor may be formed by connecting a capacitor C1 and a capacitor C2 in series, as shown in FIG. 7; or the direct current bus capacitor may be directly implemented by a single high-voltage capacitor C1, as shown in FIG. 8. For convenience of description, in embodiments of this application, an example in which the capacitor C1 and the capacitor C2 are connected in series to form the bus capacitor is used, and a reference potential is virtualized, that is, a voltage of a point M shown in FIG. 7.

[0051] A control method is further provided in an embodiment, and is used to control the foregoing conversion circuits shown in FIG. 6, FIG. 7, and FIG. 8.

[0052] To describe in detail the control method provided in this embodiment, FIG. 9 is a time sequence diagram of driving logic of switch devices in the conversion circuit. In a converter control process, a common technology is used for dead-time control between complementary switch tubes in a converter bridge arm, and therefore in the time sequence diagram shown in FIG. 9, a dead time between the complementary switch devices in the converter bridge arm is not considered, but only a schematic diagram of a drive waveform is shown.

[0053] As shown in FIG. 9, in the first switch unit, a switching cycle of each switch device is Tsw, and a pulse width is obtained by the control module based on input and output conditions through pulse width modulation (pulse width modulation, PWM), where the first switch T1 and the fourth switch T4 are complementary switches; the second switch T2 and the third switch T3 are complementary switches; the first switch T1 and the second switch T2 are switched on/off with a phase shift of 180°; and the third switch T3 and the fourth switch T4 are switched on/off with a phase shift of 180°. Different from the first switch unit, the fifth switch T5 and the sixth switch T6 in the second switch unit are non-complementary switches, and T5 and T6 are determined, based on a time sequence of the switch devices in the first switch unit, to switched be on or off.

[0054] In FIG. 9, Vm represents a modulation voltage obtained by the control module based on feedback quantity such as an alternating current output end voltage, an inductor current, a direct current bus voltage, and an external command. Vo represents a voltage of the output end OUT of the first switch unit and the second switch unit (or referred to as the switch network) in the circuit; and for both the foregoing voltages, a voltage of a direct current bus midpoint M as a reference potential.

[0055] In the method provided in this embodiment, the control module controls each switch device in the first switch unit to perform pulse width modulation, so that the output end of the switch network outputs a required alternating current voltage, such as a high frequency impulse voltage. Further, the control module controls each switch device in the second switch unit to cooperate in switching on or off each switch device in the first switch unit. A specific control process is as follows:
Within a time in which both the first switch and the second switch are on, that is, when the output end OUT of the switch network is connected to the positive direct current bus terminal P, the control module controls the fifth switch S5 to be on for at least a period of time; and within a time in which both the third switch and the fourth switch are on, that is, when the output end OUT of the switch network is connected to the negative direct current bus terminal N, the control module controls the sixth switch to be on for at least a period of time.

[0056] Because an on-state voltage drop of the fifth switch is lower than a voltage drop obtained after the first switch and the second switch are connected in series, an on-state voltage drop of the sixth switch is lower than a voltage drop obtained after the third switch and the fourth switch are connected in series, switch-on of the fifth switch and the sixth switch may cause a decrease in a conduction voltage drop in a current flowing loop, thereby reducing a conduction loss of a converter.

[0057] Optionally, to fully use the first switch unit to reduce a switching loss of the converter, when the output end of the switch network is connected to the positive direct current bus terminal, that is, when the output end of the switch network outputs a level Vbus/2, the control module controls the fifth switch T5 to be switched on a period of time later than the first switch T1 or the second switch T2, and the first switch T1 or the second switch T2 is used to implement switching-on commutation; and when the output end of the switch network is connected to the positive direct current bus terminal or the negative direct current bus terminal through the flying clamping capacitor, that is, when the output end OUT of the switch network outputs a level 0, the control module controls the fifth switch T5 to be switched off a period of time earlier than the first switch T1 or the second switch T2, and the first switch T1 or the second switch T2 is used to implement switching-off commutation.

[0058] Similarly, when the output end of the switch network is connected to the negative direct current bus terminal, that is, when the output end of the switch network outputs a level -Vbus/2, the control module controls the sixth switch T6 to be switched on a period of time later than the first switch T3 or the second switch T4, and the third switch T3 or the fourth switch T4 is used to implement switching-on commutation; and when the output end of the switch network is connected to the positive direct current bus terminal or the negative direct current bus terminal through the flying clamping capacitor, that is, when the output end OUT of the switch network outputs a level 0, the control module controls the sixth switch T6 to be switched off a period of time earlier than the first switch T3 or the second switch T4, and the third switch T3 or the fourth switch T4 is used to implement switching-off commutation.

[0059] In this method, because the switch devices in the first switch unit are low-voltage devices and have excellent switching characteristics and low switching losses, the low-voltage devices may be used to implement commutation, thereby reducing the switching loss of the converter.

[0060] In a specific embodiment, a switch-on/off time sequence of a switch device in the second switch unit is described by using a switch time sequence of the fifth switch T5 as an example. The control method specifically includes the following:
As shown in FIG. 9, in a positive half cycle of a modulation voltage, when the first switch T1 is off and the second switch T2 is on, when the first switch T1 is switched on at a moment t0, that is, an output voltage of the switch network jumps from a zero voltage to Vbus/2, the control module controls the fifth switch T5 to be switched on a time interval Td1 later than the moment t0. The first switch T1 has completed switching-on commutation at the moment t0, a voltage between two ends of the fifth switch is zero, and therefore zero voltage switch-on can be implemented by switching on the fifth switch T5 a time interval later, so that T5 has no switching-on loss. After T5 is switched on, because a voltage drop of T5 is lower than a voltage drop obtained after T1 and T2 are connected in series, a load current mainly flows through T5, thereby reducing the conduction loss of the converter.

[0061] When both the first switch T1 and the second switch T2 are on, when the second switch T2 is to be switched off at a moment t1, the control module controls the fifth switch T5 to be switched off a time interval Td2 earlier than the moment t1, so as to switch a load current to the first switch unit. In this way, T2 is used to implement switching-off commutation and implement zero voltage switch-off of the fifth switch T5, so that T5 has no switching-off loss. In an actual control process, the control module may calculate the switch-off moment of the second switch T2 at least one switching cycle in advance, so that a switch-off moment of T5 can be obtained based on the switch-off moment of T2 and the time interval Td2 with which switching-off is performed earlier before the switch-off moment of T2.

[0062] When the first switch is on and the second switch is off, when the second switch T2 is switched on at a moment t2, the control module controls the fifth switch T5 to be switched on a time interval Td3 later than the moment t2. In this way, T2 is used to implement switching-on commutation and implement zero voltage switch-on of the fifth switch T5, so that T5 has no switching-on loss.

[0063] When both the first switch and the second switch are on, when the first switch is to be switched off at a moment t3, the control module controls the fifth switch T5 to be switched off a time interval Td4 earlier than the moment t3. In this way, T1 is used to implement switching-off commutation and implement zero voltage switch-off of the fifth switch T5, so that T5 has no switching-off loss. In an actual control process, the control module may calculate the switch-off moment of the first switch T1 at least one switching cycle in advance, so that a switch-off moment of T5 can be obtained based on the switch-off moment of T1 and the time interval Td2 with which switching-off is performed earlier before the switch-off moment of T1.

[0064] When time sequence control described above is performed, T5 can implement zero voltage switch-on and switch-off and has no switching loss, and main switching losses occur on T1 and T2. T1 and T2 are low-voltage devices and have low switching losses, and therefore the switching loss of the converter can be reduced in the foregoing manner.

[0065] A time interval with which the fifth switch T5 is switched on later than the first switch T1 or the second switch T2 and a time interval with which the fifth switch T5 is switched off earlier than the first switch T1 or the second switch T2 may be determined on the basis of switching characteristics of the switch devices in the first switch unit and the second switch unit, such as a current rise time and a current fall time. Optionally, the time interval may be set solely by the control module. Generally, the time interval is between several nanoseconds and several microseconds. For example, the time interval is any value between 0 ns and 10 µs.

[0066] Similarly, in a negative half cycle of the modulation voltage, a switch-on/off time sequence of the sixth switch T6 is equivalent to that of the fifth switch T5, and the switch time sequence of the sixth switch T6 is determined by the third switch T3 and the fourth switch T4.

[0067] Specifically, when the third switch T3 is on and the fourth switch T4 is off, when the fourth switch T4 is switched on at a moment t5, the control module controls the sixth switch T6 to be switched on a time interval Td5 later than the switch-on moment t5 of the fourth switch T4. In this way, the fourth switch T4 is used to implement switching-on commutation and implement zero voltage switch-on of T6, so that T6 has no switching-on loss.

[0068] When both the third switch T3 and the fourth switch T4 are on, when the third switch T3 is to be switched off at a moment t6, the control module controls the sixth switch T6 to be switched off a time interval Td6 earlier than the switch-off moment t6 of the third switch T3, so as to switch a load current to the first switch unit. In this way, T3 is used to implement switching-off commutation and implement zero voltage switch-off of T6, so that T6 has no switching-off loss. When the third switch T3 is off and the fourth switch T4 is on, when the third switch T3 is switched on at a moment t7, the control module controls the sixth switch T6 to be switched on a time interval Td7 later than the switch-on moment t7 of the third switch T3. In this way, T3 is used to implement switching-on commutation and implement zero voltage switch-on of T6, so that T6 has no switching-on loss.
when both the third switch T3 and the fourth switch T4 are on, when the fourth switch T4 is to be switched off at a moment t8, the control module controls the sixth switch T6 to be switched off a time interval Td8 earlier than the switch-off moment t8 of the fourth switch T4. In this way, T4 is used to implement switching-off commutation and implement zero voltage switch-off of T6, so that T6 has no switching-off loss.

[0069] When time sequence control described above is performed, T6 can implement zero voltage switch-on and switch-off and has no switching loss, and main switching losses occur on T3 and T4. T3 and T4 are low-voltage devices and have low switching losses, and therefore the switching loss of the converter can be reduced in the foregoing manner.

[0070] It should be noted that, a difference between "switch-on" and "on" of a switch in this embodiment lies in that "switch-on" is mainly for an action performed on the switch and emphasizes a transient state of switching on the switch, and "on" mainly means a steady state of the switch and that the semiconductor switch is in a state of being in a closed circuit.

[0071] In the circuit structure and the control method provided in this embodiment, the switching loss of the converter may be reduced by using a flying capacitor three-level circuit topology in combination with low-voltage devices, and the conduction loss of the converter may be reduced by using a conventional bridge-type two-level circuit topology in combination with high-voltage devices.

[0072] Compared with a mixed type NPC three-level inverter circuit, in the circuit structure provided in this application, a flying capacitor is used to replace diodes, such as the diode D2 and the diode D3 shown in FIG. 5. This reduces a quantity of semiconductors, and simplifies a circuit structure, facilitating power module layout. In addition, because the flying capacitor is used and there are no diodes D2 and D3, a direct current bus does not need to use a large capacity capacitor for voltage division to generate a midpoint voltage. Therefore, there is no problem of midpoint voltage fluctuation, a direct current bus capacitor structure is simplified, and a bus capacitor is saved.

[0073] In addition, in the circuit control method provided in this embodiment, each switch of the first switch unit and the second switch unit is controlled to be switched on or off, so that the output end of the first switch unit and the second switch unit is alternately connected to the positive direct current bus terminal and the negative direct current bus terminal according to a preset switch-on/off time sequence, and commutation is implemented through switch-on or switch-off of the four switches in the first switch unit, and switch-on of the fifth switch and the sixth switch in the second switch unit causes a decrease in the conduction voltage drop of the current flowing loop, thereby reducing the conduction loss of the converter.

[0074] Optionally, for an application system in which a maximum direct current input voltage is 1 kV, generally, the switches T1 to T4 and the anti-parallel diodes D1 to D4 in the first switch unit each may be a switch device with a withstand voltage of 600 V or 650 V, and T5, T6, D5, and D5 in the second switch unit each may be a switch device with a withstand voltage of 1200 V. Based on conduction voltage drops and switching loss characteristics, T1 to T4 each may be a device with a low switching loss, and T5 and T6 each may be a device with a low conduction voltage drop.

Embodiment 2



[0075] In a circuit provided in this embodiment, four switch devices in a first switch unit each include an IGBT and an anti-parallel diode D. A difference from Embodiment 1 lies in that a fifth switch T5 and a sixth switch T6 in a second switch unit include only IGBTs (T5 and T6) but include no anti-parallel diode. Other devices and connection relationships are the same as those in Embodiment 1, as shown in FIG. 10.

[0076] Specifically, the circuit includes an input terminal, an output terminal, a control module, and a switch network formed by semiconductor switching devices. The switch network includes two switch units: the first switch unit and the second switch unit. The first switch unit includes a first switch (T1&D1), a second switch (T2&D2), a third switch (T3&D3), a fourth switch (T4&D4), and a flying clamping capacitor Cc, and the second switch unit includes a fifth switch (T5) and a sixth switch (T6). In the first switch unit, the first switch (T1&D1), the second switch (T2&D2), the third switch (T3&D3), and the fourth switch (T4&D4) are connected in series to form a first converter bridge arm; a first end of the first switch is connected to a positive direct current bus terminal P, the other end of the first switch is connected to the second switch, and a junction point is SP. A junction point of the second switch and the third switch forms an output end of the first switch unit, the other end of the third switch is connected to one end of the fourth switch, and a junction point is SN. The other end of the fourth switch is connected to a negative direct current bus terminal N, and a first end of the flying clamping capacitor is connected to SP and the other end of the flying clamping capacitor is connected to SN. In the second switch unit, the fifth switch and the sixth switch are connected in series to form a second converter bridge arm; a first end of the fifth switch is connected to the positive direct current bus terminal P, the other end of the fifth switch is connected to one end of the sixth switch, and a junction point is an output end of the second switch unit; and the other end of the sixth switch is connected to the negative direct current bus terminal N. A filtering module includes an inductor, located between an output end OUT of the first switch unit and the second switch unit and an alternating current voltage Vac.

[0077] The control module is connected to the first switch unit and the second switch unit, and is configured to control the first switch unit to perform pulse width modulation, so that the output end of the switch network outputs a required alternating current voltage. Further, a control process includes the following: Within a time in which both the first switch and the second switch are on, that is, when the output end of the switch network is connected to the positive direct current bus terminal, the control module controls the fifth switch to be on for at least a period of time. Within a time in which both the third switch and the fourth switch are on, that is, when the output end of the switch network is connected to the negative direct current bus terminal, the control module controls the sixth switch to be on for at least a period of time. Specifically, a process in which the control module controls the second switch unit to cooperate in switching on or off each switch in the first switch unit is the same as that in the method of the foregoing specific embodiment, and details are not repeated in this embodiment.

[0078] Compared with the circuit structure in Embodiment 1, a switch tube in the second switch unit in this embodiment includes no anti-parallel diode, and only the diodes in the first switch unit are used for freewheeling, thereby making a commutation loop structure simpler and facilitating module layout and circuit control.

Embodiment 3



[0079] FIG. 11 shows a form of a three-phase inverter circuit based on a circuit topology provided in Embodiment 1, and the circuit includes a direct current source, an alternating current source, an inverter circuit, a filtering module, and a control module.

[0080] To implement electric energy conversion between the direct current source and the alternating current source, each phase circuit is formed by the circuit provided in Embodiment 1, and energy conversion between a three-phase alternating current and a three-phase direct current can be implemented by using the control module.

[0081] Specifically, a composition structure of each phase circuit and the control method performed by the control module are the same as those in Embodiment 1, and details are not repeated in this embodiment.

[0082] It should be noted that, the conversion circuits provided in the foregoing Embodiment 1 and Embodiment 2 each are a single-phase circuit or a part of a single-phase circuit, and the circuit in Embodiment 3 is a three-phase circuit or a part of a three-phase circuit. In addition, the circuit in Embodiment 3 may alternatively be a multi-phase circuit or a constituent part of a multi-phase circuit. This is not limited in this application.

[0083] In addition, the conversion circuit in the foregoing embodiments may be a rectifying circuit, an inverter circuit, or a constituent part of a rectifying circuit or an inverter circuit.

[0084] In actual hardware implementation, this application further provides a device, where the device includes the conversion circuit in the foregoing embodiments and a control method for the circuit, and is configured to implement power conversion between a direct current voltage and an alternating current voltage.

[0085] Further, the device may be a converter, or an AC/DC converter or a DC/AC converter in FIG. 3 or FIG. 4. In addition, the conversion circuit can also be applied to another device or apparatus, and has a function of implementing power conversion between a direct current voltage and an alternating current voltage.

[0086] In the foregoing embodiments, the first switch, the second switch, the third switch, and the fourth switch each are a semiconductor switching device such as an IGBT or a MOSFET, and the IGBT includes an anti-parallel diode. The fifth switch and the sixth switch each are a semiconductor switching device such as an IGBT or a MOSFET, and the IGBT may include an anti-parallel diode, or may not include an anti-parallel diode.

[0087] In addition, the semiconductor switching device in the switch network may be a separate single-tube device, or a power module that is formed by packaging a switch device wafer, and control logic is implemented by a control chip such as a digital signal processor, a complex programmable logic device, or a digital/analog discrete integrated circuit.

[0088] The control module includes a processor. Specifically, the processor may be a central processing unit (central processing unit, CPU), a digital signal processor (digital signal processor, DSP), or another signal processing unit. The processor may further include a hardware chip. The hardware chip may be an application-specific integrated circuit (application-specific integrated circuit, ASIC), a programmable logic device (programmable logic device, PLD), or a combination thereof. The foregoing PLD may be a complex programmable logic device (complex programmable logic device, CPLD), a field-programmable gate array (field-programmable gate array, FPGA), generic array logic (generic array logic, GAL), or any combination thereof.

[0089] In a control process of an actual converter application, the control module may calculate a switch-off moment of each switch device in the first switch unit at least one switching cycle in advance, so that a corresponding switch device may be switched off in advance based on the calculated switch-off moment and a time interval with which switch-off is performed earlier before the switch-off moment.

[0090] The control module may further include a memory configured to store a control method and strategy of the conversion circuit. Further, the memory may be a magnetic disk, an optical disc, a read-only memory (read-only memory, ROM), a random access memory (random access memory, RAM), or the like.

[0091] In a specific application technology scenario, the conversion circuit and the control method provided in the foregoing embodiments of this application may be applied to a photovoltaic power generation system. Specifically, referring to FIG. 4, the photovoltaic power generation system includes a photovoltaic cell, a photovoltaic inverter, and an alternating current power grid, where the photovoltaic inverter includes an input end, an output end, and the conversion circuit provided in any one of the foregoing embodiments. Specifically, for a structure and a function of the conversion circuit, refer to the foregoing embodiments, and details are not repeated. The input end of the photovoltaic inverter is connected to the photovoltaic cell; the output end of the photovoltaic inverter is connected to the alternating current power grid; and the conversion circuit is configured to convert voltages at the input end and the output end of the photovoltaic inverter.

[0092] Optionally, the photovoltaic cell includes a photovoltaic panel, and the photovoltaic inverter may be a DC/AC rectifier or the like.

[0093] Optionally, the photovoltaic inverter may further include other auxiliary function modules, such as a monitoring module, a maximum power tracking module, a communications module, a lightning protection module, and a grid-connected module.

[0094] Optionally, the photovoltaic power generation system may further include a centralized communications unit, a centralized control unit, or other devices such as an alternating current distribution device and an isolation transformer device, and this is not limited in this application.

[0095] A person skilled in the art may clearly understand that, the technologies in the embodiments of the present invention may be implemented by software in addition to a necessary general hardware platform. Based on such an understanding, the technical solutions of the present invention essentially or the part contributing to the prior art may be implemented in a form of a software product. The software product is stored in a storage medium, such as a ROM/RAM, a magnetic disk, or an optical disc, and includes several instructions for instructing a computer device (which may be a personal computer, a server, or a network device) to perform the methods described in the embodiments or some parts of the embodiments of the present invention.

[0096] Same and similar parts between the various embodiments in this specification can be referred to each other. Especially, the foregoing Embodiment 2 and Embodiment 3 are basically similar to a method embodiment, and therefore is described briefly. For related parts, refer to descriptions in the method embodiment.

[0097] The foregoing descriptions are implementation of the present invention, but are not intended to limit the protection scope of the present invention which is defined by the appended claims.


Claims

1. A conversion circuit, wherein the circuit comprises an input terminal, an output terminal, a control module, and a first switch unit and a second switch unit that are formed by semiconductor switching devices;

the input terminal comprises a positive direct current bus terminal (P) and a negative direct current bus terminal (N), and the output terminal comprises an alternating current output end (Vac);

the first switch unit comprises a flying clamping capacitor (Cc) and a first converter bridge arm that is formed by connecting a first switch (S1), a second switch (S2), a third switch (S3), and a fourth switch (S4) in series, wherein two ends of the first converter bridge arm are respectively connected to the positive direct current bus terminal (P) and the negative direct current bus terminal (N), a first end of the flying clamping capacitor (Cc) is connected to a series connection point (SP) between the first switch (S1) and the second switch (S2), a second end of the flying clamping capacitor (Cc) is connected to a series connection point (SN) between the third switch (S3) and the fourth switch (S4), and a series connection point between the second switch (S2) and the third switch (S3) forms an output end (OUT) of the first switch unit;

the second switch unit comprises a second converter bridge arm that comprises a fifth switch (S5) and a sixth switch (S6), two ends of the second converter bridge arm are respectively connected to the positive direct current bus terminal (P) and the negative direct current bus terminal (N), and a series connection point between the fifth switch (S5) and the sixth switch (S6) is connected to an output end of the second switch unit;

the output end (OUT) of the first switch unit and the second switch unit is connected to the alternating current output end (Vac); and

the first switch unit and the second switch unit are connected to the control module, and the conversion circuit is configured to achieve switching under control of the control module, so that the conversion circuit converts between a direct current voltage and an alternating current voltage, wherein the control module is configured to implement controlling within a time in which both the first switch (S1) and the second switch (S2) are on, the fifth switch (S5) to be on for at least a period of time; and

controlling within a time in which both the third switch (S3) and the fourth switch (S4) are on, the sixth switch (S6) to be on for at least a period of time, wherein the controlling, by the control module within a time in which both the first switch (S1) and the second switch (S2) are on, the fifth switch (S5) to be on for at least a period of time comprises:

when the first switch (S1) is off and the second switch (S2) is on, when the first switch (S1) is switched on, controlling, by the control module, the fifth switch (S5) to be switched on a time interval Td1 later than a switch-on moment of the first switch (S1);

when both the first switch (S1) and the second switch (S2) are on, when the second switch (S2) is to be switched off, controlling, by the control module, the fifth switch (S5) to be switched off a time interval Td2 earlier than a switch-off moment of the second switch (S2);

when the first switch (S1) is on and the second switch (S2) is off, when the second switch (S2) is switched on, controlling, by the control module, the fifth switch (S5) to be switched on a time interval Td3 later than a switch-on moment of the second switch (S5); and

when both the first switch (S1) and the second switch (S2) are on, when the first switch (S1) is to be switched off, controlling, by the control module, the fifth switch (S5) to be switched off a time interval Td4 earlier than a switch-off moment of the first switch (S1), wherein the first switch (S1) and the fourth switch (S4) are complementary switches, the second switch (S2) and the third switch (S3) are complementary switches, the control module is configured to control each switch device in the first switch unit to perform pulse width modulation, the four switches (S1, S2, S3, S4) in the first switch unit each have a first switching cycle (TSW), the two switches (S5, S6) in the second switch unit each have a second switching cycle (TSW/2) that equals half of the first switching cycle, wherein the fifth switch (S5) is only switched during a positive half cycle, and the sixth switch (S6) is only switched during a negative half cycle.


 
2. The circuit according to claim 1, wherein the circuit further comprises a filtering module; and
one end of the filtering module is connected to the output end (OUT) of the first switch unit and the second switch unit, and the other end of the filtering module is connected to the alternating current output end (Vac).
 
3. The circuit according to claim 1, wherein
the first switch (S1), the second switch (S2), the third switch (S3), the fourth switch (S4), the fifth switch (S5), and the sixth switch (S6) each comprise an IGBT (T1-T6) or a MOSFET device, and the IGBT (T1-T6) comprises an anti-parallel diode (D1-D6).
 
4. The circuit according to claim 1, wherein
the first switch (S1), the second switch (S2), the third switch (S3), and the fourth switch (S4) each comprise an IGBT (T1-T4) and an anti-parallel diode (D1-D4), and the fifth switch (S5) and the sixth switch (S6) each comprise an IGBT (T5-T6).
 
5. The circuit according to any one of claims 1 to 4, wherein the circuit is a part of a single-phase circuit, a three-phase circuit, or a multiphase circuit.
 
6. A rectifying circuit or an inverter circuit comprising a circuit according to any one of claims 1 to 4.
 
7. A control method, used to control a conversion circuit, wherein

the conversion circuit comprises an input terminal, an output terminal, a control module, and a first switch unit and a second switch unit that are formed by semiconductor switching devices;

the input terminal comprises a positive direct current bus terminal (P) and a negative direct current bus terminal (N), and the output terminal comprises an alternating current output end (Vac);

the first switch unit comprises a flying clamping capacitor (Cc) and a first converter bridge arm that is formed by connecting a first switch (S1), a second switch (S2), a third switch (S3), and a fourth switch (S4) in series, wherein two ends of the first converter bridge arm are respectively connected to the positive direct current bus terminal (P) and the negative direct current bus terminal (N), a first end of the flying clamping capacitor (Cc) is connected to a series connection point (SP) between the first switch (S1) and the second switch (S2), a second end of the flying clamping capacitor (Cc) is connected to a series connection point (SN) between the third switch (S3) and the fourth switch (S4), and a series connection point between the second switch (S2) and the third switch (S3) forms an output end (OUT) of the first switch unit;

the second switch unit comprises a second converter bridge arm that comprises a fifth switch (S5) and a sixth switch (S6), two ends of the second converter bridge arm are respectively connected to the positive direct current bus terminal (P) and the negative direct current bus terminal (N), and a series connection point between the fifth switch (S5) and the sixth switch (S6) is connected to an output end of the second switch unit;

an output end (OUT) of the first switch unit and the second switch unit is connected to the alternating current output end (Vac); and

the first switch unit and the second switch unit are connected to the control module, and

the conversion circuit is configured to achieve switching under control of the control module, so that the conversion circuit converts between a direct current voltage and an alternating current voltage;

the circuit control method comprises:

controlling, by the control module within a time in which both the first switch (S1) and the second switch (S2) are on, the fifth switch (S5) to be on for at least a period of time; and

controlling, by the control module within a time in which both the third switch (S3) and the fourth switch (S4) are on, the sixth switch (S6) to be on for at least a period of time, wherein the controlling, by the control module within a time in which both the first switch (S1) and the second switch (S2) are on, the fifth switch (S5) to be on for at least a period of time comprises:

when the first switch (S1) is off and the second switch (S2) is on, when the first switch (S1) is switched on, controlling, by the control module, the fifth switch (S5) to be switched on a time interval Td1 later than a switch-on moment of the first switch (S1);

when both the first switch (S1) and the second switch (S2) are on, when the second switch (S2) is to be switched off, controlling, by the control module, the fifth switch (S5) to be switched off a time interval Td2 earlier than a switch-off moment of the second switch (S2);

when the first switch (S1) is on and the second switch (S2) is off, when the second switch (S2) is switched on, controlling, by the control module, the fifth switch (S5) to be switched on a time interval Td3 later than a switch-on moment of the second switch (S5); and

when both the first switch (S1) and the second switch (S2) are on, when the first switch (S1) is to be switched off, controlling, by the control module, the fifth switch (S5) to be switched off a time interval Td4 earlier than a switch-off moment of the first switch (S1), wherein the first switch (S1) and the fourth switch (S4) are complementary switches, the second switch (S2) and the third switch (S3) are complementary switches, the control module is configured to control each switch device in the first switch unit to perform pulse width modulation, the four switches (S1, S2, S3, S4) in the first switch unit each have a first switching cycle (TSW), the two switches (S5, S6) in the second switch unit each have a second switching cycle (TSW/2) that equals half of the first switching cycle, wherein the fifth switch (S5) is only switched during a positive half cycle, and the sixth switch (S6) is only switched during a negative half cycle.


 
8. The method according to claim 7, wherein
a switching frequency of each of the four switches (S1-S4) in the first switch unit is a high frequency.
 
9. The method according to any one of claims 7 to 8, wherein the method further comprises:
determining, by the control module, the time intervals based on switching characteristics of the switch devices in the first switch unit and the second switch unit, wherein the time interval is between 0 ns and 10 µs.
 
10. The method according to any one of claims7 to 8, wherein the method further comprises:
setting, by the control module, the time intervals solely.
 
11. The method according to any one of claims 7 to 10, wherein the circuit further comprises a filtering module; one end of the filtering module is connected to the output end of the first switch unit and the second switch unit, and the other end of the filtering module is connected to the alternating current output end (Vac); and
the filtering module is configured to filter out a ripple of a voltage of the output end (OUT) of the first switch unit and the second switch unit.
 
12. A power supply device, wherein the power supply device comprises the conversion circuit according to any one of claims 1 to 6, and is configured to implement power conversion between a direct current voltage and an alternating current voltage.
 
13. A photovoltaic power generation system, wherein the system comprises a photovoltaic cell, a photovoltaic inverter, and an alternating current power grid;

the photovoltaic inverter comprises an input end, an output end, and a conversion circuit according to any one of claims 1 to 6;

the input end of the photovoltaic inverter is connected to the photovoltaic cell, and the output end of the photovoltaic inverter is connected to the alternating current power grid; and

the conversion circuit is configured to convert voltages at the input end and the output end of the photovoltaic inverter.


 


Ansprüche

1. Wandlungsschaltung, wobei die Schaltung einen Eingangsanschluss, einen Ausgangsanschluss, ein Steuermodul und eine erste Schaltereinheit und eine zweite Schaltereinheit, die durch Halbleiterschaltvorrichtungen gebildet sind, umfasst;

wobei der Eingangsanschluss einen positiven Gleichstrom-Sammelleitungsanschluss (P) und einen negativen Gleichstrom-Sammelleitungsanschluss (N) umfasst, und der Ausgangsanschluss ein Wechselstrom-Ausgangsende (Vac) umfasst;

wobei die erste Schaltereinheit einen fliegenden Klemmkondensator (Cc) und einen ersten Wandlerbrückenarm, der durch Verbinden eines ersten Schalters (S1), eines zweiten Schalters (S2), eines dritten Schalters (S3) und eines vierten Schalters (S4) in Serie gebildet wird, umfasst, wobei zwei Enden des ersten Wandlerbrückenarms jeweils mit dem positiven Gleichstrom-Sammelleitungsanschluss (P) und dem negativen Gleichstrom-Sammelleitungsanschluss (N) verbunden sind, ein erstes Ende des fliegenden Klemmkondensators (Cc) mit einem Serienverbindungspunkt (SP) zwischen dem ersten Schalter (S1) und dem zweiten Schalter (S2) verbunden ist, ein zweites Ende des fliegenden Klemmkondensators (Cc) mit einem Serienverbindungspunkt (SN) zwischen dem dritten Schalter (S3) und dem vierten Schalter (S4) verbunden ist, und ein Serienverbindungspunkt zwischen dem zweiten Schalter (S2) und dem dritten Schalter (S3) ein Ausgangsende (OUT) der ersten Schaltereinheit bildet;

wobei die zweite Schaltereinheit einen zweiten Wandlerbrückenarm, der einen fünften Schalter (S5) und einen sechsten Schalter (S6) umfasst, umfasst, wobei zwei Enden des zweiten Wandlerbrückenarms jeweils mit dem positiven Gleichstrom-Sammelleitungsanschluss (P) und dem negativen Gleichstrom-Sammelleitungsanschluss (N) verbunden sind, und ein Serienverbindungspunkt zwischen dem fünften Schalter (S5) und dem sechsten Schalter (S6) mit einem Ausgangsende der zweiten Schaltereinheit verbunden ist;

wobei das Ausgangsende (OUT) der ersten Schaltereinheit und der zweiten Schaltereinheit mit dem Wechselstrom-Ausgangsende (Vac) verbunden ist; und

die erste Schaltereinheit und die zweite Schaltereinheit mit dem Steuermodul verbunden sind, und die Wandlungsschaltung ausgelegt ist zum Erreichen von Schalten unter der Steuerung des Steuermoduls, so dass die Wandlungsschaltung zwischen einer Gleichstrom-Spannung und einer Wechselstrom-Spannung wandelt, wobei das Steuermodul ausgelegt ist zum Implementieren von Steuern innerhalb eines Zeitraums, in dem sowohl der erste Schalter (S1) als auch der zweite Schalter (S2) eingeschaltet sind, des fünften Schalters (S5), für zumindest eine Zeitspanne eingeschaltet zu sein; und

Steuern innerhalb eines Zeitraums, in dem sowohl der dritte Schalter (S3) als auch der vierte Schalter (S4) eingeschaltet sind, des sechsten Schalters (S6), für zumindest eine Zeitspanne eingeschaltet zu sein, wobei das Steuern, durch das Steuermodul innerhalb eines Zeitraums, in dem sowohl der erste Schalter (S1) als auch der zweite Schalter (S2) eingeschaltet sind, des fünften Schalters (S5), für zumindest eine Zeitspanne eingeschaltet zu sein, Folgendes umfasst:

wenn der erste Schalter (S1) ausgeschaltet ist und der zweite Schalter (S2) eingeschaltet ist, wenn der erste Schalter (S1) eingeschaltet wird, Steuern, durch das Steuermodul, des fünften Schalters (S5), in einem Zeitintervall Td1 später als ein Einschaltzeitpunkt des ersten Schalters (S1) eingeschaltet zu sein;

wenn sowohl der erste Schalter (S1) als auch der zweite Schalter (S2) eingeschaltet sind, wenn der zweite Schalter (S2) ausgeschaltet werden soll, Steuern, durch das Steuermodul, des fünften Schalters (S5), in einem Zeitintervall Td2 früher als ein Ausschaltzeitpunkt des zweiten Schalters (S2) ausgeschaltet zu sein;

wenn der erste Schalter (S1) eingeschaltet ist und der zweite Schalter (S2) ausgeschaltet ist, wenn der zweite Schalter (S2) eingeschaltet wird, Steuern, durch das Steuermodul, des fünften Schalters (S5), in einem Zeitintervall Td3 später als ein Einschaltzeitpunkt des zweiten Schalters (S5) eingeschaltet zu sein; und

wenn sowohl der erste Schalter (S1) als auch der zweite Schalter (S2) eingeschaltet sind, wenn der erste Schalter (S1) ausgeschaltet werden soll, Steuern, durch das Steuermodul, des fünften Schalters (S5), in einem Zeitintervall Td4 früher als ein Ausschaltzeitpunkt des ersten Schalters (S1) ausgeschaltet zu sein, wobei der erste Schalter (S1) und der vierte Schalter (S4) komplementäre Schalter sind, der zweite Schalter (S2) und der dritte Schalter (S3) komplementäre Schalter sind, das Steuermodul ausgelegt ist zum Steuern von jeder Schaltervorrichtung in der ersten Schaltereinheit, eine Pulsweitenmodulation durchzuführen, die vier Schalter (S1, S2, S3, S4) in der ersten Schaltereinheit jeweils einen ersten Schaltzyklus (TSW) aufweisen, die zwei Schalter (S5, S6) in der zweiten Schaltereinheit jeweils einen zweiten Schaltzyklus (TSW/2) aufweisen, der gleich der Hälfte des ersten Schaltzyklus ist, wobei der fünfte Schalter (S5) nur während eines positiven Halbzyklus geschaltet wird und der sechste Schalter (S6) nur während eines negativen Halbzyklus geschaltet wird.


 
2. Schaltung nach Anspruch 1, wobei die Schaltung ferner ein Filterungsmodul umfasst; und
ein Ende des Filterungsmoduls mit dem Ausgangsende (OUT) der ersten Schaltereinheit und der zweiten Schaltereinheit verbunden ist, und das andere Ende des Filterungsmoduls mit dem Wechselstrom-Ausgangsende (Vac) verbunden ist.
 
3. Schaltung nach Anspruch 1, wobei
der erste Schalter (S1), der zweite Schalter (S2), der dritte Schalter (S3), der vierte Schalter (S4), der fünfte Schalter (S5) und der sechste Schalter (S6) jeweils einen IGBT (T1-T6) oder eine MOSFET-Vorrichtung umfassen und der IGBT (T1-T6) eine Antiparalleldiode (D1-D6) aufweist.
 
4. Schaltung nach Anspruch 1, wobei
der erste Schalter (S1), der zweite Schalter (S2), der dritte Schalter (S3) und der vierte Schalter (S4) jeweils einen IGBT (T1-T4) und eine Antiparalleldiode (D1-D4) umfassen, und der fünfte Schalter (S5) und der sechste Schalter (S6) jeweils einen IGBT (T5-T6) umfassen.
 
5. Schaltung nach einem der Ansprüche 1 bis 4, wobei die Schaltung ein Teil einer Einphasenschaltung, einer Dreiphasenschaltung oder einer Mehrphasenschaltung ist.
 
6. Gleichrichtende Schaltung oder Wechselrichterschaltung, die eine Schaltung nach einem der Ansprüche 1 bis 4 umfasst.
 
7. Steuerverfahren, verwendet zum Steuern einer Wandlungsschaltung, wobei

die Wandlungsschaltung einen Eingangsanschluss, einen Ausgangsanschluss, ein Steuermodul und eine erste Schaltereinheit und eine zweite Schaltereinheit, die durch Halbleiterschaltvorrichtungen gebildet sind, umfasst;

wobei der Eingangsanschluss einen positiven Gleichstrom-Sammelleitungsanschluss (P) und einen negativen Gleichstrom-Sammelleitungsanschluss (N) umfasst, und der Ausgangsanschluss ein Wechselstrom-Ausgangsende (Vac) umfasst;

wobei die erste Schaltereinheit einen fliegenden Klemmkondensator (Cc) und einen ersten Wandlerbrückenarm, der durch Verbinden eines ersten Schalters (S1), eines zweiten Schalters (S2), eines dritten Schalters (S3) und eines vierten Schalters (S4) in Serie gebildet wird, umfasst, wobei zwei Enden des ersten Wandlerbrückenarms jeweils mit dem positiven Gleichstrom-Sammelleitungsanschluss (P) und dem negativen Gleichstrom-Sammelleitungsanschluss (N) verbunden sind, ein erstes Ende des fliegenden Klemmkondensators (Cc) mit einem Serienverbindungspunkt (SP) zwischen dem ersten Schalter (S1) und dem zweiten Schalter (S2) verbunden ist, ein zweites Ende des fliegenden Klemmkondensators (Cc) mit einem Serienverbindungspunkt (SN) zwischen dem dritten Schalter (S3) und dem vierten Schalter (S4) verbunden ist, und ein Serienverbindungspunkt zwischen dem zweiten Schalter (S2) und dem dritten Schalter (S3) ein Ausgangsende (OUT) der ersten Schaltereinheit bildet;

wobei die zweite Schaltereinheit einen zweiten Wandlerbrückenarm, der einen fünften Schalter (S5) und einen sechsten Schalter (S6) umfasst, umfasst, wobei zwei Enden des zweiten Wandlerbrückenarms jeweils mit dem positiven Gleichstrom-Sammelleitungsanschluss (P) und dem negativen Gleichstrom-Sammelleitungsanschluss (N) verbunden sind, und ein Serienverbindungspunkt zwischen dem fünften Schalter (S5) und dem sechsten Schalter (S6) mit einem Ausgangsende der zweiten Schaltereinheit verbunden ist;

wobei ein Ausgangsende (OUT) der ersten Schaltereinheit und der zweiten Schaltereinheit mit dem Wechselstrom-Ausgangsende (Vac) verbunden ist; und

die erste Schaltereinheit und die zweite Schaltereinheit mit dem Steuermodul verbunden sind, und

die Wandlungsschaltung ausgelegt ist zum Erreichen von Schalten unter der Steuerung des Steuermoduls, so dass die Wandlungsschaltung zwischen einer Gleichstrom-Spannung und einer Wechselstrom-Spannung wandelt;

wobei das Schaltungssteuerverfahren Folgendes umfasst:

Steuern, durch das Steuermodul, innerhalb eines Zeitraums, in dem sowohl der erste Schalter (S1) als auch der zweite Schalter (S2) eingeschaltet sind, des fünften Schalters (S5), für zumindest eine Zeitspanne eingeschaltet zu sein; und

Steuern, durch das Steuermodul, innerhalb eines Zeitraums, in dem sowohl der dritte Schalter (S3) als auch der vierte Schalter (S4) eingeschaltet sind, des sechsten Schalters (S6), für zumindest eine Zeitspanne eingeschaltet zu sein, wobei das Steuern, durch das Steuermodul, innerhalb eines Zeitraums, in dem sowohl der erste Schalter (S1) als auch der zweite Schalter (S2) eingeschaltet sind, des fünften Schalters (S5), für zumindest eine Zeitspanne eingeschaltet zu sein, Folgendes umfasst:

wenn der erste Schalter (S1) ausgeschaltet ist und der zweite Schalter (S2) eingeschaltet ist, wenn der erste Schalter (S1) eingeschaltet wird, Steuern, durch das Steuermodul, des fünften Schalters (S5), in einem Zeitintervall Td1 später als ein Einschaltzeitpunkt des ersten Schalters (S1) eingeschaltet zu sein;

wenn sowohl der erste Schalter (S1) als auch der zweite Schalter (S2) eingeschaltet sind, wenn der zweite Schalter (S2) ausgeschaltet werden soll, Steuern, durch das Steuermodul, des fünften Schalters (S5), in einem Zeitintervall Td2 früher als ein Ausschaltzeitpunkt des zweiten Schalters (S2) ausgeschaltet zu sein;

wenn der erste Schalter (S1) eingeschaltet ist und der zweite Schalter (S2) ausgeschaltet ist, wenn der zweite Schalter (S2) eingeschaltet wird, Steuern, durch das Steuermodul, des fünften Schalters (S5), in einem Zeitintervall Td3 später als ein Einschaltzeitpunkt des zweiten Schalters (S5) eingeschaltet zu sein; und

wenn sowohl der erste Schalter (S1) als auch der zweite Schalter (S2) eingeschaltet sind, wenn der erste Schalter (S1) ausgeschaltet werden soll, Steuern, durch das Steuermodul, des fünften Schalters (S5), in einem Zeitintervall Td4 früher als ein Ausschaltzeitpunkt des ersten Schalters (S1) ausgeschaltet zu sein, wobei der erste Schalter (S1) und der vierte Schalter (S4) komplementäre Schalter sind, der zweite Schalter (S2) und der dritte Schalter (S3) komplementäre Schalter sind, das Steuermodul ausgelegt ist zum Steuern von jeder Schaltervorrichtung in der ersten Schaltereinheit, eine Pulsweitenmodulation durchzuführen, die vier Schalter (S1, S2, S3, S4) in der ersten Schaltereinheit jeweils einen ersten Schaltzyklus (TSW) aufweisen, die zwei Schalter (S5, S6) in der zweiten Schaltereinheit jeweils einen zweiten Schaltzyklus (TSW/2) aufweisen, der gleich der Hälfte des ersten Schaltzyklus ist, wobei der fünfte Schalter (S5) nur während eines positiven Halbzyklus geschaltet wird und der sechste Schalter (S6) nur während eines negativen Halbzyklus geschaltet wird.


 
8. Verfahren nach Anspruch 7, wobei
eine Schaltfrequenz von jedem der vier Schalter (S1-S4) in der ersten Schaltereinheit eine Hochfrequenz ist.
 
9. Verfahren nach einem der Ansprüche 7 bis 8,
wobei das Verfahren ferner Folgendes umfasst:
Bestimmen, durch das Steuermodul, der Zeitintervalle auf der Grundlage von Schaltcharakteristika der Schaltervorrichtungen in der ersten Schaltereinheit und der zweiten Schaltereinheit, wobei die Zeitintervalle zwischen 0 ns und 10 µs liegen.
 
10. Verfahren nach einem der Ansprüche 7 bis 8,
wobei das Verfahren ferner Folgendes umfasst:
ausschließliches Einstellen, durch das Steuermodul, der Zeitintervalle.
 
11. Verfahren nach einem der Ansprüche 7 bis 10,

wobei die Schaltung ferner ein Filterungsmodul umfasst; ein Ende des Filterungsmoduls mit dem Ausgangsende der ersten Schaltereinheit und der zweiten Schaltereinheit verbunden ist, und das andere Ende des Filterungsmoduls mit dem Wechselstrom-Ausgangsende (Vac) verbunden ist; und

das Filterungsmodul ausgelegt ist zum Ausfiltern einer Welligkeit einer Spannung des Ausgangsendes (OUT) der ersten Schaltereinheit und der zweiten Schaltereinheit.


 
12. Stromversorgungsvorrichtung, wobei die Stromversorgungsvorrichtung die Wandlungsschaltung nach einem der Ansprüche 1 bis 6 umfasst und ausgelegt ist zum Implementieren von Leistungswandlung zwischen einer Gleichstrom-Spannung und einer Wechselstrom-Spannung.
 
13. Photovoltaisches Leistungserzeugungssystem, wobei das System eine photovoltaische Zelle, einen photovoltaischen Wechselrichter und ein Wechselstromstromnetz umfasst;

wobei der photovoltaische Wechselrichter ein Eingangsende, ein Ausgangsende und eine Wandlungsschaltung nach einem der Ansprüche 1 bis 6 umfasst;

wobei das Eingangsende des photovoltaischen Wechselrichters mit der photovoltaischen Zelle verbunden ist, und das Ausgangsende des photovoltaischen Wechselrichters mit dem Wechselstromstromnetz verbunden ist; und

wobei die Wandlungsschaltung ausgelegt ist zum Wandeln von Spannungen an dem Eingangsende und dem Ausgangsende des photovoltaischen Wechselrichters.


 


Revendications

1. Circuit de conversion, dans lequel le circuit comprend une borne d'entrée, une borne de sortie, un module de commande, et une première unité de commutation et une deuxième unité de commutation qui sont formées par des dispositifs de commutation à semi-conducteurs ;

la borne d'entrée comprend une borne de bus de courant continu positive (P) et une borne de bus de courant continu négative (N), et la borne de sortie comprend une extrémité de sortie de courant alternatif (Vac) ;

la première unité de commutation comprend un condensateur de blocage volant (Cc) et une première branche de pont de convertisseur qui est formée en connectant un premier commutateur (S1), un deuxième commutateur (S2), un troisième commutateur (S3) et un quatrième commutateur (S4) en série, dans lequel deux extrémités de la première branche de pont de convertisseur sont respectivement connectées à la borne de bus de courant continu positive (P) et à la borne de bus de courant continu négative (N), une première extrémité du condensateur de blocage volant (Cc) est connectée à un point de connexion en série (SP) entre le premier commutateur (S1) et le deuxième commutateur (S2), une deuxième extrémité du condensateur de blocage volant (Cc) est connectée à un point de connexion en série (SN) entre le troisième commutateur (S3) et le quatrième commutateur (S4), et un point de connexion en série entre le deuxième commutateur (S2) et le troisième commutateur (S3) forme une extrémité de sortie (OUT) de la première unité de commutation ;

la deuxième unité de commutation comprend une deuxième branche de pont de convertisseur qui comprend un cinquième commutateur (S5) et un sixième commutateur (S6), deux extrémités de la deuxième branche de pont de convertisseur sont respectivement connectées à la borne de bus de courant continu positive (P) et à la borne de bus de courant continu négative (N), et un point de connexion en série entre le cinquième commutateur (S5) et le sixième commutateur (S6) est connecté à une extrémité de sortie de la deuxième unité de commutation ;

l'extrémité de sortie (OUT) de la première unité de commutation et de la deuxième unité de commutation est connectée à l'extrémité de sortie de courant alternatif (Vac) ; et

la première unité de commutation et la deuxième unité de commutation sont connectées au module de commande, et le circuit de conversion est configuré pour réaliser la commutation sous la commande du module de commande, de sorte que le circuit de conversion effectue une conversion entre une tension de courant continu et une tension de courant alternatif, dans lequel le module de commande est configuré pour mettre en œuvre la commande, pendant un temps au cours duquel à la fois le premier commutateur (S1) et le deuxième commutateur (S2) sont en fonction, le cinquième commutateur (S5) pour qu'il soit en fonction pendant au moins une période de temps ; et

la commande, pendant un temps au cours duquel à la fois le troisième commutateur (S3) et le quatrième commutateur (S4) sont en fonction, le sixième commutateur (S6) pour qu'il soit en fonction pendant au moins une période de temps, dans lequel la commande, par le module de commande pendant un temps au cours duquel à la fois le premier commutateur (S1) et le deuxième commutateur (S2) sont en fonction, du cinquième commutateur (S5) pour qu'il soit en fonction pendant au moins une période de temps comprend de :

lorsque le premier commutateur (S1) est hors fonction et que le deuxième commutateur (S2) est en fonction, lorsque le premier commutateur (S1) est mis en fonction, commander, par le module de commande, le cinquième commutateur (S5) pour qu'il soit mis en fonction un intervalle de temps Td1 après un moment de mise en fonction du premier commutateur (S1) ;

lorsque le premier commutateur (S1) et le deuxième commutateur (S2) sont tous deux en fonction, lorsque le deuxième commutateur (S2) doit être mis hors fonction, commander, par le module de commande, le cinquième commutateur (S5) pour qu'il soit mis hors fonction un intervalle de temps Td2 avant un moment de mise hors fonction du deuxième commutateur (S2) ;

lorsque le premier commutateur (S1) est en fonction et que le deuxième commutateur (S2) est hors fonction, lorsque le deuxième commutateur (S2) est mis en fonction, commander, par le module de commande, le cinquième commutateur (S5) pour qu'il soit mis en fonction un intervalle de temps Td3 après un moment de mise en fonction du deuxième commutateur (S2) ; et

lorsque le premier commutateur (S1) et le deuxième commutateur (S2) sont tous deux en fonction, lorsque le premier commutateur (S1) doit être mis hors fonction, commander, par le module de commande, le cinquième commutateur (S5) pour qu'il soit mis hors fonction un intervalle de temps Td4 avant un moment de mise hors fonction du premier commutateur (S1),

dans lequel le premier commutateur (S1) et le quatrième commutateur (S4) sont des commutateurs complémentaires, le deuxième commutateur (S2) et le troisième commutateur (S3) sont des commutateurs complémentaires, le module de commande est configuré pour commander chaque dispositif de commutation dans la première unité de commutation pour effectuer une modulation d'impulsions en durée, les quatre commutateurs (S1, S2, S3, S4) dans la première unité de commutation ont chacun un premier cycle de commutation (TSW), les deux commutateurs (S5, S6) dans la deuxième unité de commutation ont chacun un deuxième cycle de commutation (Tsw/2) qui est égal à la moitié du premier cycle de commutation, dans lequel le cinquième commutateur (S5) est seulement commuté pendant un demi-cycle positif, et le sixième commutateur (S6) est seulement commuté pendant un demi-cycle négatif.


 
2. Circuit selon la revendication 1, dans lequel le circuit comprend en outre un module de filtrage ; et
une extrémité du module de filtrage est connectée à l'extrémité de sortie (OUT) de la première unité de commutation et de la deuxième unité de commutation, et l'autre extrémité du module de filtrage est connectée à l'extrémité de sortie de courant alternatif (Vac).
 
3. Circuit selon la revendication 1, dans lequel
le premier commutateur (S1), le deuxième commutateur (S2), le troisième commutateur (S3), le quatrième commutateur (S4), le cinquième commutateur (SS) et le sixième commutateur (S6) comprennent chacun un IGBT (T1-T6) ou un dispositif MOSFET, et l'IGBT (T1-T6) comprend une diode antiparallèle (D1-D6).
 
4. Circuit selon la revendication 1, dans lequel
le premier commutateur (S1), le deuxième commutateur (S2), le troisième commutateur (S3) et le quatrième commutateur (S4) comprennent chacun un IGBT (T1-T4) et une diode antiparallèle (D1-D4), et le cinquième commutateur (S5) et le sixième commutateur (S6) comprennent chacun un IGBT (T5-T6).
 
5. Circuit selon l'une quelconque des revendications 1 à 4, dans lequel le circuit est une partie d'un circuit monophasé, d'un circuit triphasé, ou d'un circuit polyphasé.
 
6. Circuit redresseur ou circuit inverseur comprenant un circuit selon l'une quelconque des revendications 1 à 4.
 
7. Procédé de commande, utilisé pour commander un circuit de conversion, dans lequel

le circuit de conversion comprend une borne d'entrée, une borne de sortie, un module de commande, et une première unité de commutation et une deuxième unité de commutation qui sont formées par des dispositifs de commutation à semi-conducteurs ;

la borne d'entrée comprend une borne de bus de courant continu positive (P) et une borne de bus de courant continu négative (N), et la borne de sortie comprend une extrémité de sortie de courant alternatif (Vac) ;

la première unité de commutation comprend un condensateur de blocage volant (Cc) et une première branche de pont de convertisseur qui est formée en connectant un premier commutateur (S1), un deuxième commutateur (S2), un troisième commutateur (S3) et un quatrième commutateur (S4) en série, dans lequel deux extrémités de la première branche de pont de convertisseur sont respectivement connectées à la borne de bus de courant continu positive (P) et à la borne de bus de courant continu négative (N), une première extrémité du condensateur de blocage volant (Cc) est connectée à un point de connexion en série (SP) entre le premier commutateur (S1) et le deuxième commutateur (S2), une deuxième extrémité du condensateur de blocage volant (Cc) est connectée à un point de connexion en série (SN) entre le troisième commutateur (S3) et le quatrième commutateur (S4), et un point de connexion en série entre le deuxième commutateur (S2) et le troisième commutateur (S3) forme une extrémité de sortie (OUT) de la première unité de commutation ;

la deuxième unité de commutation comprend une deuxième branche de pont de convertisseur qui comprend un cinquième commutateur (S5) et un sixième commutateur (S6), deux extrémités de la deuxième branche de pont de convertisseur sont respectivement connectées à la borne de bus de courant continu positive (P) et à la borne de bus de courant continu négative (N), et un point de connexion en série entre le cinquième commutateur (S5) et le sixième commutateur (S6) est connecté à une extrémité de sortie de la deuxième unité de commutation ;

une extrémité de sortie (OUT) de la première unité de commutation et de la deuxième unité de commutation est connectée à l'extrémité de sortie de courant alternatif (Vac) ; et

la première unité de commutation et la deuxième unité de commutation sont connectées au module de commande, et le circuit de conversion est configuré pour réaliser une commutation sous la commande du module de commande, de sorte que le circuit de conversion effectue une conversion entre une tension de courant continu et une tension de courant alternatif ;

le procédé de commande de circuit comprend de :
commander, par le module de commande pendant un temps au cours duquel à la fois le premier commutateur (S1) et le deuxième commutateur (S2) sont en fonction, le cinquième commutateur (S5) pour qu'il soit en fonction pendant au moins une période de temps ; et commander, par le module de commande pendant un temps au cours duquel à la fois le troisième commutateur (S3) et le quatrième commutateur (S4) sont en fonction, le sixième commutateur (S6) pour qu'il soit en fonction pendant au moins une période de temps, dans lequel la commande, par le module de commande pendant un temps au cours duquel à la fois le premier commutateur (S1) et le deuxième commutateur (S2) sont en fonction, du cinquième commutateur (S5) pour qu'il soit en fonction pendant au moins une période de temps comprend de :

lorsque le premier commutateur (S1) est hors fonction et que le deuxième commutateur (S2) est en fonction, lorsque le premier commutateur (S1) est mis en fonction, commander, par le module de commande, le cinquième commutateur (S5) pour qu'il soit mis en fonction un intervalle de temps Td1 après un moment de mise en fonction du premier commutateur (S1) ;

lorsque le premier commutateur (S1) et le deuxième commutateur (S2) sont tous deux en fonction, lorsque le deuxième commutateur (S2) doit être mis hors fonction, commander, par le module de commande, le cinquième commutateur (S5) pour qu'il soit mis hors fonction un intervalle de temps Td2 avant un moment de mise hors fonction du deuxième commutateur (S2) ;

lorsque le premier commutateur (S1) est en fonction et que le deuxième commutateur (S2) est hors fonction, lorsque le deuxième commutateur (S2) est mis en fonction, commander, par le module de commande, le cinquième commutateur (S5) pour qu'il soit mis en fonction un intervalle de temps Td3 après un moment de mise en fonction du deuxième commutateur (S2) ; et

lorsque le premier commutateur (S1) et le deuxième commutateur (S2) sont tous deux en fonction, lorsque le premier commutateur (S1) doit être mis hors fonction, commander, par le module de commande, le cinquième commutateur (S5) pour qu'il soit mis hors fonction un intervalle de temps Td4 avant un moment de mise hors fonction du premier commutateur (S1),

dans lequel le premier commutateur (S1) et le quatrième commutateur (S4) sont des commutateurs complémentaires, le deuxième commutateur (S2) et le troisième commutateur (S3) sont des commutateurs complémentaires, le module de commande est configuré pour commander chaque dispositif de commutation dans la première unité de commutation pour effectuer une modulation d'impulsions en durée, les quatre commutateurs (S1, S2, S3, S4) dans la première unité de commutation ont chacun un premier cycle de commutation (TSW), les deux commutateurs (S5, S6) dans la deuxième unité de commutation ont chacun un deuxième cycle de commutation (Tsw/2) qui est égal à la moitié du premier cycle de commutation, dans lequel le cinquième commutateur (S5) est seulement commuté pendant un demi-cycle positif, et le sixième commutateur (S6) est seulement commuté pendant un demi-cycle négatif.


 
8. Procédé selon la revendication 7, dans lequel
une fréquence de commutation de chacun des quatre commutateurs (S1-54) dans la première unité de commutation est une fréquence élevée.
 
9. Procédé selon l'une des revendications 7 à 8,
dans lequel le procédé comprend en outre de :
déterminer, par le module de commande, les intervalles de temps sur la base de caractéristiques de commutation des dispositifs de commutation dans la première unité de commutation et la deuxième unité de commutation, dans lequel l'intervalle de temps est compris entre 0 ns et 10 µs.
 
10. Procédé selon l'une des revendications 7 à 8,
dans lequel le procédé comprend en outre de :
régler, par le module de commande, les intervalles de temps seuls.
 
11. Procédé selon l'une des revendications 7 à 10,

dans lequel le circuit comprend en outre un module de filtrage ; une extrémité du module de filtrage est connectée à l'extrémité de sortie de la première unité de commutation et de la deuxième unité de commutation, et l'autre extrémité du module de filtrage est connectée à l'extrémité de sortie de courant alternatif (Vac) ; et

le module de filtrage est configuré pour filtrer une ondulation d'une tension de l'extrémité de sortie (OUT) de la première unité de commutation et de la deuxième unité de commutation.


 
12. Dispositif d'alimentation électrique, dans lequel le dispositif d'alimentation électrique comprend le circuit de conversion selon l'une quelconque des revendications 1 à 6, et est configuré pour mettre en œuvre une conversion de puissance entre une tension de courant continu et une tension de courant alternatif.
 
13. Système de production d'énergie photovoltaïque, dans lequel le système comprend une cellule photovoltaïque, un onduleur photovoltaïque et un réseau électrique à courant alternatif ;

l'onduleur photovoltaïque comprend une extrémité d'entrée, une extrémité de sortie, et un circuit de conversion selon l'une quelconque des revendications 1 à 6 ;

l'extrémité d'entrée de l'onduleur photovoltaïque est connectée à la cellule photovoltaïque, et l'extrémité de sortie de l'onduleur photovoltaïque est connectée au réseau électrique à courant alternatif ; et

le circuit de conversion est configuré pour convertir des tensions à l'extrémité d'entrée et à l'extrémité de sortie de l'onduleur photovoltaïque.


 




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Cited references

REFERENCES CITED IN THE DESCRIPTION



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Patent documents cited in the description