(19)
(11)EP 3 491 726 B1

(12)EUROPEAN PATENT SPECIFICATION

(45)Mention of the grant of the patent:
25.03.2020 Bulletin 2020/13

(21)Application number: 18731854.8

(22)Date of filing:  21.06.2018
(51)International Patent Classification (IPC): 
H02M 1/36(2007.01)
H02M 3/07(2006.01)
H02M 3/156(2006.01)
H02M 1/00(2006.01)
(86)International application number:
PCT/EP2018/066657
(87)International publication number:
WO 2018/234499 (27.12.2018 Gazette  2018/52)

(54)

POWER MANAGEMENT INTEGRATED CIRCUIT WITH PROGRAMMABLE COLD START

INTEGRIERTE LEISTUNGSVERWALTUNGSSCHALTUNG MIT PROGRAMMIERBAREM KALTSTART

CIRCUIT INTÉGRÉ DE GESTION DE PUISSANCE AVEC DÉMARRAGE À FROID PROGRAMMABLE


(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: 22.06.2017 EP 17177506

(43)Date of publication of application:
05.06.2019 Bulletin 2019/23

(73)Proprietor: e-peas S.A.
1435 Mont-Saint-Guibert (BE)

(72)Inventors:
  • DE VOS, Julien
    1435 Mont-Saint-Guibert (BE)
  • GOSSET, Geoffroy
    1435 Mont-Saint-Guibert (BE)
  • HOCQUET, Cédric
    1435 Mont-Saint-Guibert (BE)

(74)Representative: Pecher, Nicolas et al
Pecher & Partners Rue Louis de Geer, 6
1348 Louvain-la-Neuve
1348 Louvain-la-Neuve (BE)


(56)References cited: : 
JP-A- 2008 199 745
US-A1- 2012 313 612
US-A1- 2006 152 200
  
  • Semiconductors E.Peas: "AEM10940: Highly Efficient, Dual Regulated Output, Ambient Energy Manager", , 17 November 2016 (2016-11-17), XP055432104, Retrieved from the Internet: URL:https://e-peas.com/wp-content/uploads/ 2016/02/DS_AEM10940_REV1.3.pdf [retrieved on 2017-12-05] cited in the application
  
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

Field of the invention



[0001] The present invention relates to a power management integrated circuit (PMIC) for managing energy from an energy harvester. The present invention also relates to an energy harvesting system comprising a PMIC, an energy harvester and an energy storage device and/or an application load.

[0002] The invention further relates to a method for energy harvesting from an energy harvester using a voltage converter comprising a main voltage converter circuit and a cold-start converter circuit.

Description of prior art



[0003] A PMIC for energy harvesting is a microchip that is designed to acquire and manage the microwatts to milliwatts of power generated by an energy harvester. These PMIC's for energy harvesting are known in the art and typically comprise a first input terminal for making a connection with the energy harvester so as to receive an input power. The PMIC comprises a voltage converter that receives the input power from the energy harvester and converts the input power in an output power that is transferred to one or more output terminals. An example of such a PMIC is known under reference AEM10940 and provided by the company e-peas S.A., Belgium.

[0004] A first output terminal can for example be connected with an energy storage device for storing the energy harvested from the energy harvester. Some PMIC's also comprise a load regulating circuit for regulating a transfer of power from the energy storage device to an application load that is connected to a second output terminal. The application load is for example an application circuit such as a microcontroller or a radio transceiver. The load regulating circuit can regulate the output voltage at the second output to a specific voltage value in accordance with the requirements of the application load used.

[0005] A power management integrated circuit is for example available from the applicant of the current patent application and known under the reference number AEM10940. The PMIC has to be construed as an interface between the energy harvester and an energy storage device and, generally, also an interface to one or more application loads or application circuits. During operation, energy is extracted from the energy harvester source and transferred to the energy storage device via the PMIC. The energy stored in the energy storage device can then be supplied to the one or more application circuits or alternatively, energy of the energy harvester is transferred directly to the application load via the voltage converter.

[0006] Examples of energy harvesters are photovoltaic cells (PV), thermoelectric generators (TEG) and electromagnetic energy sources. Examples of storage devices are Li-ion battery, a thin film battery or a super or a conventional capacitor.

[0007] A voltage converter for converting an input voltage Vin into an output voltage Vout_VC at an output of the voltage converter, generally comprises a high-efficient main voltage converter circuit comprising for example a DC-DC boost converter for increasing the input voltage Vin, or a buck converter for decreasing the input voltage, or a buck-boost converter for both decreasing or increasing the input voltage.

[0008] As known in the art, the main voltage converter circuit generally comprises a power point tracker circuit for repetitively determining a nominal start-up voltage VN. The main voltage converter circuit is then started when the input voltage of the PMIC corresponds to this nominal start-up voltage VN. This nominal start-up voltage VN is determined for optimally extracting power from the energy harvester with the main voltage converter circuit. In this way, the main voltage converter circuit obtains a high efficiency for extracting power. For example, with the PMIC with reference AEM10940 mentioned above, extraction efficiencies in the range between 65% and 95% have been obtained. The power point tracker is also named maximum power point tracker (MPPT). When solar cells are used as an energy harvester, the power point tracker circuit typically determines the nominal start-up voltage VN as a 90% fraction of the open-circuit voltage of the energy harvester.

[0009] A further example for determining the maximum power point for starting operating the main voltage converter is disclosed in US2012/0313612, wherein during nominal operation of the main voltage converter a feedforward circuit is used to dynamically adjust an operational point for starting the main voltage converter.

[0010] In addition, the main voltage converter circuit requires a minimum operational voltage to drive the main voltage converter circuit. Typically, for operating a main voltage converter circuit an operational voltage of for example 1.5 V or more is needed. The operational voltage to drive the main voltage converter circuit is available when the PMIC is in a normal operation mode wherein a minimum output voltage Vout_MIN is available to drive the main voltage converter circuit. When for example the energy storage device has no energy or a too low energy level, the output voltage Vout_VC is zero or too low to operate the main voltage converter circuit. Another example is when the energy harvester has not been deployed yet. In this case, before using the energy harvester for the first time, the storage device is disconnected from the PMIC to avoid that when for example a rechargeable battery is used as a storage device, this battery discharges it's energy into the PMIC before the system is fully deployed. Hence, also in this situation, when starting energy harvesting for the first time, the minimum voltage Vout_MIN at the output of the voltage converter will not be available to start energy harvesting with the main voltage converter circuit.

[0011] Therefore, the voltage converter generally comprises, in addition to the main voltage converter circuit, a cold-start voltage converter circuit that allows to start acquiring energy from the energy harvester in a PMIC degraded mode without the use of the main voltage converter circuit. The cold-start voltage converter circuit has however a low efficiency. The PMIC remains in the degraded mode until the PMIC operational voltage is above the minimum operational voltage needed to start operating the main voltage converter circuit. These cold-start voltage converter circuits are configured to start operating with a low voltage input and a low power. The PMIC with reference AEM10940 comprises for example a cold-start voltage converter circuit that starts to operate at an input voltage Vin as low as 380 mV and with an input power of 11 microwatt. The input voltage at which the cold-start circuit starts operating is also named cold-start start-up voltage.

[0012] However, one of the problems with the cold-start voltage converter circuits of the prior art PMIC's used for energy harvesting is that the extraction of power from the energy harvester in the PMIC degraded mode is not efficient because the cold-start voltage converter is not operating at the optimum voltage for extracting energy from the energy harvester. An optimum voltage for extracting energy is for example a voltage where a maximum of power can be extracted from the energy harvester. The optimum voltage to start a cold-circuit depends however on the type of energy harvester and on the specific characteristics of the energy harvester. For example, for a photovoltaic cell (PV) the optimum voltage to extract power depends on the cell technology (e.g. Silicon or Gallium Arsenide) and on the cell topology. This is illustrated in Fig. 1a where the typical power-voltage (P-V) curve is shown for two PV cells having a different technology: for the first cell technology (curve 2) the maximum power is extracted at an optimum voltage of 0.4 V and for the second cell technology (curve 3) at 0.6 V. In Fig. 1b, the P-V curve for three photovoltaic panels having the same size, i.e. delivering the same power, but having three different topologies is shown. The three topologies presented are a single cell topology (curve 4), a two cells in series topology (curve 5) and a three cells in series topology (curve 6). In this example, the optimum voltage to extract maximum power is at three different voltage values.

[0013] A further problem is related to the fact that the cold-start voltage converter circuit needs a minimum power PMINCS to start operating. When the cold-start voltage converter is designed to operate at a given voltage VCS, the minimum power is not necessarily always available from the energy harvester. This is illustrated in Fig.2a where the P-V curve for two different solar panels receiving a given small light illumination L1 is shown: one panel with a one cell topology (curve 7) and one panel with a three cell (curve 8) topology. The minimum power PMINCS needed to start the cold-start voltage converter is indicated on the figure. For the one cell topology when at the cold-start voltage of VCS, the minimum power PMINCS needed to start the cold-start circuit is available. However, when using the three cell topology, when at VCS, there is not enough power available to start the cold-start voltage converter circuit and hence the PMIC will not harvest any energy at this illumination L1. Fig. 2b shows the P-V curve of the same two panels having a different topology, under a higher illumination L2. Curve 9 corresponds to a one cell panel and curve 10 corresponds to a three cell panel. As shown on Fig.2b, the three cell panel (curve 10) can start harvest energy only at this higher illumination. Hence, for a given topology of the energy harvester, the starting of the cold start circuit will depend on the available illumination.

Summary of the invention



[0014] It is an object of the present invention to provide a PMIC that provides a solution for the problems mentioned above with respect to performing a more efficient operation of the cold-start voltage converter circuit for various types of energy harvesters, comprising various technologies and topologies.

[0015] The present invention is defined in the appended independent claims. Preferred embodiments are defined in the dependent claims.

[0016] According to a first aspect of the invention, a power management integrated circuit (PMIC) for managing energy from an energy harvester is provided. Such a PMIC comprises a first input terminal for receiving electrical power from the energy harvester, a first output terminal for connecting an energy storage device, and a voltage converter for converting an input power into an output power. The voltage converter is operable for providing the output power at an output voltage Vout_VC. The voltage converter comprises a main voltage converter circuit operable when the output voltage Vout_VC is equal or larger than a minimum voltage value Vout_MIN, and a cold-start circuit operable when the output voltage Vout_VC is lower than the minimum voltage value Vout_MIN. The PMIC comprises a conducting path for transferring the electrical power from the first input terminal to the voltage converter and a first connecting circuit for transferring the output power of the voltage converter to the first output terminal.

[0017] The PMIC according to the invention is characterized in that the PMIC further comprises a second input terminal for receiving a voltage VEN-CS, a voltage comparator configured for monitoring this voltage VEN-CS at the second input terminal and for comparing the voltage VEN-CS with a reference voltage Vref. The PMIC further comprises a controller for controlling the voltage converter. The controller is configured for enabling the cold-start circuit when the voltage VEN-CS is equal or larger than the reference voltage Vref and the output voltage Vout_VC is lower than the minimum output voltage value Vout_MIN. Enabling the cold-start circuit has to be construed as enabling operation of the cold-start circuit.

[0018] Advantageously, by providing a second input terminal for providing a voltage VEN-CS and comparing this voltage with a reference voltage, the moment the cold-start is enabled to start harvesting energy of the harvester will depend on the voltage VEN-CS applied at the second input terminal. Indeed, as the voltage comparator is monitoring this voltage VEN-CS, the cold-start is only enabled when this voltage VEN-CS is equal or larger than the reference voltage Vref. By configuring this voltage VEN-CS applied to the second input terminal as a fraction of the voltage Vin present at the first input terminal, i.e. VEN-CS = Vin/N, with N being the reduction factor, the moment the cold-start will start operating will depend on the input voltage Vin, on the reduction factor N selected and on the reference voltage Vref of the comparator. Hence by taking into account the value of the reference voltage Vref provided by the comparator and by selecting the reduction factor N, the user can program at what optimum input voltage Vin the PMIC should start enabling the cold-start circuit.

[0019] Advantageously, depending on the type of energy harvester to be used, the reduction factor can be adequately defined such that the cold-start circuit is triggered only when the input voltage at the voltage converter has a value that is optimum for, for example, maximum power extraction from the energy harvester.

[0020] Advantageously, the same PMIC can be used for various types of harvesters or for various topologies. Only the external voltage reducer has to be adjusted by selecting the right reduction factor N for a given energy harvester type in order to start the power extraction at an optimum input voltage.

[0021] In preferred embodiments, the voltage converter is further configured for disabling the cold-start circuit and enabling the main-voltage converter circuit when the output voltage Vout_VC is equal or larger than the minimum output voltage value Vout_MIN.

[0022] In embodiments, the main voltage converter circuit comprises an inductive boost converter circuit for increasing the input voltage, or a buck converter circuit for decreasing the input voltage, or a buck-boost converter circuit for both decreasing or increasing the input voltage.

[0023] In preferred embodiments, the cold-start circuit comprises a charge pump and one or more oscillators and the controller is enabling or disabling the cold-start circuit by enabling or disabling the one or more oscillators.

[0024] The present invention is also related to an energy harvesting system comprising a power management integrated circuit PMIC according to the invention, an energy harvester connected to the first input terminal, an energy storage device connected to the first output terminal and a voltage reducer configured for generating the voltage VEN-CS at the second input terminal. The voltage reducer is configured for generating a voltage VEN-CS that is proportional with an input voltage Vin at the first input terminal and wherein the voltage VEN-CS can be expressed as VEN-CS = Vin/N with N > 1 and N being a voltage reduction factor.

[0025] In preferred embodiments, the voltage reducer comprises a first impedance with impedance value Z1 conductively connected with a first end to the first input terminal and conductively connected with a second end to the second input terminal, and a second impedance with impedance value Z2 conductively connected with a first end to the second input terminal and conductively connected with a second end to a common ground level. In this way, the voltage VEN-CS at the second input terminal can be expressed as VEN-CS = Vin x Z2/(Z1+Z2).

[0026] According to a second aspect of the invention, a method for energy harvesting from an energy harvester is provided as disclosed in the appended claims.

Short description of the drawings



[0027] These and further aspects of the invention will be explained in greater detail by way of example and with reference to the accompanying drawings in which:
Fig.1a
shows a power-voltage curve for exemplary PV cells having two different technologies,
Fig.1b
shows examples of power-voltage curves for three different cell topologies,
Fig.2a
illustrates a power-voltage curve for two different cell topologies obtained when a low illumination is present,
Fig.2b
illustrates a power-voltage curve for two different cell topologies obtained when a high illumination is present,
Fig. 3
shows an example of a PMIC according to the invention,
Fig. 4
shows a further example of a PMIC according to the invention,
Fig. 5
shows an example of an energy harvesting system according to the invention
Fig. 6
illustrates an evolution of the output voltage of the voltage converter,
Fig. 7
shows a further example of an energy harvesting system,
Fig. 8
shows an energy harvesting system comprising an a storage device and an application load,
Fig. 9
shows an exemplary circuit of a main voltage converter,
Fig. 10
shows an example of a cold start circuit,

Detailed description of preferred embodiments



[0028] According to a first aspect of the invention a power management integrated circuit (PMIC) for energy harvesting is provided. Examples of energy harvesting PMIC's according to the invention are schematically illustrated in Fig.3 and Fig. 4.

[0029] The PMIC according to the invention has to be construed as a microchip comprising integrated circuits and a number of input/output pins, also named terminals. Some PMIC's can have for example, 16 or 32 terminals. Generally, the PMIC's have a compact packaging resulting in a square or rectangular footprint with sides having a length between 3 and 5 mm. On Fig. 3 and Fig. 4, the rectangular with a dotted pattern schematically illustrates the footprint of the PMIC packaging and the terminals are schematically indicated with small black rectangles.

[0030] A power management integrated circuit PMIC for managing energy from an energy harvester, comprises a first input terminal 11 for connecting the energy harvester so as to receive an input power from the energy harvester and a first output terminal 12 for connecting the energy storage device or for connecting the application load.

[0031] As will be further discussed, the PMIC according to the invention is not limited to one output terminal. As will be shown, in embodiments according to the invention, multiple output terminals can be present. For example, a first output terminal can be used to connect the storage device and one or more additional output terminals can be used to connect one or more application loads.

[0032] The PMIC comprises a voltage converter 20 for converting an input power into an output power. The voltage converter is operable for providing the output power at an output voltage Vout_VC.

[0033] The voltage converter 20 comprises a main voltage converter circuit 22 and a cold-start circuit 21. The main voltage converter circuit 22 is operable when the PMIC is in a normal operation mode wherein the output voltage Vout_VC is equal or larger than a minimum voltage value Vout_MIN. Typically the main voltage converter 22 comprises a number of switches that need a minimum operational voltage to operate and therefore the main voltage converter 22 is only operable if this minimum voltage Vout_MIN has been reached. To reach this minimum voltage Vout_MIN, a cold-start circuit is used. The cold-start voltage converter 21 is operable when the PMIC is in a degraded mode. The degraded mode is a mode wherein the output voltage Vout_VC is smaller than the minimum voltage value Vout_MIN. Hence in this degraded mode, the main voltage converter is not operable as the minimum operational voltage to drive the main voltage converter 22 is not available. As known in the art, the cold-start circuit has a low power transfer efficiency when compared to the main voltage converter circuit, which generally has a high power transfer efficiency.

[0034] As illustrated in Fig. 3, the PMIC according to the invention comprises a conducting path 18 for transferring the input power from the first input terminal 11 to the voltage converter 20 and a first connecting circuit 26 for transferring the controlled output power from the voltage converter 20 to the first output terminal 12.

[0035] The output voltage Vout at the first output terminal 12 can be equal or different from the output voltage Vout_VC at the output of the voltage converter 20. For example if the first connecting circuit 26 is a conductor or a conducting path, the voltage at the output terminal will be equal to Vout_VC. In other embodiments, as will be discussed below, the first connecting circuit 26 can for example comprise a storage controller for controlling a storage device. For these embodiments, the output voltage can be different from the output voltage of the voltage converter.

[0036] The PMIC according to the invention is characterized in that the PMIC further comprises a second input terminal 13 for receiving a voltage VEN-CS and a voltage comparator 30. The voltage comparator is configured for monitoring the voltage VEN-CS at the second input terminal 13 and for comparing the voltage VEN-CS with a reference voltage Vref. The name of the voltage VEN-CS monitored at the second input terminal is not important for the invention and can be given any name, it can be named enabling voltage for the cold start as the enabling of the cold start is based on this voltage or it could be named feedback voltage in the sense that as will be discussed below, in embodiments of an energy harvesting system this voltage VEN-CS is proportional with the input voltage at the energy harvester, and hence in the broadest sense of the word feedback, gives feedback information with respect to the input voltage at the energy harvester.

[0037] The PMIC according to the invention further comprises a controller 10 for controlling the voltage converter 20. The controller is configured for enabling the cold-start circuit 21 when VEN-CS ≥ Vref and Vout_VC ≤ Vout_MIN. As discussed above, enabling the cold-start circuit has to be construed as enabling operation of the cold-start circuit. In preferred embodiments, the controller 10 is further configured for disabling the cold-start circuit and enabling, i.e. enabling operation, the main voltage converter circuit 22 when Vout_VC > Vout_MIN. This is schematically illustrated on Fig. 3 and Fig. 4 where an arrow ECS and an arrow EMC indicate the enabling signal for the cold-start converter circuit 21 and the enabling signal for the main voltage converter circuit 22 by the controller 10, respectively, when the above defined conditions are fulfilled. The controller 10 is configured for generating these signals ECS and EMC, which are generally digital signals.

[0038] The PMIC uses an output voltage sensing circuit 29 configured for comparing the output voltage Vout_VC with the minimum voltage Vout_MIN. Depending on the detailed architecture of the PMIC, the output voltage sensing circuit 29 is either part of the controller 10, or, in other embodiments as schematically illustrated in Fig. 4, it can also be an additional element to the controller 10. In Fig. 3, a dotted line connecting the output of the converter with the controller 10, schematically illustrates the controller receiving the output voltage Vout_VC.

[0039] In Fig. 6, an example is shown illustrating the evolution of the output voltage Vout_VC as function of time for a PMIC that starts from a complete OFF state, i.e. a state where the output voltage Vout_VC is zero Volt. This is for example the case when a fully depleted energy storage device is connected to the first output terminal and hence no energy is available to drive the switches of the main voltage converter. As schematically illustrated in Fig. 6, the voltage converter operates first in the degraded operation mode M1 until the minimum output voltage of Vout_MIN is reached before switching to the normal operation M2. The degraded mode starts in this example at time TCS when the condition VEN-CS ≥ Vref and the condition Vout_VC < Vout_MIN are fulfilled. The normal operation mode starts at time TMC when the condition Vout_VC ≥ Vout_MIN is fulfilled. In this example shown on Fig. 6, the voltage Vout_MAX corresponds to the maximum voltage the voltage at the output of the voltage converter can reach.

[0040] As discussed above, the main voltage converter circuit 22 comprises for example a boost converter circuit, a buck converter circuit or a buck-boost converter circuit, known in the art. An exemplary voltage converter 20 comprising a boost converter circuit is schematically illustrated on Fig. 9. Such a boost converter circuit uses an inductor 25 and a first 23 and a second 24 voltage converter switch that are controlled by a voltage converter controller 19. In some embodiments this voltage converter controller 19 can be part of the controller 10. As shown on Fig. 9, when a boost converter is used, the inductor 25 is placed in series with the conducting path 18. The conducting path 18, as shown on Fig. 3, is connected with the first input terminal 11 for receiving the electrical power from the energy harvester. As well known in the art, by cyclically controlling the first and second switch, magnetic energy stored in the inductor is cyclically transferred to a load connected to the voltage converter output that is at a higher voltage Vout_VC than the voltage Vin at the converter input. This load connected to the voltage converter output is for example a capacitor. In some embodiments, as illustrated in Fig. 7 and Fig. 8, the inductor 25 is located outside the PMIC and terminals 15,16 are provided to the PMIC to connect the inductor 25. The voltage converter controller 19, shown on Fig. 9, uses the output voltage Vout_VC to control the first 23 and second 24 switch of the main voltage converter. This second switch 24 can be a diode. As discussed above, a minimum voltage Vout_MIN is needed for driving the first and second switch. An example of a cold-start circuit known in the art is shown on Fig.10. This cold-start circuit comprises an oscillator 35 and a charge pump 36. The oscillator is enabled by the enabling signal ECS from controller 10 and the output of the oscillator is the clock signal CLK of a charge pump circuit. The output of the charge pump supplies the node Vout_VC.

[0041] As discussed above, the comparator 30 compares the reference voltage Vref with the voltage VEN-CS and the cold-start circuit 21 is turned on by the control signal ECS generated by the controller 10 when VEN-CS ≥ Vref. This control signal ECS is for example a binary digital signal with value 0 or 1. The PMIC uses, as illustrated in Fig. 4, a output voltage sensing circuit 29 configured for comparing the output voltage Vout_VC with the minimum voltage Vout_MIN needed for operating the main voltage converter 22. Such a sensing and comparison circuit for defining the switching from the cold-start circuit to the main voltage converter circuit is well known in the art, for example known from the PMIC with reference number AEM10940 mentioned above. The controller 10 is configured for generating the control signal EMC when Vout_VC ≥ Vout_MIN. This signal is for example also a binary signal 0/1. This signal allows for disabling the cold-start and enabling the start of the main voltage converter 22. The signal EMC turns off the one or more oscillators of the cold-start circuit 21.

[0042] The use of voltage comparators in electronic circuits is also well known in the art and for example a comparator based on an operational amplifier can be used. For providing a reference voltage, such as Vref, the PMIC uses a reference voltage generator. Various reference voltage generating devices working at low voltage exist in the art. For example, in patent US6870229, an ultra-low power reference voltage generator is disclosed using n-MOS and p-MOS transistor technology. The comparator reference voltage Vref is a fixed value associated to the PMIC and has a typical value between 0.2 V and 0.6 V.

[0043] The comparator 30, the output voltage sensing circuit 29 and the controller 10 are schematically presented on Fig. 3 as separated elements. However in other embodiments the controller 10 can be construed as an overall controller comprising the comparator 30 and the output voltage sensing circuit 29.

[0044] In Fig. 5, an example of an energy harvesting system 100 is schematically shown. The energy harvesting system comprises a power management integrated circuit PMIC according to the invention, an energy harvester 40 connected to the first input terminal 11, an energy storage device 60 connected to the first output terminal 12 and a voltage reducer 50 configured for generating the voltage VEN-CS at the second input terminal 13. The voltage reducer generates a voltage VEN-CS that is proportional with the input voltage Vin at the first input terminal 11. The voltage VEN-CS can be expressed as VEN-CS = Vin/N with N being a voltage reduction factor that is larger than one.

[0045] In embodiments, the voltage reducer 50 has to be construed as a voltage divider. For these embodiments, the voltage reducer comprises a first impedance with impedance value Z1 and a second impedance with impedance value Z2. As schematically shown on Fig. 5, the first impedance is conductively connected with a first end to the first input terminal 11 and conductively connected with a second end to the second input terminal 13. The second impedance is conductively connected with a first end to the second input terminal 13 and conductively connected with a second end to a common ground level such that VEN-CS = Vin x Z2/(Z1+Z2).

[0046] An advantage of the PMIC according to the invention is that various energy harvester technologies and/or various topologies can be used for providing the input power to the PMIC. Depending on the type of energy harvester, the reduction factor N is chosen such that the cold-start converter circuit will start operation when an optimum input voltage at the first input terminal is reached. This optimum input voltage is for example the voltage where the maximum power can be extracted from the energy harvester and this optimum voltage is, as discussed above and illustrated with Figures 1a, 1b, 2a and 2b, different for each energy harvester type (e.g. PV cells, TEG's, electromagnetic energy sources) or for each topology used. By choosing the adequate reduction factor N, the cold start converter circuit will only start energy harvesting when the energy harvester is providing the input power at the optimum input voltage.

[0047] Typically, the energy harvester used with the PMIC according to the invention is capable of providing an input power having a value between 1 microwatt and 1 Watt and an input voltage at the first input terminal 11 between 0.05 V and 100 V.

[0048] In Fig.4 a further example of a PMIC according to the invention comprising a number of additional terminals 14,15,16 is shown. A storage capacitor terminal 14 is conductively connected with the output of the voltage converter. The storage capacitor terminal 14 allows to connect, as shown on Fig. 7 and Fig. 8, a storage capacitor Csto. As the storage capacitor is connected with the output of the voltage converter, the voltage at the output of the voltage converter corresponds to the voltage across the storage capacitor. The storage capacitor can for example have a value between 5 and 15 microfarad. The advantage of using such a storage capacitor Csto is that the minimum output voltage Vout_MIN, generated by the cold-start circuit 21, can be reached faster when compared to a system without such a storage capacitor, as shown on Fig. 5, where the output of the voltage converter is only connected to a storage device. Depending of the size and type of storage device, charging the storage device to reach the minimum voltage Vout_MIN can take a long time. Therefore, when a storage capacitor Csto is connected to the storage capacitor terminal 14, the storage device can be disconnected during the cold start by a switch comprised in the connecting circuit 26.

[0049] In embodiments, as shown on Fig. 4, Fig. 7 and Fig. 8, the first connecting circuit 26 for transferring the output power of the voltage converter 20 to the first output terminal 12 comprises a storage regulating circuit 27. This storage regulating circuit 27 is configured for regulating the voltage of the storage device connected to the first output terminal 12. For example, the storage device regulating circuit 27 can comprise one or more switches, controlled by the controller 10, for regulating the charging of a storage device such as a battery, a capacitor or supercapacitor. The storage device regulating circuit can for example limit the voltage at the first output to a maximum voltage value.

[0050] In the embodiment shown on Fig. 4, the PMIC also comprises a first inductor terminal 15 and a second inductor terminal 16. These additional terminals allow to couple an external inductor 25 as shown for example on Fig. 7 and Fig. 8. As discussed above, this inductor 25 is used by the main voltage converter circuit for converting the input power into the output power.

[0051] In Fig. 8, an energy harvesting system 100 according to the invention comprising a storage device 60 connected to a first output terminal 12 and an application load 70 connected to a second output terminal 17 is shown. In Fig. 8, reference number 31 schematically represents a second connecting circuit for connecting the second output terminal 17 with the voltage converter 20 and/or with the first output terminal 12. Generally the second connecting circuit comprises a load regulating circuit 28 for regulating the transfer of electrical power from the storage device and/or from the voltage converter to the application load 70 that is connected to the second output terminal 17. The load control circuit 28 typically comprises an LDO (Low Drop-Out) regulator for supplying a voltage Vout2 at the second output terminal 17. For example, the application load can be a microcontroller or a radio transceiver.

[0052] In embodiments, as illustrated on Fig. 8, an optional input capacitor Cin can be connected to an additional capacitor terminal 9 which is conductively connected with the input of the voltage converter 20. In some exemplary embodiments wherein the voltage converter is a DC/DC boost converter, the capacitor terminal 9 can be merged with the first inductor terminal 15. The input capacitor avoids that the input node collapses when the inductor current is building-up.

[0053] According to a second aspect of the invention, a method for starting energy harvesting from an energy harvester using a voltage converter 20 for converting an input power at a voltage Vin into an output power at an output voltage Vout_VC is provided.

[0054] The method makes use of a voltage converter that comprises a main voltage converter circuit and a cold-start converter circuit. The main voltage converter circuit 22 operates the voltage converter in a normal operation mode M2 wherein the output voltage Vout_VC is equal or larger than a minimum voltage value Vout_MIN. The cold-start circuit 21 operates the voltage converter in a degraded mode M1 wherein the output voltage Vout_VC is lower than the minimum voltage value Vout_MIN.

[0055] The method according to the invention comprises steps of
  • coupling the energy harvester with the voltage converter for providing the input power to the voltage converter,
  • defining an optimum voltage Vopt for extracting power from the energy harvester,
  • providing a voltage comparator for comparing an input voltage with a comparator reference voltage Vref,
  • defining a voltage reduction factor N = Vopt/Vref,
  • using a voltage reducer to generate a voltage VEN-CS = Vin/N, wherein Vin is the input voltage at the voltage converter and N is the reduction factor,
  • using said voltage VEN-CS as the input voltage for said voltage comparator so as to compare said voltage VEN-CS with said comparator reference voltage Vref,
  • enabling operation of the voltage converter in said degraded operation mode (M1) with said cold-start circuit (21) when VEN-CS ≥ Vref and when Vout_VC < Vout_MIN,
  • enabling operation of the voltage converter in said normal operation mode (M2) with said main voltage converter circuit (22) when Vout_VC ≥ Vout_MIN.


[0056] The method according the invention is not limited by the order of the steps given above.

[0057] The present invention has been described in terms of specific embodiments, which are illustrative of the invention and not to be construed as limiting. It will be appreciated by persons skilled in the art that the present invention is not limited by what has been particularly shown and/or described above. The scope of the invention is defined in the appended claims. Use of the verb "to comprise", as well as the respective conjugations, does not exclude the presence of elements other than those stated. Use of the article "a", "an" or "the" preceding an element does not exclude the presence of a plurality of such elements.


Claims

1. A power management integrated circuit (1) for managing energy from an energy harvester, said power management integrated circuit (1) comprising

• a first input terminal (11) for receiving electrical power from the energy harvester,

• a first output terminal (12) for connecting an energy storage device or an application load,

• a voltage converter (20) for converting an input power into an output power, and wherein the voltage converter is operable for providing said output power at an output voltage Vout_VC, said voltage converter (20) comprises

a) a main voltage converter circuit (22) operable when the output voltage Vout_VC is equal or larger than a minimum voltage value Vout_MIN, and

b) a cold-start circuit (21) operable when the output voltage Vout_VC is lower than said minimum voltage value Vout_MIN,

• a conducting path (18) for transferring the electrical power from the first input terminal (11) to the voltage converter (20),

• a first connecting circuit (26) for transferring the output power of the voltage converter (20) to said first output terminal (12),

characterized in that said power management integrated circuit (1) further comprises

• a second input terminal (13)for receiving a voltage VEN-CS,

• a voltage comparator (30) configured for monitoring said voltage VEN-CS at the second input terminal (13) and for comparing said voltage VEN-CS with a reference voltage Vref,

• a controller (10) for controlling the voltage converter (20) and wherein the controller (10) is configured for enabling said cold-start circuit (21) when VEN-CS ≥ Vref and Vout_VC < Vout_MIN.


 
2. A power management integrated circuit (1) according to claim 1 wherein said controller (10) is further configured for disabling said cold-start circuit and enabling said main voltage converter circuit (22) when Vout_VC ≥ Vout_MIN.
 
3. A power management integrated circuit (1) according to any of previous claims comprising a reference voltage generator for generating said reference voltage Vref.
 
4. A power management integrated circuit (1) according to any of previous claims comprising a output voltage sensing circuit (29) configured for comparing the output voltage Vout_VC with said minimum voltage Vout_MIN.
 
5. A power management integrated circuit (1) according to any of previous claims wherein said main voltage converter circuit (22) comprises an inductive boost converter circuit or a buck converter circuit or a buck-boost converter circuit.
 
6. A power management integrated circuit (1) according to any of previous claims wherein said cold-start circuit (21) comprises a charge pump (36) and one or more oscillators (35) and wherein said controller (10) is enabling or disabling said cold-start circuit by enabling or disabling said one or more oscillators.
 
7. A power management integrated circuit (1) according to any of previous claims wherein said comparator reference voltage Vref has a value between 0.2 V and 0.6 V.
 
8. A power management integrated circuit (1) according to any of previous claims comprising a storage capacitor terminal (14) for connecting a storage capacitor and wherein said storage capacitor terminal (14) is conductively connected with an output of the voltage converter.
 
9. A power management integrated circuit(1) according to any of previous claims comprising a first (15) and a second (16) inductor terminal configured for coupling an external inductor to the voltage converter (20).
 
10. A power management integrated circuit (1) according to any of previous claims comprising

• a second output terminal (17) for connecting the application load, and

• a second connecting circuit (31) for connecting the second output terminal (17) with the voltage converter (20) and/or with the first output terminal (12).


 
11. An energy harvesting system (100) comprising

a) a power management integrated circuit (1) according to any of claims 1 to 10,

b) an energy harvester (40) connected to said first input terminal (11),

c) an energy storage device (60) connected to said first output terminal (12),

d) a voltage reducer (50) configured for generating said voltage VEN-CS at said second input terminal (13) and wherein said voltage VEN-CS is proportional with an input voltage Vin at said first input terminal (11) and wherein VEN-CS = Vin/N with N > 1 being a voltage reduction factor.


 
12. An energy harvesting system (100) according to claim 11 wherein said voltage reducer (50) comprises

a) a first impedance with impedance value Z1 conductively connected with a first end to the first input terminal (11) and conductively connected with a second end to the second input terminal (13),

b) a second impedance with impedance value Z2 conductively connected with a first end to the second input terminal (13) and conductively connected with a second end to a common ground level such that VEN-CS = Vin x Z2/(Z1+Z2).


 
13. An energy harvesting system (100) comprising

a) a power management integrated circuit (1) according to claim 10,

b) an energy harvester (40) connected to said first input terminal (11),

c) an energy storage device (60) connected to said first output terminal (12),

d) a voltage reducer (50) configured for generating a voltage VEN-CS at said second input terminal (13) and wherein said voltage VEN-CS is proportional with an input voltage Vin at said first input terminal (11) and wherein VEN-CS = Vin/N with N > 1 being a voltage reduction factor,

e) an application load (70) connected to said second output terminal (17).


 
14. An energy harvesting system (100) according to any of claims 11 to 13 wherein said energy harvester is capable of providing an input power having a value between 1 microwatt and 1 Watt at an input voltage Vin at the first input terminal (11) having a value between 0.05 V and 100 V.
 
15. A method for energy harvesting from an energy harvester using a voltage converter (20) for converting an input power at a voltage Vin into an output power at an output voltage Vout_VC, and wherein said voltage converter (20) comprises

• a main voltage converter circuit (22) for operating the voltage converter in a normal operation mode (M2) wherein the output voltage Vout_VC is equal or larger than a minimum voltage value Vout_MIN, and

• a cold-start circuit (21) for operating the voltage converter (20) in a degraded mode (M1) wherein the output voltage Vout_VC is lower than said minimum voltage value Vout_MIN,

said method comprising steps of

∘ coupling the energy harvester with the voltage converter for providing said input power,

∘ defining an optimum voltage Vopt for extracting power from said energy harvester,

∘ providing a voltage comparator for comparing an input voltage with a reference voltage Vref,

∘ defining a voltage reduction factor N = Vopt/Vref,

∘ using a voltage reducer (50) to generate a voltage VEN-CS= Vin/N, wherein Vin is said input voltage and N is said reduction factor,

∘ using said voltage VEN-CS as the input voltage for said voltage comparator so as to compare said voltage VEN-CS with said reference voltage Vref,

∘ enabling operation of the voltage converter in said degraded operation mode (M1) with said cold-start circuit (21) when VEN-CS ≥ Vref and when Vout_VC < Vout_MIN,

∘ enabling operation of the voltage converter in said normal operation mode (M2) with said main voltage converter circuit (22) when Vout_VC ≥ Vout_MIN.


 


Ansprüche

1. Integrierte Leistungsverwaltungsschaltung (1) zum Verwalten von Energie von einem Energy-Harvester, wobei die integrierte Leistungsverwaltungsschaltung (1) aufweist

• einen ersten Eingangsanschluss (11) zum Erhalten von elektrischer Leistung von dem Energy-Harvester,

• einen ersten Ausgangsanschluss (12) zum Verbinden einer Energiespeichervorrichtung oder einer Anwendungslast,

• einen Spannungswandler (20) zum Umwandeln einer Eingangsleistung in eine Ausgangsleistung und wobei der Spannungswandler zum Bereitstellen der Ausgangsleistung bei einer Ausgangsspannung Vout_VC betreibbar ist, wobei der Spannungswandler (20) aufweist

a) eine Hauptspannungswandlerschaltung (22), die betreibbar ist, wenn die Ausgangsspannung Vout_VC gleich oder größer einem Mindestspannungswert Vout_MIN ist, und

b) eine Kaltstartschaltung (21), die betreibbar ist, wenn die Ausgangsspannung Vout_VC niedriger ist als der Mindestspannungswert Vout_MIN,

• eine Leiterbahn (18) zum Übertragen der elektrischen Leistung von dem ersten Eingangsanschluss (11) an den Spannungswandler (20),

• eine erste Verbindungsschaltung (26) zum Übertragen der Ausgangsleistung des Spannungswandlers (20) an den ersten Ausgangsanschluss (12),

dadurch gekennzeichnet, dass die integrierte Leistungsverwaltungsschaltung (1) ferner aufweist

• einen zweiten Eingangsanschluss (13) zum Erhalten einer Spannung VEN-CS,

• einen Spannungskomparator (30), der zum Überwachen der Spannung VEN-CS an dem zweiten Eingangsanschluss (13) und zum Vergleichen der Spannung VEN-CS mit einer Referenzspannung Vref ausgebildet ist,

• eine Steuereinrichtung (10) zum Steuern des Spannungswandlers (20) und wobei die Steuereinrichtung (10) zum Aktivieren der Kaltstartschaltung (21) ausgebildet ist, wenn VEN-CS ≥ Vref und Vout_VC < Vout_MIN gilt.


 
2. Integrierte Leistungsverwaltungsschaltung (1) nach Anspruch 1, wobei die Steuereinrichtung (10) ferner zum Deaktivieren der Kaltstartschaltung und zum Aktivieren der Hauptspannungswandlerschaltung (22) ausgebildet ist, wenn Vout_VC ≥ Vout_MIN gilt.
 
3. Integrierte Leistungsverwaltungsschaltung (1) nach einem der vorhergehenden Ansprüche, die einen Referenzspannungserzeuger zum Erzeugen der Referenzspannung Vref aufweist.
 
4. Integrierte Leistungsverwaltungsschaltung (1) nach einem der vorhergehenden Ansprüche, die eine Ausgangsspannungserfassungsschaltung (29) aufweist, die zum Vergleichen der Ausgangsspannung Vout_VC mit der Mindestspannung Vout_MIN ausgebildet ist.
 
5. Integrierte Leistungsverwaltungsschaltung (1) nach einem der vorhergehenden Ansprüche, wobei die Hauptspannungswandlerschaltung (22) eine induktive Hochsetzstellerschaltung oder eine Tiefsetzstellerschaltung oder eine Tief-Hochsetzstellerschaltung aufweist.
 
6. Integrierte Leistungsverwaltungsschaltung (1) nach einem der vorhergehenden Ansprüche, wobei die Kaltstartschaltung (21) eine Ladungspumpe (36) und einen oder mehrere Oszillatoren (35) aufweist und wobei die Steuereinrichtung (10) die Kaltstartschaltung durch Aktivieren oder Deaktivieren des einen oder der mehreren Oszillatoren aktiviert oder deaktiviert.
 
7. Integrierte Leistungsverwaltungsschaltung (1) nach einem der vorhergehenden Ansprüche, wobei die Komparatorreferenzspannung Vref einen Wert zwischen 0,2 V und 0,6 V aufweist.
 
8. Integrierte Leistungsverwaltungsschaltung (1) nach einem der vorhergehenden Ansprüche, die einen Speicherkondensatoranschluss (14) zum Verbinden eines Speicherkondensators aufweist und wobei der Speicherkondensatoranschluss (14) leitend mit einem Ausgang des Spannungswandlers verbunden ist.
 
9. Integrierte Leistungsverwaltungsschaltung (1) nach einem der vorhergehenden Ansprüche, die einen ersten (15) und einen zweiten (16) Induktivitätsanschluss aufweist, die zum Koppeln einer externen Induktivität mit dem Spannungswandler (20) ausgebildet sind.
 
10. Integrierte Leistungsverwaltungsschaltung (1) nach einem der vorhergehenden Ansprüche, aufweisend

• einen zweiten Ausgangsanschluss (17) zum Verbinden der Anwendungslast und

• eine zweite Verbindungsschaltung (31) zum Verbinden des zweiten Ausgangsanschlusses (17) mit dem Spannungswandler (20) und/oder mit dem ersten Ausgangsanschluss (12).


 
11. Energy-Harvesting-System (100), aufweisend

a) eine integrierte Leistungsverwaltungsschaltung (1) nach einem der Ansprüche 1 bis 10,

b) einen Energy-Harvester (40), der mit dem ersten Eingangsanschluss (11) verbunden ist,

c) eine Energiespeichervorrichtung (60), die mit dem ersten Ausgangsanschluss (12) verbunden ist,

d) einen Spannungsreduzierer (50), der zum Erzeugen der Spannung VEN-CS an dem zweiten Eingangsanschluss (13) ausgebildet ist und wobei die Spannung VEN-CS proportional zu einer Eingangsspannung Vin an dem ersten Eingangsanschluss (11) ist und wobei VEN-CS = Vin / N gilt mit N > 1 als einem Spannungsreduzierungsfaktor.


 
12. Energy-Harvesting-System (100) nach Anspruch 11, wobei der Spannungsreduzierer (50) aufweist

a) eine erste Impedanz mit Impedanzwert Z1, die mit einem ersten Ende mit dem ersten Eingangsanschluss (11) leitend verbunden ist und mit einem zweiten Ende mit dem zweiten Eingangsanschluss (13) leitend verbunden ist,

b) eine zweite Impedanz mit Impedanzwert Z2, die mit einem ersten Ende mit dem zweiten Eingangsanschluss (13) leitend verbunden ist und mit einem zweiten Ende mit einem gemeinsamen Erdpotential leitend verbunden ist, so dass VEN-CS = Vin x Z2 / Z1 + Z2) gilt.


 
13. Energy-Harvesting-System (100), aufweisend

a) eine integrierte Leistungsverwaltungsschaltung (1) nach Anspruch 10,

b) einen Energy-Harvester (40), der mit dem ersten Eingangsanschluss (11) verbunden ist,

c) eine Energiespeichervorrichtung (60), die mit dem ersten Ausgangsanschluss (12) verbunden ist,

d) einen Spannungsreduzierer (50), der zum Erzeugen einer Spannung VEN-CS an dem zweiten Eingangsanschluss (13) ausgebildet ist und wobei die Spannung VEN-CS proportional zu einer Eingangsspannung Vin an dem ersten Eingangsanschluss (11) ist und wobei VEN-CS = Vin / N gilt mit N > 1 als einem Spannungsreduzierungsfaktor,

e) eine Anwendungslast (70), die mit dem zweiten Ausgangsanschluss (17) verbunden ist.


 
14. Energy-Harvesting-System (100) nach einem der Ansprüche 11 bis 13, wobei es der Energy-Harvester vermag, eine Eingangsleistung mit einem Wert zwischen 1 Mikrowatt und 1 Watt bei einer Eingangsspannung Vin an dem ersten Eingangsanschluss (11) mit einem Wert zwischen 0,05 V und 100 V bereitzustellen.
 
15. Verfahren für Energy-Harvesting von einem Energy-Harvester unter Verwendung eines Spannungswandlers (20) zum Umwandeln einer Eingangsleistung bei einer Spannung Vin in eine Ausgangsleistung bei einer Ausgangsspannung Vout_VC und wobei der Spannungswandler (20) aufweist

• eine Hauptspannungswandlerschaltung (22) zum Betreiben des Spannungswandlers in einem Normalbetriebsmodus (M2), wobei die Ausgangsspannung Vout_VC gleich oder größer einem Mindestspannungswert Vout_MIN ist, und

• eine Kaltstartschaltung (21) zum Betreiben des Spannungswandlers (20) in einem herabgesetzten Modus (M1), wobei die Ausgangsspannung Vout_VC niedriger ist als der Mindestspannungswert Vout_MIN,

wobei das Verfahren Schritte umfasst des

∘ Koppelns des Energy-Harvesters mit dem Spannungswandler zum Bereitstellen der Eingangsleistung,

∘ Definierens einer optimalen Spannung Vopt zum Entnehmen von Leistung aus dem Energy-Harvester,

∘ Bereitstellens eines Spannungskomparators zum Vergleichen einer Eingangsspannung mit einer Referenzspannung Vref,

∘ Definierens eines Spannungsreduzierungsfaktors N = Vopt / Vref,

∘ Verwendens eines Spannungsreduzierers (50) zum Erzeugen einer Spannung VEN-CS = Vin / N, wobei Vin die Eingangsspannung ist und N der Reduzierungsfaktor ist,

∘ Verwendens der Spannung VEN-CS als die Eingangsspannung für den Spannungskomparator, um die Spannung VEN-CS mit der Referenzspannung Vref zu vergleichen,

∘ Aktivierens des Betriebs des Spannungswandlers in dem herabgesetzten Betriebsmodus (M1) mit der Kaltstartschaltung (21), wenn VEN-CS ≥ Vref und wenn Vout_VC < Vout_MIN gilt,

∘ Aktivierens des Betriebs des Spannungswandlers in dem Normalbetriebsmodus (M2) mit der Hauptspannungswandlerschaltung (22), wenn Vout_VC ≥ Vout MIN gilt.


 


Revendications

1. Circuit intégré de gestion de puissance (1) servant à gérer l'énergie en provenance d'un récupérateur d'énergie, ledit circuit intégré de gestion de puissance (1) comprenant

• une première borne d'entrée (11) destinée à recevoir une puissance électrique en provenance du récupérateur d'énergie,

• une première borne de sortie (12) servant à connecter un dispositif de stockage d'énergie ou une charge d'application,

• un convertisseur de tension (20) servant à convertir une puissance d'entrée en une puissance de sortie, et le convertisseur de tension étant utilisable pour fournir ladite puissance de sortie à une tension de sortie Vout_VC, ledit convertisseur de tension (20) comprenant

a) un circuit convertisseur de tension principal (22) apte à fonctionner lorsque la tension de sortie Vout_VC est supérieure ou égale à une valeur de tension minimale Vout_MIN, et

b) un circuit de démarrage à froid (21) apte à fonctionner lorsque la tension de sortie Vout_VC est inférieure à ladite valeur de tension minimale Vout_MIN,

• un chemin conducteur (18) servant à transférer la puissance électrique de la première borne d'entrée (11) au convertisseur de tension (20),

• un premier circuit connecteur (26) servant à transférer la puissance de sortie du convertisseur de tension (20) à ladite première borne de sortie (12),

ledit circuit intégré de gestion de puissance (1) étant caractérisé en ce qu'il comprend en outre

• une deuxième borne d'entrée (13) servant à recevoir une tension VEN-CS,

• un comparateur de tension (30) configuré pour surveiller ladite tension VEN-CS à la deuxième borne d'entrée (13) et pour comparer ladite tension VEN-CS à une tension de référence Vref,

• une unité de commande (10) servant à commander le convertisseur de tension (20), et l'unité de commande (10) étant configurée pour activer ledit circuit de démarrage à froid (21) lorsque VEN-CS ≥ Vref et Vout_VC < Vout_MIN.


 
2. Circuit intégré de gestion de puissance (1) selon la revendication 1, dans lequel ladite unité de commande (10) est configurée en outre pour désactiver ledit circuit de démarrage à froid et activer ledit circuit convertisseur de tension principal (22) lorsque Vout_VC ≥ Vout_MIN.
 
3. Circuit intégré de gestion de puissance (1) selon l'une quelconque des revendications précédentes, comprenant un générateur de tension de référence servant à générer ladite tension de référence Vref.
 
4. Circuit intégré de gestion de puissance (1) selon l'une quelconque des revendications précédentes, comprenant un circuit détecteur de tension de sortie (29) configuré pour comparer la tension de sortie Vout_VC à ladite tension minimale Vout_MIN.
 
5. Circuit intégré de gestion de puissance (1) selon l'une quelconque des revendications précédentes, dans lequel ledit circuit convertisseur de tension principal (22) comprend un circuit convertisseur élévateur inductif ou un circuit convertisseur abaisseur ou un circuit convertisseur abaisseur-élévateur.
 
6. Circuit intégré de gestion de puissance (1) selon l'une quelconque des revendications précédentes, dans lequel ledit circuit de démarrage à froid (21) comprend une pompe de charge (36) et un ou plusieurs oscillateurs (35), et dans lequel ladite unité de commande (10) active ou désactive ledit circuit de démarrage à froid en activant ou en désactivant lesdits un ou plusieurs oscillateurs.
 
7. Circuit intégré de gestion de puissance (1) selon l'une quelconque des revendications précédentes, dans lequel ladite tension de référence Vref du comparateur prend une valeur comprise entre 0,2 V et 0,6 V.
 
8. Circuit intégré de gestion de puissance (1) selon l'une quelconque des revendications précédentes, comprenant une borne (14) de condensateur de stockage servant à connecter un condensateur de stockage, et dans lequel ladite borne (14) de condensateur de stockage est connectée de manière conductrice à une sortie du convertisseur de tension.
 
9. Circuit intégré de gestion de puissance (1) selon l'une quelconque des revendications précédentes, comprenant des première (15) et deuxième (16) bornes d'inductance configurées pour coupler une inductance externe au convertisseur de tension (20).
 
10. Circuit intégré de gestion de puissance (1) selon l'une quelconque des revendications précédentes, comprenant

• une deuxième borne de sortie (17) servant à connecter la charge d'application, et

• un deuxième circuit connecteur (31) servant à connecter la deuxième borne de sortie (17) au convertisseur de tension (20) et/ou à la première borne de sortie (12).


 
11. Système récupérateur d'énergie (100), comprenant

a) un circuit intégré de gestion de puissance (1) selon l'une quelconque des revendications 1 à 10,

b) un récupérateur d'énergie (40) connecté à ladite première borne d'entrée (11),

c) un dispositif de stockage d'énergie (60) connecté à ladite première borne de sortie (12),

d) un réducteur de tension (50) configuré pour générer ladite tension VEN-CS à ladite deuxième borne d'entrée (13), et ladite tension VEN-CS étant proportionnelle à une tension d'entrée Vin à ladite première borne d'entrée (11) et VEN-CS = Vin/N, N > 1 étant un facteur de réduction de tension.


 
12. Système récupérateur d'énergie (100) selon la revendication 11, dans lequel ledit réducteur de tension (50) comprend

a) une première impédance d'une valeur d'impédance Z1 connectée de manière conductrice, par une première extrémité, à la première borne d'entrée (11) et connectée de manière conductrice, par une deuxième extrémité, à la deuxième borne d'entrée (13),

b) une deuxième impédance d'une valeur d'impédance Z2 connectée de manière conductrice, par une première extrémité, à la deuxième borne d'entrée (13) et connectée de manière conductrice, par une deuxième extrémité, à un niveau de terre commun de sorte que VEN-CS = Vin x Z2/(Z1+Z2).


 
13. Système récupérateur d'énergie (100), comprenant

a) un circuit intégré de gestion de puissance (1) selon la revendication 10,

b) un récupérateur d'énergie (40) connecté à ladite première borne d'entrée (11),

c) un dispositif de stockage d'énergie (60) connecté à ladite première borne de sortie (12),

d) un réducteur de tension (50) configuré pour générer ladite tension VEN-CS à ladite deuxième borne d'entrée (13), et ladite tension VEN-CS étant proportionnelle à une tension d'entrée Vin à ladite première borne d'entrée (11) et VEN-CS = Vin/N, N > 1 étant un facteur de réduction de tension,

e) une charge d'application (70) connectée à ladite deuxième borne de sortie (17).


 
14. Système récupérateur d'énergie (100) selon l'une quelconque des revendications 11 à 13, dans lequel ledit récupérateur d'énergie est apte à fournir une puissance d'entrée d'une valeur comprise entre 1 microwatt et 1 watt, à une tension d'entrée Vin à la première borne d'entrée (11) d'une valeur comprise entre 0,05 V et 100 V.
 
15. Procédé de récupération d'énergie à partir d'un récupérateur d'énergie à l'aide d'un convertisseur de tension (20) servant à convertir une puissance d'entrée à une tension Vin en une puissance de sortie à une tension de sortie Vout_VC, et ledit convertisseur de tension (20) comprenant

• un circuit convertisseur de tension principal (22) servant à faire fonctionner le convertisseur de tension dans un mode de fonctionnement normal (M2), la tension de sortie Vout_VC étant supérieure ou égale à une valeur de tension minimale Vout_MIN, et

• un circuit de démarrage à froid (21) servant à faire fonctionner le convertisseur de tension (20) dans un mode dégradé (M1), la tension de sortie Vout_VC étant inférieure à ladite valeur de tension minimale Vout_MIN,

ledit procédé comprenant les étapes suivantes

∘ couplage du récupérateur d'énergie au convertisseur de tension pour la fourniture de ladite puissance d'entrée,

∘ définition d'une tension optimale Vopt pour l'extraction de puissance à partir dudit récupérateur d'énergie,

∘ fourniture d'un comparateur de tension pour la comparaison d'une tension d'entrée à une tension de référence Vref,

∘ définition d'un facteur de réduction de tension N = Vopt/Vref,

∘ utilisation d'un réducteur de tension (50) pour générer une tension VEN-CS = Vin/N, Vin représentant ladite tension d'entrée et N représentant ledit facteur de réduction de tension,

∘ utilisation de ladite tension VEN-CS comme tension d'entrée pour ledit comparateur de tension de manière à comparer ladite tension VEN-CS à ladite tension de référence Vref,

∘ activation du fonctionnement du convertisseur de tension dans ledit mode de fonctionnement dégradé (M1) au moyen dudit circuit de démarrage à froid (21) lorsque VEN-CS ≥ Vref et lorsque Vout_VC < Vout_MIN,

∘ activation du fonctionnement du convertisseur de tension dans ledit mode de fonctionnement normal (M2) au moyen dudit circuit convertisseur de tension principal (22) lorsque Vout_VC ≥ Vout_MIN.


 




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Cited references

REFERENCES CITED IN THE DESCRIPTION



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Patent documents cited in the description