(19)
(11)EP 3 457 552 B1

(12)EUROPEAN PATENT SPECIFICATION

(45)Mention of the grant of the patent:
13.05.2020 Bulletin 2020/20

(21)Application number: 18194612.0

(22)Date of filing:  14.09.2018
(51)International Patent Classification (IPC): 
H02M 5/458(2006.01)
H02J 7/14(2006.01)
H02J 1/10(2006.01)
B60L 50/12(2019.01)
H02K 16/04(2006.01)
H02J 3/46(2006.01)
H02K 16/00(2006.01)
B60L 50/10(2019.01)
B60L 50/13(2019.01)

(54)

ELECTRICAL POWER SYSTEM COMPRISING A PLURALITY OF GENERATORS DRIVEN BY ROTATION ON A COMMON SHAFT SUPPLYING ACTIVE RECTIFIERS, AND LOAD SHARING CONTROL

ELEKTRISCHES LEISTUNGSVERSORGUNGSSYSTEM MIT EINER VIELZAHL VON AUF EINER WELLE ANGETRIEBENEN GENERATOREN, DIE AKTIVE GLEICHRICHTER SPEISEN, UND LASTVERTEILUNGSREGELUNG

SYSTÈME D'ALIMENTATION ÉLECTRIQUE COMPRENANT UNE PLURALITÉ DE GÉNÉRATEURS ENTRAÎNÉS PAR ROTATION SUR UN ARBRE COMMUN ALIMENTANT DES REDRESSEURS ACTIFS, ET UN CONTRÔLE DE RÉPARTITION DE CHARGE.


(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: 14.09.2017 US 201715704531

(43)Date of publication of application:
20.03.2019 Bulletin 2019/12

(73)Proprietor: Hamilton Sundstrand Corporation
Charlotte, NC 28217-4578 (US)

(72)Inventors:
  • ROZMAN, Gregory I.
    Myrtle Beach, SC 29577 (US)
  • GIERAS, Jacek F.
    Glastonbury, CT 06033 (US)
  • MOSS, Steven J.
    Rockford, IL 61114 (US)

(74)Representative: Dehns 
St. Bride's House 10 Salisbury Square
London EC4Y 8JD
London EC4Y 8JD (GB)


(56)References cited: : 
EP-A2- 0 743 215
US-A- 4 927 329
  
      
    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

    BACKGROUND



    [0001] The present disclosure relates to electrical power systems, and more particularly to a modular electrical power system that incorporates a multistage axial flux generator whose stages are driven by rotation of a common shaft.

    [0002] Reliability in power delivery is important in many vehicles, such as military ground vehicles, which must be suitable for combat operations. A typical military ground vehicle may include a plurality of electrical generators that power a load over a bus. Certain operating conditions may cause unpredictable conditions on the bus, such as the failure of a generator, or uneven load distribution.

    SUMMARY



    [0003] The present invention provides an electrical power system according to claim 1 and a method of operating an electrical power system according to claim 10. Preferred embodiments are defined in the dependent claims.

    [0004] An example electrical power system includes a direct current (DC) bus connected to a load, a plurality of generators driven by rotation of a common shaft, and a plurality of power converters. Each power converter includes an active rectifier controller that operates a respective active rectifier to rectify alternating current (AC) from a respective one of the generators to DC on the DC bus. A load sharing controller is operable to provide a respective adjustment signal to each respective power converter that is enabled, the respective adjustment signals based on a difference between an average output current across all of the active rectifiers that are enabled, and a particular output current of the respective power converter. Each active rectifier controller is operable to determine a quadrature current value for its associated generator based on its adjustment signal. A method of operating an electrical power system is also disclosed.

    [0005] The embodiments, examples, and alternatives of the preceding paragraphs, the claims, or the following description and drawings, including any of their various aspects or respective individual features, may be taken independently or in any combination. Features described in connection with one embodiment are applicable to all embodiments, unless such features are incompatible.

    [0006] Electrical power systems are disclosed in US 4,927,329 and EP 0743215.

    BRIEF DESCRIPTION OF THE DRAWINGS



    [0007] 

    Figure 1A is a schematic view of a military ground vehicle incorporating a multistage permanent magnet generator whose stages are driven by a common shaft.

    Figure 1B is a schematic view of a plurality of an example multistage axial flux permanent magnet generator.

    Figure 2 is a schematic view of an example electrical power system.

    Figure 3 is a schematic view of an active rectifier from the system of Figure 2.

    Figure 4 is a schematic view of an example active rectifier controller.

    Figure 5 is a schematic view of an example load sharing controller.

    Figure 6 is a schematic view of another example active rectifier controller.

    Figure 7 is a schematic view of another example load sharing controller.

    Figure 8 is flowchart of an example method of operating an electrical power system.


    DETAILED DESCRIPTION



    [0008] Of the many types of electrical generators, synchronous permanent magnet generators (PMGs), such as axial flux PMGs or radial flux PMGs, are well-suited for use in military ground vehicles due to their high efficiency and power density. Of these two types of synchronous PMGs, axial flux PMGs offer higher power density, efficiency, and compact multistage structure in comparison with radial flux PMGs.

    [0009] Figure 1A is a schematic view of a military ground vehicle 4 that includes a multistage axial flux PMG 5. The vehicle 4 also includes a prime mover engine 7 (e.g., a diesel or gas turbine engine) that rotates a common shaft 8 to drive operation of the axial flux PMG 5. Each stage of the axial flux PMG 5 is coupled to a respective power converter 10A-N that converts AC from its generator stage to DC. Although the vehicle 4 is depicted as a tank, it is understood that this is only an example, and that other vehicles could be used (e.g., an automobile or underwater vehicle).

    [0010] Figure 1B is a schematic view of an example multistage axial flux PMG 5 having a plurality of generator stages 6A-B that are driven by the common shaft 8. Each generator stage 6A-B includes a stator 12, and a rotor 13 that rotates permanent magnets 14. Steel disks 15 separate the generator stages 6 from each other. A housing is formed by end bells 16 and a cylindrical outer portion 17. Bearings 18 facilitate rotation of the shaft 8. The generator stages 6A-B are modular, and if they malfunction they can be disabled and replaced in a modular fashion. Although only two generator stages 6A-B are shown in Figure 1 (which collectively include two stator blocks 12 and three rotor blocks 13, it is understood that other quantities of generator stages 6 could be used (e.g., 3-20).

    [0011] Figure 2 is a schematic view of an example electrical power system 16 that may be incorporated into a vehicle, such as the military ground vehicle 4. The electrical power system 16 includes a power generating section 17 and a DC load 18. The power generating section 17 includes a plurality of generator stages 6A-N, prime mover engine 7, a plurality of modular power converters 10A-N, a load sharing / fault management controller 40, and an output filter 41. The prime mover engine 7 rotates the common shaft 8 that drives operation of the generator stages 6A-N.

    [0012] Each generator stage 6 has a plurality of stator windings (shown schematically as 12 in Figure 1) that provide a plurality of phases of current on respective output lines A, B, C. Thus, generator stage 6A has stator winding outputs A1, B1, C1, and generator stage 6N has stator winding outputs AN, BN, CN. The stator windings serve as boost inductors during active rectifier 22 operation.

    [0013] Each power converter 10A-N is associated with a given one of the generator stages 6A-N and includes a respective active rectifier 22, active rectifier controller 24, and gate drive 26.

    [0014] A DC bus includes a positive rail 30A and a negative rail 30B (collectively DC bus 30) that connect the outputs of the active rectifiers 22 to the DC load 18. The plurality of active rectifiers 22 are connected in parallel to each other on the DC bus 30.

    [0015] As will be discussed below in greater detail, the electrical power system 16 provides coordination between the various generator stages 6 to supply load power demand, maintain DC bus 30 voltage within specification requirements, and compensate active rectifier 22 losses. In addition, the electrical power system 16 provides for disconnecting faulty ones of the generator stages 6 and reconfiguring the remaining enabled active rectifiers 22 using corrective signals and a phase shifted carrier signal. The carrier signals used by each power converter 10 are phase shifted from each other by T / N where T is a period of the carrier signal and N is a quantity of the active rectifiers 22 that are enabled.

    [0016] The active rectifiers 22 rectify AC from their associated generator stages 6 to DC on the DC bus 30. In particular, each active rectifier controller 24 utilizes its gate drive 26 to perform pulse width modulation on the switches S1-S6 of its active rectifier 22. In some examples, the active rectifier controllers 24 use an interleaved technique that technique facilitates a reduced power rating of each active rectifier 22, a reduced size of the output filter 41, and a scalable modular design.

    [0017] The example active rectifiers 22 shown in Figure 2 are 2-level pulse width modulated power converters. However, it is understood that other topologies, such as multilevel power converters can be utilized instead.

    [0018] Active rectifier 22A is illustrated in more detail in Figure 3. The active rectifier 22A has a plurality of switching legs, 34, 35, 36, each of which controls connection of a respective one of the winding outputs A1, B1, C1 to the DC bus 30. Switching leg 34 includes power switches S1A, S2A; switching leg 35 includes power switches S3A, S4A; and switching leg 36 includes power switches S5A, S6A. Each of the power switches S1A, S3A, S5A has a node that connects to the positive rail 30A of the DC bus 30. Each of the power switches S2A, S4A, S6A has a node that connects to the negative rail 30B of the DC bus 30. Each of the power switches S1A-S6A also has a node that connects to its respective winding output A1, B1, C1. Each power switch S1A-S6A also has an associated freewheeling diode D1A - D6A that forms a current path when its respective power switch S1A-S6A is turned OFF.

    [0019] The active rectifier controller 24A operates gate drive 26A to control the switches S1A-S6A over control lines 38. Although the power switches S1A-S6A are shown as being metal-oxide semiconductor field-effect transistors (MOSFETs) in Figure 3, it is understood that other types of switches could be used, such as insulated-gate bipolar transistors (IGBTs).

    [0020] Each active rectifier 22 also includes a DC link capacitor 38 that is connected across the DC bus 30.

    [0021] Referring again to Figure 2, each active rectifier 22 has pair of associated contactors C1, C2 that can be used to disconnect from the positive rail 30A and the negative rail 30B of the DC bus 30. In one example, the contactors C1, C2 are commanded to disable their associated active rectifier 22 by disconnecting the active rectifier 22 from the DC bus 30 if their associated generator stage 6 experiences a fault condition.

    [0022] In an alternative embodiment (not shown), each contactor C1 is replaced with a diode that permits current flow from active rectifier 22 onto the positive rail 30A, but prevents current from flowing in the reverse direction from the positive rail 30A back to the active rectifier 22. Use of such a diode can improve power density in some examples.

    [0023] The load sharing / fault detection controller 40 is in communication with the individual active rectifier controllers 24, and is operable to detect a fault condition occurring in any of the generator stages 6. Upon detection of such a condition, the controller 40 commands the active rectifier 22 associated with the faulty generator stage 6 to disconnect from the DC bus 30 (e.g., by opening contactors C1, C2), and adjusts its respective corrective signals that are provided to each active rectifier 22. In the event of a fault condition that causes a generator stage 6 to be disabled, the phase shifting of the carrier signal among the remaining enabled active rectifiers 22 is also adjusted.

    [0024] The controller 40 provides a load sharing feature among the various active rectifiers 22 by providing its respective corrective signals. For example, if there are five active rectifiers 22 and one must be disabled, then the controller 40 can adjust the corrective signals so that the remaining non-disabled active rectifiers 22 still maintain a desired voltage on the DC bus 30. In some examples, the controller performs a load balancing that evenly balances a load among the non-disabled active rectifiers 22.

    [0025] The output filter 41 is shared by the plurality of active rectifiers 22A-N. The output filter 41 is situated on the DC bus 30 between the load 18 and the plurality of active rectifiers 22A-N. On each of the positive rail 30A and negative rail 30B of the DC bus 30, the output filter 41 includes a pair of inductors 42, 43. Inductor 43 is connected in parallel with a respective resistor 44 between two nodes 45, 46. Inductor 42 is connected in series to node 45. A filter capacitor 48 is connected across the DC bus 30 between the nodes 46A-B. The output filter 41 minimizes voltage ripple on the DC bus 30 and provides for stable operation in the presence of constant power loads.

    [0026] Figure 4 is a schematic view of an example active rectifier controller 24A that utilizes the corrective signal discussed above. The active rectifier controller 24A shown in Figure 4 uses a vector control technique. For the discussion below, the active rectifier controller 24A will be discussed, which is associated with generator stage 6A and active rectifier 22A. In the discussion below, the ^ symbol represents feedback and/or estimate signals, and the * symbol represents reference signals or commands.

    [0027] A summer 50 determines a difference between a voltage

    on the DC bus 30 and an output voltage dc1 of active rectifier 22A to determine a difference signal εvdc1 which is input into a proportional integrator (PI) block 52 to determine an amount of power

    that is being requested from the active rectifier 22A to support the DC load 18. A divider 53 divides the power value

    by a rotational speed NoRPM (measured in revolutions per minute "RPM") of the common shaft 8 to determine a torque value

    corresponding to a torque at the generator stage 6 operating speed. A divider 54 divides the torque value

    by a torque constant kT to obtain a quadrature current value

    which represents a quadrature component of the stator current, and which is input into summer 55.

    [0028] Individual output currents of the generator stage 6A, a1, a2, a3 and a rotational position θ of the common shaft 8 are input into an ABC to DQ transformation block 56 which performs a transformation from a stationary reference frame to a synchronous reference frame, and outputs a quadrature component current q1 and a direct component current Îd1.

    [0029] The quadrature component current q1 is input into summer 55, and is separately multiplied by a rotational speed ωrad/s of the common shaft 8, using multiplier 57, to obtain gain LS representing a synchronous inductance of the generator stage 6A, which is input into summer 68.

    [0030] The direct component current d1 is input into summer 64 and is also multiplied by a rotational speed ωrad/s of the common shaft 8, using multiplier 58, to obtain gain LS representing a synchronous inductance of the generator stage 6A, which is input into summer 60.

    [0031] The summer 55 receives quadrature current value

    quadrature component current q1, and corrective signal

    as inputs to determine a difference signal εiq1, which is input into PI block 59. The output of PI block 59 is input, along with gain LS, representing synchronous inductance, into summer 60. Summer 62 determines a difference between a voltage Vqm and the output of summer 60 to determine a quadrature voltage



    [0032] The summer 64 receives direct component current d1 and reference direct component current

    which is set to zero to allow operation at near unity power factor, to determine a difference signal εid1, which is input into PI block 66. The reference direct component

    may also be derived by use of closed loop reactive power control (not shown). The output of PI block 66 is input, along with gain LS, representing synchronous inductance, into summer 68. Summer 70 determines a difference between a voltage Vdm, which is also set to zero, and the output of summer 68 to determine a direct component voltage

    The summers 60, 62, 68, 70 and multipliers 57, 58 are part of a voltage decoupling block 71 that minimizes a coupling between the DQ current and voltage values.

    [0033] The DQ voltage values

    and

    are input, along with the rotational position θ of the common shaft 8, into a DQ to ABC transformation 72 which performs a transformation from the synchronous reference frame back into the stationary reference frame, and outputs target output voltages



    and

    The target output voltages are input, along with a carrier signal 76, into a sinusoidal pulse width modulator 74 that provides output commands to the various switches S1A-S6A of the active rectifier 22A.

    [0034] The carrier signal 76 of the first active rectifier 22A is not phase shifted, but the carrier signal 76 for the remaining N ones of the active rectifiers 22 that are enabled are phase shifted with respect to each other by an amount equal to T / N, where T is a period of the carrier signal 76 and N is a quantity of the active rectifiers 22 that are enabled (see block 78).

    [0035] The active rectifier controllers 24 for the other generator stages 6 operate in the same fashion, except that they each have their own respective adjustment signal

    and their own respective phase shift.

    [0036] Figure 5 is a schematic view of an example load sharing controller 40 that is compatible with the active rectifier controllers 24, and is operable to determine the corrective signals

    through

    for the active rectifier controllers 24 of Figure 6. Figure 5 illustrates the corrective signal determination feature of the controller 40, but not its fault detection features.

    [0037] A current Idc on the DC bus 30 is divided by a number N of enabled active rectifiers 22, using divider 79, to determine an average current Idc_ave provided by each active rectifier 22. For each of the active rectifiers 22, a respective summer 80A-N receives the average current Idc_ave and a specific current Îdc output by the active rectifier 22 as inputs, and determines a difference signal εidc. Using the example of the Nth active rectifier 22A, the specific current is dcN and the difference signal is εidcN. A respective PI block 82A-N receives the difference signal and determines a respective corrective signal

    For the Nth active rectifier 22, for example, the corrective signal is

    The respective corrective current signals

    are then provided to the respective active rectifier controllers 24.

    [0038] Figure 6 is a schematic view of an example active rectifier controller 124 that provides an alternative configuration to that shown in Figure 4. In one example, this alternative configuration corresponds to use of a diode in place of contactor C1, as discussed above. Here too, the active rectifier controller 124 will be discussed in connection with active rectifier 22A. Instead of receiving a corrective current signal

    as an input to summer 55, the active rectifier controller 124 receives a corrective voltage signal

    into summer 50. Thus, instead of determining a difference between a voltage on the DC bus 30

    and an output voltage dc1 of active rectifier 22A to determine a difference signal εvdc1, the summer 50 of Figure 6 instead determines a difference between the corrective voltage signal

    and the output voltage dc1 of active rectifier 22A to determine the difference signal εvdc1. Also, in the controller 124, summer 55 does not receive the corrective signal. Instead, it is summer 50 that receives the corrective signal. Aside from these differences, the controllers 24, 124 operate in the same manner.

    [0039] Figure 7 is a schematic view of an example load sharing controller 140 that is compatible with the active rectifier controllers 124, and is operable to determine the corrective signals

    through

    for the active rectifier controllers 124, one of which is depicted in Figure 6. Here too, the corrective signal determination features of the controller 140 are depicted, but not its fault detection features.

    [0040] Divider 79 and summers 80A-N operate the same as described above in Figure 5. In Figure 7, however, the output of PI blocks 82A-N are provided to respective summers 84A-N. Each summer 84A-N sums the output of its respective PI block 82A-N with the voltage on the DC bus 30

    to determine a respective corrective voltage signal

    through

    which allows for equal load sharing between the active rectifiers 22. The respective corrective voltage signals

    are then provided to the respective active rectifier controllers 124.

    [0041] Figure 8 is a flowchart 300 of an example method of operating an electrical power system 16. A plurality of axial flux generators 6A-N are driven through rotation of a common shaft 8 (block 302). A plurality of power converters 10, each comprising an active rectifier 22, are operated to rectify AC from a respective one of the generators 6 to DC on DC bus 30 that powers a DC load 18 (block 304). Load sharing is performed amongst the plurality of power converters 10 by providing a respective adjustment signal to each respective power converter 10 that is enabled, the respective adjustment signals based on a difference between an average output current across all of the active rectifiers that are enabled, and a particular output current of the respective power converter 10 (block 306). A quadrature current value for each power converter 10 is determined based on the adjustment signal provided to the power converter 10 (block 308).

    [0042] Referring again to Figure 2, a rotor position sensor 90, such as a Hall Effect sensor is used to detect a rotational position of the common shaft 8, and its output is communicated on sensing line 92. From this, the rotational speed of the common shaft 8 can be determined. Alternatively, a sensorless technique could be used which includes a state observer that utilizes voltages and currents of the generator stages 6, and a phase locked loop (PLL) to obtain rotor position and velocity. Because such sensorless techniques are understood by those of ordinary skill in the art, they are not discussed at length herein.

    [0043] Sensing lines 94A-N, each of which are shown schematically and may include a respective set of multiple sensing lines, provides voltage and current output information for each phase of their associated generator stage 6 to their associated active rectifier controller 24. Respective current transducers CT1, CT2, CT3 may be used to obtain the AC current values over sensing lines 94A-N.

    [0044] Sensing lines 96A-N, each of which are shown schematically and may include a respective set of multiple sensing lines, provides voltage and current values for an output of their associated active rectifier 22 to their associated active rectifier controller 24.

    [0045] Sensing line 98, which is shown schematically and may include multiple sensing lines, provides voltage and current values for the DC bus 30, after the filter circuit 41, to the load sharing / fault detection controller 40. Current transducer CT4 may be used to obtain AC current values over sensing line 98. The DC bus 30 voltage may be measured across the filter capacitor 48, for example.

    [0046] A communication bus 100 interconnects the active rectifier controllers 24A-N to controller 40 for sharing information and commands.

    [0047] The example electrical power system 16 discussed herein provides a number of benefits over prior art systems, including improvements in availability of power delivery, fault tolerance, and overall reliability. By sharing a common output filter 41 among the multiple generator stages 6, the electrical power system 16 can also reduce output filter size over prior art systems.

    [0048] The electrical power system 16 also enables scalable design through its modular construction, and the fact that the various generator stages 6 can be dynamically enabled and disabled. The load sharing features discussed above accommodate steady-state and dynamic variations in parameters of the multiple generator stages 6 and active rectifiers 22, and improve overall system performance.

    [0049] Although three phase generator stages 6A-N are described above that include three windings A, B, C and three switching legs 34-36, it is understood that this is only an example and that other quantities of phases could be used if desired (e.g., more than three or less than three).

    [0050] Although the various generator stages 6A-N have been described as being part of a single modular axial flux generator, it is understood that in some examples the generator stages 6A-N are instead discrete generators that are not part of a single, modular axial flux generator. Also, it is understood that other types of generators can be used that are driven by a common shaft other than axial flux generators.


    Claims

    1. An electrical power system comprising:

    a direct current, DC, bus (30) connected to a load (18);

    a plurality of generators (6) driven by rotation of a common shaft (8); and

    a plurality of power converters (10) characterized in that each power converter (10) comprises an active rectifier controller (24) that operates a respective active rectifier (22) to rectify alternating current, AC, from a respective one of the generators to DC on the DC bus; and said system further comprising:

    a load sharing controller (40) operable to provide a respective adjustment signal to each respective power converter that is enabled, the respective adjustment signals based on a difference between an average output current across all of the active rectifiers that are enabled, and a particular output current of the respective power converter;

    wherein each active rectifier controller is operable to determine a quadrature component current value for its associated generator based on its adjustment signal.


     
    2. The electrical power system of claim 1, comprising:
    an output filter situated on the DC bus between the load and a node that connects each of the plurality of active rectifiers that are enabled to the DC bus.
     
    3. The electrical power system of claim 2, wherein the output filter comprises a first filter on a positive rail of the DC bus, and a second filter on a negative rail of the DC bus, each of the first and second filters comprising a pair of inductors (42, 43), one of which is connected in parallel with a resistor (44) between first and second nodes, and the other which is connected in series to the first node.
     
    4. The electrical power system of claim 1, 2 or 3;
    wherein each active rectifier controller is configured to:

    determine a second quadrature component current based on feedback current values from each phase of its associated generator;

    determine a third quadrature component current based on a rotational speed of the common shaft and a difference between a DC bus voltage and an output voltage of its associated active rectifier; and
    determine a target output voltage for its active rectifier based on the first, second, and third quadrature component currents; or

    wherein the respective adjustment signal comprises a reference voltage (V*dc1,.., V*dcN); and

    wherein each active rectifier controller is configured to:

    determine a first quadrature component current based on feedback current values from each phase of its associated generator;

    determine a second quadrature component current based on a rotational speed of the common shaft and a difference between the reference voltage and an output voltage of its associated active rectifier; and

    determine a target output voltage for its active rectifier based on the first and second quadrature component currents.


     
    5. The electrical power system of any preceding claim, wherein each active rectifier controller is operable to disable its respective active rectifier based on a detected fault condition in its associated generator, and preferably wherein to disable its associated active rectifier, the active rectifier controller is configured to disconnect the active rectifier from at least one of a positive rail and a negative rail of the DC bus.
     
    6. The electrical power system of any preceding claim, wherein each active rectifier controller is operable to:

    utilize a carrier signal to perform pulse width modulation on its active rectifier; and

    phase shift its respective carrier signal relative to the other active rectifiers based on a quantity of the power converters that are enabled.


     
    7. The electrical power system of any preceding claim, wherein the plurality of active rectifiers are connected in parallel to each other on the DC bus.
     
    8. The electrical power system of any preceding claim, comprising a prime mover engine (7) that rotates the common shaft.
     
    9. The electrical power system of any preceding claim, wherein each generator is an axial flux permanent magnet generator.
     
    10. A method of operating an electrical power system, comprising:

    driving a plurality of generators (6) through rotation of a common shaft (8);

    operating a plurality of power converters (10); characterized in that each power converter (10) comprises an active rectifier (22), to rectify alternating current, AC, from a respective one of the generators to direct current, DC, on a DC bus that powers a DC load; said method further comprising:

    performing load sharing amongst the plurality of power converters by providing a respective adjustment signal to each respective power converter that is enabled, the respective adjustment signals based on a difference between an average output current across all of the active rectifiers that are enabled, and a particular output current of the respective power converter; and

    determining a quadrature component current value for the generator associated with each power converter based on the adjustment signal provided to the power converter.


     
    11. The method of claim 10, the method comprising, for each power converter:

    determining a second quadrature component current based on feedback current values from each phase of its associated generator;

    determining a third quadrature current based on a rotational speed of the common shaft and a difference between a DC bus voltage and an output voltage of its associated active rectifier; and

    determining a target output voltage for its active rectifier based on the first, second, and third quadrature component currents; or

    wherein the adjustment signal comprises a reference voltage, the method comprising, for each power converter:

    determining a first quadrature component current based on feedback current values from each phase of its associated generator;

    determining a second quadrature current based on a rotational speed of the common shaft and a difference between a the reference voltage and an output voltage of its associated active rectifier; and

    determining a target output voltage for its active rectifier based on the first and second quadrature component currents.


     
    12. The method of claim 10 or 11, comprising:

    detecting a fault condition on a given one of the generators; and

    disabling the active rectifier associated with the given generator based on said detecting, and preferably wherein disabling an active rectifier comprises disconnecting the active rectifier from at least one of a positive rail and a negative rail of the DC bus.


     
    13. The method of any of claims 10 to 12, comprising:
    phase shifting respective pulse width modulation carrier signals of the active rectifiers relative to each other based on a quantity of the active rectifiers that are enabled.
     
    14. The method of claim 13, wherein each power converter comprises a plurality of switching legs, each controlling connection of a respective stator winding of its associated generator to the DC bus, the method comprising:
    performing pulse width modulation on the plurality of switching legs based on the respective pulse width modulation carrier signals.
     
    15. The method of any of claims 10 to 14, comprising:
    filtering an output of the plurality of active rectifiers that are enabled through a shared output filter (41) that is situated on the DC bus between the load and the plurality of active rectifiers, the shared filter comprising a first filter on a positive rail of the DC bus, and a second filter on a negative rail of the DC bus, each of the first and second filters comprising a pair of inductors (42, 43), one of which is connected in parallel with a resistor (44) between first and second nodes, and the other which is connected in series to the first node.
     


    Ansprüche

    1. Elektrisches Leistungsversorgungssystem, Folgendes umfassend:

    eine Gleichstrom(DC)-Sammelschiene (30), die an einen Verbraucher (18) angeschlossen ist;

    eine Vielzahl von Generatoren (6), die durch Rotation einer gemeinsamen Welle (8) angetrieben wird; und

    eine Vielzahl von Leistungsumformern (10), dadurch gekennzeichnet, dass jeder Leistungsumformer (10) eine aktive Gleichrichtersteuerung (24) umfasst, die einen jeweiligen aktiven Gleichrichter (22) betreibt, um Wechselstrom, AC, von einem jeweiligen der Generatoren auf DC an der DC-Sammelschiene gleichzurichten; wobei das System ferner Folgendes umfasst:

    eine Lastverteilungssteuerung (40), die dazu betrieben werden kann, jedem jeweiligen Leistungsumformer, der aktiviert ist, ein jeweiliges Anpassungssignal bereitzustellen, wobei die jeweiligen Anpassungssignale auf einem Unterschied zwischen einem durchschnittlichen Ausgangsstrom über alle aktiven Gleichrichter hinweg, die aktiviert sind, und einem bestimmten Ausgangsstrom des jeweiligen Leistungsumformers basieren;

    wobei jede aktive Gleichrichtersteuerung dazu betrieben werden kann, einen Quadraturkomponenten-Stromwert für ihren zugeordneten Generator basierend auf ihrem Anpassungssignal bereitzustellen.


     
    2. Elektrisches Leistungsversorgungssystem nach Anspruch 1, Folgendes umfassend:
    einen Ausgangsfilter, der an der DC-Sammelschiene zwischen dem Verbraucher und einem Knoten angeordnet ist, der jeden der Vielzahl von aktiven Gleichrichtern, die aktiviert sind, mit der DC-Sammelschiene verbindet.
     
    3. Elektrisches Leistungsversorgungssystem nach Anspruch 2, wobei der Ausgangsfilter einen ersten Filter auf einer positiven Schiene der DC-Sammelschiene und einen zweiten Filter auf einer negativen Schiene der DC-Sammelschiene umfasst, wobei jeder von dem ersten und zweiten Filter ein Paar Induktoren (42, 43) umfasst, von denen einer mit einem Widerstand (44) zwischen dem ersten und zweiten Knoten parallel geschaltet ist und der andere mit dem ersten Knoten in Reihe geschaltet ist.
     
    4. Elektrisches Leistungsversorgungssystem nach Anspruch 1, 2 oder 3;
    wobei jede aktive Gleichrichtersteuerung zu Folgendem konfiguriert ist:

    Bestimmen eines zweiten Quadraturkomponentenstroms basierend auf Rückkopplungsstromwerten aus jeder Phase ihres zugehörigen Generators;

    Bestimmen eines dritten Quadraturkomponentenstroms basierend auf einer Drehgeschwindigkeit der gemeinsamen Welle und einem Unterschied zwischen einer DC-Sammelschienenspannung und einer Ausgangsspannung ihres zugeordneten aktiven Gleichrichters; und

    Bestimmen einer Sollausgangsspannung für ihren aktiven Gleichrichter basierend auf dem ersten, zweiten und dritten Quadraturkomponentenstrom; oder

    wobei das jeweilige Anpassungssignal eine Referenzspannung (V*dc1, ... , V*dcN) ; umfasst; und

    wobei jede aktive Gleichrichtersteuerung zu Folgendem konfiguriert ist:

    Bestimmen eines ersten Quadraturkomponentenstroms basierend auf Rückkopplungsstromwerten aus jeder Phase ihres zugehörigen Generators;

    Bestimmen eines zweiten Quadraturkomponentenstroms basierend auf einer Drehgeschwindigkeit der gemeinsamen Welle und einem Unterschied zwischen der Referenzspannung und einer Ausgangsspannung ihres zugeordneten aktiven Gleichrichters; und

    Bestimmen einer Sollausgangsspannung für ihren aktiven Gleichrichter basierend auf dem ersten, zweiten und dritten Quadraturkomponentenstrom.


     
    5. Elektrisches Leistungsversorgungssystem nach einem der vorangehenden Ansprüche, wobei jede aktive Gleichrichtersteuerung dazu betrieben werden kann, ihren jeweiligen aktiven Gleichrichter basierend auf einem erfassten Fehlerzustand in ihrem zugeordneten Generator zu deaktivieren, und wobei vorzugsweise die aktive Gleichrichtersteuerung zum Aktivieren ihres zugeordneten aktiven Gleichrichters dazu konfiguriert ist, den aktiven Gleichrichter von mindestens einer von einer positiven Schiene und einer negativen Schiene der DC-Sammelschiene zu entkoppeln.
     
    6. Elektrisches Leistungsversorgungssystem nach einem der vorangehenden Ansprüche, wobei jede aktive Gleichrichtersteuerung zu Folgendem betrieben werden kann:

    Verwenden eines Trägersignals, um eine Pulsbreitenmodulation an ihrem aktiven Gleichrichter durchzuführen; und

    Phasenverschieben ihres jeweiligen Trägersignals relativ zu den anderen aktiven Gleichrichtern basierend auf einer Anzahl von Leistungsumformern, die aktiviert sind.


     
    7. Elektrisches Leistungsversorgungssystem nach einem der vorangehenden Ansprüche, wobei die Vielzahl von aktiven Gleichrichtern parallel zueinander auf der DC-Sammelschiene geschaltet sind.
     
    8. Elektrisches Leistungsversorgungssystem nach einem der vorangehenden Ansprüche, umfassend eine Antriebsmaschine (7), die die gemeinsame Welle dreht.
     
    9. Elektrisches Leistungsversorgungssystem nach einem der vorangehenden Ansprüche, wobei jeder Generator ein Dauermagnetgenerator mit axialem Fluss ist.
     
    10. Verfahren zum Betreiben eines elektrischen Leistungsversorgungssystems, Folgendes umfassend:

    Antreiben einer Vielzahl von Generatoren (6) durch Rotation einer gemeinsamen Welle (8);

    Betreiben einer Vielzahl von Leistungsumformern (10); dadurch gekennzeichnet, dass jeder Leistungsumformer (10) einen aktiven Gleichrichter (22) umfasst, um Wechselstrom, AC, von einem jeweiligen der Generatoren auf Gleichstrom, DC, an der DC-Sammelschiene gleichzurichten; wobei das Verfahren ferner Folgendes umfasst:

    Durchführen einer Lastverteilung unter der Vielzahl von Leistungsumformern durch Bereitstellen eines jeweiligen Anpassungssignals, wobei die jeweiligen Anpassungssignale auf einem Unterschied zwischen einem durchschnittlichen Ausgangsstrom über alle aktiven Gleichrichter hinweg, die aktiviert sind, und einem bestimmten Ausgangsstrom des jeweiligen Leistungsumformers basieren; und

    Bestimmen eines Quadraturkomponenten-Stromwerts für den Generator, der jedem Leistungsumformer zugeordnet ist, basierend auf dem Anpassungssignal, das dem Leistungsumformer bereitgestellt wird.


     
    11. Verfahren nach Anspruch 10, wobei das Verfahren für jeden Leistungsumformer Folgendes umfasst:

    Bestimmen eines zweiten Quadraturkomponentenstroms basierend auf Rückkopplungsstromwerten aus jeder Phase seines zugehörigen Generators;

    Bestimmen eines dritten Quadraturkomponentenstroms basierend auf einer Drehgeschwindigkeit der gemeinsamen Welle und einem Unterschied zwischen einer DC-Sammelschienenspannung und einer Ausgangsspannung seines zugeordneten aktiven Gleichrichters; und

    Bestimmen einer Sollausgangsspannung für seinen aktiven Gleichrichter basierend auf dem ersten, zweiten und dritten Quadraturkomponentenstrom; oder

    wobei das Anpassungssignal eine Referenzspannung umfasst, wobei das Verfahren für jeden Leistungsumformer Folgendes umfasst:

    Bestimmen eines ersten Quadraturkomponentenstroms basierend auf Rückkopplungsstromwerten aus jeder Phase seines zugehörigen Generators;

    Bestimmen eines zweiten Quadraturkomponentenstroms basierend auf einer Drehgeschwindigkeit der gemeinsamen Welle und einem Unterschied zwischen der Referenzspannung und einer Ausgangsspannung des zugeordneten aktiven Gleichrichters; und

    Bestimmen einer Sollausgangsspannung für seinen aktiven Gleichrichter basierend auf dem ersten, zweiten und dritten Quadraturkomponentenstrom.


     
    12. Verfahren nach Anspruch 10 oder 11, Folgendes umfassend:

    Erfassen eines Fehlerzustands bei einem gegebenen der Generatoren; und

    Deaktivieren des aktiven Gleichrichters, der dem gegebenen Generator zugeordnet ist, basierend auf dem Erfassen, und wobei vorzugsweise das Deaktivieren eines aktiven Gleichrichters das Entkoppeln des aktiven Gleichrichters von mindestens einer von einer positiven Schiene und einer negativen Schiene der DC-Sammelschiene umfasst.


     
    13. Verfahren nach einem der Ansprüche 10 bis 12, Folgendes umfassend:
    Phasenverschieben von jeweiligen Pulsbreitenmodulation-Trägersignalen der aktiven Gleichrichter relativ zueinander basierend auf einer Anzahl von aktiven Gleichrichtern, die aktiviert sind.
     
    14. Verfahren nach Anspruch 13, wobei jeder der Leistungsumformer eine Vielzahl von Schaltschenkeln umfasst, von denen jeder die Verbindung einer jeweiligen Statorwicklung seines zugeordneten Generators mit der DC-Sammelschiene steuert, wobei das Verfahren Folgendes umfasst:
    Durchführen einer Pulsbreitenmodulation an der Vielzahl von Schaltschenkeln basierend auf den jeweiligen Pulsbreitenmodulation-Trägersignalen.
     
    15. Verfahren nach einem der Ansprüche 10 bis 14, Folgendes umfassend:
    Filtern einer Ausgabe der Vielzahl aktiver Gleichrichter, die aktiviert sind, durch einen geteilten Ausgangsfilter (41), der auf der DC-Sammelschiene zwischen einem Verbraucher und der Vielzahl von aktiven Gleichrichtern angeordnet sind, wobei der geteilte Filter einen ersten Filter auf einer positiven Schiene der DC-Sammelschiene und einen zweiten Filter auf einer negativen Schiene der DC-Sammelschiene umfasst, wobei jeder von dem ersten und zweiten Filter ein Paar Induktoren (42, 43) umfasst, von denen einer mit einem Widerstand (44) zwischen dem ersten und zweiten Knoten parallel geschaltet ist und der andere mit dem ersten Knoten in Reihe geschaltet ist.
     


    Revendications

    1. Système d'alimentation électrique comprenant :
    un bus (30) à courant continu, CC, connecté à une charge (18) :

    une pluralité de générateurs (6) entraînés par rotation d'un arbre commun (8) ; et

    une pluralité de convertisseurs de puissance (10) caractérisés en ce que chaque convertisseur de puissance (10) comprend un contrôleur de redresseurs actifs (24) qui actionne un redresseur actif respectif (22) pour rectifier le courant alternatif, CA, d'un générateur respectif des générateurs à CC sur le bus CC ; ledit système comprenant en outre :

    un contrôleur de répartition de charge (40) permettant de fournir un signal d'ajustement respectif à chaque convertisseur de puissance respectif qui est activé, les signaux d'ajustement respectifs étant basés sur une différence entre un courant de sortie moyen à travers tous les redresseurs actifs qui sont activés, et un courant de sortie particulier du convertisseur de puissance respectif ;

    dans lequel chaque contrôleur de redresseurs actifs permet de déterminer une valeur de courant de composante en quadrature pour son générateur associé en fonction de son signal de réglage.


     
    2. Système d'alimentation électrique selon la revendication 1, comprenant :
    un filtre de sortie situé sur le bus CC entre la charge et un nœud qui connecte chacun de la pluralité de redresseurs actifs qui sont activés au bus CC.
     
    3. Système d'alimentation électrique selon la revendication 2, dans lequel le filtre de sortie comprend un premier filtre sur un rail positif du bus CC, et un deuxième filtre sur un rail négatif du bus CC, chacun des premier et deuxième filtres comprenant une paire d'inducteurs (42, 43), dont l'un est connecté en parallèle avec une résistance (44) entre les premier et deuxième nœuds, et dont l'autre est connecté en série au premier nœud.
     
    4. Système d'alimentation électrique selon la revendication 1, 2 ou 3 ;
    dans lequel chaque contrôleur de redresseurs actifs est configuré pour :

    déterminer un deuxième courant de composante en quadrature en fonction des valeurs de courant de rétroaction à partir de chaque phase de son générateur associé ;

    déterminer un troisième courant de composante en quadrature en fonction d'une vitesse de rotation de l'arbre commun et d'une différence entre une tension de bus CC et une tension de sortie de son redresseur actif associé ; et

    déterminer une tension de sortie cible pour son redresseur actif en fonction des premier, deuxième et troisième courants de composante en quadrature ; ou

    dans lequel le signal de réglage respectif comprend une tension de référence (V*dc1,..., V*dcN) ; et

    dans lequel chaque contrôleur de redresseurs actifs est configuré pour :

    déterminer un premier courant de composante en quadrature en fonction des valeurs de courant de rétroaction à partir de chaque phase de son générateur associé;

    déterminer un deuxième courant de composante en quadrature en fonction d'une vitesse de rotation de l'arbre commun et d'une différence entre la tension de référence et une tension de sortie de son redresseur actif associé ; et

    déterminer une tension de sortie cible pour son redresseur actif en fonction du premier et du deuxième courants de composante en quadrature.


     
    5. Système d'alimentation électrique selon l'une quelconque des revendications précédentes, dans lequel chaque contrôleur de redresseurs actifs permet de désactiver son redresseur actif respectif en fonction d'une condition de défaut détectée dans son générateur associé, et de préférence dans lequel, pour désactiver son redresseur actif associé, le contrôleur de redresseurs actifs est configuré pour déconnecter le redresseur actif d'au moins l'un d'un rail positif et d'un rail négatif du bus CC.
     
    6. Système d'alimentation électrique selon l'une quelconque des revendications précédentes, dans lequel chaque contrôleur de redresseurs actifs permet de :

    utiliser un signal porteur pour effectuer une modulation de largeur d'impulsion sur son redresseur actif ; et

    déphaser son signal porteur respectif par rapport aux autres redresseurs actifs en fonction d'une quantité de convertisseurs de puissance activés.


     
    7. Système d'alimentation électrique selon l'une quelconque des revendications précédentes, dans lequel les différents redresseurs actifs sont connectés en parallèle les uns aux autres sur le bus CC.
     
    8. Système d'alimentation électrique selon l'une quelconque des revendications précédentes, comprenant un moteur d'entraînement (7) qui fait tourner l'arbre commun.
     
    9. Système d'alimentation électrique selon l'une quelconque des revendications précédentes, dans lequel chaque générateur est un générateur à aimant permanent à flux axial.
     
    10. Procédé de fonctionnement d'un système d'alimentation électrique, consistant à :
    entraîner une pluralité de générateurs (6) par rotation d'un arbre commun (8) ; faire fonctionner une pluralité de convertisseurs de puissance (10); caractérisée en ce que chaque convertisseur de puissance (10) comprend un redresseur actif (22) pour rectifier le courant alternatif, CA, de l'un respectif des générateurs au courant continu, CC, sur un bus CC qui alimente une charge CC ; ledit procédé consistant en outre à :

    effectuer une répartition de charge entre les différents convertisseurs de puissance en fournissant un signal de réglage respectif à chaque convertisseur de puissance respectif qui est activé, les signaux de réglage respectifs étant établis en fonction d'une différence entre un courant de sortie moyen à travers tous les redresseurs actifs qui sont activés, et un courant de sortie particulier du convertisseur de puissance respectif ; et

    déterminer une valeur de courant de composante en quadrature pour le générateur associé à chaque convertisseur de puissance en fonction du signal de réglage fourni au convertisseur de puissance.


     
    11. Procédé selon la revendication 10, le procédé consistant, pour chaque convertisseur de puissance, à :

    déterminer un deuxième courant de composante en quadrature en fonction de valeurs de courant de rétroaction à partir de chaque phase de son générateur associé ;

    déterminer un troisième courant de composante en quadrature en fonction d'une vitesse de rotation de l'arbre commun et d'une différence entre une tension de bus CC et une tension de sortie de son redresseur actif associé ; et

    déterminer une tension de sortie cible pour son redresseur actif en fonction des premier, deuxième et troisième courants de composante en quadrature ; ou

    dans lequel le signal de réglage comprend une tension de référence, le procédé consistant, pour chaque convertisseur de puissance, à :

    déterminer un premier courant de composante en quadrature en fonction de valeurs de courant de rétroaction à partir de chaque phase de son générateur associé ;

    déterminer un deuxième courant de composante en quadrature en fonction d'une vitesse de rotation de l'arbre commun et d'une différence entre la tension de référence et une tension de sortie de son redresseur actif associé ; et

    déterminer une tension de sortie cible pour son redresseur actif en fonction des premier et deuxième courants de composante en quadrature.


     
    12. Procédé selon la revendication 10 ou 11, consistant à :

    détecter une condition de panne sur un générateur donné parmi les générateurs ; et

    désactiver le redresseur actif associé au générateur donné en fonction de ladite détection, la désactivation d'un redresseur actif comprenant de préférence la déconnexion du redresseur actif d'au moins l'un d'un rail positif et d'un rail négatif du bus CC.


     
    13. Procédé selon l'une quelconque des revendications 10 à 12, consistant à :
    déphaser des signaux porteurs respectifs de modulation de largeur d'impulsion des redresseurs actifs les uns par rapport aux autres en fonction du nombre de redresseurs actifs qui sont activés.
     
    14. Procédé selon la revendication 13, dans lequel chaque convertisseur de puissance comprend une pluralité de branches de commutation, chacune contrôlant la connexion d'un enroulement de stator respectif de son générateur associé au bus CC, le procédé consistant à :
    effectuer une modulation de largeur d'impulsion sur la pluralité des branches de commutation en fonction des signaux respectifs porteurs de modulation de largeur d'impulsion.
     
    15. Procédé selon l'une quelconque des revendications 10 à 14, consistant à :
    filtrer une sortie de la pluralité de redresseurs actifs qui sont activés au moyen d'un filtre de sortie partagé (41) qui est situé sur le bus CC, entre la charge et la pluralité de redresseurs actifs, le filtre partagé comprenant un premier filtre sur un rail positif du bus CC, et un deuxième filtre sur un rail négatif du bus CC, chacun des premier et deuxième filtres comprenant une paire d'inducteurs (42, 43), dont l'un est connecté en parallèle avec une résistance (44) entre les premier et deuxièmes nœuds, et dont l'autre est connecté en série au premier nœud.
     




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    Cited references

    REFERENCES CITED IN THE DESCRIPTION



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    Patent documents cited in the description