Control device, program, and control method

Abstract

The present invention provides a control device that can suppress a decrease in the operating efficiency of the system. [Solution] The control device 70 is applied to a power supply system 100 comprising a first module 10A and a second module 10B. The control device 70 controls the first power converter 21A and the second power converter 21B to create an output difference between the first power converter 21A and the second power converter 21B. Each power converter 21A, 21B has the characteristic that, in the relationship between the operating point and power conversion efficiency, the power conversion efficiency decreases on the lower output side and the higher output side than a predetermined operating point. The control device 70 includes a command setting unit 71 that sets an output command value for each power converter 21A, 21B so that when an output difference is created, each power converter 21A, 21B operates within a predetermined high-efficiency operating region including a predetermined operating point, and first and second control units 72A, 72B that control each power converter 21A, 21B based on the set output command value.

Description

Technical Field

[0007] ,

[0001] The present disclosure relates to a control device, a program, and a control method.

Background Art

[0002] Conventionally, a system including a power converter that performs power conversion between a plurality of power storage units has been known. As an example of such a technology, the technology disclosed in Patent Document 1 can be cited.

Prior Art Document

Patent Document

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0008] In this disclosure, when an output difference is generated between the power converters, the output command value of each power converter is set so that each power converter operates within a high-efficiency operating region. With a configuration in which each power converter is controlled based on the set output command value, each power converter can be operated at an operating point with higher power conversion efficiency compared to a comparative example in which an output difference is generated without restrictions on the operating point of each power converter. As a result, the operating efficiency of the system can be improved. [Brief explanation of the drawing]

[0009] [Figure 1] Overall configuration diagram of the power supply system according to the first embodiment. [Figure 2] A diagram showing an example of a power converter. [Figure 3] A diagram showing the relationship between the operating point of a power converter and its power conversion efficiency. [Figure 4] A flowchart showing the control process steps executed by the control device. [Figure 5] A time chart showing an example of power supply system operation. [Figure 6]A diagram showing an example of the operating point of each power converter shifting. [Figure 7] A diagram showing an example of the operating point of each power converter according to a modification of the first embodiment. [Figure 8] A diagram for explaining a method of setting a current lower limit value. [Figure 9] A diagram for explaining a method of setting a current lower limit value. [Figure 10] A flowchart showing a control processing procedure executed by a control device according to the second embodiment. [Figure 11] A diagram showing an example of the operating point of each power converter. [Figure 12] An overall configuration diagram of a power supply system according to the third embodiment. [Figure 13] A flowchart showing a control processing procedure executed by a control device. [Figure 14] A configuration diagram of a module according to other embodiments.

Modes for Carrying Out the Invention

[0010] A plurality of embodiments will be described while referring to the drawings. In a plurality of embodiments, parts that are functionally and / or structurally corresponding and / or associated may be assigned the same reference numerals, or reference numerals with different hundreds or more digits. For corresponding parts and / or associated parts, the description of other embodiments can be referred to.

[0011] <First Embodiment> Hereinafter, a first embodiment in which a control device according to the present disclosure is embodied will be described while referring to the drawings. In the present embodiment, the control device is applied to an in-vehicle power supply system. The power supply system is mounted on an electric vehicle having a motor as a driving power source.

[0012] As shown in FIG. 1, the power supply system 100 includes a plurality of modules 10A and 10B. In this embodiment, the power supply system 100 includes two modules, specifically, a first module 10A (corresponding to the "first power supply unit") and a second module 10B (corresponding to the "second power supply unit"). The first and second modules 10A and 10B include storage batteries 11A and 11B. The storage batteries 11A and 11B are secondary batteries such as lithium-ion batteries or nickel-metal hydride batteries, for example. In this embodiment, the rated voltages of the storage batteries 11A and 11B are the same value (for example, 400V).

[0013] The power supply system 100 includes a main high-potential path 30, a main low-potential path 31, and an electrical load 12. The electrical load 12 is connected to the main high-potential path 30 and the main low-potential path 31.

[0014] The positive electrode sides of the respective modules 10A and 10B are connected to the main high-potential path 30. The negative electrode sides of the respective modules 10A and 10B are connected to the main low-potential path 31. As a result, the respective modules 10A and 10B are connected in parallel to the electrical load 12.

[0015] In this embodiment, the electrical load 12 includes a three-phase inverter 13 and a rotating electric machine 14. The rotating electric machine 14 has as many armature windings as the number of phases electrically connected to the inverter 13. The inverter 13 controls the current flowing through each phase winding. The rotating electric machine 14 is an in-vehicle main machine, and the rotor of the rotating electric machine 14 is capable of power transmission to the drive wheels of the vehicle. The rotating electric machine 14 is, for example, a permanent magnet synchronous machine.

[0016] The inverter 13 converts the DC power supplied from the respective modules 10A and 10B into AC power and supplies the power to each phase winding of the rotating electric machine 14. In this case, the rotating electric machine 14 becomes a driving power source for the vehicle. Further, the rotating electric machine 14 performs regenerative power generation by the rotational force applied to the rotor. The inverter 13 converts the generated AC power into DC power and outputs the power to the respective modules 10A and 10B.

[0017] Each module 10A and 10B is equipped with power converters 21A and 21B. Hereinafter, the battery 11A and power converter 21A of the first module 10A will be referred to as "first battery 11A" and "first power converter 21A," and the battery 11B and power converter 21B of the second module 10B will be referred to as "second battery 11B" and "second power converter 21B." The first battery 11A corresponds to the "first energy storage unit," and the second battery 11B corresponds to the "second energy storage unit."

[0018] The connection relationship between the battery and the power converter in each module 10A and 10B will be explained in detail. The configurations of modules 10A and 10B are basically the same. Therefore, the following explanation will focus on module 10A.

[0019] Figure 2 shows an example of the first power converter 21A. The first power converter 21A is a center-tapped, isolated DC-DC converter. The first power converter 21A comprises a primary circuit 51 and a secondary circuit 52. As shown in Figures 1 and 2, the primary circuit 51 has a first high-potential terminal 41A and a first low-potential terminal 42A. The first high-potential terminal 41A is connected to the positive terminal side of the first battery 11A. The first low-potential terminal 42A is connected to the negative terminal side of the first battery 11A. Thus, the primary circuit 51 is connected in parallel to the first battery 11A.

[0020] The secondary circuit 52 has a second high-potential terminal 43A and a second low-potential terminal 44A. The second high-potential terminal 43A is connectable to the electrical load 12 via the main high-potential path 30. The second low-potential terminal 44A is connected to the positive side and the first high-potential terminal 41A of the first battery 11A. As a result, the secondary circuit 52 is connected in series with the first battery 11A on the positive side of the first battery 11A. The negative side of the first battery 11A is connectable to the electrical load 12 via the main low-potential path 31. In this embodiment, the second high-potential terminal 43A corresponds to the "output terminal" and the second low-potential terminal 44A corresponds to the "connection terminal".

[0021] As shown in Figure 2, the primary circuit 51 includes first and second upper arm switches S1H and S2H, and first and second lower arm switches S1L and S2L as primary switches. In this embodiment, the first and second upper arm switches S1H and S2H and the first and second lower arm switches S1L and S2L are semiconductor switching elements, more specifically N-channel MOSFETs. Each switch S1H, S2H, S1L, and S2L has a body diode D1H, D2H, D1L, and D2L.

[0022] The first high-potential terminal 41A is connected to the drain of the first upper arm switch S1H and the drain of the second upper arm switch S2H. The source of the first upper arm switch S1H is connected to the drain of the first lower arm switch S1L. The source of the second upper arm switch S2H is connected to the drain of the second lower arm switch S2L. The first low-potential terminal 42A is connected to the source of the first lower arm switch S1L and the source of the second lower arm switch S2L.

[0023] The secondary circuit 52 includes a first switch SA and a second switch SB as secondary switches, and a reactor 53. In this embodiment, the first and second switches SA and SB are semiconductor switching elements, more specifically N-channel MOSFETs. The first and second switches SA and SB also have body diodes DA and DB. Note that each switch S1H, S2H, S1L, S2L, SA, and SB may be, for example, an N-channel IGBT. In this case, a freewheeling diode is connected in antiparallel to each switch S1H, S2H, S1L, S2L, SA, and SB.

[0024] The first power converter 21A includes an isolation transformer 60 that connects the primary circuit 51 and the secondary circuit 52. The isolation transformer 60 includes a primary coil 60a and a secondary coil 60b having a center tap 60c. The primary coil 60a and the secondary coil 60b are wound around a common core. As a result, the primary coil 60a and the secondary coil 60b are magnetically coupled by the common core. The first end of the primary coil 60a is connected to the connection point between the first upper arm switch S1H and the first lower arm switch S1L. The second end of the primary coil 60a is connected to the connection point between the second upper arm switch S2H and the second lower arm switch S2L.

[0025] The first end of the secondary coil 60b is connected to the source of the first switch SA. The drain of the first switch SA is connected to the first end of the reactor 53. The second end of the secondary coil 60b is connected to the source of the second switch SB. The drain of the second switch SB is connected to the first end of the reactor 53. The second end of the reactor 53 is connected to the second high-potential terminal 43A. The center tap 60c of the secondary coil 60b is connected to the second low-potential terminal 44A.

[0026] The primary circuit 51 includes a first capacitor 54. The first capacitor 54 connects a first high-potential terminal 41A and a first low-potential terminal 42A. The secondary circuit 52 includes a second capacitor 55. The second capacitor 55 connects a second high-potential terminal 43A and a second low-potential terminal 44A.

[0027] The second power converter 21B, like the first power converter 21A, is a center-tapped isolated DC-DC converter and comprises a primary circuit, a secondary circuit, and an isolated transformer. The configuration of the second power converter 21B is the same as that of the first power converter 21A, so a detailed explanation is omitted. Each power converter 21A and 21B is also referred to as a partial power converter (PPC). Each power converter 21A and 21B is controlled by the control device 70 provided in the power supply system 100.

[0028] As shown in Figure 1, the primary circuit of the second power converter 21B has a first high-potential terminal 41B and a first low-potential terminal 42B. The secondary circuit of the second power converter 21B has a second high-potential terminal 43B and a second low-potential terminal 44B. In the second module 10B, the connection relationships between each terminal 41B to 44B of the second power converter 21B, the second storage battery 11B, and the electrical load 12 are the same as in the first module 10A, so a detailed explanation of the connection relationships is omitted.

[0029] The first module 10A is equipped with first and second changeover switches 61A and 62A. The second module 10B is equipped with third and fourth changeover switches 61B and 62B. Each changeover switch 61A, 61B, 62A, and 62B is a switch for switching the energization and disconnection of each module 10A and 10B from the electrical load 12. Each changeover switch 61A, 61B, 62A, and 62B is, for example, a mechanical relay or a semiconductor switching element.

[0030] The first changeover switch 61A is located in the main high-potential path 30, in the portion between the second high-potential terminal 43A of the first power converter 21A and the electrical load 12. The second changeover switch 62A is located in the main low-potential path 31, in the portion between the connection point with the first low-potential terminal 42A of the first power converter 21A and the electrical load 12.

[0031] The third changeover switch 61B is located in the main high-potential path 30, between the second high-potential terminal 43B of the second power converter 21B and the electrical load 12. The fourth changeover switch 62B is located in the main low-potential path 31, between the connection point with the first low-potential terminal 42B of the second power converter 21B and the electrical load 12.

[0032] The first module 10A is equipped with a first short-circuit switch 63A. The first short-circuit switch 63A connects the second high-potential terminal 43A and the second low-potential terminal 44A of the first power converter 21A. The second module 10B is equipped with a second short-circuit switch 63B. The second short-circuit switch 63B connects the second high-potential terminal 43B and the second low-potential terminal 44B of the second power converter 21B. Each short-circuit switch 63A, 63B is, for example, a mechanical relay or a semiconductor switching element. In each module 10A, 10B, when the short-circuit switches 63A, 63B are turned on, the second high-potential terminals 43A, 43B and the second low-potential terminals 44A, 44B are electrically short-circuited. In each module 10A, 10B, when the short-circuit switches 63A, 63B are turned off, the second high-potential terminals 43A, 43B and the second low-potential terminals 44A, 44B are electrically connected via the secondary circuits of the power converters 21A, 21B. Each switch 61A, 61B, 62A, 62B, 63A, 63B is turned on and off by the control device 70.

[0033] The power supply system 100 includes a battery voltage sensor 90, a battery current sensor 91, and a load current sensor 92. The battery voltage sensor 90 detects the voltages VbatA and VbatB of each battery 11A and 11B. The battery current sensor 91 detects the current flowing through each battery 11A and 11B. The load current sensor 92 detects the load current Io flowing through the electrical load 12. The detected values ​​from each sensor 90 to 92 are input to the control device 70.

[0034] The control device 70 is an electronic control unit (ECU) that performs various controls on the power supply system 100, and includes a processor and memory unit as hardware. In the power supply system 100, each device can be controlled by the ECU corresponding to the inverter 13 and each power converter 21A, 21B as described above. However, for convenience, Figure 1 shows multiple ECUs as a single control device 70.

[0035] The memory unit of the control device 70 includes memory and storage as hardware. The memory is a storage device for storing data used in the processing of the control device 70. The memory provides the processor with a workspace for temporary use when the processor is performing processing. The memory includes, for example, ROM or RAM. The storage is a storage device that stores various programs and data for the processor to read and execute, and is a non-transitory tangible storage medium. The storage includes, for example, an HDD or flash memory. The storage stores program information for processing, such as those shown in Figures 4, 10, and 13 described later.

[0036] For example, program information stored on a non-transitional physical recording medium is installed in the storage unit of the control device 70. The recording medium is, for example, a USB memory stick, CD-ROM, or DVD. In addition, program information transmitted via a communication network, such as OTA (Over The Air), is also installed in the storage unit.

[0037] The control device 70 includes a command setting unit 71, a first control unit 72A, and a second control unit 72B, as configurations for controlling the output power of each power converter 21A, 21B.

[0038] The command setting unit 71 sets command voltages VAc and VBc (corresponding to "output command values") that command the secondary voltages VA and VB of each power converter 21A and 21B. In each power converter 21A and 21B, the secondary voltages VA and VB are the voltages applied between the second high-potential terminals 43A and 43B and the second low-potential terminals 44A and 44B.

[0039] For example, the command setting unit 71 sets the command voltages VAc and VBc of each power converter 21A and 21B so that the output voltages of each module 10A and 10B are the same. The output voltage of the first module 10A is the sum of the voltage VbatA of the first battery 11A and the secondary voltage VA of the first power converter 21A. The output voltage of the second module 10B is the sum of the voltage VbatB of the second battery 11B and the secondary voltage VB of the second power converter 21B.

[0040] The first control unit 72A receives the command voltage VAc set by the command setting unit 71. The first control unit 72A performs switching control of the first power converter 21A so that the secondary voltage VA of the first power converter 21A is set to the command voltage VAc. The second control unit 72B receives the command voltage VBc set by the command setting unit 71. The second control unit 72B performs switching control of the second power converter 21B so that the secondary voltage VB of the second power converter 21B is set to the command voltage VBc.

[0041] The control device 70 controls the output power of each power converter 21A, 21B so as to create an output difference between them. For example, there may be a difference in the State of Charge (SOC) (corresponding to "storage amount") in each battery 11A, 11B. In this case, the control device 70 creates a difference in the secondary currents IA and IB of each power converter 21A, 21B in order to reduce the SOC difference between each battery 11A, 11B. The secondary currents IA and IB of each power converter 21A, 21B are, for example, the currents flowing to the second high-potential terminals 43A and 43B. In each module 10A, 10B, the secondary currents IA and IB flow in the direction of discharging the batteries 11A, 11B or in the direction of charging the batteries 11A, 11B. The control in the case of creating an output difference between each power converter 21A, 21B will be described below.

[0042] The control device 70 comprises an acquisition unit 73 and a processing unit 74. The acquisition unit 73 acquires the amount of charge stored in each of the batteries 11A and 11B. In this embodiment, the acquisition unit 73 receives the detected value from the battery voltage sensor 90 and the detected value from the battery current sensor 91 as input. Based on the detected values ​​from the input sensors 90 and 91, the acquisition unit 73 calculates the State of Charge (SOC) of the first battery 11A (hereinafter referred to as "first calculated value SOCA") and the SOC of the second battery 11B (hereinafter referred to as "second calculated value SOCB"). The acquisition unit 73 acquires the first and second calculated values ​​SOCA and SOCB as the amount of charge stored in the first and second batteries 11A and 11B.

[0043] The processing unit 74 receives the calculated values ​​SOCA and SOCB obtained by the acquisition unit 73. The processing unit 74 determines whether the difference in stored energy ΔSOC, which is the difference between the calculated values ​​SOCA and SOCB, is greater than the determination value TH.

[0044] The command setting unit 71 sets the command voltages VAc and VBc of each power converter 21A and 21B to create a difference in the secondary currents IA and IB, provided that the processing unit 74 determines that the difference in stored energy ΔSOC is greater than the determination value TH. For example, if the SOC of the first battery 11A is higher than the SOC of the second battery 11B, the command setting unit 71 sets the command voltages VAc and VBc of each power converter 21A and 21B to be greater than the secondary current IA of the first power converter 21A and IB of the second power converter 21B. As a result, the power supplied from the first module 10A to the electrical load 12 is higher than that supplied from the second module 10B. Consequently, the SOC difference between each battery 11A and 11B can be reduced.

[0045] Incidentally, when generating an output difference between the power converters 21A and 21B, the power converters 21A and 21B are operated at different operating points. In this case, the power conversion efficiency η of at least one of the power converters 21A and 21B may decrease.

[0046] The power conversion efficiencies ηA and ηB of each power converter 21A and 21B vary depending on the operating point of each power converter 21A and 21B. The operating points of each power converter 21A and 21B are determined by the secondary voltages VA and VB and the secondary currents IA and IB. When the secondary voltages VA and VB of each power converter 21A and 21B are constant and the secondary currents IA and IB change, the power conversion efficiencies ηA and ηB of each power converter 21A and 21B tend to follow the trend shown in Figure 3. More specifically, the power conversion efficiencies ηA and ηB of each power converter 21A and 21B decrease at both the lower and higher output sides compared to a predetermined efficiency peak current Ip. At the lower output side compared to the efficiency peak current Ip, the decrease in power conversion efficiencies ηA and ηB with respect to the secondary currents IA and IB is more pronounced compared to the higher output side compared to the efficiency peak current Ip. In this case, the power conversion efficiency η may decrease significantly in the low-power converter among the power converters 21A and 21B.

[0047] The reason why the degree of decrease in power conversion efficiency ηA and ηB differs between the lower and higher output sides of the efficiency peak current Ip is that the main causes of power loss differ between the region below the efficiency peak current Ip and the region above the efficiency peak current Ip. In the region below the efficiency peak current Ip, the ratio of the switching loss of each power converter 21A and 21B to the input power of each power converter 21A and 21B increases, causing the power conversion efficiency ηA and ηB to decrease. In the region above the efficiency peak current Ip, the conduction loss increases due to the increase in the secondary currents IA and IB of each power converter 21A and 21B, causing the power conversion efficiency ηA and ηB to decrease.

[0048] There are concerns that the operating efficiency of the power supply system 100 is low due to the low power conversion efficiency η of at least one of the power converters 21A and 21B.

[0049] In detail, the overall efficiency ηt of each power converter 21A and 21B is expressed as shown in equation (1) below, where PA is the output power of the first power converter 21A and PB is the output power of the second power converter 21B.

[0050] ηt=(PA+PB) / (PA / ηA+PB / ηB) (1) In equation (1) above, ηA is the power conversion efficiency of the first power converter 21A, and ηB is the power conversion efficiency of the second power converter 21B. The lower at least one of the power conversion efficiencies ηA and ηB becomes, the lower the overall efficiency ηt becomes. Therefore, there is concern that the operating efficiency of the power supply system 100 is low due to at least one of the power conversion efficiencies ηA and ηB being low.

[0051] Therefore, the command setting unit 71 sets the command voltages VAc and VBc for each power converter 21A and 21B so that each power converter 21A and 21B operates within the high-efficiency operating region Ra. The high-efficiency operating region Ra is the region on the high-output side with respect to the efficiency peak current Ip, as shown in Figure 3. In other words, the current lower limit IL (corresponding to the "output lower limit") when each power converter 21A and 21B is operated within the high-efficiency operating region Ra is set to the efficiency peak current Ip. Note that on the high-output side with respect to the efficiency peak current Ip, the decrease in power conversion efficiency η is more gradual than on the low-output side with respect to the efficiency peak current Ip, so it is not necessary to set current upper limits for the secondary currents IA and IB of each power converter 21A and 21B in the high-efficiency operating region Ra.

[0052] Specifically, the command setting unit 71 sets the command voltages VAc and VBc of each power converter 21A and 21B to satisfy the following first and second conditions when the SOC of the first battery 11A is higher than the SOC of the second battery 11B. The first condition is that the secondary current IA of the first power converter 21A is greater than the secondary current IB of the second power converter 21B. The second condition is that the secondary currents IA and IB of each power converter 21A and 21B are greater than the current lower limit value IL.

[0053] The command setting unit 71 sets the command voltages VAc and VBc of each power converter 21A and 21B to satisfy the second condition above and the following third condition, when the SOC of the second battery 11B is higher than the SOC of the first battery 11A. The third condition is that the secondary current IB of the second power converter 21B is greater than the secondary current IA of the first power converter 21A.

[0054] Due to the small load current Io flowing through the electrical load 12, it may not be possible to set the secondary currents IA and IB of each power converter 21A and 21B to a value greater than the current lower limit IL. In this case, it is possible to supply the load current Io to the electrical load 12 from only one of the power converters 21A or 21B to avoid the power converters operating at an inefficient operating point.

[0055] The control device 70 includes a power determination unit 75 and a switch control unit 76. The power determination unit 75 determines whether the power condition is met, which is that the required drive power required for the electrical load 12 is lower than the total power that can be output when each power converter 21A, 21B is operated at the lower current limit IL. In this embodiment, the power determination unit 75 determines that the power condition is met when it determines that the load current Io flowing through the electrical load 12 is less than the total current "2 × IL" (i.e., "2 × Ip") that can be output when each power converter 21A, 21B is operated at the lower current limit IL.

[0056] If the power determination unit 75 determines that the power conditions are met, the switch control unit 76 turns on only one of the first and second changeover switches 61A and 62A, or the third and fourth changeover switches 61B and 62B. If the power determination unit 75 determines that the power conditions are met, the command setting unit 71 sets the command voltage so that only the power converter of the module whose changeover switch is turned on among the modules 10A and 10B is operated.

[0057] If the power determination unit 75 determines that the power conditions are not met, the switch control unit 76 turns on each of the changeover switches 61A, 61B, 62A, and 62B. If the power determination unit 75 determines that the power conditions are not met, the command setting unit 71 sets the command voltages VAc and VBc of each power converter 21A and 21B so that each power converter 21A and 21B operates within the high-efficiency operating region Ra.

[0058] Figure 4 shows the control process performed by the control device 70. This control is executed repeatedly at predetermined intervals.

[0059] In step S10, the acquisition unit 73 acquires the first calculated value SOCA and the second calculated value SOCB. In step S11, the processing unit 74 determines whether the energy storage difference ΔSOC is greater than the determination value TH. If the determination in step S11 is negative, the process proceeds to step S12. In this embodiment, the processing in step S11 performed by the processing unit 74 corresponds to the "energy storage amount determination unit".

[0060] In step S12, the command setting unit 71 sets the command voltages VAc and VBc for each power converter 21A and 21B. Here, the command voltages VAc and VBc for each power converter 21A and 21B are set without restricting the operating point of each power converter 21A and 21B by the first to third conditions described above. For example, the command voltages VAc and VBc for each power converter 21A and 21B are set so that the output voltages of each module 10A and 10B are the same. In step S13, the first control unit 72A and the second control unit 72B perform switching control of each power converter 21A and 21B so that the secondary voltages VA and VB of each power converter 21A and 21B are set to the command voltages VAc and VBc. In this embodiment, the first control unit 72A and the second control unit 72B correspond to the "converter control unit".

[0061] If a positive result is obtained in step S11, the process proceeds to step S14. In step S14, the processing unit 74 determines whether the first calculated value SOCA is higher than the second calculated value SOCB. If a positive result is obtained in step S13, the process proceeds to step S15.

[0062] In step S15, the power determination unit 75 acquires the load current Io flowing through the electrical load 12. The load current Io can be the value detected by the load current sensor 92. In step S16, the power determination unit 75 determines whether the power condition is met based on the acquired load current Io.

[0063] If a negative result is obtained in step S16, the process proceeds to step S17. In step S17, the switch control unit 76 turns on each of the changeover switches 61A, 61B, 62A, and 62B, and turns off each of the short-circuit switches 63A and 63B. In step S18, the command setting unit 71 sets the command voltages VAc and VBc of each of the power converters 21A and 21B to satisfy the first and second conditions.

[0064] On the other hand, if a positive determination is made in step S16, the process proceeds to step S19. In step S19, the switch control unit 76 turns on the first and second changeover switches 61A, 62A and the first short-circuit switch 63A, while turning off the third and fourth changeover switches 61B, 62B and the second short-circuit switch 63B. In step S20, the command setting unit 71 sets the command voltage VAc of the first power converter 21A to 0[V]. In this case, for example, while the first storage battery 11A is discharging, the power conversion operation of the first power converter 21A is stopped with the first and second upper and lower arm switches S1H, S2H, S1L, S2L fixed to OFF, and the first and second switches SA, SB fixed to OFF or ON. Also, for example, while the first storage battery 11A is charging, the power conversion operation of the first power converter 21A is stopped with the first and second switches SA, SB fixed to ON. Therefore, when the power conversion operation of the first power converter 21A is stopped, conduction losses occur due to current flowing through the secondary circuit 52 of the first power converter 21A. However, as explained in Figure 2 above, power can be exchanged between the first battery 11A and the electrical load 12 while avoiding problems such as a decrease in power conversion efficiency ηA at low output.

[0065] If a negative result is obtained in step S14, proceed to step S21. The processing in step S21 is the same as in step S15. The processing in step S22 is the same as in step S16.

[0066] If a negative determination is made in step S22, the process proceeds to step S23. In step S23, the switch control unit 76 turns on each of the changeover switches 61A, 61B, 62A, and 62B, and turns off each of the short-circuit switches 63A and 63B. In step S24, the command setting unit 71 sets the command voltages VAc and VBc of each of the power converters 21A and 21B to satisfy the second and third conditions.

[0067] On the other hand, if a positive determination is made in step S22, the process proceeds to step S25. In step S25, the switch control unit 76 turns off the first and second changeover switches 61A, 62A and the first short-circuit switch 63A, while turning on the third and fourth changeover switches 61B, 62B and the second short-circuit switch 63B. In step S26, the command setting unit 71 sets the command voltage VBc of the second power converter 21B to 0[V]. After processing in steps S18, S20, S24, and S26, the process proceeds to step S13.

[0068] Figure 5 shows an example of the control operation performed by the control device 70. In Figure 5, (a) shows the transition of the voltage VbatA of the first battery 11A and the transition of the voltage VbatB of the second battery 11B, (b) shows the transition of the command voltage VAc of the first power converter 21A, (c) shows the transition of the command voltage VBc of the second power converter 21B, (d) shows the transition of the secondary current IA of the first power converter 21A, (e) shows the transition of the secondary current IB of the second power converter 21B, (f) shows the transition of the load current Io, and (g) to (l) show the on / off status of each switch 61A, 61B, 62A, 62B, 63A, 63B. This section describes an example of operation in which a difference is created in the secondary currents IA and IB to reduce the difference in SOC between batteries 11A and 11B when the SOC of the first battery 11A is higher than that of the second battery 11B.

[0069] Before time t1, switches 61A, 61B, 62A, 62B, 63A, and 63B are turned off. In this case, the secondary currents IA and IB of each power converter 21A and 21B do not flow. At time t1, the power supply system 100 is started up. Accordingly, each power converter 21A and 21B becomes operational. In Figure 5, during the period from time t1 to time t2, the command setting unit 71 sets the command voltage VAc of the first power converter 21A to 0[V] and raises the command voltage VBc of the second power converter 21B to the set value V2. For example, the set value V2 is a value corresponding to the voltage difference between each battery 11A and 11B. Specifically, if the voltage of the first battery 11A is 390[V] and the voltage of the second battery 11B is 385[V], the set value V2 is 5[V].

[0070] During the period from time t2 to time t3, the power determination unit 75 determines that the power conditions are met. The switch control unit 76 switches the first and second changeover switches 61A, 62A and the first short-circuit switch 63A from off to on. In this case, power is supplied to the electrical load 12 only from the first module 10A of the modules 10A and 10B. As a result, the secondary current IA of the first power converter 21A increases, and the load current Io also increases.

[0071] The command voltage VAc of the first power converter 21A is set to 0[V]. In this case, for example, the first and second switches SA and SB are fixed to the off position, and the power conversion operation of the first power converter 21A is stopped. This allows the first battery 11A to be discharged while suppressing power loss caused by the power conversion operation of the first power converter 21A. Furthermore, by turning on the first short-circuit switch 63A, a path is formed connecting the first battery 11A and the electrical load 12 without going through the secondary circuit 52 of the first power converter 21A. This makes it possible to effectively reduce the conduction loss that occurs in the secondary circuit 52 of the first power converter 21A compared to when the first short-circuit switch 63A is off.

[0072] During the period from time t3 to time t4, the load current Io exceeds twice the current lower limit IL. In this case, the power determination unit 75 determines that the power condition is not met. The switch control unit 76 switches the first short-circuit switch 63A from on to off, and switches the third and fourth changeover switches 61B and 62B from off to on. The command setting unit 71 sets the command voltages VAc and VBc such that the secondary current IA of the first power converter 21A is greater than the current lower limit IL, and the secondary current IB of the second power converter 21B is equal to the current lower limit IL.

[0073] More specifically, the command setting unit 71 sets the command voltage VAc of the first power converter 21A to a first setting value V1 > 0[V]. The command setting unit 71 sets the command voltage VBc of the second power converter 21B to a second setting value V2. The second setting value V2 is the same value as before time t3 and corresponds to the voltage difference between each battery 11A and 11B. If the first setting value V1 is higher than 0[V], the output voltage of the first module 10A is made higher than the output voltage of the second module 10B, and the secondary current IA of the first power converter 21A is made greater than the secondary current IB of the second power converter 21B. For example, the command setting unit 71 may calculate a first setting value V1 such that IA > IB = IL based on the voltages VbatA and VbatB of each battery 11A and 11B and the circuit constants of the power supply system 100, including the wiring resistance of each path 30 and 31, and set the calculated first setting value V1 as the command voltage VAc.

[0074] During the period from time t3 to time t4, power is supplied to the electrical load 12 from the first power converter 21A and from the second power converter 21B. As a result, the portion of the load current Io borne by the first power converter 21A is reduced, and the secondary current IA of the first power converter 21A is reduced compared to time t3. When the load current Io is constant, the secondary current IA of the first power converter 21A is made greater than the current lower limit IL, and the secondary current IB of the second power converter 21B is set to the current lower limit IL. This reduces the difference in the amount of charge stored in each battery 11A and 11B, while allowing each power converter 21A and 21B to operate within the high-efficiency operating region Ra.

[0075] At time t4, the load current Io falls below twice the current lower limit IL. In this case, the power determination unit 75 determines that the power condition is met. The switch control unit 76 switches the first short-circuit switch 63A from off to on, and switches the third and fourth changeover switches 61B and 62B from on to off. The command setting unit 71 sets the command voltages VAc and VBc of each power converter 21A and 21B to 0[V]. In this case, power is supplied to the electrical load 12 only from the first module 10A of the modules 10A and 10B.

[0076] Figure 6 shows an example of the case where the operating points of each power converter 21A and 21B are shifted. The operating point before the shift is after time t3 in Figure 5, and represents the timing before the secondary current IB of the second power converter 21B reaches the current lower limit IL. The operating point after the shift is after time t3 in Figure 5, and represents the timing when the secondary currents IA and IB of each power converter 21A and 21B become constant.

[0077] At the operating point before the shift, the power conversion efficiency ηB of the second power converter 21B is significantly reduced because the secondary current IB of the second power converter 21B is smaller than the efficiency peak current Ip. From this state, the secondary current IB of the second power converter 21B is set to the current lower limit IL. In this embodiment, the current lower limit IL is set to the efficiency peak current Ip. Therefore, when operating each power converter 21A, 21B within the high-efficiency operating region Ra, the power conversion efficiency ηB of the second power converter 21B can be accurately improved. Furthermore, when the secondary current IB of the second power converter 21B is set to the efficiency peak current Ip, the power conversion efficiency ηB of the second power converter 21B can be increased compared to a configuration in which the secondary current IB of the second power converter 21B is controlled to a value larger than the efficiency peak current Ip. As a result, the operating efficiency of the power supply system 100 can be accurately improved.

[0078] According to the embodiment described in detail above, the following effects can be obtained.

[0079] When an output difference is generated between the power converters 21A and 21B, the command voltages VAc and VBc of each power converter 21A and 21B are set so that each power converter 21A and 21B operates within the high-efficiency operating region Ra. With a configuration in which each power converter 21A and 21B is controlled based on the set command voltages VAc and VBc, each power converter 21A and 21B can be operated at an operating point with higher power conversion efficiencies ηA and ηB compared to a comparative example in which an output difference is generated without restrictions on the operating point of each power converter 21A and 21B. As a result, the operating efficiency of the power supply system 100 can be improved.

[0080] When operating each power converter 21A, 21B within the high-efficiency operating region Ra while creating a difference in the secondary currents IA, IB of each power converter 21A, 21B, the command voltages VAc, VBc are set so that a difference is created in the output voltages of each module 10A, 10B. In this case, even if there is a difference in the voltages VbatA, VbatB of each battery 11A, 11B, the secondary currents IA, IB can be adjusted by creating a difference in the output voltages of each module 10A, 10B. Therefore, in a power supply system 100 in which each module 10A, 10B is connected in parallel to an electrical load 12, control to operate each power converter 21A, 21B within the high-efficiency operating region Ra can be suitably performed.

[0081] If it is determined that the power conditions are not met, the respective changeover switches 61A, 61B, 62A, and 62B are turned on, and the respective command voltages VAc and VBc are set so that the respective power converters 21A and 21B operate within the high-efficiency operating region Ra. On the other hand, if it is determined that the power conditions are met, only one of the first and second changeover switches 61A and 62A, or the third and fourth changeover switches 61B and 62B, is turned on, and the power converter of the module whose changeover switch is turned on among the respective modules 10A and 10B is operated. In this case, the number of modules that provide power output is reduced when the required drive power of the electrical load 12 is low. This prevents a situation in which the power conversion efficiency ηA and ηB of the respective power converters 21A and 21B decreases due to the power converters 21A and 21B operating at an operating point lower than the current lower limit value IL when under low load. As a result, the operating efficiency of the power supply system 100 at low load can be improved.

[0082] The command voltages VAc and VBc are set so that each power converter 21A and 21B operates within the high-efficiency operating region Ra, provided that the difference in stored energy ΔSOC is determined to be greater than the determination value TH. This prevents the unnecessary execution of control that limits the operating point of each power converter 21A and 21B.

[0083] <Modified form of the first embodiment> The command setting unit 71 may set the command voltage such that the secondary current of the low-output converter is greater than the current lower limit IL when operating each power converter 21A and 21B within the high-efficiency operating region Ra. In Figure 7, the low-output converter is the second power converter 21B. Even in this case, it is possible to suppress a decrease in the power conversion efficiency of the second power converter 21B compared to the comparative example in which the operating point of the second power converter 21B is not limited to within the high-efficiency operating region Ra.

[0084] For example, when setting the command voltage of a low-power converter so that the secondary current of the low-power converter is greater than the current lower limit IL, the command setting unit 71 may set the command voltage of the low-power converter higher the larger the load current Io is. This ensures that the power supplied to the electrical load 12 is adequately secured. Alternatively, for example, the command setting unit 71 may set the command voltage of the low-power converter higher the larger the secondary current of the high-power converter, which is the higher-output power converter among the power converters 21A and 21B. This increases the secondary current of the low-power converter above the current lower limit IL while bringing the secondary current of the high-power converter as close as possible to the efficiency peak current Ip. As a result, the power conversion efficiencies ηA and ηB of each power converter 21A and 21B can be adequately improved.

[0085] The lower current limit IL for the high-efficiency operating region Ra is not limited to the efficiency peak current Ip; it may also be set to a lower output level than the efficiency peak current Ip.

[0086] For example, it is possible to determine the lower limit of the current IL by considering the rate of change of the power conversion efficiencies ηA and ηB with respect to the secondary currents IA and IB of each power converter 21A and 21B. Figure 8 shows the characteristics of the relationship between the secondary currents IA and IB and the power conversion efficiencies ηA and ηB of each power converter 21A and 21B, and the rate of change of the power conversion efficiencies ηA and ηB with respect to each secondary current IA and IB. The rate of change of the power conversion efficiencies ηA and ηB with respect to each secondary current IA and IB is shown with a positive slope indicating a decrease in power conversion efficiencies ηA and ηB. The slope of efficiency decrease of power conversion efficiencies ηA and ηB is 0 at the efficiency peak current Ip, and increases on the high-output and low-output sides relative to the efficiency peak current Ip. However, on the low-output side relative to the efficiency peak current Ip, the slope of efficiency decrease of power conversion efficiencies ηA and ηB is higher than the predetermined rate of change αk at the upper limit Ik of the secondary currents IA and IB of each power converter 21A and 21B. For example, the upper limit Ik is determined based on the performance of each power converter 21A, 21B.

[0087] The current lower limit IL may be a value on the lower output side of the efficiency peak current Ip, and may be set to a value such that the slope of the efficiency decrease of power conversion efficiencies ηA and ηB is less than or equal to a predetermined rate of change αk. In this case, the current lower limit IL can be set within a range where the degree of decrease in power conversion efficiencies ηA and ηB from the efficiency peak current Ip is not as large as when the current lower limit IL is set such that the slope of the efficiency decrease of power conversion efficiencies ηA and ηB is greater than the predetermined rate of change αk. For example, the current lower limit IL may be a value within the setting region Rb shown in Figure 8, and may be set to a value on the lower output side of the efficiency peak current Ip. In this case, the current lower limit IL can be set within a range where the decrease in power conversion efficiencies ηA and ηB is not as large when the predetermined current is reduced from the efficiency peak current Ip as it is when the predetermined current is increased from the efficiency peak current Ip. Therefore, even if the command voltage of each power converter 21A, 21B is set so that the secondary current of either one of the power converters 21A, 21B becomes the current lower limit value IL, it is possible to suppress a significant decrease in the power conversion efficiencies ηA, ηB.

[0088] The lower current limit IL in the high-efficiency operating region Ra may be set to a higher output level than the efficiency peak current Ip. For example, it may be a value within the setting region Rb shown in Figure 8, and set to a value on the higher output level than the efficiency peak current Ip.

[0089] The high-efficiency operating region Ra may be defined as the region where the power conversion efficiencies ηA and ηB are equal to or greater than a predetermined efficiency ηa, as shown in Figure 9. For example, the predetermined efficiency ηa is a value of 90% or higher. In this case, the high-efficiency operating region Ra is defined by the current lower limit IL and the current upper limit IH, which is higher than the efficiency peak current Ip.

[0090] · After time t3 in Figure 5, the command setting unit 71 may set the command voltage VAc of the first power converter 21A to the first setting value V1 = 0 [V], and set the command voltage VBc of the second power converter 21B to a value lower than the second setting value V2. Even in this case, it is possible to create a difference in the output voltages of each module 10A, 10B so that the secondary current IA of the first power converter 21A is output to be greater than the secondary current IB of the second power converter 21B. For example, the command setting unit 71 may calculate a second setting value V2 such that IA > IB = IL based on the voltages VbatA, VbatB of each battery 11A, 11B and the circuit constants of the power supply system 100, and set the calculated second setting value V2 as the command voltage VBc.

[0091] <Second Embodiment> The second embodiment will be described below, focusing on the differences from the first embodiment, with reference to the drawings. In this embodiment, the processing performed by the processing unit 74 has been changed.

[0092] Figure 10 shows the control processing procedure performed by the control device 70.

[0093] After processing in step S15, the process proceeds to step S30. In step S30, the processing unit 74 sets the current lower limit IL of the high-efficiency operating region Ra to a variable value. In this embodiment, when the energy storage difference ΔSOC is less than or equal to a predetermined difference value, the current lower limit IL is set to the efficiency peak current Ip. When the energy storage difference ΔSOC is greater than the predetermined difference value, the current lower limit IL is set to a value smaller than the efficiency peak current Ip. In this case, as shown in Figure 11, when the energy storage difference ΔSOC is large, it is possible to increase the output difference between each power converter 21A, 21B compared to when the current lower limit IL is set to the efficiency peak current Ip. This makes it possible to quickly reduce the energy storage difference ΔSOC while limiting the operating point of each power converter 21A, 21B to within the high-efficiency operating region Ra. Also, when the energy storage difference ΔSOC is less than or equal to a predetermined difference value, the current lower limit IL is set to the efficiency peak current Ip. Therefore, control to operate each power converter 21A, 21B at high efficiency can be suitably performed.

[0094] For example, the current lower limit IL can be set to be variable by changing it in steps with respect to the energy storage difference ΔSOC, or by changing it continuously with respect to the energy storage difference ΔSOC. When setting the current lower limit IL by changing it continuously, the current lower limit IL may be set to decrease from the efficiency peak current Ip as the energy storage difference ΔSOC becomes larger. After processing in step S30, the process proceeds to step S16.

[0095] After processing in step S21, the process proceeds to step S31. In step S31, the same processing as in step S30 is performed. After processing in step S31, the process proceeds to step S22. In this embodiment, the processing in steps S30 and S31 performed by the processing unit 74 corresponds to the "area setting unit".

[0096] <Third Embodiment> The third embodiment will now be described, focusing on the differences from the first embodiment, with reference to the drawings. In this embodiment, as shown in Figure 12, the power supply system 100 includes three modules 10X, 10Y, and 10Z. Each module 10X, 10Y, and 10Z is connected in parallel to the electrical load 12.

[0097] Each module 10X, 10Y, and 10Z is equipped with a battery 11X, 11Y, and 11Z, and a power converter 21X, 21Y, and 21Z, similar to the first module 10A described in Figure 1 above. In each module 10X, 10Y, and 10Z, the connection relationship between the first high-potential terminals 41X, 41Y, and 41Z, the first low-potential terminals 42X, 42Y, and 42Z, the second high-potential terminals 43X, 43Y, and 43Z, and the second low-potential terminals 44X, 44Y, and 44Z of the power converters 21X, 21Y, and 21Z, the battery 11X, 11Y, and 11Z, and the electrical load 12 is the same as in the first module 10A, so a detailed explanation of the connection relationship is omitted.

[0098] Each module 10X, 10Y, and 10Z is equipped with high-potential-side changeover switches 61X, 61Y, and 61Z, low-potential-side changeover switches 62X, 62Y, and 62Z, and short-circuit switches 63X, 63Y, and 63Z, similar to the first module 10A described in Figure 1. Each high-potential-side changeover switch 61X, 61Y, and 61Z has the same configuration as the first changeover switch 61A described in Figure 1. Each low-potential-side changeover switch 62X, 62Y, and 62Z has the same configuration as the second changeover switch 62A described in Figure 1. Each short-circuit switch 63X, 63Y, and 63Z has the same configuration as the first short-circuit switch 63A described in Figure 1.

[0099] The battery voltage sensor 90 detects the voltages VbatX, VbatY, and VbatZ of each battery 11X, 11Y, and 11Z. The battery current sensor 91 detects the current flowing through each battery 11X, 11Y, and 11Z. The command setting unit 71 sets the command voltages VXc, VYc, and VZc that command the secondary voltages VX, VY, and VZ of each power converter 21X, 21Y, and 21Z. The control device 70 includes control units 72X, 72Y, and 72Z. The command voltages VXc, VYc, and VZc set by the command setting unit 71 are input to each control unit 72X, 72Y, and 72Z. Each control unit 72X, 72Y, and 72Z controls the switching of each power converter 21X, 21Y, and 21Z so that the secondary voltages VX, VY, and VZ of each power converter 21X, 21Y, and 21Z become the command voltages VXc, VYc, and VZc, respectively.

[0100] Figure 13 shows the control process performed by the control device 70. This control is performed prior to the execution of step S10 in Figures 4 and 10. Here, we will describe the control when each of the batteries 11X, 11Y, and 11Z is discharged.

[0101] In step S40, the acquisition unit 73 acquires the amount of charge stored in each of the batteries 11X, 11Y, and 11Z. In this embodiment, the State of Charge (SOC) of each battery 11X, 11Y, and 11Z is calculated based on the detected values ​​of the battery voltage sensor 90 and the battery current sensor 91, and the calculated values ​​SOCX, SOCY, and SOCZ are acquired as the amount of charge stored in each of the batteries 11X, 11Y, and 11Z.

[0102] In step S41, the processing unit 74 selects the module with the highest battery charge among the modules 10X, 10Y, and 10Z as the direct-connect module. This process can use the charge amounts of each battery 11X, 11Y, and 11Z acquired by the acquisition unit 73. The module selected as the direct-connect module among the modules 10X, 10Y, and 10Z corresponds to the "third power supply unit". The battery of the direct-connect module among the batteries 11X, 11Y, and 11Z corresponds to the "third energy storage unit". The power converter of the direct-connect module among the power converters 21X, 21Y, and 21Z corresponds to the "third power converter".

[0103] In step S42, the switch control unit 76 turns on the changeover switch and short-circuit switch of the selected direct-coupled module. In step S43, the command voltage is set to stop the power conversion operation of the power converter of the selected direct-coupled module. In this embodiment, the command voltage of the power converter of the selected direct-coupled module is set to 0[V].

[0104] After processing in step S43, the process proceeds to step S10 in Figure 4, 10. In this case, among the modules 10X, 10Y, and 10Z, the modules other than the selected direct-connected module are designated as the first module 10A and the second module 10B, and the processes in steps S10 to S26, S30, and S31 are performed. For example, in steps S18, S20, S24, and S26, the command setting unit 71 sets the command voltages VAc and VBc such that the output voltage of the direct-connected module is the highest among the modules.

[0105] For example, as shown in Figure 12, if the voltage VbatX of battery 11X is 390[V], the voltage VbatY of battery 11Y is 395[V], and the voltage VbatZ of battery 11Z is 400[V], then module 10Z is selected as the direct-connect module. Module 10X is designated as the first module 10A, and module 10Y is designated as the second module 10B, and the control described in Figures 4 and 10 above is executed.

[0106] According to this embodiment, in the selected direct-connection module, power is supplied from the battery to the electrical load 12 while the power conversion operation of the power converter is stopped. This makes it possible to supply power from the direct-connection module to the electrical load 12 while suppressing power loss in the power converter of the direct-connection module, compared to when the power converter is operating.

[0107] If it is determined that the power conditions are not met, the power converters in the modules 10X, 10Y, and 10Z, excluding the directly connected modules, are operated within the high-efficiency operating region Ra. If it is determined that the power conditions are met, only the power converters of the modules 10X, 10Y, and 10Z, excluding the directly connected modules, whose changeover switch is turned on, are operated. This allows the power converters to be operated with high efficiency depending on whether the power conditions are met or not. Therefore, the operating efficiency of the power supply system 100, which has three modules 10X, 10Y, and 10Z, can be accurately improved.

[0108] Of the modules 10X, 10Y, and 10Z, the module with the highest stored charge in its battery 11X, 11Y, or 11Z is selected as the direct-connect module. This allows the battery in the direct-connect module to be discharged more actively than the batteries in the other modules 10X, 10Y, and 10Z. Therefore, during discharge, the stored charge in each battery 11X, 11Y, or 11Z can be appropriately equalized.

[0109] Each module 10X, 10Y, and 10Z is equipped with short-circuit switches 63X, 63Y, and 63Z, respectively. This allows for the effective suppression of conduction losses in the secondary circuit of the power converter when the short-circuit switches are turned on in the directly coupled modules. Therefore, the operating efficiency of the power supply system 100 can be further improved.

[0110] <Modified form of the third embodiment> · When each of the storage batteries 11X, 11Y, and 11Z is charged, the control described in FIG. 13 above may be executed. In this case, in step S41, in the processing unit 74, among the modules 10X, 10Y, and 10Z, the module with the lowest power storage amount of the storage battery may be selected as the directly connected module. Thereby, it becomes possible to actively charge the storage battery of the directly connected module compared to the storage batteries of the modules other than the directly connected module among the modules 10X, 10Y, and 10Z. Therefore, during charging, the equalization of the power storage amounts of the storage batteries 11X, 11Y, and 11Z can be suitably performed.

[0111] · When the processes of steps S16 and S22 in FIGS. 4 and 10 above are executed after the directly connected module is selected, the power condition may be changed. Specifically, the power condition may be such that the power obtained by subtracting the load share of the directly connected module from the required drive power required for the electric load 12 is the power when the remaining power converters 21A and 21B are operated at the current lower limit value IL, and is lower than the total power that can be output from the remaining modules 10A and 10B. Here, the remaining modules 10A and 10B are the modules other than the directly connected module among the modules 10X, 10Y, and 10Z. The remaining power converters 21A and 21B are the power converters of the remaining modules 10A and 10B. For example, in steps S16 and S22, in the power determination unit 75, it may be determined whether "Io-ID<IL×2" is satisfied. "ID" is the secondary-side current of the directly connected module. For example, as the secondary-side current ID of the directly connected module, it is possible to use the detection value of the battery current sensor 91 or the rated current of the storage battery of the directly connected module.

[0112] According to this embodiment, the output power of the directly connected module is considered in the determination of whether the power condition is satisfied. Therefore, when one of the three modules is used as the directly connected module, control for operating the remaining modules 10A and 10B with high efficiency can be suitably executed.

[0113] <Other Embodiments> Note that each of the above embodiments may be implemented with the following modifications.

[0114] In each module 10A, 10B, 10X, 10Y, 10Z, the secondary circuit of the power converters 21A, 21B, 21X, 21Y, 21Z may be connected in series with the negative terminal side of the batteries 11A, 11B, 11X, 11Y, 11Z, instead of the positive terminal side of the batteries 11A, 11B, 11X, 11Y, 11Z.

[0115] For example, referring to Figure 14 and using the first module 10A as an example, the first high-potential terminal 41A of the first power converter 21A is connected to the positive terminal of the first battery 11A and to the first changeover switch 61A. The first low-potential terminal 42A is connected to the negative terminal of the first battery 11A. The second high-potential terminal 43A is connected to the negative terminal of the first battery 11A, the first low-potential terminal 42A, and the first short-circuit switch 63A. The second low-potential terminal 44A is connected to the second changeover switch 62A and the first short-circuit switch 63A. In this embodiment, the second low-potential terminal 44A corresponds to the "output terminal," and the second high-potential terminal 43A corresponds to the "connection terminal."

[0116] The power converter is not limited to the one described in Figure 2; it may also be an isolated DC-DC converter with a full-bridge secondary circuit. Furthermore, the power converter is not limited to isolated types; non-isolated DC-DC converters such as resonant DC-DC converters and buck converters can also be used.

[0117] In the first and second embodiments, the first module 10A may be equipped with only one of the first and second changeover switches 61A and 62A. The second module 10B may be equipped with only one of the third and fourth changeover switches 61B and 62B. In the third embodiment, each module 10X, 10Y, and 10Z may be equipped with only one of the high-potential side changeover switches 61X, 61Y, and 61Z, and only one of the low-potential side changeover switches 62X, 62Y, and 62Z. Even in this case, the control device 70 can perform the control described in Figures 4, 10, and 13 above.

[0118] In the first and second embodiments, each module 10A, 10B does not need to be equipped with a changeover switch. In this case, in Figures 4 and 10 above, the processes in steps S15 to S17, S19 to S23, S25, and S26 do not need to be executed. In this case, depending on the determination result of steps S11 and S14, the process in step S12, the process in step S18, or the process in step S24 is executed.

[0119] In the first to third embodiments, each module 10A, 10B, 10X, 10Y, and 10Z does not need to be equipped with a short-circuit switch.

[0120] In the first and second embodiments, the command setting unit 71 may set the command current (corresponding to the "output command value") that commands the secondary currents IA and IB of each power converter 21A and 21B. Even in this case, the command setting unit 71 can set the command current of each power converter 21A and 21B so that each power converter 21A and 21B operates within the high-efficiency operating region Ra. In the third embodiment, in each module 10X, 10Y, and 10Z other than the direct-coupled module, the command current of each power converter may be set so that each power converter operates within the high-efficiency operating region Ra.

[0121] The command setting unit 71 may, instead of equalizing the amount of charge stored in each battery 11A and 11B, set the command voltages VAc and VBc of each power converter 21A and 21B to create an output difference between them in order to increase the difference in the amount of charge stored in each battery 11A and 11B. In this case, in step S11 of Figure 4, 10, the processing unit 74 may determine whether or not there is a request to increase the difference in the amount of charge stored in each battery 11A and 11B. For example, if one of the batteries 11A and 11B is degraded and it is necessary to replace the degraded battery in a factory or the like, it is conceivable that there is a situation where it is desirable to use up the charge stored in the degraded battery preferentially over that of the normal battery. In this case, a request to increase the difference in the amount of charge stored in each battery 11A and 11B may arise.

[0122] In the second embodiment, in steps S30 and S31 of Figure 10, if the energy storage difference ΔSOC is less than or equal to a predetermined difference value, the current lower limit IL may be set to the value described in Figures 8 and 9 instead of the efficiency peak current Ip. In this case, the current lower limit IL when the energy storage difference ΔSOC is greater than the predetermined difference value may be set to a smaller value than the current lower limit IL set when the energy storage difference ΔSOC is less than or equal to the predetermined difference value.

[0123] The acquisition unit 73 may acquire not only the State of Charge (SOC) of each battery 11A, 11B, and 11C, but also energy storage parameters indicating the amount of stored energy, such as energy and open-circuit voltage (OCV). In this case as well, the processing unit 74 can perform the various processes described in Figures 4, 10, and 13 above.

[0124] The first, second, and third energy storage units are not limited to batteries, but may include, for example, large-capacity electric double-layer capacitors, or both batteries and electric double-layer capacitors. Furthermore, the first, second, and third energy storage units may be fuel cells.

[0125] The power supply system may not be mounted on a vehicle; for example, it may be on a mobile body such as an aircraft or a ship. If the mobile body is an aircraft, the rotating electric machine will be the power source for the aircraft's flight; if the mobile body is a ship, the rotating electric machine will be the power source for the ship's navigation. Furthermore, the power supply system is not limited to being mounted on a mobile body; it can also be used as a stationary power source.

[0126] The electrical load is not limited to the inverter 13 and the rotating electric machine 14. For example, the electrical load may be an external charger. The external charger is, for example, a stationary charger installed outside the vehicle, which charges each of the storage batteries 11A, 11B, and 11C.

[0127] The first, second, and third power supply units do not necessarily have to be composed of modules that integrate a battery and a power converter into a single package.

[0128] The control unit and its method described herein may be implemented by a dedicated computer provided by configuring a processor and memory programmed to perform one or more functions embodied by a computer program. Alternatively, the control unit and its method described herein may be implemented by a dedicated computer provided by configuring a processor by one or more dedicated hardware logic circuits. Alternatively, the control unit and its method described herein may be implemented by one or more dedicated computers configured by a combination of a processor and memory programmed to perform one or more functions and a processor configured by one or more hardware logic circuits. Furthermore, the computer program may be stored as instructions executed by the computer on a computer-readable non-transitional tangible recording medium.

[0129] The technical concepts extracted from the above-described embodiments are described below. [Configuration 1] A first power supply unit (10A) having a first energy storage unit (11A) and a first power converter (21A) connected to the first energy storage unit, A second power supply unit (10B) having a second energy storage unit (11B) and a second power converter (21B) connected to the second energy storage unit, A system comprising the first power supply unit and the second power supply unit, applied to a system (100) in which the first power supply unit and the second power supply unit are connected in parallel, and a control device (70) that controls the first power converter and the second power converter to create an output difference between the first power converter and the second power converter, Each of the aforementioned power converters has a characteristic in the relationship between the operating point and power conversion efficiency where the power conversion efficiency decreases at lower and higher output levels than a predetermined operating point. A command setting unit (71) sets the output command value of each power converter so that, when the aforementioned output difference occurs, each power converter is operated within a predetermined high-efficiency operating region including the predetermined operating point, Based on the output command value set by the command setting unit, the converter control units (72A, 72B) control each of the power converters, A control device equipped with the following features. [Configuration 2] The aforementioned power converter A primary side circuit (51) including first high-potential side terminals (41A, 41B) and first low-potential side terminals (42A, 42B), A secondary circuit (52) including second high-potential terminals (43A, 43B) and second low-potential terminals (44A, 44B), An isolation transformer (60) connecting the primary circuit and the secondary circuit, It has, In each of the power supply units, the first high-potential terminal is connected to the positive electrode side of the energy storage unit, and the first low-potential terminal is connected to the negative electrode side of the energy storage unit. In each of the power supply units, one of the second high-potential terminal and the second low-potential terminal is an output terminal connected to an electrical load (12), and the other of the second high-potential terminal and the second low-potential terminal is a connection terminal connected to the energy storage unit so as to connect the secondary circuit and the energy storage unit in series. The control device according to Configuration 1, wherein the command setting unit sets the output command value for commanding the voltage to be applied between the second high-potential side terminal and the second low-potential side terminal of each power converter, so as to create a difference in the output voltage of each power supply unit when each power converter is operated within the high-efficiency operating region while the difference in current flowing to the output terminals of each power converter is generated as the output difference. [Configuration 3] The control device according to configuration 1 or 2, further comprising a region setting unit (74) that sets a smaller output lower limit value for the high-efficiency operating region when the difference in the amount of stored energy between the amount of stored energy in the first energy storage unit and the amount of stored energy in the second energy storage unit is greater than a predetermined difference value, compared to when the difference in the amount of stored energy is less than or equal to the predetermined difference value. [Structure 4] The control device according to configuration 3, wherein the region setting unit sets the output corresponding to the predetermined operating point as the lower limit of the output when the difference in stored energy is less than or equal to the predetermined difference value. [Composition 5] The control device according to configuration 3, wherein the region setting unit sets the output lower limit value to a value such that, when the difference in stored energy is less than or equal to the predetermined difference value, the slope of the output decrease on the lower output side below the predetermined operating point in the characteristics is less than or equal to a predetermined value. [Composition 6] The control device according to configuration 3, wherein the region setting unit sets the lower output limit value to a value such that, when the difference in stored energy is less than or equal to the predetermined difference value, the slope of the output decrease on the lower output side below the predetermined operating point is smaller than the slope of the output decrease on the higher output side above the predetermined operating point in the characteristics. [Composition 7] The aforementioned system, A high-potential path (30) connects the high-potential side of each power supply unit to the electrical load, A low-potential path (31) connects the low-potential side of each power supply unit to the electrical load, Equipped with, Each of the power supply units is provided in at least one of the high-potential path and the low-potential path and has a changeover switch (61A, 61B, 62A, 62B) that can switch between supplying and disconnecting power to the electrical load. A power determination unit (75) determines whether or not the power condition is met such that the required drive power for the electrical load is lower than the total power that can be output from each power supply unit when each power converter is operated at the lower limit of the output of the high-efficiency operating region, A switch control unit (76) that controls the on / off state of each of the aforementioned changeover switches, Equipped with, The switch control unit, If the power determination unit determines that the power condition is not met, the changeover switch of the first power supply unit and the changeover switch of the second power supply unit are turned ON. If the power determination unit determines that the power condition is met, either the changeover switch of the first power supply unit or the changeover switch of the second power supply unit is turned off. The command setting unit, If the power determination unit determines that the power conditions are not met, the output command value is set so that the first power converter and the second power converter are operated within the high-efficiency operating region. A control device according to any one of configurations 2 to 6, wherein, when the power determination unit determines that the power condition is met, the output command value is set to operate the power converter of the power supply unit having the ON changeover switch among the power supply units. [Structure 8] The system further comprises a third power supply unit (10X, 10Y, 10Z) having a third energy storage unit (11X, 11Y, 11Z) and a third power converter (21X, 21Y, 21Z) connected to the third energy storage unit. The third power converter is A primary side circuit (51) including a first high-potential side terminal and a first low-potential side terminal, A secondary circuit (52) including a second high-potential terminal and a second low-potential terminal, An isolation transformer (60) connecting the primary circuit and the secondary circuit, It has, In the third power supply unit, the first high-potential terminal is connected to the positive electrode side of the third energy storage unit, and the first low-potential terminal is connected to the negative electrode side of the third energy storage unit. In the third power supply unit, one of the second high-potential terminal and the second low-potential terminal is an output terminal connected to the electrical load, and the other of the second high-potential terminal and the second low-potential terminal is a connection terminal connected to the third energy storage unit so as to connect the secondary circuit and the third energy storage unit in series. The control device according to any one of configurations 2 to 6, wherein the command setting unit sets the output command values ​​of the first power converter and the second power converter so that they operate within the high-efficiency operating region, and sets the output command value of the third power converter so that it stops the power conversion operation. [Composition 9] The aforementioned system, A high-potential path (30) connects the high-potential side of each power supply unit to the electrical load, A low-potential path (31) connects the low-potential side of each power supply unit to the electrical load, Equipped with, Each of the aforementioned power supply units is provided in at least one of the high-potential path and the low-potential path and has a changeover switch (61X, 61Y, 61Z, 62X, 62Y, 62Z) that can switch between supplying and disconnecting power to the electrical load. A power determination unit (75) determines whether the power condition is met such that the amount of the required drive power for the electrical load, excluding the portion borne by the third power supply unit, is the power that can be output when the first power converter and the second power converter are operated at the lower limit of the high-efficiency operating region, and is lower than the total power that can be output from the first power supply unit and the second power supply unit. A switch control unit (76) that controls the on / off state of each of the aforementioned changeover switches, Equipped with, The switch control unit, Regardless of whether the aforementioned power conditions are met or not, the changeover switch on the third power supply unit is turned ON. If the power determination unit determines that the power condition is not met, the changeover switch of the first power supply unit and the changeover switch of the second power supply unit are turned ON. If the power determination unit determines that the power condition is met, either the changeover switch of the first power supply unit or the changeover switch of the second power supply unit is turned off. The command setting unit, If the power determination unit determines that the power conditions are not met, the output command value is set so that the first power converter and the second power converter are operated within the high-efficiency operating region. The control device according to configuration 8, wherein, when the power determination unit determines that the power condition is met, the output command value is set to operate the power converter of the power supply unit whose changeover switch is turned ON, among the first power supply unit and the second power supply unit. [Configuration 10] The control device according to configuration 8 or 9, wherein the third energy storage unit is the energy storage unit with the highest energy storage capacity among the aforementioned energy storage units, or the energy storage unit with the lowest energy storage capacity among the aforementioned energy storage units. [Composition 11] The control device according to configuration 8 or 9, wherein the third power supply unit includes short-circuit switches (63X, 63Y, 63Z) that short-circuit the second high-potential side terminal and the second low-potential side terminal of the third power converter. [Composition 12] The system includes a power storage amount determination unit (74) that determines whether or not to generate the output difference based on the difference in power storage amounts between the power storage amount of the first power storage unit and the power storage amount of the second power storage unit. The control device according to any one of configurations 1 to 11, wherein the command setting unit sets the output command value so as to operate each power converter within the high-efficiency operating region, on the condition that the stored energy determination unit determines that the output difference occurs. [Explanation of Symbols]

[0130] 10A, 10B...1st and 2nd modules (1st and 2nd power supply units), 11A, 11B...1st and 2nd storage batteries (1st and 2nd energy storage units), 21A, 21B...1st and 2nd power converters, 70...control device, 71...command setting unit, 72A, 72B...1st and 2nd control units (converter control units), 100...power supply system.

Claims

1. A first power supply unit (10A) having a first energy storage unit (11A) and a first power converter (21A) connected to the first energy storage unit, A second power supply unit (10B) having a second energy storage unit (11B) and a second power converter (21B) connected to the second energy storage unit, A system comprising the first power supply unit and the second power supply unit, applied to a system (100) in which the first power supply unit and the second power supply unit are connected in parallel, and a control device (70) that controls the first power converter and the second power converter to generate an output difference between the first power converter and the second power converter, Each of the aforementioned power converters has a characteristic in the relationship between the operating point and power conversion efficiency where the power conversion efficiency decreases at lower and higher output levels than a predetermined operating point. A command setting unit (71) sets the output command value of each power converter so that, when the aforementioned output difference occurs, each power converter is operated within a predetermined high-efficiency operating region including the predetermined operating point, Based on the output command value set by the command setting unit, the converter control units (72A, 72B) control each of the power converters, A control device equipped with the following features.

2. The aforementioned power converter A primary side circuit (51) including first high-potential side terminals (41A, 41B) and first low-potential side terminals (42A, 42B), A secondary circuit (52) including second high-potential terminals (43A, 43B) and second low-potential terminals (44A, 44B), An isolation transformer (60) connecting the primary circuit and the secondary circuit, It has, In each of the power supply units, the first high-potential terminal is connected to the positive electrode side of the energy storage unit, and the first low-potential terminal is connected to the negative electrode side of the energy storage unit. In each of the power supply units, one of the second high-potential terminal and the second low-potential terminal is an output terminal connected to an electrical load (12), and the other of the second high-potential terminal and the second low-potential terminal is a connection terminal connected to the energy storage unit so as to connect the secondary circuit and the energy storage unit in series. The control device according to claim 1, wherein the command setting unit sets the output command value for commanding the voltage to be applied between the second high-potential side terminal and the second low-potential side terminal of each power converter so as to create a difference in the output voltage of each power supply unit when each power converter is operated within the high-efficiency operating region while the difference in current flowing to the output terminals of each power converter is generated as the output difference.

3. The control device according to claim 1 or 2, further comprising a region setting unit (74) that sets a smaller output lower limit value for the high-efficiency operating region when the difference in the amount of stored energy between the amount of stored energy in the first energy storage unit and the amount of stored energy in the second energy storage unit is greater than a predetermined difference value, compared to when the difference in the amount of stored energy is less than or equal to the predetermined difference value.

4. The control device according to claim 3, wherein the region setting unit sets the output corresponding to the predetermined operating point as the lower limit of the output when the difference in stored energy is less than or equal to the predetermined difference value.

5. The control device according to claim 3, wherein the region setting unit sets a value such that, when the difference in stored energy is less than or equal to the predetermined difference value, the slope of the output decrease on the lower output side below the predetermined operating point in the characteristics is less than or equal to a predetermined value, as the lower output limit value.

6. The control device according to claim 3, wherein the region setting unit sets the lower output limit value to a value such that, when the difference in stored energy is less than or equal to the predetermined difference value, the slope of the output decrease on the lower output side below the predetermined operating point is smaller than the slope of the output decrease on the higher output side above the predetermined operating point in the characteristics.

7. The aforementioned system, A high-potential path (30) connects the high-potential side of each power supply unit to the electrical load, A low-potential path (31) connects the low-potential side of each power supply unit to the electrical load, Equipped with, Each of the power supply units is provided in at least one of the high-potential path and the low-potential path and has a changeover switch (61A, 61B, 62A, 62B) that can switch between supplying and disconnecting power to the electrical load. A power determination unit (75) determines whether the power condition is met such that the required drive power for the electrical load is lower than the total power that can be output from each power supply unit when each power converter is operated at the lower limit of the output of the high-efficiency operating region, A switch control unit (76) that controls the on / off state of each of the aforementioned changeover switches, Equipped with, The switch control unit, If the power determination unit determines that the power condition is not met, the changeover switch of the first power supply unit and the changeover switch of the second power supply unit are turned ON. If the power determination unit determines that the power condition is met, either the changeover switch of the first power supply unit or the changeover switch of the second power supply unit is turned off. The command setting unit, If the power determination unit determines that the power conditions are not met, the output command value is set so that the first power converter and the second power converter are operated within the high-efficiency operating region. The control device according to claim 2, wherein, when the power determination unit determines that the power condition is met, the output command value is set to operate the power converter of the power supply unit having the ON changeover switch among the power supply units.

8. The system further comprises a third power supply unit (10X, 10Y, 10Z) having a third energy storage unit (11X, 11Y, 11Z) and a third power converter (21X, 21Y, 21Z) connected to the third energy storage unit. The third power converter is A primary side circuit (51) including a first high-potential side terminal and a first low-potential side terminal, A secondary circuit (52) including a second high-potential terminal and a second low-potential terminal, An isolation transformer (60) connecting the primary circuit and the secondary circuit, It has, In the third power supply unit, the first high-potential terminal is connected to the positive electrode side of the third energy storage unit, and the first low-potential terminal is connected to the negative electrode side of the third energy storage unit. In the third power supply unit, one of the second high-potential terminal and the second low-potential terminal is an output terminal connected to the electrical load, and the other of the second high-potential terminal and the second low-potential terminal is a connection terminal connected to the third energy storage unit so as to connect the secondary circuit and the third energy storage unit in series. The control device according to claim 2, wherein the command setting unit sets the output command values ​​of the first power converter and the second power converter so as to operate the first power converter and the second power converter within the high-efficiency operating region, and sets the output command value of the third power converter so as to stop the power conversion operation.

9. The aforementioned system, A high-potential path (30) connects the high-potential side of each power supply unit to the electrical load, A low-potential path (31) connects the low-potential side of each power supply unit to the electrical load, Equipped with, Each of the power supply units is provided in at least one of the high-potential path and the low-potential path and has a changeover switch (61X, 61Y, 61Z, 62X, 62Y, 62Z) that can switch between supplying and disconnecting power to the electrical load. A power determination unit (75) determines whether the power condition is met such that the amount of the required drive power for the electrical load, excluding the portion borne by the third power supply unit, is the power that can be output when the first power converter and the second power converter are operated at the lower limit of the output value of the high-efficiency operating region, and is lower than the total power that can be output from the first power supply unit and the second power supply unit. A switch control unit (76) that controls the on / off state of each of the aforementioned changeover switches, Equipped with, The switch control unit, Regardless of whether the above power conditions are met or not, the changeover switch on the third power supply unit is turned ON. If the power determination unit determines that the power condition is not met, the changeover switch of the first power supply unit and the changeover switch of the second power supply unit are turned ON. If the power determination unit determines that the power condition is met, either the changeover switch of the first power supply unit or the changeover switch of the second power supply unit is turned off. The command setting unit, If the power determination unit determines that the power conditions are not met, the output command value is set so that the first power converter and the second power converter are operated within the high-efficiency operating region. The control device according to claim 8, wherein, when the power determination unit determines that the power condition is met, the output command value is set to operate the power converter of the power supply unit whose changeover switch is turned ON, among the first power supply unit and the second power supply unit.

10. The control device according to claim 8 or 9, wherein the third energy storage unit is the energy storage unit with the highest energy storage capacity among the aforementioned energy storage units, or the energy storage unit with the lowest energy storage capacity among the aforementioned energy storage units.

11. The control device according to claim 8 or 9, wherein the third power supply unit includes short-circuit switches (63X, 63Y, 63Z) that short-circuit the second high-potential side terminal and the second low-potential side terminal of the third power converter.

12. The system includes a power storage amount determination unit (74) that determines whether or not to generate the output difference based on the difference in power storage amounts between the power storage amount of the first power storage unit and the power storage amount of the second power storage unit. The control device according to claim 1 or 2, wherein the command setting unit sets the output command value so as to operate each power converter within the high-efficiency operating region, on the condition that the stored energy determination unit has determined that the output difference occurs.

13. A first power supply unit (10A) having a first energy storage unit (11A) and a first power converter (21A) connected to the first energy storage unit, A second power supply unit (10B) having a second energy storage unit (11B) and a second power converter (21B) connected to the second energy storage unit, A system comprising the first power supply unit and the second power supply unit connected in parallel, applied to a system (100), and a program that causes a computer (70) to execute a process to control the first power converter and the second power converter so as to create an output difference between the first power converter and the second power converter, Each of the aforementioned power converters has a characteristic in the relationship between the operating point and power conversion efficiency where the power conversion efficiency decreases at lower and higher output levels than a predetermined operating point. A command setting process to set the output command value of each power converter so that, when the aforementioned output difference occurs, each power converter is operated within a predetermined high-efficiency operating region including the predetermined operating point, Based on the output command value set by the command setting process, a converter control process is performed to control each of the power converters. A program that performs a process that includes this.

14. A first power supply unit (10A) having a first energy storage unit (11A) and a first power converter (21A) connected to the first energy storage unit, A second power supply unit (10B) having a second energy storage unit (11B) and a second power converter (21B) connected to the second energy storage unit, A control method applied to a system (100) comprising the first power supply unit and the second power supply unit connected in parallel, wherein the first power converter and the second power converter are controlled to produce an output difference between the first power converter and the second power converter, Each of the aforementioned power converters has a characteristic in the relationship between the operating point and power conversion efficiency where the power conversion efficiency decreases at lower and higher output levels than a predetermined operating point. A command setting step in which, when the aforementioned output difference occurs, the output command value of each power converter is set so that each power converter is operated within a predetermined high-efficiency operating region including the predetermined operating point, A converter control step in which each power converter is controlled based on the output command value set in the command setting step, A control method including

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