Power supply system and control program

Abstract

A power supply system (10) comprises: storage batteries (31, 61); conversion circuits (40, 70) that each have a primary-side terminal pair (41, 42, 71, 72) connected in parallel to a storage battery, and a secondary-side terminal pair (47, 48, 77, 78) connected in series to the storage battery, and that converts power through the driving of a switching element; and a control unit (16b) that controls charging / discharging current of the storage batteries by turning on and off the switching element according to a switching command. The control unit is capable of executing multiple control modes in which a switching command is calculated on the basis of an output current command value for the conversion circuit, and concurrently executes switching command calculations in the multiple control modes, and then selects any one switching command from among the calculated switching commands and drives the switching element on the basis of the selected switching command.

Description

Power supply system and control program CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based on Japanese Application No. 2023-108737, filed on June 30, 2023, the contents of which are incorporated herein by reference.

[0002] The present disclosure relates to a power supply system.

[0003] For example, there is a system in which a positive electrode and a negative electrode of a storage battery are connected to a pair of input terminals of a conversion circuit, and the storage battery is connected in series to a pair of output terminals of the conversion circuit (see Patent Document 1). Patent Document 1 suggests switching control based on whether the storage battery is being discharged or charged, or on the state of charge (SOC) of the storage battery, in order to discharge or charge the storage battery.

[0004] IEEE ECCE2019 (P5783-P5790)

[0005] However, in the system described in Patent Document 1, when switching between controls, delays in control response and current overshoots may occur, which may result in a decrease in current control accuracy. In particular, systems that are mounted on vehicles and supply power to loads require high current control accuracy.

[0006] The present disclosure has been made to solve the above-mentioned problems, and its main purpose is to improve the accuracy of current control in a power supply system in which the primary terminal pair of a conversion circuit is connected in parallel to a storage battery and the secondary terminal pair is connected in series to the storage battery.

[0007] A first means for solving the above problem is a power supply system comprising: a storage battery; a conversion circuit whose primary side terminal pair is connected in parallel to the storage battery and whose secondary side terminal pair is connected in series to the storage battery, and which converts power by driving a switching element; and a control unit which controls the charge / discharge current of the storage battery by driving the switching element on and off based on a switching command, wherein the control unit is capable of executing a plurality of control modes which calculate the switching command based on an output current command value for the conversion circuit, executes the calculation of the switching command using the plurality of control modes in parallel, selects one of the calculated plurality of switching commands, and drives the switching element based on the selected switching command.

[0008] According to the above configuration, the conversion circuit has a primary-side terminal pair connected in parallel to the storage battery and a secondary-side terminal pair connected in series to the storage battery, and converts power by driving a switching element. Therefore, the sum of the output voltage Vb of the storage battery and the output voltage Vo of the conversion circuit is the output voltage Vm of the storage battery module including the storage battery and the conversion circuit. Therefore, compared to a storage battery module in which the storage battery is connected in parallel to the secondary-side terminal pair of the conversion circuit, the output voltage Vo required of the conversion circuit when the output voltage Vm of the storage battery module is required can be reduced. Therefore, the rated voltage of the conversion circuit can be lowered, and thus the rated capacity of the conversion circuit can be reduced, thereby enabling the conversion circuit to be made more compact.

[0009] The control unit controls the charge / discharge current of the storage battery by driving the switching element on and off based on a switching command. The control unit can execute a plurality of control modes that calculate the switching command based on an output current command value for the conversion circuit. Therefore, when controlling the charge / discharge current of the storage battery, the control unit can switch between a plurality of control modes according to requirements of the power supply system.

[0010] Here, the control unit executes calculation of the switching commands according to the plurality of control modes in parallel. Therefore, regardless of which control mode is to be switched to, the switching commands for the plurality of control modes can be calculated in advance. The control unit then selects one of the calculated switching commands and drives the switching element based on the selected switching command. Therefore, regardless of which control mode switching command is selected, the switching element can be quickly driven based on the already calculated switching command. Therefore, it is possible to suppress the occurrence of a control response delay when switching the control mode, and to improve the current control accuracy.

[0011] In the second means, the control unit is capable of executing a plurality of the control modes when discharging or charging the storage battery, and selects the switching command with the earliest switching timing from the plurality of switching commands calculated when discharging or charging the storage battery.

[0012] According to the above configuration, the control unit can execute the plurality of control modes when discharging or charging the storage battery. Therefore, when discharging or charging the storage battery, the control unit can switch between the plurality of control modes according to the demands on the power supply system. The control unit then selects the switching command with the earliest switching timing (e.g., rising timing of an on / off drive signal) from among the plurality of switching commands calculated for discharging or charging the storage battery. Therefore, when the switching command changes, the change in the switching command can be quickly reflected in the drive of the switching element. Therefore, the response delay of the control can be further reduced.

[0013] In a third aspect, a plurality of current sensors are provided to detect currents in different paths, and the plurality of control modes during discharging or charging include a control mode in which the switching command is calculated based on the detected values ​​of at least two of the plurality of current sensors. With this configuration, the plurality of current sensors can detect currents in different paths. Therefore, it is possible to execute control modes with different control methods based on the detected values ​​of at least two of the plurality of current sensors, and to improve the current control accuracy in each control mode.

[0014] In a fourth aspect, the plurality of current sensors include at least two of a current sensor that detects a primary current flowing through the primary terminal pair of the conversion circuit, a current sensor that detects a secondary current flowing through the secondary terminal pair of the conversion circuit, and a current sensor that detects a current flowing through the storage battery. With this configuration, it is possible to execute a peak current mode based on a peak current value and an input current, or to execute an average current mode based on an average current value and an output current.

[0015] In a fifth aspect, the plurality of control modes during discharging or charging include a peak current mode in which the switching command is calculated based on a peak value of a current flowing through the primary terminal pair of the conversion circuit, and an average current mode in which the switching command is calculated based on an average value of a current flowing through the secondary terminal pair of the conversion circuit. With this configuration, the peak current mode can improve the control response of the charge / discharge current of the storage battery, and the average current mode can improve the control accuracy of the charge / discharge current of the storage battery.

[0016] In a sixth aspect, at least one of the average current modes includes a continuous current mode in which current flowing through the secondary terminal pair is continuous, and a discontinuous current mode including a period in which the current flowing through the secondary terminal pair is zero, and the control unit has different correction terms for the switching command in the continuous current mode and the discontinuous current mode. With this configuration, it is possible to improve the current control accuracy when the continuous current mode and the discontinuous current mode are executed.

[0017] In a seventh aspect, the control unit calculates the correction term based on the primary-side voltage between the primary-side terminal pair and the secondary-side voltage between the secondary-side terminal pair. With this configuration, the correction term can be appropriately calculated, and the current control accuracy can be improved both when executing a continuous current mode and when executing a discontinuous current mode. The input voltage can be calculated by multiplying the output voltage by the turns ratio of the transformer.

[0018] In an eighth aspect, when only a predetermined control mode is executed for the current output current command value for the conversion circuit, the control unit does not execute the calculation of the switching command for the plurality of control modes in parallel, but prioritizes executing only the calculation of the switching command for the predetermined control mode. With this configuration, when only the predetermined control mode is executed for the current output current command value for the conversion circuit, it is possible to omit unnecessary calculation of switching commands, thereby reducing the processing load on the control unit.

[0019] In the ninth means, the control unit selects the switching command to be selectable from the plurality of switching commands calculated based on the output current command value for the conversion circuit, and selects one of the switching commands from the selectable switching commands.

[0020] According to the above configuration, first, the selectable switching commands can be narrowed down from the calculated plurality of switching commands based on the output current command value for the conversion circuit. Then, one of the selectable switching commands is selected. Therefore, even if the calculated plurality of switching commands is large in number, it is easy to select an appropriate switching command.

[0021] Specifically, in a tenth aspect, the control unit is configured to select, from the plurality of calculated switching commands, the switching command for the control mode that can be executed when discharging the storage battery when the output current command value for the conversion circuit is greater than 0, and to select, from the plurality of calculated switching commands, the switching command for the control mode that can be executed when charging the storage battery when the output current command value for the conversion circuit is less than 0. With this configuration, it is possible to smoothly switch between the control mode for discharging and the control mode for charging, with the output current command value becoming 0 as the dividing line.

[0022] The eleventh means includes a primary current sensor that detects a primary current flowing through the primary terminal pair of the conversion circuit, and a secondary current sensor that detects a secondary current flowing through the secondary terminal pair of the conversion circuit, and the plurality of control modes include a control mode that calculates the switching command based on the detection values ​​of the primary current sensor and the secondary current sensor, and the storage battery and the conversion circuit constitute a storage battery module, and the storage battery module includes the primary current sensor.

[0023] According to the above configuration, a switching command can be calculated based on the detected value of the primary current sensor included in the storage battery module, so there is no need to provide a dedicated current sensor just for detecting the current flowing through the primary terminal pair of the conversion circuit.

[0024] In a twelfth aspect, the present invention further includes a secondary-side voltage sensor that detects the voltage across the pair of secondary-side terminals of the converter circuit, and the control unit calculates the switching command based on the voltage detected by the secondary-side voltage sensor. Alternatively, the present invention further includes a bus voltage sensor that detects the voltage of a power supply bus to which the storage battery and the converter circuit are connected, and the control unit calculates the switching command based on the voltage detected by the bus voltage sensor. With this configuration, the switching command is calculated based on either the secondary-side voltage sensor or the bus voltage sensor, so the other can be omitted. Note that the voltage across the pair of secondary-side terminals can be calculated by subtracting the voltage of the storage battery (i.e., the voltage across the pair of primary-side terminals) from the voltage detected by the bus voltage sensor.

[0025] The thirteenth means is a control program applied to a power supply system including a storage battery and a conversion circuit having a primary side terminal pair connected in parallel to the storage battery and a secondary side terminal pair connected in series to the storage battery, which converts power by driving a switching element, and causes a computer to execute the following processes: a process of controlling the charge / discharge current of the storage battery by driving the switching element based on a switching command; a process of executing a plurality of control modes that calculate the switching command based on an output current command value for the conversion circuit; and a process of calculating the switching command using the plurality of control modes in parallel, selecting one of the calculated plurality of switching commands, and driving the switching element based on the selected switching command.

[0026] According to the above configuration, by causing a computer to execute a control program applied to the power supply system, it is possible to achieve the same effects as those of the first means.

[0027] The above and other objects, features, and advantages of the present disclosure will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which Fig. 1 is a circuit diagram of a power supply system, Fig. 2 is a circuit diagram showing an example of a conversion circuit, Fig. 3 is a flowchart showing a control mode switching procedure, Fig. 4 is a time chart showing currents in continuous mode and discontinuous mode, Fig. 5 is a block diagram showing FF terms in continuous mode and discontinuous mode, Fig. 6 is a block diagram showing a flow of outputting a drive signal based on switching timing, Fig. 7 is a time chart showing a current command value and a primary-side current in a peak current mode during discharge, and Fig. 8 is a time chart showing a current command value and a primary-side current in an average current mode during discharge. FIG. 10 is a time chart showing the current command value in the peak current mode during discharge and the primary current in the average current mode during discharge; FIG. 11 is a circuit diagram of a modified example of the power supply system; FIG. 12 is a circuit diagram of another modified example of the power supply system; FIG. 13 is a circuit diagram of another modified example of the power supply system; FIG. 14 is a circuit diagram of a modified example of the conversion circuit; FIG. 15 is a circuit diagram of another modified example of the conversion circuit; and FIG. 16 is a circuit diagram of a modified example of the storage battery module.

[0028] Hereinafter, an embodiment of a power supply system that is mounted on a vehicle and supplies power to a load will be described with reference to the drawings.

[0029] 1 , the power supply system 10 includes buses 11 and 12 (power supply buses), a first storage battery module 30, a second storage battery module 60, a voltage sensor 13, a current sensor 19, an ECU (Electronic Control Unit) 16, etc. The positive side of the buses is referred to as bus 11, and the negative side of the buses is referred to as bus 12. The bus 12 is grounded.

[0030] A first storage battery module 30 (storage battery module), a second storage battery module 60 (storage battery module), a load 21, and a voltage sensor 13 are connected in parallel to the buses 11 and 12. The storage battery modules 30 and 60 input and output power to and from the buses 11 and 12. The load 21 inputs power from and inputs and outputs power to and from the buses 11 and 12. The voltage sensor 13 (bus voltage sensor) detects a bus voltage Vbus, which is the voltage between the bus 12 and the bus 11. The current sensor 19 detects a current flowing through the bus 12 (load 21).

[0031] The load 21 is, for example, a combination of an inverter and a motor generator (MG) (inverter-equipped motor unit), an electric heater, a DC-DC converter, etc. The MG (motor generator) drives, for example, an electric vehicle using power supplied from the inverter, or generates electricity regeneratively using rotational force imparted by the electric vehicle. The inverter converts power between the buses 11 and 12 and the MG. The electric heater generates heat using high voltage supplied from the buses 11 and 12, for example, to warm the interior of the vehicle or the battery. The DC-DC converter converts DC power supplied from the buses 11 and 12, for example, to supply DC power, or converts DC power supplied from a solar panel or the like to supply DC power to the buses 11 and 12. The load 21 may be single or multiple.

[0032] The first storage battery module 30 includes a first storage battery 31, a first current sensor 33, a first drive circuit 35, a first conversion circuit 40, and relays 40a and 40b. The first storage battery 31 (storage battery) is a high-voltage secondary battery, such as a lithium-ion battery or a nickel-metal hydride battery, and may be of any type. The first current sensor 33 (current sensor) detects the current flowing through the first storage battery 31. The value detected by the first current sensor 33 is input to the ECU 16 and used, for example, to calculate the state of charge (SOC) of the first storage battery 31. The first drive circuit 35 (drive circuit) drives switching elements (described below) included in the first conversion circuit 40 to turn on and off. The first drive circuit 35 is controlled by the ECU 16. The relays 40a and 40b connect and disconnect the storage battery module 30 to and from the buses 11 and 12, respectively. The first storage battery 31 (storage battery) may be a secondary battery that is not a high voltage battery.

[0033] The first conversion circuit 40 (conversion circuit) includes a primary-side terminal pair, that is, a primary-side positive terminal 41 and a negative terminal 42, and a secondary-side terminal pair, that is, a secondary-side positive terminal 47 and a negative terminal 48. The negative terminal of the first storage battery 31 is connected to the bus 12. The primary-side positive terminal 41 is connected to the positive terminal of the first storage battery 31, and the primary-side negative terminal 42 is connected to the negative terminal of the first storage battery 31. The secondary-side negative terminal 48 is also connected to the positive terminal of the first storage battery 31. The secondary-side positive terminal 47 is connected to the bus 11. That is, the positive and negative terminals of the first storage battery 31 are connected to the primary-side terminal pair 41, 42 of the first conversion circuit 40, respectively (the first storage battery 31 is connected in parallel), and the first storage battery 31 is connected in series to the secondary-side terminal pair 47, 48 of the first conversion circuit 40. The first conversion circuit 40 converts the power input from the first storage battery 31 to the pair of primary side terminals 41 and 42 and outputs it from the pair of secondary side terminals 47 and 48. The first conversion circuit 40 also converts the power input to the pair of secondary side terminals 47 and 48 and outputs it from the pair of primary side terminals 41 and 42. In other words, the first conversion circuit 40 is a bidirectional conversion circuit.

[0034] The second storage battery module 60 has a configuration similar to that of the first storage battery module 30 and includes a second storage battery 61 (storage battery), a second current sensor 63 (current sensor), a second drive circuit 65 (drive circuit), a second conversion circuit 70, relays 70a and 70b, etc. The second conversion circuit 70 (conversion circuit) has a configuration similar to that of the first conversion circuit 40 and includes a primary-side terminal pair consisting of a primary-side positive terminal 71 and a negative terminal 72, and a secondary-side terminal pair consisting of a secondary-side positive terminal 77 and a negative terminal 78. The connection configuration of these components is also similar to that of the first storage battery module 30, and therefore the above description of the first storage battery module 30 is incorporated herein. Note that although the first storage battery module 30 and the second storage battery module 60 have components with similar functions, the ratings and withstand voltages of the respective components may differ from each other.

[0035] FIG. 2 shows an example of the first conversion circuit 40. The first conversion circuit 40 is a well-known center-tap isolated DC-DC converter. The first conversion circuit 40 (first storage battery module 30) includes switching elements 43 to 46, 54, and 55, smoothing capacitors 50 and 57, a transformer 53, a reactor 56, voltage sensors 51 and 59, and current sensors 52 and 58. The switching elements 43 to 46, 54, and 55 are, for example, FETs or IGBTs (insulated gate bipolar transistors). The switching elements 43 to 46 form a full-bridge circuit. The connection point between the switching element 43 and the switching element 44 and the connection point between the switching element 45 and the switching element 46 are connected to both ends of the primary coil of the transformer 53, respectively. The switching elements 54 and 55 are connected between both ends of the secondary coil of the transformer 53 and the reactor 56, respectively. The voltage sensor 51 (primary-side voltage sensor) detects the voltage between the negative terminal 42 and the positive terminal 41 on the primary side, i.e., the output voltage Vb (primary-side voltage) of the first storage battery 31. The current sensor 52 (primary-side current sensor) detects the input current Ii (primary-side current) that is input to (flows through) the primary circuit (primary-side terminal pair 41, 42). The voltage sensor 59 (secondary-side voltage sensor) detects the voltage between the negative terminal 48 and the positive terminal 47 on the secondary side, i.e., the output voltage Vo (secondary-side voltage) of the first conversion circuit 40. The current sensor 58 (secondary-side current sensor) detects the current flowing through the reactor 56, i.e., the output current Io (secondary-side current flowing through the secondary-side terminal pair 47, 48) of the first conversion circuit 40. The values ​​detected by the voltage sensors 51, 59 and the current sensors 52, 58 are input to the ECU 16.

[0036] The ECU 16 (control device) is configured as a microcomputer (computer) including, for example, a CPU, ROM, RAM, an input / output interface, etc. The ECU 16 controls the states of the relays 40a, 40b, 70a, and 70b and the state of the load 21. Furthermore, the ECU 16 executes a control program applied to the power supply system 10 to realize the functions of a bus voltage setting unit 16a, a control unit 16b, etc.

[0037] The bus voltage setting unit 16a sets a bus voltage request value Vbus*, which is a voltage that is requested to be supplied from the buses 11 and 12 to the load 21. The bus voltage setting unit 16a sets the bus voltage request value Vbus* based on the state of the load 21.

[0038] The control unit 16b controls the output voltages Vo1 and Vo2 of the conversion circuits 40 and 70 so that the output voltages Vm1 and Vm2 of the storage battery modules 30 and 60 become equal to (approach) the required bus voltage value Vbus* during discharge. For example, the control unit 16b calculates the first required output voltage value Vo1* of the first conversion circuit 40 by subtracting the first output voltage Vb1 of the first storage battery 31 from the required bus voltage value Vbus*. The control unit 16b calculates a first output current command value Io1* of the first conversion circuit 40 based on the first required output voltage value Vo1*. The control unit 16b calculates switching commands (a duty command value Duty and a drive signal G, which is an on-off pulse signal) in multiple control modes during discharge based on the first output current command value Io1* and the detected values ​​of the voltage sensors 51 and 59 and the current sensors 52 and 58. That is, the control unit 16b is capable of executing a plurality of control modes that calculate switching commands based on the output current command value Io1* for the conversion circuit 40. The plurality of control modes include a peak current mode and an average current mode. The control unit 16b then outputs a drive signal G to the first drive circuit 35 of the switching elements 43 to 46 to drive the switching elements 43 to 46 on and off. The plurality of control modes will be described later. Similarly, the control unit 16b controls the second output voltage Vo2 of the second conversion circuit 70 based on the second output current command value Io2* for the second conversion circuit 70.

[0039] Furthermore, the control unit 16b controls the charging voltage or charging current of the storage batteries 31, 61 during charging. For example, the control unit 16b calculates a first output current command value Io1* as a charging current command value for the first conversion circuit 40 based on the state of charge (SOC) of the storage battery 31. The control unit 16b calculates switching commands (duty command value Duty and drive signal G, which is an on-off pulse signal) in the control mode during charging based on the first output current command value Io1* and the detected values ​​by the voltage sensors 51, 59 and the current sensors 52, 58. The control unit 16b then outputs the drive signal G to the first drive circuit 35 of the switching elements 54, 55 to drive the switching elements 54, 55 on and off. Similarly, the control unit 16b controls the charging voltage or charging current of the second storage battery 61 based on a second output current command value Io2* for the second conversion circuit 70.

[0040] 3 is a flowchart showing the control mode switching procedure. This series of processes is repeatedly executed at predetermined intervals by the ECU 16 for each of the storage battery modules 30, 60. Here, the process for the first storage battery module 30 will be described as an example.

[0041] First, the output current command value Io* is obtained (S10), then the input current sensor detection value is obtained (S11), and then the output current sensor detection value is obtained (S12). The output current command value Io* is calculated by the control unit 16b as described above. The input current sensor detection value is the input current Ii detected by the current sensor 52. The output current sensor detection value is the output current Io detected by the current sensor 58.

[0042] Subsequently, calculations of switching timing commands (switching commands) in a plurality of control modes are executed in parallel (S13, S14, S15).

[0043] In the process of S13, a switching timing command is calculated in the discharge peak current mode. Because the peak current mode is a well-known control mode, a detailed description will be omitted and only an outline will be provided. For example, the peak value of the input current Ii is set based on the acquired output current command value Io* and the turns ratio of the transformer 53, and the input current command value Ii* is calculated based on the peak value. The duty command value Duty is calculated based on the input current command value Ii*, the input current Ii detected by the current sensor 52, and the slope compensation value. The duty command value Duty (switching timing command) is a value that indicates the time ratio of the on-period in a switching period when the switching element is driven on and off at a predetermined switching period by duty control. That is, in the discharge peak current mode, the duty command value Duty is calculated based on the peak value of the input current of the first conversion circuit 40.

[0044] In the process of S14, a switching timing command is calculated in the discharge average current mode. Because the average current mode is a well-known control mode, a detailed description will be omitted and only an outline will be provided. For example, a duty command value Duty (switching timing command) for the switching elements 43 to 46 is calculated based on the average value of the output current Io of the first conversion circuit 40 detected by the current sensor 58 and the output current command value Io*. The average current mode includes a continuous mode (continuous current mode) shown in FIG. 4(a) and a discontinuous mode (discontinuous current mode) shown in FIG. 4(b). As shown in FIG. 4(a), the output current Io is continuous in the continuous mode. On the other hand, as shown in FIG. 4(b), the discontinuous mode includes a period in which the output current Io becomes zero. As shown in FIG. 5, in the average current mode, a feedback correction term (FB term) using PI control, a feedforward correction term for the continuous mode (continuous FF term), and a feedforward correction term for the discontinuous mode (discontinuous FF term) are calculated. The continuous FF term during discharge is expressed as continuous FF term = Vo / Vi, where Vi is the input voltage and Vo is the output voltage of the first conversion circuit 40. The input voltage Vi is detected by the voltage sensor 51, and the output voltage Vo is detected by the voltage sensor 59. The discontinuous FF term is expressed as √{2Lf(Io*) × (Vi - Vo) / ViVo}, where L is the reactance of the reactor 56, and f is the switching frequency in duty control. The smaller of the continuous FF term and the discontinuous FF term is adopted as the FF term. The FB term and the FF term are then added together to calculate the duty command value Duty in the average current mode.

[0045] In the process of S15, the switching timing command is calculated in the charging average current mode. The charging average current mode is similar to the discharging average current mode except that the duty command value Duty (switching timing command) for the switching elements 54, 55 is calculated and the continuous FF term for charging = 1 - Vo / Vi is used.

[0046] Next, it is determined whether the output current command value Io* is equal to or greater than 0 (S16). If it is determined that the output current command value Io* is equal to or greater than 0 (S16: YES), it is determined whether the output current command value Io* is equal to or greater than a threshold value α (S17). The threshold value α is a current value that can determine, for example, a large current region where a high-speed response is required for controlling the discharge current. If it is determined that the output current command value Io* is equal to or greater than the threshold value α (S17: YES), a drive signal G calculated based on the duty command value Duty calculated in the discharge peak current mode is output to the drive circuit 35 of the switching elements 43 to 46 (S18).

[0047] On the other hand, if it is determined in S17 that the output current command value Io* is not equal to or greater than the threshold value α (S17: NO), it is then determined whether the switching timing of the peak current mode is earlier than the switching timing of the average current mode during discharge (S19). For example, as shown in FIG. 6 , the larger of the duty command value Duty calculated in the peak current mode and the duty command value Duty calculated in the average current mode during discharge is set as the duty command value Duty with the earlier switching timing (the rising timing of the drive signal G). The adopted duty command value Duty is then converted into the drive signal G, for example, by an RSFF (Reset Set Flip). If it is determined in this determination that the switching timing of the peak current mode is earlier than the switching timing of the average current mode during discharge (S19: YES), the process proceeds to S18.

[0048] On the other hand, if it is determined in step S19 that the switching timing of the peak current mode is not earlier than the switching timing of the discharge average current mode (S19: NO), a drive signal G calculated based on the duty command value Duty calculated in the discharge average current mode is output to the drive circuit 35 of the switching elements 43 to 46 (S20). That is, two selectable duty command values ​​Duty are selected from the three calculated duty command values ​​Duty (switching commands) based on the output current command value Io* for the conversion circuit 40 (S16, S17), and one of the two selectable duty command values ​​Duty is selected (S18 to S20). Specifically, when the output current command value Io* is equal to or greater than 0 (greater than 0), the duty command values ​​Duty of the discharge peak current mode and the discharge average current mode, which are executable during discharge, are selectable. Furthermore, when the output current command value Io* is not equal to or greater than 0 (is smaller than 0), the duty command value Duty of the charging average current mode that can be executed during charging can be selected.

[0049] Furthermore, if it is determined in step S16 that the output current command value Io* is not equal to or greater than 0 (S16: NO), the controller 10 outputs a drive signal G calculated based on the duty command value Duty calculated in the charging average current mode to the drive circuit 35 of the switching elements 54, 55 (S21). The same process is performed for the second storage battery module 60.

[0050] 7 is a time chart showing the input current command value Ii* and the primary side input current Ii in the peak current mode during discharge. By using the peak current mode in the large current region, the discharge current can be controlled with high speed response.

[0051] 8 is a time chart showing the output current command value Io* and the secondary-side output current Io in the average current mode during discharge. By using the average current mode in the small current region, the discharge current can be precisely controlled.

[0052] FIG. 9 is a time chart showing the output current command value Io* and the output current Io. In a region where the output current command value Io* is equal to or greater than the threshold value α, a switching command for the peak current mode during discharge is selected. In a region where the output current command value Io* is smaller than the threshold value α and equal to or greater than 0, a switching command for the peak current mode during discharge or the average current mode during discharge is selected. In this case, the switching command with the earlier switching timing is selected between the peak current mode during discharge and the average current mode during discharge. In a region where the output current command value Io* is less than 0, a switching command for the average current mode during charge is selected. In this case, the discontinuous mode is selected in the small current region and the continuous mode is selected in the large current region. When switching between any of the above control modes, the switching commands are calculated in parallel in advance, and then the control mode is switched. Therefore, fluctuations in the output current Io are suppressed when switching the control mode, improving the control accuracy of the output current Io. Furthermore, when switching between the discontinuous mode and the continuous mode, the fluctuation of the output current Io is suppressed by switching between the discontinuous FF term and the continuous FF term.

[0053] The present embodiment described above in detail has the following advantages.

[0054] The first conversion circuit 40 has its primary terminal pair 41, 42 connected in parallel to the storage battery 31 and its secondary terminal pair 47, 48 connected in series to the storage battery 31, and converts power by driving switching elements 43-46, 54, and 55. Therefore, the sum of the output voltage Vb of the storage battery 31 and the output voltage Vo of the first conversion circuit 40 is the output voltage Vm of the storage battery module 30, including the storage battery 31 and the first conversion circuit 40. Therefore, compared to a storage battery module in which the storage battery 31 is connected in parallel to the secondary terminal pair 47, 48 of the first conversion circuit 40, the output voltage Vo required of the first conversion circuit 40 when the output voltage Vm is required of the storage battery module 30 can be reduced. Therefore, the rated voltage of the first conversion circuit 40 can be lowered, and thus the rated capacity of the first conversion circuit 40 can be reduced, thereby enabling the first conversion circuit 40 to be made more compact. The same applies to the second conversion circuit 70.

[0055] The control unit 16b controls the output current Io (charge / discharge current) of the storage battery 31 by driving the switching elements 43 to 46, 54, and 55 to turn on and off based on a switching command (duty command value Duty, drive signal G). The control unit 16b can execute a plurality of control modes that calculate switching commands based on the output current command value Io* for the first conversion circuit 40. Therefore, when controlling the output current Io of the storage battery 31, the control unit 16b can switch between a plurality of control modes according to the demands made on the power supply system 10.

[0056] The control unit 16b executes calculations of switching commands for multiple control modes in parallel. Therefore, regardless of which control mode is switched to, the switching commands for multiple control modes can be calculated in advance. The control unit 16b then selects one of the calculated switching commands and drives the switching elements 43 to 46, 54, and 55 based on the selected switching command. Therefore, regardless of which control mode switching command is selected, the switching elements 43 to 46, 54, and 55 can be quickly driven by the already calculated switching command. Therefore, it is possible to suppress the occurrence of a control response delay when switching the control mode, and improve the current control accuracy.

[0057] The control unit 16b can execute multiple control modes when the storage battery 31 is being discharged. Therefore, when the storage battery 31 is being discharged, the control unit 16b can switch between multiple control modes in accordance with the demands made on the power supply system 10. The control unit 16b then selects the switching command with the earliest switching timing (the rising timing of the drive signal G) from among the multiple switching commands calculated for when the storage battery 31 is being discharged. Therefore, when the switching command changes, the change in the switching command can be quickly reflected in the driving of the switching elements 43 to 46. This can further reduce the response delay in the control.

[0058] The power supply system 10 includes a plurality of current sensors 52, 58 that detect currents in different paths in the first conversion circuit 40, and the plurality of control modes during discharge include control modes (peak current mode, average current mode) that calculate switching commands based on the detected values ​​of the plurality of current sensors 52, 58. With this configuration, the plurality of current sensors 52, 58 can detect currents in different paths in the first conversion circuit 40. Therefore, control modes with different control methods can be executed based on the detected values ​​of the plurality of current sensors 52, 58.

[0059] The multiple current sensors 52, 58 include a current sensor 52 that detects an input current Ii input to the primary-side terminal pair 41, 42 of the first conversion circuit 40, and a current sensor 58 that detects an output current Io output from the secondary-side terminal pair 47, 48 of the first conversion circuit 40. With this configuration, it is possible to execute the peak current mode based on the peak value of the current and the input current Ii, or to execute the average current mode based on the average value of the current and the output current Io.

[0060] The multiple control modes during discharge include a peak current mode in which a switching command is calculated based on the peak value of the input current input to the primary-side terminal pair 41, 42 of the first conversion circuit 40, and an average current mode in which a switching command is calculated based on the average value of the output current output from the secondary-side terminal pair 47, 48 of the first conversion circuit 40. With this configuration, the peak current mode can improve the control response of the discharge current of the storage battery 31, and the average current mode can improve the control accuracy of the discharge current of the storage battery 31.

[0061] The average current mode includes a continuous mode in which the discharge (charge) current is continuous during discharge (charge), and a discontinuous mode in which the discharge (charge) current is zero during discharge (charge). The control unit 16b has a continuous FF term and a discontinuous FF term as correction terms for the switching command. This configuration improves the current control accuracy when the continuous mode and the discontinuous mode are executed.

[0062] The control unit 16b calculates the FF term based on the input voltage Vi to the primary terminal pair 41, 42 and the output voltage Vo from the secondary terminal pair 47, 48. This configuration allows the FF term to be calculated appropriately, improving the current control accuracy both when the continuous mode is being executed and when the discontinuous mode is being executed. Note that the input voltage Vi can also be calculated by multiplying the output voltage Vo by the turns ratio of the transformer 53.

[0063] Based on the output current command value Io* for the first conversion circuit 40, it is possible to narrow down the selectable switching commands from the multiple calculated switching commands. Then, one switching command is selected from the selectable switching commands. Therefore, even if the number of calculated multiple switching commands is large, it becomes easier to select an appropriate switching command.

[0064] When the output current command value Io* for the first conversion circuit 40 is greater than 0, the control unit 16b can select, from the plurality of calculated switching commands, a switching command for a control mode that can be executed when discharging the storage battery 31. Also, when the output current command value Io* for the first conversion circuit 40 is less than 0, the control unit 16b can select, from the plurality of calculated switching commands, a switching command for a control mode that can be executed when charging the storage battery 31. With this configuration, the control mode for discharging and the control mode for charging can be smoothly switched, with the output current command value Io* becoming 0 as the dividing line.

[0065] The switching command can be calculated based on the detection value of the primary-side current sensor 52 included in the storage battery module 30. Therefore, there is no need to provide a dedicated current sensor just for detecting the input current Ii input to the primary-side terminal pair 41, 42 of the first conversion circuit 40.

[0066] The above-described advantageous effects can be achieved by causing the ECU 16 (computer) to execute the control program applied to the power supply system 10 .

[0067] The above embodiment can be modified as follows: The same parts as those in the above embodiment are denoted by the same reference numerals and the description thereof will be incorporated herein.

[0068] The control unit 16b includes a voltage sensor 59 that detects the voltage (output voltage Vo) between the secondary-side terminal pair 47, 48 of the first conversion circuit 40, and calculates a switching command based on the output voltage Vo detected by the voltage sensor 59. Here, the bus voltage Vbus can be calculated by adding the output voltage Vo of the conversion circuit 40 detected by the voltage sensor 59 to the output voltage Vb of the storage battery 31 detected by the voltage sensor 51. Therefore, the voltage sensor 13 that detects the bus voltage Vbus can be omitted. On the other hand, the output voltage Vo of the conversion circuit 40 can be calculated by subtracting the output voltage Vb of the storage battery 31 detected by the voltage sensor 51 from the bus voltage Vbus detected by the voltage sensor 13. In this case, the voltage sensor 59 can be omitted.

[0069] - The control unit 16b can also use the current flowing through the first storage battery 31 detected by the first current sensor 33 (current sensor) and the current flowing through the second storage battery 61 detected by the second current sensor 63 (current sensor) to control the charging and discharging current.

[0070] - For example, when the output current command value Io* decreases, the control unit 16b can select the switching command with the earliest falling timing of the drive signal G as the switching command with the earliest switching timing from among the multiple switching commands calculated.

[0071] In the flowchart of FIG. 3, the processing of S19 may be omitted, and if it is determined in S17 that the output current command value Io* is not equal to or greater than the threshold value α (S17: NO), the processing may proceed to S20.

[0072] In FIG. 5, the FF term can be omitted.

[0073] As shown in FIG. 9 , when the storage battery 31 is being charged, the control unit 16b executes only the charging average current mode. That is, when the storage battery 31 is being charged, the control unit 16b switches between the discontinuous FF term (discontinuous mode) and the continuous FF term (continuous mode), but does not switch the control mode. Therefore, when the current output current command value Io* is less than 0 and only the charging average current mode is being executed, the control unit 16b may execute only the calculation of the switching command in the charging average current mode, without executing the calculation of the switching command in the discharging peak current mode and the discharging average current mode in parallel. That is, when only a predetermined control mode is being executed for the current output current command value Io* for the first conversion circuit 40, the control unit 16b may prioritize executing only the calculation of the switching command in the predetermined control mode, without executing the calculation of the switching command in multiple control modes in parallel. This configuration allows unnecessary calculation of switching commands to be omitted when only a predetermined control mode is being executed for the current output current command value Io* for the first conversion circuit 40. Therefore, the processing load on the control unit 16b (ECU 16) can be reduced.

[0074] As shown in Fig. 10, a switching command can be selected so that the input current Ii in the average current mode is limited by the input current command value Ii* in the peak current mode. With this configuration, even if an overcurrent occurs due to biased magnetization when the average current mode is being executed, the overcurrent can be suppressed by the switching command for the peak current mode that is calculated in advance in parallel.

[0075] During charging, in addition to the average current mode during charging, the peak current mode during charging can also be executed. The peak current mode during charging is similar to the peak current mode during discharging, except that a duty command value Duty (switching timing command) for the switching elements 54, 55 is calculated. As in the processes of S17 to S20 in the flowchart of FIG. 3, it is possible to switch between outputting a drive signal G calculated based on the duty command value Duty calculated in the peak current mode during charging, and outputting a drive signal G calculated based on the duty command value Duty calculated in the average current mode during charging.

[0076] 11 , a predetermined storage battery module 120 including a storage battery 121 but no conversion circuit may be connected to the buses 11 and 12. The predetermined storage battery module 120 includes a voltage sensor 121a that detects the voltage of the storage battery 121 and relays 120a and 120b that connect and disconnect the predetermined storage battery module 120 to and from the buses 11 and 12. The storage battery modules 30 and 60 also include voltage sensors 31a and 61a, relays 40a and 40b, and relays 70a and 70b, respectively. With this configuration, power can be supplied from the predetermined storage battery module 120 to the buses 11 and 12. Furthermore, the storage battery modules 30 and 60, each including a conversion circuit 40 and 70, can adjust the output voltages Vm1 and Vm2 of the storage battery modules 30 and 60 to the output voltage Vmb of the predetermined storage battery module 120, for example, 400 V, by controlling the output voltages Vo1 and Vo2 of the conversion circuits 40 and 70, which are added to the output voltages Vb1 and Vb2 of the storage batteries 31 and 61, respectively. The control unit 16b can then execute the process shown in the flowchart of FIG. 3 for the storage battery modules 30 and 60. This reduces the number of conversion circuits in the entire power supply system 210 while suppressing inrush currents and circulating currents between the storage battery modules 30 and 60 and the predetermined storage battery module 120. As a result, the power supply system 210 can be further miniaturized. The predetermined storage battery module 120 can also be replaced with, for example, the first storage battery module 30, and the process shown in the flowchart of FIG. 3 can be executed for the first storage battery module 30.

[0077] As the load 21, for example, two or more combinations of an inverter and an MG (Motor Generator) (motor units with inverters) may be connected in parallel to the buses 11 and 12. In this case, the more motor units with inverters there are, the more storage battery modules may be connected to the buses 11 and 12.

[0078] As shown in FIG. 12 , the load 28 may be connected in parallel to the second storage battery 61 (storage battery) of the second storage battery module 60 (storage battery module). In this case, the charge amount of the second storage battery 61 can be reduced by supplying power from the second storage battery 61 to the load 28. This makes it easier to reduce the second output voltage Vb2 of the second storage battery 61 of the second storage battery module 60 below the first output voltage Vb1 of the first storage battery 31 of the first storage battery module 30. This makes it easier to control the addition of the second output voltage Vo2 of the second conversion circuit 70 to the second output voltage Vb2 of the second storage battery 61 of the second storage battery module 60, thereby regulating the second output voltage Vm2 of the second storage battery module 60 to the required bus voltage value Vbus*. Furthermore, the paths 22 to 24 and relays 25 to 27 (switching circuits) can switch between a series connection and a parallel connection of the storage battery modules 30, 60 with respect to the buses 11, 12.

[0079] As shown in FIG. 13 , the power supply system 210 may include a path 211 connecting a connection point N7 between the third conversion circuit 100 of the third storage battery module 90 and the relay 90a to a connection point N8 between the first storage battery 31 of the first storage battery module 30 and the relay 40b. Furthermore, the power supply system 210 may include a path 213 connecting a connection point N9 between the first conversion circuit 40 of the first storage battery module 30 and the relay 40a to a connection point N10 between the second storage battery 61 of the second storage battery module 60 and the relay 70b. The path 211 is provided with a relay 212 (switch) that connects and disconnects the path 211. The path 213 is provided with a relay 214 (switch) that connects and disconnects the path 213. The relays 212 and 214 are controlled by the ECU 16. The paths 211, 213, and the relays 212 and 214 form a switching circuit. That is, the power supply system 210 may include three or more storage battery modules (plurality of storage battery modules), and the switching circuit may switch the three or more storage battery modules between series connection and parallel connection with the buses 11 and 12 .

[0080] As shown in Fig. 14, in the first conversion circuit 40 (conversion circuit), the switching elements 54 and 55 in Fig. 2 may be connected between the transformer 53 and the negative terminal 48. With this configuration, it is possible to achieve the same effects as the first conversion circuit 40 in Fig. 2. The same applies to the second conversion circuit 70 (conversion circuit).

[0081] As shown in FIG. 15 , the first conversion circuit 40 (conversion circuit) may be a well-known isolated DC-DC converter including a non-center-tapped transformer 153 and a secondary-side full-bridge circuit composed of switching elements 143 to 146. The switching elements 143 to 146 are, for example, FETs or IGBTs (insulated gate bipolar transistors). The switching elements 143 to 146 are controlled by the ECU 16. In this case, the control unit 16b also executes parallel calculations of switching commands in multiple control modes, selects one of the calculated multiple switching commands, and drives the switching elements 43 to 46 and 143 to 146 based on the selected switching command. The same applies to the second conversion circuit 70 (conversion circuit).

[0082] A resonant DC-DC converter can also be used as the first conversion circuit 40 (conversion circuit). A non-isolated DC-DC converter such as a buck converter can also be used as the first conversion circuit 40 (conversion circuit). In this case, the control unit 16b can also execute the calculation of switching commands in multiple control modes in parallel, select one of the calculated multiple switching commands, and drive the switching elements based on the selected switching command. The same applies to the second conversion circuit 70 (conversion circuit).

[0083] The storage battery modules 30, 60 may be configured as shown in FIG. 16 . That is, the positive electrode of the first storage battery 31 is connected to the bus 11. The positive electrode of the first storage battery 31 is connected to the primary-side positive terminal 41 of the first conversion circuit 40, and the negative electrode of the first storage battery 31 is connected to the primary-side negative terminal 42 of the first conversion circuit 40. The negative electrode of the first storage battery 31 is connected to the secondary-side positive terminal 47 of the first conversion circuit 40. The secondary-side negative terminal 48 of the first conversion circuit 40 is connected to the bus 12. In this case, too, the primary-side terminal pair 41, 42 of the first conversion circuit 40 is connected in parallel to the first storage battery 31, and the secondary-side terminal pair 47, 48 of the first conversion circuit 40 is connected in series to the first storage battery 31. This configuration can achieve the same effects as the above-described embodiment. The same applies to the second storage battery module 60 (storage battery module).

[0084] At least one of the functions of the bus voltage setting unit 16a and the control unit 16b of the ECU 16 can be realized by, for example, a power control ECU (Electronic Control Unit) that controls the power of the electric vehicle or a vehicle control ECU (host ECU) that controls the electric vehicle in an integrated manner. Furthermore, when the power supply system 10, 210 is used as, for example, a stationary power source, the functions of the bus voltage setting unit 16a and the control unit 16b of the ECU 16 can be realized by a stationary power source control ECU (control device) that controls the stationary power source.

[0085] The ECU 16 and the methods described herein may be implemented by a special-purpose computer configured with a processor and memory programmed to execute one or more functions (instructions) embodied in a computer program. Alternatively, the ECU 16 and the methods described herein may be implemented by a special-purpose computer configured with a processor implemented by one or more dedicated hardware logic circuits. Alternatively, the ECU 16 and the methods described herein may be implemented by one or more special-purpose computers configured with a processor and memory programmed to execute one or more functions and a processor implemented by one or more hardware logic circuits. Furthermore, the computer program may be stored as instructions executed by a computer on a computer-readable non-transitory storage medium.

[0086] The above-described embodiment and modifications may be combined within the scope of possible combinations.

[0087] The following describes characteristic configurations extracted from the above-described embodiments and modified examples. [Configuration 1] A power supply system (10, 210) including a storage battery (31, 61), a conversion circuit (40, 70) having a pair of primary-side terminals (41, 42, 71, 72) connected in parallel to the storage battery and a pair of secondary-side terminals (47, 48, 77, 78) connected in series to the storage battery, and converting power by driving switching elements (43-46, 54, 55, 143-146), and a control unit (16b) that controls charge / discharge current of the storage battery by driving the switching elements on and off based on switching commands, wherein the control unit is capable of executing a plurality of control modes that calculate the switching command based on an output current command value for the conversion circuit, calculates the switching command using the plurality of control modes in parallel, selects one of the calculated plurality of switching commands, and drives the switching elements based on the selected switching command. [Configuration 2] The power supply system of Configuration 1, wherein the control unit is capable of executing a plurality of the control modes when discharging or charging the storage battery, and selects the switching command with the earliest switching timing from the plurality of switching commands calculated for discharging or charging the storage battery. [Configuration 3] The power supply system of Configuration 2, further comprising a plurality of current sensors (19, 33, 52, 58, 63) that detect currents in different paths, respectively, and the plurality of control modes when discharging or charging includes a control mode that calculates the switching command based on detection values ​​of at least two of the plurality of current sensors. [Configuration 4] The power supply system of Configuration 3, wherein the plurality of current sensors include at least two of a current sensor (52) that detects a primary current flowing through the primary terminal pair of the conversion circuit, a current sensor (58) that detects a secondary current flowing through the secondary terminal pair of the conversion circuit, and a current sensor (33, 63) that detects a current flowing through the storage battery.[Configuration 5] The power supply system of any one of Configurations 2 to 4, wherein the plurality of control modes during discharging or charging include a peak current mode that calculates the switching command based on a peak value of a current flowing through the primary-side terminal pair of the conversion circuit, and an average current mode that calculates the switching command based on an average value of a current flowing through the secondary-side terminal pair of the conversion circuit. [Configuration 6] The power supply system of Configuration 5, wherein at least one of the average current modes includes a continuous current mode in which a current flows continuously through the secondary-side terminal pair, and a discontinuous current mode that includes a period in which the current flowing through the secondary-side terminal pair becomes zero, and wherein the control unit has a correction term for the switching command that differs between the continuous current mode and the discontinuous current mode. [Configuration 7] The power supply system of Configuration 6, wherein the control unit calculates the correction term based on a primary-side voltage between the primary-side terminal pair and a secondary-side voltage between the secondary-side terminal pair. [Configuration 8] The power supply system of any one of Configurations 1 to 7, wherein the control unit does not execute calculation of the switching commands according to the plurality of control modes in parallel when only a predetermined control mode is executed for the current output current command value for the conversion circuit, and prioritizes executing calculation of the switching commands according to only the predetermined control mode. [Configuration 9] The power supply system of any one of Configurations 1 to 8, wherein the control unit selects selectable switching commands from the calculated plurality of switching commands based on the output current command value for the conversion circuit, and selects one of the selectable switching commands. [Configuration 10] The power supply system of Configuration 9, wherein the control unit selects a switching command for a control mode that can be executed when discharging the storage battery from the calculated plurality of switching commands when the output current command value for the conversion circuit is greater than 0, and selects a switching command for a control mode that can be executed when charging the storage battery from the calculated plurality of switching commands when the output current command value for the conversion circuit is less than 0.

[0088] Although the present disclosure has been described with reference to the embodiments, it is understood that the present disclosure is not limited to the embodiments or structures. The present disclosure also encompasses various modifications and equivalent modifications. In addition, various combinations and forms, including only one element, more than one element, or less than one element, are also within the scope and spirit of the present disclosure.

Claims

1. A power supply system (10, 210) comprising: a storage battery (31, 61); a conversion circuit (40, 70) having a primary side terminal pair (41, 42, 71, 72) connected in parallel to the storage battery and a secondary side terminal pair (47, 48, 77, 78) connected in series to the storage battery, which converts power by driving switching elements (43-46, 54, 55, 143-146); and a control unit (16b) which controls a charge / discharge current of the storage battery by driving the switching elements on and off based on a switching command, wherein the control unit is capable of executing a plurality of control modes for calculating the switching command based on an output current command value for the conversion circuit, executes calculation of the switching command using the plurality of control modes in parallel, selects one of the calculated switching commands, and drives the switching element based on the selected switching command.

2. The power supply system of claim 1, wherein the control unit is capable of executing a plurality of the control modes when discharging or charging the storage battery, and selects the switching command having the earliest switching timing from the plurality of switching commands calculated when discharging or charging the storage battery.

3. A power supply system as described in claim 2, comprising a plurality of current sensors (19, 33, 52, 58, 63) each detecting current in a different path, and the plurality of control modes during discharging or charging includes a control mode in which the switching command is calculated based on the detection values ​​of at least two of the plurality of current sensors.

4. The power supply system of claim 3, wherein the plurality of current sensors include at least two of a current sensor (52) that detects a primary current flowing through the primary terminal pair of the conversion circuit, a current sensor (58) that detects a secondary current flowing through the secondary terminal pair of the conversion circuit, and a current sensor (33, 63) that detects a current flowing through the storage battery.

5. A power supply system as claimed in any one of claims 2 to 4, wherein the plurality of control modes during discharging or charging include a peak current mode in which the switching command is calculated based on a peak value of a current flowing through the primary side terminal pair of the conversion circuit, and an average current mode in which the switching command is calculated based on an average value of a current flowing through the secondary side terminal pair of the conversion circuit.

6. The power supply system according to claim 5, wherein at least one of the average current modes includes a continuous current mode in which a current flowing through the secondary side terminal pair is continuous, and a discontinuous current mode including a period in which the current flowing through the secondary side terminal pair becomes zero, and the control unit has a correction term for the switching command which differs between the continuous current mode and the discontinuous current mode.

7. The power supply system according to claim 6, wherein the control unit calculates the correction term based on a primary-side voltage between the primary-side terminal pair and a secondary-side voltage between the secondary-side terminal pair.

8. A power supply system as described in any one of claims 1 to 4, wherein, when only a predetermined control mode is executed for the current output current command value for the conversion circuit, the control unit does not execute the calculation of the switching command using the multiple control modes in parallel, but prioritizes executing only the calculation of the switching command using the predetermined control mode.

9. A power supply system as described in any one of claims 1 to 4, wherein the control unit selects a selectable switching command from the calculated multiple switching commands based on the output current command value for the conversion circuit, and selects one of the selectable switching commands.

10. The power supply system of claim 9, wherein the control unit is capable of selecting, from the plurality of calculated switching commands, a switching command of the control mode that can be executed when discharging the storage battery when the output current command value for the conversion circuit is greater than 0, and is capable of selecting, from the plurality of calculated switching commands, a switching command of the control mode that can be executed when charging the storage battery when the output current command value for the conversion circuit is less than 0.

11. A power supply system as described in claim 1 or 2, comprising a primary side current sensor (52) that detects a primary side current flowing through the primary side terminal pair of the conversion circuit, and a secondary side current sensor (58) that detects a secondary side current flowing through the secondary side terminal pair of the conversion circuit, wherein the plurality of control modes include a control mode in which the switching command is calculated based on the detection values ​​of the primary side current sensor and the secondary side current sensor, respectively, wherein the storage battery and the conversion circuit constitute a storage battery module (30, 60), and the storage battery module includes the primary side current sensor.

12. A power supply system as described in claim 1 or 2, further comprising a secondary voltage sensor (59) that detects the voltage between the secondary terminal pair of the conversion circuit, and the control unit calculates the switching command based on the voltage detected by the secondary voltage sensor, or further comprising a bus voltage sensor (13) that detects the voltage of a power supply bus (11, 12) to which the storage battery and the conversion circuit are connected, and the control unit calculates the switching command based on the voltage detected by the bus voltage sensor.

13. A control program applied to a power supply system (10, 210) including a storage battery (31, 61) and a conversion circuit (40, 70) having a primary side terminal pair (41, 42, 71, 72) connected in parallel to the storage battery and a secondary side terminal pair (47, 48, 77, 78) connected in series to the storage battery, and converting power by driving switching elements (43-46, 54, 55, 143-146), the control program causing a computer (16) to execute the following processes: a process of controlling a charge / discharge current of the storage battery by driving the switching element based on a switching command; a process of executing a plurality of control modes that calculate the switching command based on an output current command value for the conversion circuit; and a process of executing in parallel the calculation of the switching command using the plurality of control modes, selecting one of the calculated plurality of switching commands, and driving the switching element based on the selected switching command.

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