Power supply system

Abstract

To reduce imbalance of a remaining power amount of a plurality of connected cartridges.SOLUTION: When a first / second index indicating total remaining power amount of a cartridge of all the first / second battery circuit modules satisfies predetermined conditions indicating imbalance, in a control period in which the cartridge of the battery circuit module having a smaller value of the first / second index is switched to a non-connection state in a first / second control period, equalization control is executed in which a switch circuit is controlled so as to temporarily switch at least one cartridge to be charged from among the cartridges of the battery circuit module having a smaller value of the first / second index to a connected state and the switch circuit is controlled so as to temporarily switch at least one of the cartridges that are not controlled to be in the connected state from among the cartridges of the battery circuit module having a larger value of the first / second index to the connected state in order to supply power to the cartridge to be charged.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to a power supply system, and in particular, to a power supply system that exchanges power with the outside. [Background Art]

[0002] Conventionally, there has been a power supply system that includes a plurality of battery modules each having a battery, and includes a power supply circuit in which the batteries in the battery modules can be connected in series with each other in accordance with a gate drive signal from a control controller (see, for example, Patent Document 1). In this power supply system, AC voltages having different phases from each other are output by temporally changing the number of batteries connected in series in each power supply circuit. [Prior Art Literature] [Patent Literature]

[0003] [Patent Document 1] Japanese Unexamined Patent Publication No. 2022-120255 [Summary of the Invention] [Problem to be Solved by the Invention]

[0004] In a power supply system such as that disclosed in Patent Document 1, imbalance may occur in the remaining capacity of each battery. Therefore, when the capacity of series-connected batteries is exhausted, an AC voltage as required can no longer be output.

[0005] The present disclosure has been made to solve the above-described problem, and an object of the present disclosure is to provide a power supply system capable of alleviating imbalance in the remaining power amount of a plurality of connected power storage devices. [Means for Solving the Problem]

[0006] The power supply system described in this disclosure is a system for exchanging power with the outside, and comprises a plurality of first energy storage units, a plurality of second energy storage units, first and second terminals for inputting and outputting power, and a control device for controlling the plurality of first and second energy storage units. Each of the plurality of first energy storage units includes a first energy storage device that applies a voltage from the second terminal to the first terminal when electrically connected between the first and second terminals, and a first switching unit that switches between a connected state in which the first energy storage device is electrically connected between the first and second terminals and a disconnected state in which it is electrically disconnected. Each of the plurality of second energy storage units includes a second energy storage device that applies a voltage from the first terminal to the second terminal when electrically connected between the first and second terminals, and a second switching unit that switches between a connected state in which the second energy storage device is electrically connected between the first and second terminals and a disconnected state in which it is electrically disconnected. The plurality of first energy storage devices and the plurality of second energy storage devices are connected in series with each other when connected. The control device alternately repeats a first control period in which it controls the first switching unit to switch at least one of the first energy storage devices to a connected state and the second switching unit to switch all of the second energy storage devices to a disconnected state, so that the output voltage between the first terminal and the second terminal becomes a predetermined AC waveform, and a second control period in which it controls the second switching unit to switch at least one of the second energy storage devices to a connected state and the first switching unit to switch all of the first energy storage devices to a disconnected state, and the first indicator showing the total remaining power of all first energy storage devices and the second indicator showing the total remaining power of all second energy storage devices are not When predetermined conditions indicating equilibrium are met, during the first or second control period in which the energy storage device with the smaller value of the first and second indicators is switched to a disconnected state, the switching unit is controlled to temporarily switch at least one of the energy storage devices to be charged from the energy storage device with the smaller value of the first and second indicators to a connected state, and equalization control is performed by controlling the switching unit to temporarily switch at least one of the energy storage devices with the larger value of the first and second indicators that is not controlled to be connected to a connected state in order to supply power to the energy storage device to be charged.

[0007] With this configuration, if the first indicator, which shows the total remaining energy of all first energy storage devices, and the second indicator, which shows the total remaining energy of all second energy storage devices, are unbalanced, at least one of the energy storage devices to be charged that is controlled to be disconnected (the one with the smaller value of either the first or second indicator) is temporarily switched to the connected state, and at least one of the other energy storage devices that is not controlled to be connected (the one with the larger value of either the first or second indicator) is temporarily switched to the connected state to supply power to the energy storage device to be charged. As a result, the energy storage device with the larger value of either the first or second indicator supplies power to the energy storage device with the smaller value. Consequently, a power supply system can be provided that can mitigate the imbalance in the remaining energy of multiple connected energy storage devices.

[0008] The control device may perform equalization control when there is sufficient margin in the total voltage that can be output by the energy storage device with the larger value of the first and second indicators relative to the output voltage.

[0009] With this configuration, if there is a margin in the total voltage that the energy storage devices can output relative to the output voltage, the imbalance in the remaining energy of multiple connected energy storage devices can be mitigated.

[0010] According to other aspects of this disclosure, a power supply system is a system for exchanging power with the outside, comprising a plurality of first energy storage units, a plurality of second energy storage units, first and second terminals for inputting and outputting power, and a control device for controlling the plurality of first and second energy storage units. Each of the plurality of first energy storage units includes a first energy storage device that applies a voltage in the direction from the second terminal to the first terminal while electrically connected between the first and second terminals, and a first switching unit that switches the first energy storage device between a connected state in which it is electrically connected between the first and second terminals and a disconnected state in which it is electrically disconnected. Each of the plurality of second energy storage units includes a second energy storage device that applies a voltage in the direction from the first terminal to the second terminal while electrically connected between the first and second terminals, and a second switching unit that switches the second energy storage device between a connected state in which it is electrically connected between the first and second terminals and a disconnected state in which it is electrically disconnected. Multiple first energy storage devices and multiple second energy storage devices are connected in series with each other when connected. The control device alternately repeats a first control period in which it controls the first switching unit to switch at least one of the first energy storage devices to the connected state and the second switching unit to switch all of the second energy storage devices to the disconnected state, and a second control period in which it controls the second switching unit to switch at least one of the second energy storage devices to the connected state and the first switching unit to switch all of the first energy storage devices to the disconnected state, until the first indicator showing the total remaining energy of all first energy storage devices and the second indicator showing the total remaining energy of all second energy storage devices are unbalanced. When the predetermined conditions indicating this are met, during the first or second control period in which the energy storage device with the larger value of the first and second indicators is switched to a disconnected state, the switching unit is controlled to temporarily switch at least one of the energy storage devices to be discharged from the energy storage device with the larger value of the first and second indicators to a connected state, and equalization control is performed by controlling the switching unit to temporarily switch at least one of the energy storage devices with the smaller value of the first and second indicators that is not controlled to be connected to a connected state in order to receive power from the energy storage device to be discharged.

[0011] With this configuration, if the first indicator, which shows the total remaining energy of all first energy storage devices, and the second indicator, which shows the total remaining energy of all second energy storage devices, are unbalanced, at least one of the energy storage devices to be discharged that is controlled to be disconnected, whichever has the larger value of the first or second indicator, is temporarily switched to the connected state, and at least one of the other energy storage devices that is not controlled to be connected, which has the smaller value of the first or second indicator, is temporarily switched to the connected state in order to receive power from the energy storage device to be discharged. As a result, the energy storage device with the smaller value of the first or second indicator receives power from the energy storage device with the larger value. Consequently, a power supply system can be provided that can mitigate the imbalance in the remaining energy of multiple connected energy storage devices.

[0012] The control device may perform equalization control when there is sufficient margin in the total voltage that can be input to the energy storage device with the smaller value of the first and second indicators relative to the input voltage.

[0013] With this configuration, if there is a margin in the total voltage that can be input to the energy storage devices relative to the input voltage, the imbalance in the remaining energy of multiple connected energy storage devices can be mitigated.

[0014] A string may include a plurality of first energy storage units, a plurality of second energy storage units, a first terminal, and a second terminal. The power supply system may have three sets of strings, the second terminals of the three sets of strings may be electrically connected, and the first terminals of the three sets of strings may be used to input and output AC for each phase of a three-phase AC. Alternatively, the power supply system may have one set of strings, the second terminal of which may be connected to ground, and the first terminal may be used to input and output single-phase AC.

[0015] This configuration can mitigate imbalances in the remaining power of multiple connected energy storage devices that can input and output three-phase or single-phase AC power. [Effects of the Invention]

[0016] According to the present disclosure, a power supply system capable of alleviating imbalance in the remaining electric energy of a plurality of connected power storage devices can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] [Figure 1] FIG. 1 is a diagram outlining the circuit configuration of the power supply system according to this embodiment. [Figure 2] FIG. 2 is a diagram showing the configuration of a battery string. [Figure 3] FIG. 3 is a diagram for explaining imbalance in the remaining capacity of batteries in a battery string. [Figure 4] FIG. 4 is a flowchart showing the flow of equalization processing for executing equalization control in this embodiment. [Figure 5] FIG. 5 is a graph for explaining the result of equalization control. DESCRIPTION OF EMBODIMENTS

[0018] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the drawings, the same or corresponding portions are denoted by the same reference symbols, and description thereof will not be repeated.

[0019] FIG. 1 is a diagram outlining the circuit configuration of a power supply system 1 according to this embodiment. Referring to FIG. 1, the power supply system 1 according to this embodiment includes battery strings St1 to St3 and an EMS (Energy Management System) 100. The battery strings St1 to St3 are Y-connected so as to output three-phase AC power. The battery strings St1, St2, and St3 correspond to a U-phase battery string, a V-phase battery string, and a W-phase battery string, respectively. The battery strings St1 to St3 are electrically connected to a power system (commercial power supply) not shown in the drawing, and are configured to exchange power with the power system.

[0020] Battery strings St1 to St3 are configured to be capable of outputting electric power of a predetermined AC waveform such as sine-wave three-phase AC to output terminals Tu, Tv and Tw. Specifically, the second terminals T12, T22, and T32 of each of the battery strings St1 to St3 are connected to the neutral point N1. Then, electric wires PL1, PL2, and PL3 connect the first terminals T11, T21, and T31 of the battery strings St1, St2, and St3 to the output terminals Tu, Tv, and Tw, respectively. The electric wires PL1, PL2, and PL3 are provided with an LCL filter F connected to a neutral point N2. The LCL filter F suppresses cross current when a plurality of Y-connection systems / other power supplies are used in parallel, and attenuates current ripple components in each of the electric wires PL1, PL2, and PL3.

[0021] Between the LCL filter F and the output terminals Tu, Tv, Tw, there are provided relays RU, RV, RW that switch conduction / blocking of the electric wires PL1, PL2, PL3, respectively. Each of the relays RU, RV, RW is, for example, an electromagnetic mechanical relay. Each of the relays RU, RV, RW may switch between conduction and blocking in accordance with a user operation. During operation of the power supply system, the relays RU, RV, RW are basically maintained in a conductive state. A user may set the relays RU, RV, RW to a blocked state when interrupting use of the power supply system (for example, during maintenance).

[0022] Current sensors Ia, Ib, and Ic are provided between the LCL filter F and the battery strings St1, St2, and St3, respectively, to detect the current flowing through the wires PL1, PL2, and PL3. Each of the current sensors Ia, Ib, and Ic outputs a signal indicating the detected value to the EMS100. As will be described later, each of the battery strings St1 to St3 is controlled to output AC voltages such as the voltage waveforms D11, D12, and D13 in Figure 1. These string voltages are output to the output terminals Tu, Tv, and Tw after passing through the LCL filter F. Specifically, the line voltage Vuv is applied between output terminals Tu and Tv, the line voltage Vwu is applied between output terminals Tw and Tu, and the line voltage Vvw is applied between output terminals Tv and Tw. Each line voltage is an AC voltage waveform whose polarity (positive / negative) changes periodically. Waveforms D21, D22, and D23 in Figure 1 show examples of line voltages Vuv, Vwu, and Vvw, respectively. Although not shown in Figure 1, the power supply system is further equipped with voltage sensors that detect line voltages Vuv, Vwu, and Vvw and output each detected value to the EMS100. The EMS100 uses the detection results from the current sensor and voltage sensor to sequentially detect the three-phase AC power output from battery strings St1 to St3.

[0023] The battery strings St1 to St3 may have different configurations, but in this embodiment, the battery strings St1 to St3 have the same configuration. Hereafter, unless otherwise specified, each of the battery strings St1 to St3 will be referred to as "battery string St", each of the wires PL1 to PL3 as "wire PL", each of the first terminals T11, T21, and T31 as "first terminal T1", and each of the second terminals T12, T22, and T32 as "second terminal T2".

[0024] Figure 2 shows the configuration of a battery string St. Referring to Figure 2, the power supply system 1 according to this embodiment further comprises an SCU (String Control Unit) 200 for controlling the battery string St. The SCU 200 comprises a processor 210, a RAM (Random Access Memory) 220, and a storage device 230. The processor 210 executes a program stored in the storage device 230 to perform various processes (for example, the control shown in Figure 4, which will be described later). However, these various processes are not limited to execution by software, but can also be executed by dedicated hardware (electronic circuits). The SCU 200 may further comprise an FPGA (Field Programmable Gate Array) with a function for performing sweep control.

[0025] In the power supply system 1 according to this embodiment, an SCU200 is provided for each of the battery strings St1 to St3. For example, when the EMS100 (Figure 1) receives an energy management request regarding the power system from a server that manages the power system, the EMS100 transmits a signal (hereinafter also referred to as "EMS signal") requesting charging or discharging to the SCU200 of each battery string St in response to the request. The EMS signal indicates at least one of the requested power (hereinafter referred to as "requested W") and the requested energy (hereinafter referred to as "requested Wh"). In the EMS signal according to this embodiment, the power on the discharge side is represented as positive (+) and the power on the charging side is represented as negative (-).

[0026] The battery string St comprises multiple battery circuit modules 10A and 10B connected in series. Each battery circuit module 10A and 10B is also provided with a GD (gate driver) 300 that drives the module according to commands from the SCU 200. The number of battery circuit modules 10A and 10B included in the battery string St is arbitrary, ranging from 5 to 50, or even 100 or more.

[0027] Each of the battery circuit modules 10A and 10B includes a switch circuit SWC, a cartridge Cg, circuit breakers RB1 and RB2, and output terminals OT1 and OT2. The cartridge Cg includes a battery 20 and a monitoring unit 30. The battery 20 can be any rechargeable battery, as long as it is a polarized energy storage device. The battery 20 may also be a used battery. The battery circuit modules 10A and 10B have the same configuration, but in the battery circuit module 10A, the positive terminal of the battery 20 is on the side of the first terminal T1 and the negative terminal is on the side of the second terminal T2, while in the battery circuit module 10B, the positive terminal of the battery 20 is on the side of the second terminal T2 and the negative terminal is on the side of the first terminal T1.

[0028] In this embodiment, the cartridge Cg is configured to be detachable from the switch circuit SWC. Specifically, circuit breakers RB1 and RB2 (hereinafter referred to as "circuit breakers RB" unless otherwise specified) switch the continuity / disconnection of the wires connecting the switch circuit SWC and the cartridge Cg. Circuit breakers RB are, for example, electromagnetic mechanical relays. Each of circuit breakers RB1 and RB2 may switch between continuity / disconnection according to user operation. While the battery circuit modules 10A and 10B are in use, circuit breakers RB1 and RB2 are basically kept in a continuity state. When the user interrupts the use of the battery circuit modules 10A and 10B (for example, when replacing batteries), the user may disconnect circuit breakers RB1 and RB2 and remove the cartridge Cg from the switch circuit SWC. Since the battery string St can operate even if there are empty cartridges, the user can easily increase or decrease the number of cartridges Cg included in the battery string St. Such a battery string St is suitable for battery reuse.

[0029] The monitoring unit 30 includes a Battery Management System (BMS) that monitors the state of the battery 20. The BMS includes various sensors that detect the state of the battery 20 (e.g., voltage, current, and temperature), and a monitoring IC (integrated circuit) that receives the detection signals from the various sensors. The monitoring IC generates a signal indicating the state of the battery 20 (hereinafter also referred to as the "BMS signal") using the detection signals from the various sensors, and outputs the generated BMS signal to the SCU200. The SCU200 can acquire the state of the battery 20 (e.g., temperature, current, voltage, State of Charge (SOC), and State of Health (SOH)) based on the BMS signal. SOC indicates the remaining charge, for example, the ratio of the current charge to the charge in a fully charged state, expressed as 0 to 100%. SOH indicates the health or degradation level, for example, the ratio of the current capacity to the initial capacity, expressed as 0 to 100%.

[0030] The monitoring unit 30 further includes a storage device that stores information regarding the charging and discharging performance of the battery 20 (rated output, capacity, etc.). The storage device may be a tag. The monitoring unit 30 may output the information stored in the storage device to the SCU200 when the cartridge Cg is set in the battery circuit modules 10A and 10B.

[0031] The storage device 230 stores information about each battery 20 included in the battery string St (hereinafter referred to as "battery information"), distinguishing each battery 20 by its identification information (battery ID). The battery ID indicates the location of the battery 20. That is, based on the battery ID, the SCU 200 can identify which battery circuit module 10A, 10B the battery 20 is set in, from the end of the battery string St on the side of the first terminal T1. The battery information includes information indicating the characteristics of the battery 20 (e.g., rated output (W), capacity (Wh), power density (W / kg), and energy density (Wh / kg)) and information indicating the state of the battery 20 (e.g., temperature, current, voltage, SOC, remaining capacity, and SOH detected by the BMS). The SCU 200 obtains the latest battery information from the monitoring unit 30 and sequentially updates the battery information in the storage device 230.

[0032] The battery string St has a wire SL (string wire) that connects the battery circuit modules 10A and 10B to each other. The wire SL includes the output terminals OT1 and OT2 of each battery circuit module 10. The battery circuit modules 10A and 10B are connected when the output terminal OT2 of one battery circuit module 10A or 10B is connected to the output terminal OT1 of another battery circuit module 10A or 10B adjacent to that battery circuit module 10. The wire SL is connected to the wire PL on the side of the first terminal T1.

[0033] The switch circuit SWC is configured to switch the connection / disconnection between the battery 20 and the output terminals OT1 and OT2. Specifically, the switch circuit SWC includes a first switch 11 (hereinafter referred to as "SW11"), a second switch 12 (hereinafter referred to as "SW12"), a parallel diode 13 for SW11, a parallel diode 14 for SW12, a choke coil 15, and a capacitor 16. SW11 is located on the wire SL and switches between conduction / disconnection between the output terminals OT1 and OT2. SW12 and the choke coil 15 are located on the wire BL1 that connects the output terminal OT1 to the circuit breaker RB1 (the positive terminal of the battery 20). The output terminal OT2 is electrically connected to the circuit breaker RB2 (the negative terminal of the battery 20) via the wire BL2. The capacitor 16 is connected to the wires BL1 and BL2, respectively. Each of SW11 and SW12 is a semiconductor switch, such as an FET (field-effect transistor). Note that the configuration of the switch circuit SWC shown in Figure 2 is merely an example and can be modified as appropriate. For example, the choke coil 15 may be removed from the circuit. The wiring inductance may also be adjusted according to the circuit configuration.

[0034] During the period when battery 20 is connected to output terminals OT1 and OT2 (connection period), the voltage of battery 20 is output between output terminals OT1 and OT2. During the connection period, SW12, which is connected in series with battery 20, is controlled to be ON (conductive), and SW11, which is connected in parallel with battery 20, is controlled to be OFF (disconnected). During the period when battery 20 is disconnected from output terminals OT1 and OT2 (disconnection period), the voltage of battery 20 is not output between output terminals OT1 and OT2. During the disconnection period, SW12 is controlled to be OFF (disconnected). Also, SW11 is controlled to be ON (conductive) during the disconnection period, except during the transient period.

[0035] In the battery string St, one group of battery circuit modules 10A is called the upper cartridge group, and the other group of battery circuit modules 10B is called the lower cartridge group.

[0036] The SCU200 controls the switch circuits SWC of the battery circuit modules 10A and 10B of the battery string St, for example as shown in Japanese Patent Application Publication No. 2022-120255, by changing the number of connected batteries 20 while circulating the batteries 20 that are connected to the electric wire SL, thereby controlling the output of a sinusoidal AC voltage for one phase of a three-phase AC according to the instructions from the EMS100 between the first terminal T1 and the second terminal T2. Furthermore, during the positive side of the sinusoidal AC voltage, the SCU200 controls the battery 20 of the battery circuit module 10A of the upper cartridge group to be connected to the electric wire SL, and controls all of the batteries 20 of the battery circuit module 10B of the lower cartridge group to be disconnected from the electric wire SL. During the negative period, the system controls the battery circuit module 10B of the lower cartridge group so that at least one of its batteries 20 is connected to the wire SL, while the system controls all of the batteries 20 of the battery circuit module 10A of the upper cartridge group so that they are disconnected from the wire SL. By alternating between the positive and negative periods in this way, one phase AC voltage is output from each battery string St1 to St3, and the AC voltages output from the three battery strings St1 to St3 are combined to output a three-phase AC.

[0037] In this case, an imbalance may occur in the remaining capacity of each battery 20. Figure 3 is a diagram illustrating the imbalance in the remaining capacity of the batteries 20 in the battery string St. Referring to Figure 3, the total remaining capacity of the batteries 20 in the battery circuit module 10A included in the upper cartridge group of the battery string St and the total remaining capacity of the batteries 20 in the battery circuit module 10B included in the lower cartridge group do not usually match, as shown in Figure 3(A). Starting from this state, the output of the AC voltage is initiated. As time passes, the total remaining capacity of the batteries 20 decreases almost equally in the upper cartridge group and the lower cartridge group, as shown in Figures 3(B) and 3(C). Finally, the total remaining power of the batteries 20 in the cartridge group that originally had less remaining capacity (the lower cartridge group in Figure 3) is depleted. When the remaining power is depleted, it becomes impossible to output the AC voltage as required.

[0038] Therefore, when the SCU200 satisfies a predetermined condition indicating that the first indicator, which shows the total remaining power of all upper cartridge batteries 20, and the second indicator, which shows the total remaining power of all lower cartridge batteries 20, are unbalanced, the SCU200 controls the switch circuit SWC to temporarily switch at least one of the batteries 20 to be charged, which has smaller values ​​for the first and second indicators, to a connected state during the period when the battery 20 with smaller values ​​for the first and second indicators is switched to a disconnected state, either during the positive or negative period of the sine wave. At the same time, the SCU200 controls the switch circuit SWC to temporarily switch at least one of the batteries 20 with larger values ​​for the first and second indicators, which is not controlled to be connected, to a connected state in order to supply power to the battery 20 to be charged.

[0039] In this way, if the first indicator, which shows the total remaining power of all the batteries 20 in the upper cartridge group, and the second indicator, which shows the total remaining power of all the batteries 20 in the lower cartridge group, are unbalanced, at least one battery 20 to be charged that is controlled to be disconnected, whichever has the smaller value of the first or second indicator, is temporarily switched to the connected state, and at least one of the other batteries 20 that is not controlled to be connected, which has the larger value of the first or second indicator, is temporarily switched to the connected state in order to supply power to the battery 20 to be charged. As a result, the battery 20 with the larger value of the first or second indicator supplies power to the battery 20 with the smaller value. Consequently, the imbalance in the remaining power of the multiple connected batteries 20 can be mitigated.

[0040] Figure 4 is a flowchart showing the flow of the equalization process for performing equalization control in this embodiment. Referring to Figure 4, this equalization process is called from a higher-level process and executed by the SCU200 at predetermined control cycles.

[0041] First, the processor 210 of the SCU200 determines whether it has reached the cycle for determining the cartridge Cg to be subjected to equalization control (for example, a predetermined cycle of every 10 minutes) (step S111). If it determines that it has reached the cycle for determining the cartridge to be equalized (YES in step S111), the processor 210 acquires the SOC of each battery 20 (step S112).

[0042] Next, the processor 210 divides the upper and lower cartridge groups, calculates the total SOC, and compares the two (step S113). In this embodiment, since all batteries 20 included in the battery string St have the same fully charged capacity, the sum of the remaining energy is proportional to the sum of the SOC. For this reason, the sum of the SOC is used for comparison instead of the sum of the remaining energy.

[0043] If the comparison in step S113 indicates that the sum of both SOCs is unbalanced, the processor 210 determines one of the cartridges Cg (for example, the cartridge Cg with the lowest SOC) among the battery circuit modules 10A and 10B included in the cartridge group with the smaller sum of SOCs to be the cartridge Cg to be equalized (step S114). The predetermined condition is that the difference between the sums of both SOCs is greater than or equal to a predetermined value that indicates an imbalance. The predetermined value is a predetermined value of 0 or greater.

[0044] After step S114, or if it is determined that it is not the equalization target determination period (NO in step S111), the processor 210 obtains the current voltage command value Vcom in the output waveform instruction from EMS100 to SCU200 (step S121).

[0045] Next, the processor 210 determines whether the group of cartridges currently outputting power is in the upper or lower stage according to the command value Vcom (step S122). Specifically, if the command value Vcom is a positive value, the group of cartridges currently outputting power is determined to be in the upper stage, and if it is a negative value, the group of cartridges currently outputting power is determined to be in the lower stage. In this determination of whether it is the upper or lower stage, hysteresis may be provided to prevent specific hunting near the zero crossing.

[0046] Then, the processor 210 uses the decision result in step S114 and the identification result in step S122 to determine whether or not to perform equalization control (step S123). Specifically, if power is not being output from the cartridge group containing the cartridge Cg determined in step S114, it is determined to perform equalization control; however, if power is being output, it is determined not to perform equalization control.

[0047] If it is determined that equalization control should be performed (if YES is determined in step S123), the processor 210 calculates the output voltage Vout,cap by subtracting the voltage of the cartridge Cg to be equalized from the sum of the voltages of the cartridges Cg of the group of cartridges currently outputting power, Vctrg,active,sum (step S124).

[0048] Next, the processor 210 determines whether the output voltage Vout,cap calculated in step S124 exceeds the voltage command value Vcom obtained in step S121, that is, whether there is a margin in the output voltage (step S125). If it determines that the output voltage Vout,cap exceeds the voltage command value Vcom, that is, that there is a margin in the output voltage (YES in step S125), the processor 210 performs equalization control (step S126). In equalization control, the switch circuit SWC is controlled so that the cartridge Cg to be equalized is connected to the electric wire SL, and the switch circuit SWC of the cartridge group that does not include the cartridge Cg to be equalized is controlled so that in addition to the voltage of the voltage command value Vcom, a voltage is generated to supply power to the cartridge to be equalized.

[0049] If it is determined that equalization control should not be performed (determined as NO in step S123), if it is determined that the output voltage Vout,cap does not exceed the voltage command value Vcom, that is, there is no margin in the output voltage (determined as NO in step S125), or after step S126, the processor 210 returns the processing to be executed to the higher-level processing that called this equalization process.

[0050] Figure 5 is a graph illustrating the results of the equalization control. Referring to Figure 5, when the equalization control is started at time 17ms, during the discharge period from the upper cartridge group (the period from time 17ms to 25ms in the figure), the battery 20 of cartridge Cg in the upper cartridge group that is connected to the wire SL outputs power as a discharge current flows, while the battery 20 of cartridge Cg in the lower cartridge group that is disconnected from the wire SL but temporarily connected for charging charges charges power as a charging current flows.

[0051] In Figure 5, the lower cartridge group is discharged during the period following this charge (from 25ms to 33ms in the figure). However, to prevent malfunctions caused by switching to discharge immediately after charging, etc., the charged cartridge Cg may be controlled to skip discharge only during this period, or all cartridges Cg in the lower cartridge group, including this cartridge Cg, may be controlled to skip discharge only during this period.

[0052] [Differentiation] (1) As shown in step S113 of Figure 4, the indicator showing the total remaining energy of the batteries 20 for each cartridge group is the sum of the State of Charge (SOC). However, it is not limited to this, and the indicator showing the total remaining energy of the batteries 20 for each cartridge group may be any other indicator, such as the total remaining energy of the batteries 20 for each cartridge group, the sum of the integrated current values ​​of the batteries 20 for each cartridge group, or the average value of the voltage of the batteries 20 for each cartridge group.

[0053] (2) In the above-described embodiment, the cartridge group is controlled so that the output voltage from the battery string St becomes a predetermined AC waveform, and the case in which three-phase AC power is output from the power supply system 1 to the power grid, that is, when the power supply system 1 is discharged, has been described. However, it is not limited to this, and may also be applied when the power supply system 1 is charged. In this case, three-phase AC power is input to the power supply system 1 from the power grid, and the cartridge group is controlled so that it matches the voltage of the AC waveform of the input voltage to the battery string St.

[0054] (3) In the embodiments described above, an example of handling three-phase AC using three battery strings St was explained. However, the invention is not limited to this, and single-phase AC may be handled using one battery string St.

[0055] (4) In the embodiments described above, the AC current with a sinusoidal waveform was used. However, the input and output waveforms of the battery string St are not limited to sinusoidal waves, but may be other waveforms, such as non-sinusoidal waves like square waves or triangular waves.

[0056] (5) In the embodiment described above, as shown in step S114 of Figure 4, there is one cartridge Cg to be equalized. However, the embodiment is not limited to this, and there may be two or more cartridges Cg to be equalized. Furthermore, the number of cartridges Cg to be equalized may be set to a number that corresponds to the input / output power margin of the group of cartridges that do not contain the cartridges Cg to be equalized.

[0057] (6) The embodiments described above can be considered as disclosures of the power supply system 1. Alternatively, they can be considered as disclosures of an equalization control method or an equalization control program executed by the power supply system 1.

[0058] [summary] (1) As shown in Figures 1 and 2, the power supply system 1 is a system that exchanges power with the outside, and comprises a plurality of battery circuit modules 10A, a plurality of battery circuit modules 10B, a first terminal T1 and a second terminal T2 for inputting and outputting power, and an SCU 200 for controlling the plurality of battery circuit modules 10A and the plurality of battery circuit modules 10B. As shown in Figure 2, each of the plurality of battery circuit modules 10A includes a cartridge Cg that applies a voltage in the direction from the second terminal T2 to the first terminal T1 when electrically connected between the first terminal T1 and the second terminal T2, and a switch circuit SWC that switches between a connected state in which the cartridge Cg is electrically connected between the first terminal T1 and the second terminal T2 and a disconnected state in which it is electrically disconnected. As shown in Figure 2, each of the multiple battery circuit modules 10B includes a cartridge Cg that applies a voltage from the first terminal T1 to the second terminal T2 when electrically connected between the first terminal T1 and the second terminal T2, and a switch circuit SWC that switches between a connected state where the cartridge Cg is electrically connected between the first terminal T1 and the second terminal T2 and a disconnected state where it is electrically disconnected. As shown in Figure 2, the multiple cartridges Cg are connected in series with each other when connected.

[0059] As shown in Figure 2, the SCU200 alternately repeats a first control period in which it controls the switch circuit SWC to switch at least one of the cartridges Cg of the battery circuit module 10A to the connected state and to switch all of the cartridges Cg of the battery circuit module 10B to the disconnected state, so that the output voltage between the first terminal T1 and the second terminal T2 becomes a predetermined AC waveform, and a second control period in which it controls the switch circuit SWC to switch at least one of the cartridges Cg of the battery circuit module 10B to the connected state and to switch all of the cartridges Cg of the battery circuit module 10A to the disconnected state. As shown in Figure 4, when the SCU200 satisfies predetermined conditions indicating that the first indicator, which shows the total remaining power of the cartridges Cg of all battery circuit modules 10A, and the second indicator, which shows the total remaining power of the cartridges Cg of all battery circuit modules 10B, are unbalanced, the SCU200 controls the switch circuit SWC to temporarily switch at least one cartridge Cg to be charged from the battery circuit module with smaller values ​​for the first and second indicators to a connected state during the control period in the first or second control period in which the cartridge Cg of the battery circuit module with smaller values ​​for the first and second indicators is switched to a disconnected state, and controls the switch circuit SWC to temporarily switch at least one cartridge Cg of the battery circuit module with larger values ​​for the first and second indicators that is not controlled to be connected to a connected state in order to supply power to the cartridge Cg to be charged.

[0060] As a result, if the first indicator, which shows the total remaining power of all cartridges Cg, and the second indicator, which also shows the total remaining power of all cartridges Cg, are unbalanced, at least one cartridge Cg to be charged that is controlled to be disconnected (the one with the smaller value of the first or second indicator) is temporarily switched to the connected state, and at least one of the other cartridge Cg with the larger value of the first or second indicator (the one not controlled to be connected) is temporarily switched to the connected state to supply power to the cartridge Cg to be charged. This allows the cartridge Cg with the larger value of the first or second indicator to supply power to the cartridge Cg with the smaller value. As a result, the imbalance in the remaining power of multiple connected cartridges Cg can be mitigated. In addition, the rate at which the power of each cartridge Cg is used up can be improved.

[0061] (2) As shown in step S125 of Figure 4, the SCU200 may perform equalization control when there is a margin in the total voltage that can be output by the cartridge Cg with the larger value of the first index and the second index relative to the output voltage.

[0062] This allows for mitigating imbalances in the remaining power of multiple connected cartridges Cg when there is a margin in the total voltage that can be output by the cartridges Cg relative to the output voltage.

[0063] (3) As shown in Figures 1 and 2, the power supply system 1 is a system that exchanges power with the outside, and comprises a plurality of battery circuit modules 10A, a plurality of battery circuit modules 10B, a first terminal T1 and a second terminal T2 for inputting and outputting power, and an SCU 200 for controlling the plurality of battery circuit modules 10A and the plurality of battery circuit modules 10B. As shown in Figure 2, each of the plurality of battery circuit modules 10A includes a cartridge Cg that applies a voltage in the direction from the second terminal T2 to the first terminal T1 when electrically connected between the first terminal T1 and the second terminal T2, and a switch circuit SWC that switches between a connected state in which the cartridge Cg is electrically connected between the first terminal T1 and the second terminal T2 and a disconnected state in which it is electrically disconnected. As shown in Figure 2, each of the multiple battery circuit modules 10B includes a cartridge Cg that applies a voltage from the first terminal T1 to the second terminal T2 when electrically connected between the first terminal T1 and the second terminal T2, and a switch circuit SWC that switches between a connected state where the cartridge Cg is electrically connected between the first terminal T1 and the second terminal T2 and a disconnected state where it is electrically disconnected. As shown in Figure 2, the multiple cartridges Cg are connected in series with each other when connected.

[0064] The SCU200 alternately repeats a first control period in which it controls the switch circuit SWC to switch at least one cartridge Cg of battery circuit module 10A to the connected state and the switch circuit SWC to switch all cartridge Cg of battery circuit module 10B to the disconnected state, in accordance with the AC waveform of the input voltage between the first terminal T1 and the second terminal T2, and a second control period in which it controls the switch circuit SWC to switch at least one cartridge Cg of battery circuit module 10B to the connected state and the switch circuit SWC to switch all cartridge Cg of battery circuit module 10A to the disconnected state, thereby displaying a first indicator showing the total remaining power of all cartridge Cg of battery circuit module 10A and all cartridges of battery circuit module 10B. When the second indicator, which shows the total remaining power of the cartridges Cg, satisfies predetermined conditions indicating an imbalance, equalization control is performed during the first or second control period in which the cartridge Cg of the battery circuit module with the larger values ​​of the first and second indicators is switched to a disconnected state. This control involves controlling the switching unit to temporarily switch at least one of the cartridge Cg of the battery circuit module with the larger values ​​of the first and second indicators to a connected state, and also controlling the switching unit to temporarily switch at least one of the cartridge Cg of the battery circuit module with the smaller values ​​of the first and second indicators that is not controlled to be in a connected state to a connected state in order to receive power from the cartridge Cg to be discharged.

[0065] As a result, if the first indicator, which shows the total remaining power of all cartridges Cg in all battery circuit modules 10A, and the second indicator, which shows the total remaining power of all cartridges Cg in all battery circuit modules 10B, are unbalanced, at least one cartridge Cg to be discharged that is controlled to be disconnected, whichever has the larger value of the first or second indicator, is temporarily switched to the connected state, and at least one of the other cartridges Cg that does not have the smaller value of the first or second indicator and is not controlled to be connected, is temporarily switched to the connected state in order to receive power from the cartridge Cg to be discharged. As a result, the cartridge Cg with the smaller value of the first or second indicator receives power from the cartridge Cg with the larger value. Consequently, the imbalance in the remaining power of multiple connected cartridges Cg can be mitigated.

[0066] (4) The SCU200 may perform equalization control when there is sufficient margin in the total voltage that can be input to the cartridge Cg with the smaller value of the first index and the second index relative to the input voltage.

[0067] This allows for mitigating imbalances in the remaining power of multiple connected cartridges Cg when there is sufficient margin in the total voltage that can be input to the cartridges Cg relative to the input voltage.

[0068] (5) The battery string St may include a plurality of battery circuit modules 10A, a plurality of battery circuit modules 10B, a first terminal T1, and a second terminal T2. The power supply system 1 may have three sets of battery strings St, the second terminals T2 of the three sets of battery strings St may be electrically connected, and the first terminals T1 of the three sets of battery strings St may be used to input and output AC for each phase of the three-phase AC. Alternatively, the power supply system 1 may have one set of battery strings St, the second terminal T2 may be connected to ground, and the first terminal T1 may be used to input and output single-phase AC.

[0069] This makes it possible to alleviate the imbalance in the remaining power of multiple connected cartridges Cg, which can input and output three-phase or single-phase AC.

[0070] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of this disclosure is indicated by the claims rather than by the description of the embodiments above, and all modifications within the meaning and scope equivalent to the claims are intended to be included. [Explanation of Symbols]

[0071] 1 Power system, 10, 10A, 10B Battery circuit module, 11 First switch, 12 Second switch, 13, 14 Parallel diodes, 15 Choke coil, 16 Capacitor, 20 Battery, 30 Monitoring unit, 100 EMS, 200 SCU, 210 Processor, 220 RAM, 230 Memory device, 300 GD, BL1, BL2, PL, PL1~PL3, SL Wire, Cg Cartridge, F LCL filter, Ia, Ib, Ic Current sensor, N1, N2 Neutral point, OT1, OT2, Tu, Tv, Tw Output terminals, RB, RB1, RB2 Circuit breaker, RU, RV, RW Relay, SWC Switch circuit, St, St1~St3 Battery string, T1, T11, T21, T31 First terminal, T2, T12, T22, T32 Second terminal.

Claims

1. A power supply system that exchanges power with the outside, Multiple first energy storage units, Multiple second energy storage units, First and second terminals for inputting and outputting power, The system comprises a control device that controls the plurality of first energy storage units and the plurality of second energy storage units, Each of the plurality of first energy storage units includes a first energy storage device that applies a voltage in the direction from the second terminal to the first terminal while electrically connected between the first terminal and the second terminal, and a first switching unit that switches between a connected state in which the first energy storage device is electrically connected between the first terminal and the second terminal and a disconnected state in which it is electrically disconnected. Each of the plurality of second energy storage units includes a second energy storage device that applies a voltage in the direction from the first terminal to the second terminal while electrically connected between the first terminal and the second terminal, and a second switching unit that switches between a connected state in which the second energy storage device is electrically connected between the first terminal and the second terminal and a disconnected state in which it is electrically disconnected. The multiple first energy storage devices and the multiple second energy storage devices are connected in series with each other in the aforementioned connection state. The control device is The first control unit is controlled to switch at least one of the first energy storage devices to the connected state and the second switch unit is controlled to switch all of the second energy storage devices to the disconnected state, so that the output voltage between the first terminal and the second terminal becomes a predetermined AC waveform, and these two control periods are repeated alternately: the second switch unit is controlled to switch at least one of the second energy storage devices to the connected state and the first switch unit is controlled to switch all of the first energy storage devices to the disconnected state. A power supply system that performs equalization control, in which, when a predetermined condition is met indicating that a first indicator showing the total remaining power of all the first energy storage devices and a second indicator showing the total remaining power of all the second energy storage devices are unbalanced, the switching unit is controlled to temporarily switch at least one of the energy storage devices to be charged from the energy storage devices with smaller values ​​of the first and second indicators to the connected state during the control period in the first or second control period in which the energy storage device with the smaller values ​​of the first and second indicators is switched to the unconnected state, and the switching unit is controlled to temporarily switch at least one of the energy storage devices with larger values ​​of the first and second indicators that is not controlled to be in the connected state to the connected state in order to supply power to the energy storage device to be charged.

2. The power supply system according to claim 1, wherein the control device performs the equalization control when there is a margin in the total voltage that can be output by the energy storage device with the larger value of the first index and the second index relative to the output voltage.

3. A power supply system that exchanges power with the outside, Multiple first energy storage units, Multiple second energy storage units, First and second terminals for inputting and outputting power, The system comprises a control device that controls the plurality of first energy storage units and the plurality of second energy storage units, Each of the plurality of first energy storage units includes a first energy storage device that applies a voltage in the direction from the second terminal to the first terminal while electrically connected between the first terminal and the second terminal, and a first switching unit that switches between a connected state in which the first energy storage device is electrically connected between the first terminal and the second terminal and a disconnected state in which it is electrically disconnected. Each of the plurality of second energy storage units includes a second energy storage device that applies a voltage in the direction from the first terminal to the second terminal while electrically connected between the first terminal and the second terminal, and a second switching unit that switches between a connected state in which the second energy storage device is electrically connected between the first terminal and the second terminal and a disconnected state in which it is electrically disconnected. The multiple first energy storage devices and the multiple second energy storage devices are connected in series with each other in the aforementioned connection state. The control device is A first control period is repeated, in which the first switching unit is controlled to switch at least one of the first energy storage devices to the connected state and the second switching unit is controlled to switch all of the second energy storage devices to the disconnected state, in accordance with the AC waveform of the input voltage between the first terminal and the second terminal; and a second control period is repeated, in which the second switching unit is controlled to switch at least one of the second energy storage devices to the connected state and the first switching unit is controlled to switch all of the first energy storage devices to the disconnected state. A power supply system that performs equalization control, in which, when a predetermined condition is met indicating that a first indicator showing the total remaining power of all the first energy storage devices and a second indicator showing the total remaining power of all the second energy storage devices are unbalanced, the switching unit is controlled to temporarily switch at least one of the energy storage devices to be discharged from the device with the larger values ​​of the first and second indicators to the connected state during the control period in the first or second control period in which the energy storage device with the larger values ​​of the first and second indicators is switched to the unconnected state, and the switching unit is controlled to temporarily switch at least one of the energy storage devices with the smaller values ​​of the first and second indicators that is not controlled to be connected to the connected state in order to receive power from the energy storage device to be discharged.

4. The power supply system according to claim 3, wherein the control device performs the equalization control when there is sufficient margin in the total voltage that can be input to the energy storage device with the smaller value of the first indicator and the second indicator relative to the input voltage.

5. The string includes the plurality of first energy storage units, the plurality of second energy storage units, the first terminal, and the second terminal. The power supply system comprises three sets of strings, the second terminals of the three sets of strings are electrically connected, and AC current for each phase of a three-phase AC is input and output at the first terminals of the three sets of strings, or The power supply system according to any one of claims 1 to 4, wherein the power supply system comprises one set of strings, the second terminal is connected to ground, and single-phase AC is input and output at the first terminal.

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