Power supply system

Abstract

A power supply system is provided with a battery string (St) and a control device (200) for controlling the battery string (St). The battery string (St) includes a plurality of battery circuit modules (10) connected in series. Each of the plurality of battery circuit modules (10) includes a battery (20), output terminals (OT1, OT2), and a switching circuit (SWC) that switches connection / disconnection between the battery (20) and the output terminals (OT1, OT2). The control device (200) is configured so as to individually execute, for each battery circuit module (10), switching control for controlling the switching circuit (SWC) in accordance with a duty ratio indicating a ratio between a connection period in which the output terminals (OT1, OT2) output the voltage of the battery (20) and an off period in which the output terminals (OT1, OT2) do not output the voltage of the battery (20).

Description

Technical Field

[0001] The present disclosure relates to a power supply system. Background Art

[0002] Japanese Patent Application Laid-Open No. 2021-191095 (Patent Document 1) discloses a power storage device that outputs electric power to a power system.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2021-191095 Summary of the invention

[0006] Problems to be solved by the invention

[0007] However, in order to increase the capacity of the power storage device, a power storage device such as a battery string has been proposed. The battery string includes a plurality of battery circuit modules connected in series. Moreover, each of these battery circuit modules includes a battery, an output terminal, and a switch circuit for switching the connection / disconnection between the battery and the output terminal. By applying the voltage of the battery to the output terminal in each battery circuit module, the output voltage of each battery circuit module (the voltage applied to the output terminal) is combined to become the output voltage of the battery string.

[0008] As a method for controlling a battery string, the following method is known: a delay circuit is provided in each battery circuit module, and a signal is delayed in the delay circuit of each battery circuit module, thereby generating a command for each battery circuit module based on the signal. Hereinafter, the control of the battery string implemented by such a method is also referred to as "scanning control".

[0009] However, in recent years, from the perspective of environmental protection, the reuse of batteries is being promoted. Therefore, it may be possible to use used batteries in battery strings. The characteristics of used batteries change depending on the degree of battery deterioration. Alternatively, in order to improve the performance of the battery string, it is also considered to mount multiple batteries of different types (for example, output type batteries and capacity type batteries) on one battery string. In the case where the above-mentioned scanning control is applied to a battery string including multiple batteries with different characteristics, the input and output power of the battery string may not necessarily become the desired size. In addition, in a power supply system in which the above-mentioned scanning control is applied to a battery string, it is difficult to control the input and output of the battery string while adjusting the state of each battery included in the battery string (for example, the remaining power).

[0010] The present disclosure has been made to solve the above-mentioned problems, and an object of the present disclosure is to easily adjust the state of each battery included in the battery string while controlling the input and output of the battery string.

[0011] Technical solutions to solve problems

[0012] A power supply system according to one aspect of the present disclosure includes a battery string and a control device for controlling the battery string. The battery string includes a plurality of battery circuit modules connected in series. Each of the plurality of battery circuit modules includes a battery, an output terminal, and a switch circuit for switching connection / disconnection between the battery and the output terminal. The control device is configured to individually perform switching control of the switch circuit according to a duty ratio representing the ratio of a connection period during which the output terminal outputs a battery voltage to a disconnection period during which the output terminal does not output the battery voltage for each battery circuit module.

[0013] The control device controls the switch circuit according to the duty cycle (ratio of the connection period to the disconnection period) for each battery circuit module in the control of the battery string. According to such a control device, the duty cycle (ratio of the connection period to the disconnection period) can be adjusted for each battery, so it is easy to freely select which battery to connect and which battery to disconnect so that the input and output power of the battery string are close to the required value. Therefore, it is easy to control the input and output of the battery string while adjusting the state (current, voltage, temperature, remaining power, etc.) of each battery included in the battery string.

[0014] As battery strings, the power supply system may also include a U-phase battery string, a V-phase battery string, and a W-phase battery string. The U-phase battery string, the V-phase battery string, and the W-phase battery string may also be connected in a Y shape to output three-phase AC power. The control device may also be configured to determine the duty cycle of each battery circuit module using at least one of the required charging or discharging power, the required charging or discharging energy, the characteristics of the battery, and the state of the battery in the switch control of each of the U-phase battery string, the V-phase battery string, and the W-phase battery string.

[0015] According to the above structure, it is easy to control the three-phase AC power output by three battery strings (U-phase, V-phase, and W-phase battery strings) while adjusting the state (current, voltage, temperature, remaining power, etc.) of each battery included in the battery string.

[0016] Effects of the Invention

[0017] According to the present disclosure, it is possible to easily adjust the state of each battery included in the battery string while controlling the input and output of the battery string. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a diagram showing an outline of a circuit configuration of a power supply system according to an embodiment of the present disclosure.

[0019] Figure 2 It is shown Figure 1 Figure 2 shows the structure of a battery string.

[0020] Figure 3 This is a timing chart showing an operation example of a switching circuit according to a drive signal generated in accordance with a command from a control device in the power supply system according to the embodiment of the present disclosure.

[0021] Figure 4 1 is a flowchart showing a process of switch control performed by a control device in a power supply system according to an embodiment of the present disclosure.

[0022] Figure 5 : is a diagram for explaining energy management performed by the power supply system according to the embodiment of the present disclosure.

[0023] Figure 6 It is used to illustrate Figure 4 A diagram showing the supplementary charge and supplementary discharge performed in the process shown.

[0024] (Explanation of symbols)

[0025] 10: battery circuit module; 11: first switch; 12: second switch; 20: battery; 30: monitoring unit; 100: EMS; 200: SCU; 210: processor; 220: RAM; 230: storage device; Cg: box; OT1, OT2: output terminals; SWC: switch circuit; St, St1~St3: battery string. DETAILED DESCRIPTION

[0026] Hereinafter, the embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In addition, the same reference numerals are attached to the same or corresponding parts in the drawings, and their description will not be repeated.

[0027] Figure 1 2 is a diagram showing an overview of the circuit configuration of the power supply system according to the present embodiment. Figure 1 The power supply system of this embodiment includes battery strings St1 to St3 and an EMS (Energy Management System) 100. The battery strings St1 to St3 are connected in a Y shape to output three-phase AC power. The battery strings St1, St2, and St3 correspond to a battery string for U phase, a battery string for V phase, and a battery string for W phase, respectively. The battery strings St1 to St3 are configured to be electrically connected to an unillustrated power system (commercial power supply) and exchange power with the power system.

[0028] The battery strings St1 to St3 are configured to output three-phase AC power to the output terminals Tu, Tv, and Tw. Specifically, the negative terminals of the battery strings St1 to St3 are connected to the neutral point N1. Moreover, the power lines PL1, PL2, and PL3 connect the positive terminals of the battery strings St1, St2, and St3 to the output terminals Tu, Tv, and Tw, respectively. At the power lines PL1, PL2, and PL3, an LCL filter F connected to the neutral point N2 is provided. The LCL filter F suppresses cross current when multiple Y-connected systems / other power sources are used in parallel, or attenuates the current pulsating components in each of the power lines PL1, PL2, and PL3.

[0029] Relays RU, RV, and RW are provided between the LCL filter F and the output terminals Tu, Tv, and Tw, respectively, for switching the on / off of the electric wires PL1, PL2, and PL3. The relays RU, RV, and RW are each, for example, electromagnetic mechanical relays. The relays RU, RV, and RW can also switch on / off according to user operations. In the process of using the power supply system, the relays RU, RV, and RW are basically maintained in the on state. The user can also put the relays RU, RV, and RW in the off state when the power supply system is interrupted (for example, during maintenance).

[0030] Current sensors Ia, Ib, and Ic are provided between the LCL filter F and the battery strings St1, St2, and St3 to detect currents flowing through the electric wires PL1, PL2, and PL3, respectively. The current sensors Ia, Ib, and Ic each output a detection value to the EMS 100. The voltage of each battery string St1 to St3 is a voltage waveform with an offset of 0 V or more. Figure 1 The waveforms D11, D12, and D13 in FIG. 1 respectively represent an example of the voltage of the battery strings St1, St2, and St3. The string voltages thereof are output to the output terminals Tu, Tv, and Tw through the LCL filter F. Specifically, the line voltage Vuv is applied between the output terminals Tu and Tv, the line voltage Vwu is applied between the output terminals Tw and Tu, and the line voltage Vvw is applied between the output terminals Tv and Tw. Each line voltage is an AC voltage waveform whose polarity (positive / negative) changes periodically. Figure 1 The waveforms D21, D22, and D23 in FIG. 1 respectively represent examples of line voltages Vuv, Vwu, and Vvw. Figure 1 Although not shown, the power supply system further includes voltage sensors that detect line voltages Vuv, Vwu, and Vvw and output the detected values ​​to EMS 100. EMS 100 sequentially detects the three-phase AC power output from battery strings St1 to St3 using the detection results obtained by the current sensor and the voltage sensor.

[0031] The battery strings St1 to St3 may have different structures, but in the present embodiment, the battery strings St1 to St3 have the same structure. In the following, except for the case where they are described separately, the battery strings St1 to St3 are each described as a "battery string St", and the electric wires PL1 to PL3 are each described as a "electric wire PL".

[0032] Figure 2 is a diagram showing the structure of the battery string St. Figure 2 The power supply system of this embodiment further includes an SCU (String Control Unit) 200 for controlling the battery string St. The SCU 200 includes 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 following Figure 4 However, these various processes are not limited to being executed by software, but can also be executed by dedicated hardware (electronic circuit). In addition, SCU200 may also have an FPGA (Field Programmable Gate Array) equipped with a function for executing scan control. SCU200 is equivalent to an example of a "control device" of the present disclosure.

[0033] In the power supply system of this embodiment, the SCU 200 is respectively installed in the battery strings St1 to St3. Figure 1 ) receives an energy management request related to the power system from the server that manages the power system, and the EMS 100 sends a signal requesting charging or discharging (hereinafter also referred to as an "EMS signal") to the SCU 200 of each battery string St according to the request. The EMS signal indicates at least one of the required power (hereinafter referred to as "required W") and the required energy (hereinafter referred to as "required Wh"). The EMS signal of this embodiment uses positive (+) to indicate the power on the discharge side and negative (-) to indicate the power on the charging side.

[0034] The battery string St includes a plurality of battery circuit modules 10 connected in series. In addition, a GD (gate driver) 300 is provided for each battery circuit module 10. The GD 300 is configured to drive the battery circuit module 10 in accordance with instructions from the SCU 200. The number of battery circuit modules 10 included in the battery string St is arbitrary, and may be 5 to 50 or more than 100.

[0035] Each battery circuit module 10 includes a switch circuit SWC, a box Cg, circuit breakers RB1, RB2 and output terminals OT1, OT2. The box Cg includes a battery 20 and a monitoring unit 30. As the battery 20, any secondary battery can be used. The battery 20 can also be a second-hand battery. In the present embodiment, one battery string St is equipped with an output type battery and a capacity type battery. That is, in a certain battery circuit module 10, a box Cg including an output type battery as a battery 20 is placed, and in other battery circuit modules 10, a box Cg including a capacity type battery as a battery 20 is placed. The rated output (W) of the output type battery is greater than the rated output (W) of the capacity type battery. The rated output is the maximum discharge power designed as indicated by the battery manufacturer. The capacity (Wh) of the capacity type battery can also be greater than the capacity (Wh) of the output type battery. The battery capacity is equivalent to the amount of electricity stored in a fully charged battery. In addition, the power density of the output type battery can also be higher than the power density of the capacity type battery. The energy density of the capacity type battery can also be higher than the energy density of the output type battery.

[0036] In the present embodiment, the box Cg is configured to be loadable and removable relative to the switching circuit SWC. Specifically, the circuit breakers RB1 and RB2 (hereinafter, referred to as "circuit breakers RB" without distinction) switch the conduction / disconnection of the wires connecting the switching circuit SWC and the box Cg. The circuit breaker RB is, for example, an electromagnetic mechanical relay. The circuit breakers RB1 and RB2 can each also switch the conduction / disconnection according to the user's operation. During the use of the battery circuit module 10, the circuit breakers RB1 and RB2 are basically maintained in the on state. The user can also put the circuit breakers RB1 and RB2 in the off state when interrupting the use of the battery circuit module 10 (for example, when replacing the battery) and remove the box Cg from the switching circuit SWC. The battery string St can be operated even if there are empty boxes, so the user can easily increase or decrease the number of boxes Cg contained in the battery string St. Such a battery string St is suitable for battery recycling.

[0037] The monitoring unit 30 includes a BMS (Battery Management System) that monitors the state of the battery 20. The BMS includes various sensors that detect the state of the battery 20 (for example, voltage, current, and temperature) and a monitoring IC (Integrated Circuit) to which the detection signals obtained by the various sensors are input. The monitoring IC generates a signal indicating the state of the battery 20 (hereinafter also referred to as a "BMS signal") using the detection signals obtained by the above-mentioned various sensors, and outputs the generated BMS signal to the SCU 200. The SCU 200 can obtain the state of the battery 20 (for example, temperature, current, voltage, SOC (State Of Charge) and SOH (State Of Health)) based on the above-mentioned BMS signal. SOC indicates the remaining power, for example, 0 to 100% is used to indicate the ratio of the current power storage to the power storage in the fully charged state. SOH indicates the health level or the degree of deterioration, for example, 0 to 100% is used to indicate the ratio of the current capacity to the initial capacity.

[0038] The monitoring unit 30 further includes a storage device for storing information (rated output, capacity, etc.) related to the charging performance and discharging performance of the battery 20. The storage device may also be a label. When the cartridge Cg is placed in the battery circuit module 10, the monitoring unit 30 may output the information stored in the storage device to the SCU 200.

[0039] The storage device 230 stores information related to each battery 20 included in the battery string St (hereinafter referred to as "battery information") by distinguishing the identification information (battery ID) of the battery 20. The battery ID indicates the position of the battery 20. That is, the SCU 200 can identify the battery 20 placed in the battery circuit module 10 from the end on the positive side of the battery string St based on the battery ID. The battery information includes information indicating the characteristics of the battery 20 (for example, rated output (W), capacity (Wh), power density (W / kg), and energy density (Wh / kg)) and information indicating the state of the battery 20 (for example, temperature, current, voltage, SOC, and SOH detected by the BMS). The SCU 200 obtains the latest battery information from the monitoring unit 30 and updates the battery information in the storage device 230 sequentially.

[0040] The battery string St has an electric wire SL (string wire) connecting the battery circuit modules 10 to each other. The electric wire SL includes output terminals OT1 and OT2 of each battery circuit module 10. The battery circuit modules 10 are connected to each other by connecting the output terminal OT2 of a battery circuit module 10 to the output terminal OT1 of another battery circuit module 10 adjacent to the battery circuit module 10. The electric wire SL is connected to the electric wire PL on the positive electrode side.

[0041] The switching circuit SWC is configured to switch the connection / disconnection between the battery 20 and the output terminals OT1 and OT2. Specifically, the switching 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 of SW11, a parallel diode 14 of SW12, a choke coil 15, and a capacitor 16. SW11 is located on the wire SL, and switches on / off 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 electrode of the battery 20). The output terminal OT2 is electrically connected to the circuit breaker RB2 (the negative electrode of the battery 20) via the wire BL2. The capacitor 16 is connected between the wire BL1 and the wire BL2, respectively. SW11 and SW12 are each semiconductor switches such as FETs (field effect transistors). In addition, Figure 2 The structure of the switching circuit SWC shown is only 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 structure.

[0042] During the period when the battery 20 is connected to the output terminals OT1 and OT2 (connection period), the voltage of the battery 20 is output between the output terminals OT1 and OT2. During the connection period, the SW12 connected in series with the battery 20 is controlled to be in the ON state (conduction state), and the SW11 connected in parallel with the battery 20 is controlled to be in the OFF state (disconnection state). During the period when the battery 20 is disconnected from the output terminals OT1 and OT2 (disconnection period), the voltage of the battery 20 is not output between the output terminals OT1 and OT2. During the disconnection period, SW12 is controlled to be in the OFF state (disconnection state). In addition, during the disconnection period, SW11 is controlled to be in the ON state (conduction state) except for the transition period. The SCU200 is configured to control the voltage output between the output terminals OT1 and OT2 by controlling the switch circuit SWC according to the duty ratio representing the ratio of the connection period to the disconnection period. The duty ratio can be represented, for example, by the ratio of the length of the connection period to the total length of the connection period and the disconnection period (hereinafter referred to as "connection duty"). The larger the connection duty is, the larger the ratio of the connection period to the disconnection period is. For example, a connection duty of 0.8 (80%) means that the duty ratio (connection period: disconnection period) is "8:2". Control based on the duty ratio is generally also called "PWM (Pulse Width Modulation) control".

[0043] In the present embodiment, the SCU 200 determines the duty cycle for each battery circuit module 10 individually based on the EMS signal, and controls the switch circuit SWC (switch control) according to the determined duty cycle for each battery circuit module 10 individually. Specifically, the SCU 200 sends a signal indicating the duty cycle (hereinafter referred to as "SC signal") to the GD 300. Based on the SC signal, the GD 300 generates a drive signal for driving SW11 and SW12 in such a manner that a voltage according to the duty cycle specified by the SCU 200 is output between the output terminals OT1 and OT2, and drives SW11 and SW12 by the drive signal.

[0044] Figure 3 1 is a timing chart showing an example of the operation of the switch circuit SWC according to the drive signal generated by the GD300. Figure 3 In FIG. 1 , lines L101 and L102 represent drive signals of SW11 and SW12, respectively. Line L103 represents the evolution of the voltage output between output terminals OT1 and OT2. Line L110 represents the evolution of the state (connection / disconnection) of the battery 20. Each timing in the timing chart is abbreviated as "t".

[0045] Reference Figure 1 , Figure 2 as well as Figure 3 In this example, at t1, the connection period is switched to the disconnection period. At t1, SW11 remains in the OFF state and SW12 becomes the OFF state. Then, at a timing (t2) that is a predetermined time later than t1 (hereinafter referred to as "dt1"), SW11 becomes the ON state. Thereafter, at t3, SW11 becomes the OFF state. Further, at a timing (t4) that is a predetermined time later than t3 (hereinafter referred to as "dt2"), SW12 becomes the ON state. Thus, the connection period is switched from the disconnection period to the connection period. During the connection period, the voltage Vm of the battery 20 is output between the output terminals OT1 and OT2. Further, at t5, SW12 becomes the OFF state, and the connection period is switched to the disconnection period again.

[0046] The connection Duty represented by line L110 is 0.5. The drive signal represented by lines L101 and L102 is a drive signal generated by GD300 in a manner that outputs a voltage according to the connection Duty "0.5" between output terminals OT1 and OT2. The details will be described later. In the present embodiment, SCU200 determines whether a predetermined connection condition is satisfied for each battery circuit module 10, and performs a process (hereinafter also referred to as "connection process") to increase the connection Duty for the battery circuit module 10 for which the connection condition is satisfied. Specifically, SCU200 sends an SC signal indicating a connection Duty that is a predetermined amount greater than the current connection Duty to GD300. As a result, GD300 generates a drive signal corresponding to the increased connection Duty. For example, the connection Duty (0.5) represented by line L110 becomes the connection Duty (0.8) represented by line L120. In addition, the SCU 200 determines whether a predetermined disconnection condition is satisfied for each battery circuit module 10, and performs a process for reducing the connection duty (hereinafter also referred to as "disconnection process") for the battery circuit module 10 for which the disconnection condition is satisfied. Specifically, the SCU 200 sends an SC signal indicating a connection duty that is a predetermined amount less than the current connection duty to the GD 300. As a result, the GD 300 generates a drive signal corresponding to the reduced connection duty, for example, the connection duty (0.5) indicated by the line L110 becomes the connection duty (0.2) indicated by the line L130.

[0047] Figure 4 200 is a flowchart showing the switch control process performed by the SCU 200. The process shown in the flowchart is repeatedly performed by the SCU 200, for example, while the SCU 200 receives the EMS signal. However, at the start of the process, the connection Duty of all the batteries 20 is set to a predetermined initial value (for example, 0.5). The initial value may also be set based on the EMS signal. The SCU 200 performs the switch control process for each battery string St. Figure 4 Each step in the flowchart is abbreviated as "S".

[0048] Reference Figure 1 , Figure 2 as well as Figure 4 In S11, the SCU 200 determines whether the size (absolute value) of the request W indicated by the EMS signal is greater than a predetermined first value (hereinafter referred to as "Th1"). Then, if the size (absolute value) of the request W is greater than Th1 ("Yes" in S11), the SCU 200 classifies the batteries 20 included in the battery string St into output type batteries and capacity type batteries with output power smaller than that of the output type batteries in S12, and performs connection processing for the output type batteries. The SCU 200 may also refer to the battery information ( Figure 2), based on whether the rated output (W) of the battery 20 is greater than a predetermined threshold, each battery 20 included in the battery string St is classified as an output type battery or a capacity type battery. Through the above connection processing, the connection Duty of each output type battery included in the battery string St increases. SCU200 can also determine the amount of increase according to the size of the required W. Since the connection Duty of the output type battery increases, in order to cope with the requirement W from EMS100, the output type battery is used preferentially. As needed, SCU200 may also perform processing to reduce the connection Duty of the capacity type battery in addition to the processing to increase the connection Duty of the output type battery.

[0049] In the next S13, SCU200 further classifies each output type battery included in the battery string St into a first output type battery (hereinafter referred to as "battery α") whose current SOC value is less than a predetermined reference SOC value (third value) and a second output type battery (hereinafter referred to as "battery β") whose current SOC value is greater than the above-mentioned reference SOC value (third value). Then, SCU200 obtains the supplementary charge amount of battery α and the supplementary discharge amount of battery β in S14, and performs supplementary charge of battery α and supplementary discharge of battery β in the next S15. The details of S14 and S15 will be described later (refer to Figure 6 ).

[0050] In the next S16, SCU200 determines whether the SOC of each output type battery included in the battery string St converges to the vicinity of the above-mentioned reference SOC value. Specifically, if the SOC of each output type battery included in the battery string St falls within a predetermined SOC range based on the reference SOC value (for example, the range of reference SOC value ± hysteresis), it is judged as "yes" in S16, otherwise, it is judged as "no" in S16. When it is judged as "no" in S16, the processing returns to S13, and the supplementary charge and discharge for making the SOC of each output type battery close to the reference SOC value is executed again. On the other hand, when it is judged as "yes" in S16, Figure 4 The series of processing shown ends.

[0051] When the size (absolute value) of the required W is less than Th1 ("No" in S11), in S21, SCU200 determines whether the size (absolute value) of the required Wh indicated by the EMS signal is greater than a predetermined second value (hereinafter referred to as "Th2"). Then, when the size (absolute value) of the required Wh is greater than Th2 ("Yes" in S21), SCU200 classifies each battery 20 included in the battery string St into an output type battery and a capacity type battery in S22 in the same manner as S12, and performs a connection process for the capacity type battery. Through this connection process, the connection Duty of each capacity type battery included in the battery string St increases. SCU200 may also determine the amount of increase based on the size of the required W and the required Wh. Since the connection Duty of the capacity type battery increases, in order to cope with the required Wh from the EMS100, the capacity type battery is used preferentially. As needed, SCU200 may also perform a process to reduce the connection Duty of the output type battery in addition to the process to increase the connection Duty of the capacity type battery.

[0052] In the next S23, SCU200 calculates the arrival SOC value based on the required Wh. The arrival SOC value indicates the remaining power (arrival remaining power) after energy management is performed by charging or discharging. That is, the arrival SOC value is equivalent to the value reached by the SOC of the battery 20 when the battery 20 performs the charging or discharging required by the EMS signal. Then, SCU200 further classifies each capacity type battery included in the battery string St into a first capacity type battery (hereinafter referred to as "battery γ") having an arrival SOC value less than a predetermined lower limit SOC value (fourth value) and a second capacity type battery (hereinafter referred to as "battery σ") having an arrival SOC value greater than a predetermined upper limit SOC value (fifth value). The upper limit SOC value is an SOC value greater than the lower limit SOC value. Then, SCU200 obtains the supplementary charge amount of battery γ and the supplementary discharge amount of battery σ in S24, and performs supplementary charging of battery γ and supplementary discharging of battery σ in the next S25. Details of S24 and S25 will be described later (refer to Figure 6 ). After the process of S25 is executed, the process proceeds to S13, and the supplementary charge and discharge of the output type battery is executed through the processes of S13 to S16.

[0053] When the size (absolute value) of the required Wh is less than Th2 ("No" in S21), SCU200 obtains the SOC of each battery 20 included in the battery string St in S31, and calculates the difference (SOC difference) between the maximum SOC value and the minimum SOC value of these SOC values ​​(SOC data of each battery 20). Furthermore, SCU200 determines in S31 whether the above-mentioned SOC difference is greater than a predetermined value (hereinafter referred to as "Th3"). When the SOC difference is less than Th3 ("No" in S31), SCU200 sets the connection Duty of each battery 20 (each battery circuit module 10) included in the battery string St to a value corresponding to the required W and the required Wh in S34. Thereafter, the processing proceeds to S23. On the other hand, when the SOC difference is greater than Th3 ("Yes" in S31), the processing proceeds to S32.

[0054] In S32, SCU200 sets the equalization range (target range of SOC equalization) based on the average value or median value of the SOC of each battery 20 included in the battery string St. Then, SCU200 classifies each battery 20 included in the battery string St into batteries whose SOC is lower than the lower limit of the equalization range (hereinafter referred to as "battery ε"), batteries whose SOC is higher than the upper limit of the equalization range (hereinafter referred to as "battery ζ"), and batteries other than batteries ε and ζ. In addition, SCU200 performs supplementary charging of battery ε and supplementary discharging of battery ζ in S33. The details will be described later. In S33, SCU200 increases or decreases the connection Duty of batteries ε and ζ so as to perform charging or discharging corresponding to the required W and required Wh through the battery string St, and make the SOC of each battery 20 included in the battery string St fall within the equalization range (refer to Figure 6 ). After executing S33, Figure 4 The series of processing shown ends.

[0055] Figure 5 1 is a diagram for explaining energy management performed by battery strings St1 to St3. Figure 5 The SCU 200 receives a charging request or a discharging request for energy management from the EMS 100. The SCU 200 may also receive a power request for discharging or charging at a predetermined power and an energy request for outputting or storing a predetermined amount of energy by continuous discharging or charging.

[0056] exist Figure 5The power requirement shown in FIG. 1 requires energy management for suppressing fluctuations in the generated power output from the power generation equipment. The battery strings St1 to St3 may also perform charging and discharging to bring the actual value L12 of the generated power close to the target value L11 according to such power requirements. In the power requirements, there are many cases where high-power discharge or charging is required in a short time. The power requirements are used, for example, for energy management of naturally variable power sources (solar power generation equipment, etc.) whose power output varies according to meteorological conditions. In addition, Figure 5 The energy requirements shown require energy management for adjusting the supply-demand balance of the power system. The battery strings St1 to St3 may also perform charging and discharging for matching the power demand L21 and the power supply L22 of the power system according to such energy requirements.

[0057] Here, it is considered that the battery string St has characteristics (requirement characteristics) that can cope with both the energy requirement of Wh being X and the power requirement of W being Y. Figure 5 In the figure, line L1 shows the changes in the rated output (W) and capacity (Wh) when the number of output-type batteries is increased or decreased, with respect to a battery string St consisting only of output-type batteries. In order to ensure the capacity X by a battery string St consisting only of output-type batteries, many output-type batteries are required. In addition, line L2 shows the changes in the rated output (W) and capacity (Wh) when the number of capacity-type batteries is increased or decreased, with respect to a battery string St consisting only of capacity-type batteries. In order to ensure the rated output Y by a battery string St consisting only of capacity-type batteries, many capacity-type batteries are required. In the power supply system of the present embodiment, one battery string St is equipped with output-type batteries and capacity-type batteries, and the above-mentioned Figure 4 By performing the processing shown, the above-mentioned required characteristics can be given to the battery string St without excessively increasing the number of batteries.

[0058] In the power supply system of this embodiment, when the required charging or discharging power is greater than Th1 (in Figure 4 S11 is "Yes"), and the required charging or discharging power is less than Th1 (in Figure 4 Compared with "No" in S11 of the output type battery, the ratio of the connection period to the disconnection period is increased ( Figure 4 In addition, when the energy required for charging or discharging is greater than Th2 (in S12), SCU200 Figure 4 S21 is "Yes"), and the required charging or discharging energy is less than Th2 (in Figure 4 Compared with "No" in S21 of the embodiment, the ratio of the connection period of the capacity type battery to the disconnection period is increased ( Figure 4In such a power supply system, the SCU 200 (control unit) adjusts the duty ratio of the output type battery and the capacity type battery according to the requirements. As a result, each battery string St can easily perform charging or discharging corresponding to the required power or charging or discharging corresponding to the required energy.

[0059] Figure 6 It is used to illustrate Figure 4 A diagram showing the supplementary charge and supplementary discharge performed in the process shown.

[0060] Reference Figure 6 ,exist Figure 4 In S14, the SCU200 obtains the supplementary charge amount of the battery α corresponding to the difference between the current SOC value and the reference SOC value and the supplementary discharge amount of the battery β corresponding to the difference between the current SOC value and the reference SOC value, for example, based on the map M1 stored in the storage device 230. For example, the SCU200 obtains ΔP1 as the supplementary charge amount for the battery α whose current SOC value is V1. In addition, the SCU200 obtains ΔP2 as the supplementary discharge amount for the battery β whose current SOC value is V2. The SCU200 uses the supplementary charge amount of the battery α and the supplementary discharge amount of the battery β to determine the decrease amount of the connection Duty in the disconnection process (S15) described later related to the batteries α and β and the increase amount of the connection Duty in the connection process (S15) described later related to the batteries α and β. In addition, the SCU200 does not perform supplementary charge and discharge on the output type battery whose current SOC value is consistent with the reference SOC value.

[0061] exist Figure 4 In S24, the SCU200 obtains the supplementary charge amount of the battery γ corresponding to the difference between the arrival SOC value and the lower limit SOC value and the supplementary discharge amount of the battery σ corresponding to the difference between the arrival SOC value and the upper limit SOC value, for example, based on the map M2 stored in the storage device 230. For example, the SCU200 obtains ΔP3 as the supplementary charge amount for the battery γ whose arrival SOC value is V3. In addition, the SCU200 obtains ΔP4 as the supplementary discharge amount for the battery σ whose arrival SOC value is V4. The SCU200 uses the supplementary charge amount of the battery γ and the supplementary discharge amount of the battery σ to determine the decrease amount of the connection Duty in the disconnection process (S25) described later related to the batteries γ and σ and the increase amount of the connection Duty in the connection process (S25) described later related to the batteries γ and σ. In addition, the SCU200 does not perform supplementary charge and discharge for the capacity battery whose arrival SOC value is greater than the lower limit SOC value and less than the upper limit SOC value.

[0062] Respectively Figure 4In S15, S25, and S33, SCU200 performs connection processing or disconnection processing as described below based on which of charging and discharging is requested from EMS100. Hereinafter, the three-phase AC power output from battery strings St1 to St3 will be referred to as "three-phase AC power". The positive side and negative side of the three-phase AC power correspond to the discharge side and the charge side, respectively. In S15, S25, and S33, SCU200 sets batteries α, γ, and ε as charging objects, and sets batteries β, σ, and ζ as discharging objects, respectively.

[0063] When the EMS 100 requests discharge, the SCU 200 performs a disconnection process on the positive side of the three-phase AC power to reduce the connection duty of the charging target (batteries α, γ, ε), and performs a disconnection process on the negative side of the three-phase AC power to reduce the connection duty of the discharging target (batteries β, σ, ζ). By such a process, the SOC of the charging target with a low SOC can be increased, and the SOC of the discharging target with a high SOC can be decreased.

[0064] When the required discharge power is greater than Th1 ( Figure 4 In S15, the supplementary charge and discharge are performed by the disconnection process. Specifically, on the positive side of the three-phase AC power, SCU200 reduces the connection Duty of battery α by an amount corresponding to the supplementary charge amount obtained in S14. In addition, on the negative side of the three-phase AC power, SCU200 reduces the connection Duty of battery β by an amount corresponding to the supplementary discharge amount obtained in S14. The disconnection processes related to batteries α and β in S15 are respectively equivalent to an example of the "first disconnection process" and the "second disconnection process" of the present disclosure.

[0065] In addition, when the required discharge energy is greater than Th2 (in Figure 4 In S21 of the embodiment of the present invention, the SCU 200 determines whether the battery γ is connected to the battery γ or the battery σ is connected to the battery γ. In S25, the SCU 200 determines whether the battery γ is connected to the battery σ or the battery σ is connected to the battery γ or the battery σ is connected to the battery σ. In S25, the SCU 200 determines whether the battery γ is connected to the battery σ or the battery σ is connected to the battery γ or ...

[0066] When charging is requested from the EMS 100, the SCU 200 performs a connection process to increase the connection duty of the charging object (batteries α, γ, ε) on the negative side of the three-phase AC power, and performs a connection process to increase the connection duty of the discharging object (batteries β, σ, ζ) on the positive side of the three-phase AC power. By such a process, the SOC of the charging object with a low SOC can be increased, and the SOC of the discharging object with a high SOC can be decreased.

[0067] When the required charging power is greater than Th1 ( Figure 4 In S15, the supplementary charge and discharge are performed by the connection processing. Specifically, on the negative side of the three-phase AC power, SCU200 increases the connection Duty of battery α by an amount corresponding to the supplementary charge amount obtained in S14. In addition, on the positive side of the three-phase AC power, SCU200 increases the connection Duty of battery β by an amount corresponding to the supplementary discharge amount obtained in S14. The connection processing related to batteries α and β in S15 is respectively equivalent to an example of the "first connection processing" and the "second connection processing" of the present disclosure.

[0068] In addition, when the required charging energy is greater than Th2 (in Figure 4 In S21 of the embodiment of the present invention, the SCU 200 determines whether the battery γ is connected to the battery σ and whether the battery γ is connected to the battery σ. If the battery γ is connected to the battery σ, the SCU 200 determines whether the battery σ is connected to the battery σ and whether the battery σ is connected to the battery γ. If the battery γ is connected to the battery σ, the SCU 200 determines whether the battery σ is connected to the battery σ and whether the battery σ is connected to the battery σ. If the battery γ is connected to the battery σ, the SCU 200 determines whether the battery γ is connected to the battery σ and whether the battery σ is connected to the battery σ ..., the SCU 200 determines whether the battery γ is connected to the battery σ and whether the battery σ is connected to the battery σ. If the battery γ is connected to the battery σ, the SCU 200 determines whether the battery γ is connected to the battery σ and whether the battery σ is connected to the battery σ. If the battery γ is connected to the battery σ, the SCU 200 determines

[0069] In the power supply system of the present embodiment, when a large power (high electric power) discharge or charge is required, SCU200 (control device) adjusts the duty ratio of the output type battery according to the three-phase AC power output by the three battery strings St1 to St3 (U-phase, V-phase, and W-phase battery strings). As a result, in each of the battery strings St1 to St3, the remaining power of each output type battery can be suppressed from deviating significantly from the reference value (third value). In addition, in the above-mentioned power supply system, when a large energy (large electric power) discharge or charge is required, SCU200 (control device) adjusts the duty ratio of the capacity type battery according to the three-phase AC power output by the three battery strings St1 to St3 (U-phase, V-phase, and W-phase battery strings). As a result, in each of the battery strings St1 to St3, the remaining power of each capacity type battery can be suppressed from being less than the lower limit value (fourth value) or greater than the upper limit value (fifth value).

[0070] In the power supply system of the present embodiment, the SCU200 (control device) uses the degree of deviation between the current remaining power of the output type battery and the reference value (third value) to determine the control amount (reduction amount or increase amount) of the proportion of the connection period in each of the first and second disconnection processes and the first and second connection processes. Such a control device can easily control the duty cycle of each output type battery to suppress the deviation of the remaining power of each output type battery from the reference value (third value) when the battery strings St1 to St3 perform discharge or charge according to power requirements. In addition, the SCU200 (control device) uses the degree of deviation between the value reached by the remaining power of the capacity type battery and the threshold value (fourth value or fifth value) to determine the control amount (reduction amount or increase amount) of the proportion of the connection period in each of the third and fourth disconnection processes and the third and fourth connection processes. Such a control device can easily control the duty ratio of each capacity type battery, for example, when the battery strings St1 to St3 are discharged or charged according to the energy requirement, so as to suppress the power reserve of each capacity type battery from deviating from the threshold value (the fourth value or the fifth value). In addition, the degree of deviation can be expressed as a difference or a ratio. The closer the ratio is to 1, the smaller the degree of deviation.

[0071] exist Figure 6 In the example, waveforms D1 to D4 each represent the execution of Figure 4 The waveform D1 represents the state evolution of the battery string St during the process shown. str ). The string voltage is measured through “E str (t) = E o sinωt+V offset ”(E o : Output phase voltage amplitude, V offset Waveform D2 represents the string current (I str ). The string current flows through “I str (t) = I o sinωt”(I o The waveform D3 represents the duty ratio of the string voltage. The duty ratio of the string voltage is expressed by “duty(t)=E str (t) / V all ”(V all The total string voltage is equivalent to the multiplication of the number of batteries 20 included in the battery string St and the voltage (Vm) of each battery. Waveform D4 represents the battery current (I bat (t)). The battery current is equivalent to the average current value of each battery in the battery string St, which is expressed by “I bat (t) = Asin 2 ωt+Bsinωt”(A=Eo I o / V all , B=V offset I o / V all ) is expressed as follows.

[0072] When the battery strings St1 to St3 output three-phase AC power, the current of each battery string St evolves as shown in waveform D2. Therefore, as the battery string St, even when charging, if viewed at the time level of the AC frequency, the battery current flows on the charging side and the discharging side. Therefore, through the above Figure 4 The processing of S15, S25, and S33 can discharge only a specific battery. Figure 4 The processing of S15, S25, and S33 can also charge only a specific battery.

[0073] The embodiments disclosed this time should be considered as illustrative in all aspects and not restrictive. The scope of the present invention is indicated by the claims rather than the description of the embodiments above, and is intended to include all modifications within the meaning and scope equivalent to the claims.

Claims

1. A power supply system comprising a battery string and a control device for controlling the battery string, wherein: The battery string includes a plurality of battery circuit modules connected in series. Each of the plurality of battery circuit modules includes a battery, an output terminal, and a switch circuit for switching connection / disconnection between the battery and the output terminal. The control device is configured to individually perform switching control of the switch circuit according to a duty ratio indicating a ratio between a connection period during which the output terminal outputs the battery voltage and a disconnection period during which the output terminal does not output the battery voltage for each battery circuit module.

2. The power supply system according to claim 1, wherein: The power supply system includes a U-phase battery string, a V-phase battery string, and a W-phase battery string as the battery string. The U-phase battery string, the V-phase battery string and the W-phase battery string are connected in a Y shape to output three-phase AC power. The control device uses at least one of the required charging or discharging power, the required charging or discharging energy, the characteristics of the battery and the state of the battery to determine the duty cycle of each of the battery circuit modules in the switch control of each of the U-phase battery string, the V-phase battery string and the W-phase battery string.

3. The power supply system according to claim 2, wherein: The control device classifies each battery included in the battery string into an output type battery and a capacity type battery having an output power smaller than that of the output type battery. The control device increases the ratio of the connection period to the disconnection period of the output type battery when the required charging or discharging power is greater than a first value, compared to when the required charging or discharging power is less than the first value. When the required charge or discharge energy is greater than a second value, the control device increases the ratio of the connection period to the disconnection period of the capacity type battery compared to when the required charge or discharge energy is less than the second value.

4. The power supply system according to claim 3, wherein: The control device classifies the power type batteries included in the battery string into first power type batteries whose current power storage remaining amount is less than a third value and second power type batteries whose current power storage remaining amount is greater than the third value, The control device classifies the capacity type batteries included in the battery string into first capacity type batteries whose power reserve reached by the required charge or discharge, that is, the reached power reserve is less than a fourth value, and second capacity type batteries whose reached power reserve is greater than a fifth value greater than the fourth value, When the required discharge power is greater than the first value, the control device performs a first disconnection process on the positive side of the three-phase AC power to reduce the ratio of the connection period of the first output type battery to the disconnection period, and performs a second disconnection process on the negative side of the three-phase AC power to reduce the ratio of the connection period of the second output type battery to the disconnection period, The control device performs, when the required charging power is greater than the first value, a first connection process for increasing the ratio of the connection period of the first output type battery to the disconnection period on the negative side of the three-phase AC power, and performs a second connection process for increasing the ratio of the connection period of the second output type battery to the disconnection period on the positive side of the three-phase AC power, The control device performs, when the required discharge energy is greater than the second value, a third disconnection process for reducing the ratio of the connected period of the first capacity type battery to the disconnected period on the positive side of the three-phase AC power, and performs a fourth disconnection process for reducing the ratio of the connected period of the second capacity type battery to the disconnected period on the negative side of the three-phase AC power, When the required charging energy is greater than the second value, the control device performs a third connection process on the negative side of the three-phase AC power to increase the ratio of the connection period of the first capacity type battery to the disconnection period, and performs a fourth connection process on the positive side of the three-phase AC power to increase the ratio of the connection period of the second capacity type battery to the disconnection period.

5. The power supply system according to claim 4, wherein: The control device determines the amount of reduction in the proportion of the connection period in the first disconnection process by using the degree of deviation between the current remaining power of the first output type battery and the third value, and determines the amount of reduction in the proportion of the connection period in the second disconnection process by using the degree of deviation between the current remaining power of the second output type battery and the third value, when the required discharge power is greater than the first value. The control device determines the increase in the proportion of the connection period in the first connection process by using the degree of deviation between the current remaining power of the first output type battery and the third value when the required charging power is greater than the first value, and determines the increase in the proportion of the connection period in the second connection process by using the degree of deviation between the current remaining power of the second output type battery and the third value, The control device determines the amount of reduction in the proportion of the connection period in the third disconnection process by using the degree of deviation between the achieved remaining power of the first capacity type battery and the fourth value, and determines the amount of reduction in the proportion of the connection period in the fourth disconnection process by using the degree of deviation between the achieved remaining power of the second capacity type battery and the fifth value, when the required discharge energy is greater than the second value. The control device determines an increase in the proportion of the connection period in the third connection process using a degree of deviation between the reached power reserve of the first capacity type battery and the fourth value when the required charging energy is greater than the second value, and determines an increase in the proportion of the connection period in the fourth connection process using a degree of deviation between the reached power reserve of the second capacity type battery and the fifth value.

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