Battery control device and power storage system

Abstract

The MCU (100) of the Module Interface / F receives a detection signal of the cell voltage from the Cell Monitoring Unit (CMU), and when the cell voltage is equal to or greater than an upper limit threshold, sends a charge reduction signal to the MCU (101) of the Power Converter (PCS) to reduce the charging power of the string. During the period when the MCU (101) receives a control signal from the String Controller (SC) but does not receive the charge reduction signal from the MCU (100), it controls the Power Converter (PCS) to bring the charging power of the string closer to the charging power command value; and during the period when the MCU (101) receives the control signal from the String Controller (SC) and the charge reduction signal from the MCU (100), it controls the Power Converter to bring the charging power of the string closer to the charging power command value.

Description

Technical Field

[0001] This invention relates to a battery control device and an energy storage system. Background Technology

[0002] As a power storage system comprising a string of multiple battery modules connected in series, a power storage system is known to include a bypass mechanism that bypasses each battery module (see, for example, Patent Documents 1 and 2). In the power storage systems described in Patent Documents 1 and 2, the bypass mechanism can bypass battery modules that are fully charged or fully discharged, thereby allowing continued charging and discharging. Therefore, it is possible to have a mixture of battery modules with different charge and discharge capacities due to differences in their deterioration state or type.

[0003] Reference List

[0004] Patent documents

[0005] Patent Document 1: JP2013-31247A

[0006] Patent Document 2: JP2013-31249A Summary of the Invention

[0007] In new battery modules where performance variations during manufacturing have been prevented, or in battery modules that have reached a similar state of degradation due to use under the same environment and conditions, the voltage of all battery cells in the string can be maintained within an appropriate range by monitoring the total voltage or total current of the string and controlling the charging and discharging of the string. However, in battery modules with performance variations during manufacturing, or in battery modules with different states of degradation due to use in different environments or under different conditions, the performance of the battery cells in the battery module can vary in many cases. In the case of mixed battery modules with performance variations of battery cells, it is difficult to control the voltage of all battery cells to not exceed the upper limit and not fall below the lower limit simply by monitoring the total voltage or total current of the string and controlling the charging and discharging of the string.

[0008] Therefore, in power storage systems consisting of strings of battery modules with varying battery cell performance, it is necessary to control the charging and discharging of the string by monitoring the voltage of the battery cells (hereinafter referred to as cell voltage). However, when cell voltage information is transmitted from the cell voltage monitoring device to the controller that controls the charging and discharging of the string through the interface of the battery module, the controller determines whether the cell voltage is between the upper and lower limits and sends a control signal to the string's power converter based on the determination result. This series of communication delays can increase, and the cell voltage may exceed the upper limit or fall below the lower limit during the delay period.

[0009] In view of the above, the object of the present invention is to provide a battery control device and a power storage system that can maintain the voltage of the battery cells in the battery module within an appropriate range regardless of whether there are performance differences among the battery cells in the string.

[0010] The battery control device according to the present invention is a battery control device for controlling a power storage system. The power storage system includes a string comprising multiple series-connected battery modules and a power converter configured to convert the charging and discharging power of the string. Each battery module includes multiple series-connected battery cells and a cell voltage detection device configured to detect the voltage of each battery cell. The battery control device includes: multiple module control devices, each corresponding to a battery module and configured to control the battery modules; a power converter control device configured to control the power converter; and a string control device, corresponding to the string and configured to communicate with the multiple module control devices, the power converter control device, and a main control device, and to send control signals to the power converter control device for controlling the battery modules. A power converter is configured to bring the charging power of the string close to a charging power command value received from the main control device. Each module control device is configured to receive a detection signal of the voltage of the battery cell from the cell voltage detection device, and when the voltage of the battery cell is equal to or greater than an upper threshold, send a charging reduction signal to the power converter control device to reduce the charging power of the string. The power converter control device is configured to control the power converter to bring the charging power of the string close to the charging power command value while receiving the control signal from the string control device and not receiving the charging reduction signal from the module control device, and to control the power converter to reduce the charging power of the string while receiving both the control signal from the string control device and the charging reduction signal from the module control device.

[0011] The battery control device according to the present invention is a battery control device for controlling a power storage system. The power storage system includes a string comprising multiple series-connected battery modules and a power converter configured to convert the charging and discharging power of the string. Each battery module includes multiple series-connected battery cells and a cell voltage detection device configured to detect the voltage of each battery cell. The battery control device includes: multiple module control devices, each corresponding to a battery module and configured to control the battery modules; a power converter control device configured to control the power converter; and a string control device, corresponding to the string and configured to communicate with the multiple module control devices, the power converter control device, and a main control device, and to send control signals to the power converter control device for controlling the charging and discharging power of the string. A power converter is configured to bring the discharge power of the string close to a discharge power command value received from the main control device. Each module control device is configured to receive a detection signal of the voltage of the battery cell from the cell voltage detection device, and when the voltage of the battery cell is equal to or less than a lower threshold, send a discharge reduction signal to the power converter control device to reduce the discharge power of the string. The power converter control device is configured to control the power converter to bring the discharge power of the string close to the discharge power command value while receiving the control signal from the string control device and not receiving the discharge reduction signal from the module control device, and to control the power converter to reduce the discharge power of the string while receiving both the control signal from the string control device and the discharge reduction signal from the module control device.

[0012] The power storage system according to the present invention is a power storage system comprising: a string comprising a plurality of battery modules connected in series; a power converter configured to convert the charging and discharging power of the string, each of the battery modules comprising a plurality of battery cells connected in series, and a cell voltage detection device configured to detect the voltage of each of the battery cells; and any of the above-mentioned battery control devices.

[0013] According to the present invention, the voltage of the battery cells in the battery module can be maintained within an appropriate range regardless of whether there are fluctuations in the performance of the battery cells in the string. Attached Figure Description

[0014] Figure 1 This is a circuit diagram illustrating the circuit configuration of a power storage system including a battery control device according to an embodiment of the present invention.

[0015] Figure 2 It means Figure 1The diagram shows the control configuration of the power storage system.

[0016] Figure 3 It is a chart that represents the updated charging and discharging power command values ​​of the power storage system and the charging and discharging power command values ​​of each string.

[0017] Figure 4 It is a chart that represents the updated charging and discharging power command values ​​of the power storage system and the charging and discharging power command values ​​of each string.

[0018] Figure 5 It indicates that it is used in Figure 1 and Figure 2 The circuit diagram shown illustrates the communication circuit that enables communication between the string controller, power converter, and module interface.

[0019] Figure 6 This is a diagram illustrating the communication method of the battery control device according to the comparative example.

[0020] Figure 7 It means Figure 1 and Figure 2 A diagram illustrating the communication method of the battery control device.

[0021] Figure 8 It is a graph showing the charge / discharge power command value and the actual charge / discharge power shift, and a timing diagram showing the ON / OFF timing of the unit upper limit voltage warning signal and the unit lower limit voltage warning signal, respectively.

[0022] Figure 9 It means Figure 1 and Figure 2 The flowchart shown is for the charging control of the battery control device.

[0023] Figure 10 It means Figure 1 and Figure 2 The flowchart shown is for the discharge control of the battery control device. Detailed description

[0024] Hereinafter, the present invention will be described with reference to preferred embodiments. The present invention is not limited to the following embodiments, and appropriate modifications can be made to the embodiments without departing from the spirit of the invention. In the following embodiments, some configurations may not be described in the specification or shown in the drawings. For omitted technical details, well-known or publicly known techniques may be appropriately employed as long as they do not contradict the following description.

[0025] Figure 1This is a circuit diagram illustrating the circuit configuration of a power storage system 1 including a battery control device 2 according to an embodiment of the present invention. The power storage system 1 shown in the figure is a stationary power supply, including a string system 10 and a power storage system controller (PSC).

[0026] The Power Storage System Controller (PSC) is the highest-level control device in the Power Storage System 1, and is connected to the host server 7 (see [link]). Figure 2 ) and the string system controller SSC communicate, and control the power storage system auxiliary device 3 (see Figure 2 In addition, the power storage system controller (PSC) includes a display input device (not shown) such as a touch screen with display and input functions.

[0027] The string system 10 includes multiple strings St1 to Stx, a string bus 6, a string system controller SSC, and multiple string controllers SC1 to SCx. The string system controller SSC and the multiple string controllers SC1 to SCx will be described later. When it is not necessary to distinguish between strings St1 to Stx, strings St1 to Stx will be simply referred to as string St. When it is not necessary to distinguish between string controllers SC1 to SCx, string controllers SC1 to SCx will be simply referred to as string controller SC.

[0028] Multiple strings St are connected in parallel to string bus 6. String bus 6 is connected to an external system (not shown). Each string St includes power converters PCS1 to PCSx, and each string St includes multiple modules M1 to Mn and multiple module interfaces M. I / F 1 to M I / F n. Module interface M I / F 1 to M I / F n will be described later. When it is not necessary to distinguish between describing power converters PCS1 to PCSx, power converters PCS1 to PCSx will be simply referred to as power converter PCS. When it is not necessary to distinguish between describing modules M1 to Mn, modules M1 to Mn will be simply referred to as module M. When it is not necessary to distinguish between describing module interfaces M... I / F 1 to M I / F When n, the module interface M I / F 1 to M I / F n is abbreviated as module interface M I / F .

[0029] Module M includes a battery comprising multiple battery units C connected in series and a bypass mechanism B. Module M also includes unit monitoring devices CMU1 to CMUn. In the string St, multiple batteries are connected in series, and a bypass mechanism B is provided for each battery. The string St includes a current sensor 11 for measuring the total current of the string St, a voltage sensor (not shown) for measuring the total voltage of the string St (hereinafter referred to as the string total voltage), etc.

[0030] Battery unit C is a secondary battery unit such as a lithium-ion battery or lithium-ion capacitor. It is charged by power supplied from an external system via power converter PCS, and discharged by power converters PCS1 to PCSx to supply power to the external system. Although there are no particular limitations, the battery in module M according to this embodiment is obtained by recycling used batteries, and the degree of deterioration and performance of the battery units vary.

[0031] The bypass mechanism B includes a bypass line BL and switches S1 and S2. The bypass line BL bypasses the power supply to the battery. Switch S1 is located on the bypass line BL. Switch S1 can be, for example, a mechanical switch, a semiconductor switch, or a relay. Switch S2 is located between the positive terminal of the battery and one end of the bypass line BL. Switch S2 can be, for example, a mechanical switch, a semiconductor switch, or a relay.

[0032] The batteries of the starting module M1 and the terminal module Mn are connected to the external system via the power converter PCS and the string bus 6. When all bypass mechanisms B have their switches S1 open and S2 closed, all batteries in the string St are connected in series with the external system. On the other hand, when any bypass mechanism B has its switch S2 open and S1 closed, the battery corresponding to that bypass mechanism B is bypassed.

[0033] The power converter PCS is a bidirectional converter and is connected to the string bus 6. The power converter PCS is connected to the positive terminal of the battery of the starting module M1 and the negative terminal of the battery of the ending module Mn.

[0034] When string St is charging, the power converter PCS converts the voltage received from string bus 6 and transmits the converted voltage to the batteries of the multiple modules M. Here, the voltage on the string St side varies depending on the bypass state of the multiple modules M (the number of modules M whose batteries are bypassed) and the charging state of the batteries of the multiple modules M. Therefore, when string St is charging, the power converter PCS converts the voltage received from string bus 6 to the voltage on the string St side and transmits the converted voltage to the batteries of the multiple modules M.

[0035] On the other hand, when string St discharges, the power converter PCS converts the voltage received from the batteries of the multiple modules M and transmits the converted voltage to the string bus 6. Here, the voltage input to the power converter PCS during discharge varies according to the bypass state of the multiple modules M and the charging state of their batteries. Therefore, the voltage input to the power converter PCS changes among strings St during discharge. Thus, when string St discharges, the power converter PCS converts the input voltage to a voltage that matches other strings St and outputs the converted voltage to the string bus 6. When the current flowing through the string bus 6 is alternating current, the power converter PCS includes a synchronization device for following instantaneous value changes.

[0036] The unit monitoring devices CMU1 to CMUn are connected between the positive and negative terminals of each battery unit C, respectively, to detect the inter-terminal voltage (hereinafter referred to as unit voltage) of each battery unit C, and transmit the detection signal to the module interface M. I / F Each of the unit monitoring devices CMU1 to CMUn has a unit equalization function and equalizes the unit voltage of module M. When it is not necessary to distinguish between the unit monitoring devices CMU1 to CMUn, they will be referred to as unit monitoring device CMU.

[0037] Module Interface M I / F It has the function of controlling switches S1 and S2 of the bypass mechanism B, as well as the function of communicating with the string controller SC and the power converter PCS. These functions will be described later.

[0038] Figure 2 It means Figure 1 The diagram shows the control configuration of the power storage system 1. As shown, the power storage system 1 includes a battery control device 2. The battery control device 2 includes a power storage system controller (PSC), a string system controller (SSC), multiple string controllers (SC), and multiple module interfaces (M). I / F The system includes multiple unit monitoring units (CMUs) and multiple microcontroller units (MCUs) 101. A unit monitoring unit (CMU) is configured for each module M, and an MCU 101 is configured for each power converter (PCS).

[0039] Power storage system controller PSC, string system controller SSC, string controller SC and module interface M I / F Configurations are set for each level. The Power Storage System Controller (PSC) corresponds to the highest level, Power Storage System 1. The String System Controller (SSC) corresponds to the next level, String System 10. The String Controller (SC) corresponds to the next level, String System 10. Module Interface M I / FThis corresponds to the module M level, which is below the string St level.

[0040] The power storage system controller (PSC) communicates with the host server (7) and the string system controller (SSC) to control and manage the power storage system auxiliary device (3). The host server (7) is located in the power receiving facilities of the aggregator, building, or factory. Based on the status of the power storage system (1) and the power demand on the demand side, the host server (7) calculates the charging and discharging power command value (hereinafter referred to as the power storage system charging and discharging power command value) for the entire power storage system (1) and transmits the charging and discharging power command value to the power storage system controller (PSC).

[0041] Examples of auxiliary devices 3 for the power storage system include a temperature sensor that detects the temperature of the installation environment (e.g., a container) of the power storage system 1, and fire suppression systems (neither shown). If the temperature sensor reading exceeds a threshold, the power storage system controller (PSC) determines that the installation environment temperature of the power storage system 1 is abnormal and sends an abnormality notification to the display input device. Furthermore, the power storage system controller (PSC) monitors the operational status of the fire suppression system.

[0042] The power storage system controller PSC receives information about the status of string St (hereinafter referred to as string status information) and information about the status of string system 10 (hereinafter referred to as string system status information) from the string system controller SSC, and transmits the information to the host server 7 and the display input device.

[0043] Examples of string St states include operating states (such as charging, discharging, pause, and maintenance), string current, string total voltage, string St's state of charge (SOC) (hereinafter referred to as string SOC), string St's state of health (SOH) (hereinafter referred to as string SOH), and the limit values ​​for string St's charging and discharging power (or charging and discharging current) (hereinafter referred to as string charging and discharging power limit values).

[0044] Examples of string system 10 states include string bus 6 (see...) Figure 1 The current of the string bus 6 (hereinafter referred to as the string bus current), the voltage of the string bus 6 (hereinafter referred to as the string bus voltage), the SOC of the string system 10 (hereinafter referred to as the string system SOC), the SOH of the string system 10 (hereinafter referred to as the string system SOH), and the limit value of the charging and discharging power (or charging and discharging current) of the string system 10 (hereinafter referred to as the string system charging and discharging power limit value).

[0045] The Power Storage System Controller (PSC) estimates the state of the power storage system 1 based on the string status information and string system status information received from the string system controller (SSC). Examples of the state of the power storage system 1 include operating states (such as charging, discharging, pause, and maintenance), the State of Charge (SOC) of the power storage system 1 (hereinafter referred to as the power storage system SOC), and the State of Alternating Current (SOH) of the power storage system 1 (hereinafter referred to as the power storage system SOH). The PSC outputs the estimated state information of the power storage system 1 to a display input device as needed. In this embodiment where the string system 10 is a single string, the string system SOC is equal to the power storage system SOC, and the string system SOH is equal to the power storage system SOH.

[0046] The Power Storage System Controller (PSC) transmits the information required for processing by the host server 7 to the host server 7. Examples of the information required for processing by the host server 7 include the Power Storage System State of Charge (SOC), the Power Storage System State of OH (SOH), and the string system charge / discharge power limit values. Here, the host server 7 determines the charge / discharge command corresponding to the Power Storage System 1 based on the "information required for processing by the host server 7" received from the Power Storage System Controller (PSC), and transmits the charge / discharge command to the Power Storage System Controller (PSC). Examples of charge / discharge commands include, in addition to the power storage system charge / discharge command values, control quantities in constant voltage (CV) mode, constant current (CC) mode, and constant power (CP) mode, as well as operating methods (such as self-continuous operation or system interconnection).

[0047] The Power Storage System Controller (PSC) transmits various command information input by operators via display input devices to the String System Controller (SSC). Examples of various command information input via display input devices include commands to execute maintenance / stop mode (hereinafter referred to as maintenance / stop commands), commands to force charge / discharge, and commands to force state estimation.

[0048] Examples of maintenance stop commands include commands that force the operation of the power storage system auxiliary device 3, the string system auxiliary device 4, and the string St auxiliary device (such as the power converter PCS). By forcing the operation of the power storage system auxiliary device 3, the string system auxiliary device 4, and the string St auxiliary device, the operational status of the power storage system auxiliary device 3, the string system auxiliary device 4, and the string St auxiliary device can be verified.

[0049] Examples of forced charge / discharge commands include commands that specify a predetermined charge / discharge amount and force the power storage system 1 to perform charge / discharge. By specifying a predetermined charge / discharge amount and forcing the power storage system 1 to perform charge / discharge, it is possible to confirm whether the power storage system 1 is capable of charging or discharging the specified predetermined charge / discharge amount.

[0050] Examples of forced state estimation instructions include instructions that specify predetermined state estimation items and force the power storage system 1 to perform state estimation. By specifying predetermined state estimation items and forcing the power storage system 1 to perform state estimation, it is possible to obtain state estimation items such as the string system SOH and the power storage system SOH at any time.

[0051] The string system controller (SSC) communicates with the power storage system controller (PSC) and multiple string controllers (SC), and controls and manages the string system auxiliary devices 4. Examples of string system auxiliary devices 4 include a temperature sensor for detecting ambient temperature, a cooling device in the string system 10, a disconnection device for the string bus 6, a current sensor for detecting string bus current, and a voltage sensor for detecting string bus voltage (all not shown).

[0052] The string system controller (SSC) receives string status information from multiple string controllers (SC). Examples of string status (SSC) include operating status (such as charging, discharging, pause, and maintenance), string current, total string voltage, string SOC, string SOH, string charge / discharge power limits, and the status of the string system auxiliary device 4. Examples of the status of the string system auxiliary device 4 include string bus current and string bus voltage.

[0053] The string system controller (SSC) estimates the state of string system 10 based on string state information received from multiple string controllers (SCs). Examples of the string system 10 state include string bus current, string bus voltage, string system SOC, string system SOH, and string system charge / discharge power limits. The state of string system 10 can be estimated by the power storage system controller (PSC).

[0054] For example, if the detected values ​​of the temperature sensor, current sensor, and voltage sensor, or the estimated value of the state of the string system 10, exceed the threshold range, the string system controller SSC determines that the string system 10 is abnormal and stops the operation of the string system 10, or sends an abnormality notification to the power storage system controller PSC.

[0055] The string system controller (SSC) transmits the information required for processing by the power storage system controller (PSC) to the power storage system controller (PSC) from information received from multiple string controllers (SC) and information estimated by the string system controller (SSC). Examples of information required for processing by the power storage system controller (PSC) include the string system state of charge (SOC), the string system state of harmonics (SOH), and the string system charge / discharge power limits.

[0056] Here, the Power Storage System Controller (PSC) determines the instruction corresponding to the string system 10 based on the "information required for processing by the Power Storage System Controller (PSC)" received from the String System Controller (SSC), and transmits the instruction information to the String System Controller (SSC). Examples of instructions include charge / discharge instructions for the string system 10 in charge / discharge mode, instructions for each device in the string system 10 in individual control and maintenance mode (hereinafter referred to as individual control instructions), and state estimation instructions for the string system 10 in state estimation mode. Examples of charge / discharge instructions for the string system 10 in charge / discharge mode include, in addition to the string charge / discharge power instruction value assigned to each string St, control quantities for slope control mode, constant voltage (CV) mode, constant current (CC) mode, and constant power (CP) mode as described later, as well as operating methods (such as self-continuous operation or system interconnection). The charge / discharge instructions for the string system 10 in charge / discharge mode are issued by the Power Storage System Controller (PSC) and transmitted to the String Controller (SC) via the String System Controller (SSC). Examples of individual control commands for the string system 10 in maintenance mode include commands for individually controlling the power converter PCS, the switches S1 and S2 of the bypass mechanism B, and the string system auxiliary device 4. Examples of state estimation commands for the string system 10 in state estimation mode include commands for performing predetermined controls required to perform state estimation of the string St.

[0057] The string system controller (SSC) receives the instructions corresponding to string system 10 from the power storage system controller (PSC) and determines whether the operating state of string system 10 needs to be updated by comparing the currently received instructions with previously received instructions. If it is determined that the operating state of string system 10 needs to be updated, the string system controller (SSC) determines the operating mode of string St, the bypass request permission from string controller (SC), and the string charge / discharge power command value assigned to string St. Examples of operating modes for string St include charge / discharge mode, state estimation mode, and maintenance stop mode.

[0058] String controller SC and string system controller SSC and multiple module interfaces M I / F The auxiliary devices (such as power converter PCS) for communicating with, controlling, and managing the string St. Examples of auxiliary devices for the string St, besides the power converter PCS, include a current sensor 11 for detecting the string current (see [link to documentation]). Figure 1 ), a voltage sensor (not shown) for detecting the total voltage of the string, and a switch (not shown) for connecting and disconnecting the string St.

[0059] String controller SC from module interface M I / FReceive information about the state of module M (hereinafter referred to as module state information). Examples of module state include the temperature, current, voltage, and unit voltage of module M, as well as the state of bypass mechanism B.

[0060] The string controller SC is based on the module interface M I / F The received module status information is used to estimate the SOC, SOH, and charge / discharge power limits of module M's battery. This estimation can be achieved via module interface M. I / F Execution. In this case, module interface M I / F The estimation results can be transmitted to the string controller (SC).

[0061] The string controller SC is based on the module interface M I / F The received module status information estimates the state of the string St. Examples of string St states include string SOH, string SOC, and string charge / discharge power limits. The estimation of the string St state can be performed by the string system controller (SSC). In this case, the string controller (SC) can transmit the estimated results of the module status information and battery status to the string system controller (SSC).

[0062] When the unit voltage, total string current, or estimated string status (St) exceeds the threshold range, the string controller (SC) determines that string St is abnormal. In this case, the string controller (SC) stops the operation of string St or sends an abnormality notification to the string system controller (SSC).

[0063] The string controller SC is at the module interface M I / F From the received information and the information estimated by the string controller SC, the information required for processing by the string system controller SSC is transmitted to the string system controller SSC. Examples of the information required for processing by the string system controller SSC include the temperature, current, voltage, SOC, SOH, charge / discharge power limit values ​​of module M battery, as well as the cell voltage, the status of bypass mechanism B, string SOC, string SOH, and string charge / discharge power limit values.

[0064] The string system controller (SSC) determines the instructions for each string (St) based on the "string system controller SSC processing required information" received from the string controller (SC), and transmits the instruction information to the string controller (SC). Examples of instructions include charge / discharge instructions for string (St) in charge / discharge mode, individual control instructions for string (St) in maintenance mode, and state estimation instructions for string (St) in state estimation mode. Examples of charge / discharge instructions for string (St) in charge / discharge mode include, in addition to the string charge / discharge power instruction value, control quantities for constant voltage mode, constant current mode, and constant power mode, as well as the operating method (such as self-continuous operation or system interconnection). Examples of individual control instructions for string (St) in maintenance mode include instructions for individually controlling the bypass mechanism B. Examples of state estimation instructions in state estimation mode include performing charge / discharge at a constant current and recording the battery voltage at that time.

[0065] The string controller SC receives the instruction information for each string St from the string system controller SSC, and determines whether the bypass plan of string St needs to be updated by comparing the currently received instruction information with the previously received instruction information. The bypass plan of string St is a plan related to the battery bypass performed by the bypass mechanism B, and is determined according to predetermined criteria. The string controller SC determines whether a switch from charging to discharging or discharging to charging is performed in string St, and determines that the bypass plan needs to be updated if a switch is performed. If the bypass plan needs to be updated, the string controller SC determines the update according to the module interface M. I / F The received battery status information and the estimated battery status are used to determine the battery bypass plan.

[0066] On the other hand, the string controller SC compares the current and previous slave module interfaces M. I / F The received module status information, along with current and previous battery status estimates, determines whether string charging / discharging power control is required. If string charging / discharging power control is required, the string controller SC transmits a control signal corresponding to the string charging / discharging power command value received from the string system controller SSC to the MCU 101, which is the control device for the power converter PCS.

[0067] Here, the MCU101 of the power converter PCS and the module interface M are included. I / F The control unit MCU100 in the middle is connected via dedicated signal lines 102, 103 and 104 (see Figure 5 (Connection). When the unit voltage exceeds the upper limit threshold, it connects from the module interface M. I / FThe MCU100 sends a charge reduction signal (cell upper limit voltage warning signal, described below) to the MCU101 of the power converter PCS, indicating a reduction in charging power. When the cell voltage falls below the lower limit threshold, a signal is sent from the module interface M... I / F The MCU100 sends a discharge reduction signal (the unit lower limit voltage warning signal described below) to the MCU101 of the power converter PCS, indicating a reduction in discharge power.

[0068] The MCU101 of the power converter PCS controls the power converter PCS according to the control signal, so that the charging and discharging power of string St is close to the string charging and discharging power command value. However, when a charge reduction signal or a discharge reduction signal is transmitted during the transmission of the control signal, the MCU101 of the power converter PCS prioritizes the charge reduction signal or discharge reduction signal and controls the power converter PCS to reduce the charging and discharging power of string St. When the transmission of the charge reduction signal or discharge reduction signal stops, the MCU101 of the power converter PCS controls the power converter PCS according to the control signal, so that the charging and discharging power of string St is close to the string charging and discharging power command value.

[0069] Upon receiving a maintenance stop command from the string system controller (SSC), the SSC analyzes the received command and determines the type of maintenance to be performed. Examples of maintenance types include individual control, self-diagnosis, and battery replacement (hereinafter referred to as battery replacement).

[0070] Examples of individual control include controlling the individual switching on and off of the cooling device in string St. Examples of self-diagnosis include performing anomaly detection to identify anomalies that are difficult to detect during operation in state estimation mode or charge / discharge mode. Examples of anomaly detection include performing special control on switches S1 and S2 of the power converter PCS, bypass mechanism B, etc., acquiring their responses through various sensors, and determining whether an anomaly exists. Examples of battery replacement include guiding battery replacement for module M that has experienced degradation progression, failure, etc. When performing battery replacement, a work guide is displayed on the display input device of the power storage system controller PSC, and necessary controls such as stopping string St, where the battery to be replaced, are performed in the power storage system 1.

[0071] Upon receiving a state estimation command from the string system controller SSC, the string controller SSC compares the currently received string charge / discharge power command value with the previously received string charge / discharge power command value and determines whether there is a change. When a state estimation command is received from the string system controller SSC and the previous and current string charge / discharge power command values ​​have changed, the string controller SSC controls the switches S1 and S2 of the power converter PCS and bypass mechanism B through a predetermined method, thereby estimating the state of the string St. Examples of control methods for the power converter PCS, etc., during state estimation mode include a method of performing constant current control on the power converter PCS. Furthermore, examples of control methods for the switches S1 and S2 of the bypass mechanism B during state estimation mode include a method of sequentially bypassing the battery of a fully discharged module M during discharge.

[0072] The string controller SC records data from the module interface M. I / F Received module status information. Additionally, the string controller SC determines the status based on the module interface M. I / F The received module status information is used to update the parameters used during execution status estimation as needed. Parameter examples include the State of Harm (SOH) of module M battery, a mapping table of module M battery charge / discharge limits, and the State of Charge (SOC) open-circuit voltage (OCV) characteristic.

[0073] Module Interface M I / F It communicates with the string controller SC and the unit monitoring device CMU. The MCU100 controls the switches S1 and S2 of the bypass mechanism B, the unit monitoring device CMU, etc. Module interface M I / F The module status information is received from a unit monitoring device (CMU), etc. Examples of module status information include the total voltage of the battery in module M, the temperature of module M, and the unit voltage. The CMU receives detection signals from various sensors (not shown), such as a module voltage sensor detecting the battery voltage of module M, a unit voltage sensor detecting the unit voltage, and a module temperature sensor detecting the temperature of module M. The CMU can be configured as a single device or using the module interface M. I / F The battery device is monitored by an integrated circuit (IC) for configuration.

[0074] Module Interface M I / F The MCU100 receives module status information from the unit monitoring device (CMU) and estimates the status of module M's battery based on the received information. Examples of the estimated status of module M's battery include the battery's SOC, SOH, and charge / discharge power limits. The status of module M's battery can also be estimated by the string controller (SC).

[0075] For example, when the detected values ​​of the module voltage sensor, unit voltage sensor, and module temperature sensor, or the estimated value of the battery status of module M, exceed the threshold range, the module interface MI / F determines that module M is abnormal. Then, the module interface MI / F disconnects switch S2 of the bypass mechanism B of the module M determined to be abnormal, or sends an abnormality notification to the string controller SC. When the unit voltage exceeds the upper threshold or falls below the lower threshold, the unit upper voltage warning signal or unit lower voltage warning signal, as described below, is emitted from the module interface MI / F. I / F Transmitted to MCU101 of the power converter PCS.

[0076] Module Interface M I / F Information received from the unit monitoring device CMU and from the module interface M I / F The estimated information includes transmitting the information required for processing by the main controller, such as the string controller SC, to the string controller SC. Examples of information required for processing by the string controller SC include the temperature, current, voltage, SOC, SOH, charge / discharge power limits, and cell voltage of module M's battery, as well as the status of bypass mechanism B switches S1 and S2.

[0077] Here, the string controller SC is based on the module interface M I / F The received "information required for string controller SC processing" determines the instructions for each module M and transmits the instruction information to the module interface M. I / F Examples of instructions include module M bypass control executed by switches S1 and S2 of bypass mechanism B, and module M battery disconnection control executed by switch S2 of bypass mechanism B.

[0078] When the previous and current instruction information received from the string controller SC changes, the module interface M I / F The MCU100 controls switches S1 and S2 of the bypass mechanism B to perform the aforementioned bypass control or disconnection control. Furthermore, information received from the unit monitoring device CMU and via the module interface M... I / F When the estimated information changes, module interface M I / F Execute exception control as needed, independent of main controller instructions. Module Interface M I / F The instructions for battery balancing in module M are transmitted to the unit monitoring device (CMU).

[0079] Figure 3 and Figure 4 This is a chart representing the update of the charging and discharging power command values ​​of the power storage system and the string charging and discharging power command values ​​allocated to each string St. As shown in the chart, the charging and discharging power command values ​​of the power storage system are updated from the current value to the target value within a predetermined period (the slope control period of the charging and discharging power of the power storage system in the figure).

[0080] After the power storage system's charging and discharging power command value is updated, the system's charging and discharging power command value is maintained, and the string charging and discharging power command value of each string St is updated. The string charging and discharging power command value of each string St is updated so that it gradually becomes the target value within a predetermined period (the string charging and discharging power slope control period in the figure). After updating the power storage system's charging and discharging power command value, the string charging and discharging power command value of each string St is updated to adjust the charging and discharging power balance among the strings St.

[0081] Figure 3 The chart shows the relationship between the power storage system's power charge / discharge command value, the string power charge / discharge command value of each string St, and time when implementing control that reduces the response speed of the power storage system's power charge / discharge command value update (hereinafter referred to as standard slope control). The purpose of implementing standard slope control is to prevent drastic changes in the power storage system's power charge / discharge capacity when the power storage system's power charge / discharge command value is updated.

[0082] Figure 4 The chart in the figure illustrates the relationship between the power storage system's power charge / discharge command value, the string power charge / discharge command value of each string St, and time when implementing control to improve the response speed of power storage system charge / discharge command value updates (hereinafter referred to as shortest slope control). The purpose of implementing shortest slope control is to achieve a high-speed response when the power storage system's power charge / discharge command value is updated.

[0083] like Figure 3 As shown in the diagram, when standard slope control is executed, the charge / discharge power command value of the power storage system changes from the current value to the target value within a longer slope control period (e.g., 1.3s to 30s) than when the shortest slope control is executed. During this slope control period, the string charging power command value of each string St is gradually updated from the current value to the target value.

[0084] Here, the charging and discharging power command value of the power storage system is the sum of the charging and discharging power command values ​​of each string St. Therefore, the string system controller SSC determines the string charging and discharging power command value of each string St, so that the string charging and discharging power command value of each string St gradually changes from the current value to the target value, and the sum of the string charging and discharging power command values ​​of each string St gradually changes from the current value of the power storage system's charging and discharging power command value to the target value.

[0085] Before the start of the slope control period for the charging and discharging of the power storage system, the string system controller (SSC) determines an individual target value for the string charging and discharging power command value for each string (St). Furthermore, the string system controller (SSC) calculates the change ΔP1 of the string charging and discharging power command value for each string (St) for each predetermined period (e.g., a period of several seconds). The change ΔP1 is obtained by equally dividing the difference n between the current value and the target value of the string charging and discharging power command value for each string (St), and is determined by the resolution. n is the value obtained by dividing the time of the slope control period by the aforementioned predetermined period.

[0086] During the slope control period of the power storage system's charging and discharging, the string system controller (SSC) calculates the string charging and discharging power command value for each string (St) for each predetermined period, and transmits the calculated string charging and discharging power command value to each string controller (SC) via unicast communication. The string charging and discharging power command value is obtained by adding the aforementioned change ΔP1 to the assumed current value (hereinafter referred to as the assumed current value).

[0087] After transmitting the string charge / discharge power command value to all string controllers (SC), the string system controller (SSC) transmits a flag for updating the power converter (PCS) control (hereinafter referred to as the PCS control update flag) to all string controllers (SC) via broadcast communication.

[0088] When standard slope control is executed, at the moment when the charging and discharging power command value of the power storage system converges to the target value, the string charging and discharging power command value of each string St also converges to the target value. During the subsequent slope control of string charging and discharging power, the string charging and discharging power command value of each string St gradually changes in order to adjust the balance of string charging and discharging power of each string St.

[0089] When the charging and discharging power command value of the power storage system converges to the target value, the string system controller (SSC) determines the target value of the string charging and discharging power command value for each string (St) to adjust the balance of charging and discharging power among the strings (St). Simultaneously, the string system controller (SSC) calculates the change in string charging and discharging power command value ΔP2 for each string (St) in each predetermined period (e.g., a period of a few seconds). The method for calculating the change ΔP2 is the same as the method for calculating the change ΔP1 described above.

[0090] During each predetermined cycle of string charge / discharge power slope control, the string system controller SSC transmits the string charge / discharge power command value of each string St to the respective string controller SC via unicast communication. The string charge / discharge power command value is obtained by adding the aforementioned change ΔP2 to the assumed current value.

[0091] After transmitting the string charging and discharging power command value to all string controllers SC via unicast communication, the string system controller SSC transmits the PCS control update flag to all string controllers SC via broadcast communication.

[0092] like Figure 4 As shown in the diagram, when the shortest slope control is executed, the charge / discharge power command value of the power storage system changes from the current value to the target value within a shorter slope control period (e.g., 200ms to 2s) than when standard slope control is executed. During this slope control period, the string charging power command value of each string St is updated so that it changes from the current value to the intermediate target value within one cycle.

[0093] After the power storage system's charging and discharging power command value is updated, the power storage system's charging and discharging power command value is maintained, and the string charging and discharging power command value of each string St is updated. The string charging and discharging power command value of each string St will be updated so that it gradually changes from the intermediate target value to the final target value during the slope control period of the string charging and discharging power.

[0094] Here, the charging and discharging power command value of the power storage system is the sum of the charging and discharging power command values ​​of each string St. Therefore, the string system controller SSC determines the string charging and discharging power command value of each string St, such that the string charging and discharging power command value of each string St changes from the current value to the intermediate target value within one cycle, and the sum of the string charging and discharging power command values ​​of each string St changes from the current value of the power storage system charging and discharging power command value to the target value within one cycle.

[0095] Before the start of the slope control period for the charging and discharging of the power storage system, the string system controller (SSC) uniformly determines the intermediate target value of the charging and discharging power command for all strings (St) to be the same. During the slope control period, the string system controller (SSC) transmits the intermediate target value of the string charging and discharging power command to all string controllers (SC) via broadcast communication. Subsequently, the string system controller (SSC) transmits the PCS control update flag to all string controllers (SC) via broadcast communication. However, transmitting the PCS control update flag to all string controllers (SC) via broadcast communication is not essential.

[0096] The string controller SC controls the power converter PCS based on the intermediate target value of the received string charge / discharge power command and updates the charge / discharge power. Here, for a string St whose intermediate target value of the string charge / discharge power command exceeds the upper limit of the charge / discharge power, the corresponding string controller SC limits the charge / discharge power to be less than the intermediate target value and equal to or less than the upper limit of the charge / discharge power. In this case, the sum of the charge / discharge power of all strings St is less than the target value of the charge / discharge power for the power storage system. Therefore, in this situation, the string system controller SSC takes into account the upper limit of the charge / discharge power received from the string controller SC and pre-corrects the target value of the battery system charge / discharge power command.

[0097] When shortest slope control is executed, as the power command value for charging and discharging the power storage system converges to the target value, the string charging and discharging power command value of each string St also converges to the intermediate target value. Since the intermediate target value deviates from the final target value, string charging and discharging power slope control is executed after the power command value for charging and discharging the power storage system converges to the target value. During string charging and discharging power slope control, the string charging and discharging power command value of each string St gradually changes from the intermediate target value to the final target value, with the aim of adjusting the balance of string charging and discharging power among each string St.

[0098] When the charging and discharging power command values ​​of the power storage system converge to the target value, the string system controller (SSC) determines the final target value of the charging and discharging power command values ​​for each string (St) to adjust the balance of charging and discharging power among the strings (St). Simultaneously, the string system controller (SSC) calculates the change in the string charging and discharging power command value, ΔP3, for each string (St) individually for each predetermined period (e.g., a period of several seconds). The change ΔP3 is obtained by equally dividing the difference n between the intermediate target value and the final target value of the string charging and discharging power command values ​​for each string (St), and is determined by the resolution.

[0099] During each predetermined cycle of string charge / discharge power slope control, the string system controller SSC transmits the string charge / discharge power command value of each string St to all string controllers SC via unicast communication. The string charge / discharge power command value is obtained by adding the aforementioned change ΔP3 to the assumed current value.

[0100] After transmitting the string charging and discharging power command value to all string controllers SC via unicast communication, the string system controller SSC transmits the PCS control update flag to all string controllers SC via broadcast communication.

[0101] Figure 5 It indicates that it is used in Figure 1 and Figure 2 The string controller SC, power converter PCS, and module interface M shown are shown. I / FThe circuit diagram shows the communication circuit that enables communication between modules. As shown in the attached diagram, the module interface M... I / F The MCU100 is connected to the string controller SC via signal line 105, and to the MCU101 of the power converter PCS via dedicated signal lines 103 and 104. Module interface M I / F The MCU100 is grounded (GND) via signal line 102.

[0102] Module Interface M I / F The system includes a first optocoupler PC1 and a second optocoupler PC2. The LED of the first optocoupler PC1 is connected to MCU100 and GND. The phototransistor of the first optocoupler PC1 is connected to MCU101 of the power converter PCS via signal line 103 and to GND via signal line 102. The LED of the second optocoupler PC2 is connected to MCU100 and GND, and the phototransistor of the second optocoupler PC2 is connected to MCU101 of the power converter PCS via signal line 104 and to GND via signal line 102.

[0103] When the unit voltage transmitted from the unit monitoring device (CMU) exceeds the upper limit threshold, the module interface M... I / F The MCU100 transmits a unit upper voltage warning signal to the LED of the first optocoupler PC1. When the unit voltage transmitted from the unit monitoring device CMU is lower than the lower threshold, the module interface M... I / F The MCU100 transmits a unit lower limit voltage warning signal to the LED of the second optocoupler PC2.

[0104] When the unit upper voltage warning signal is transmitted from MCU100, the first optocoupler PC1 causes the light-emitting diode to light up, thereby turning on the phototransistor. Conversely, when the unit upper voltage warning signal is not transmitted from MCU100, the first optocoupler PC1 isolates the input side of MCU100 from the output side of MCU101.

[0105] When a unit lower limit voltage warning signal is transmitted from MCU100, the second optocoupler PC2 causes the light-emitting diode to light up, thereby turning on the phototransistor. Conversely, when no unit lower limit voltage warning signal is transmitted from MCU100, the second optocoupler PC2 isolates the input side of MCU100 from the output side of MCU101.

[0106] Signal line 103 is connected to the power supply Vcc via resistor R1, which acts as a pull-up resistor. Resistor R1 is connected between the connection point of the first optocoupler PC1 in signal line 103 and the connection point of MCU 101. The cell upper limit voltage warning signal is an H-level signal. Therefore, during the period when the cell upper limit voltage warning signal is not transmitted, the input potential of signal line 103 from MCU 101 becomes the potential of the power supply Vcc, while during the period when the cell upper limit voltage warning signal is transmitted, the input potential of signal line 103 from MCU 101 becomes 0 (L-level). When the input potential from signal line 103 drops from the potential of the power supply Vcc to 0, MCU 101 detects the cell upper limit voltage warning signal and controls the power converter PCS to reduce the charging power of string St.

[0107] Similarly, signal line 104 is connected to the power supply Vcc via resistor R2, which acts as a pull-up resistor. Resistor R2 is connected between the connection point of the second optocoupler PC2 in signal line 104 and the connection point of MCU 101. The cell lower limit voltage warning signal is a high-level signal. Therefore, during the period when the cell lower limit voltage warning signal is not transmitted, the input potential of signal line 104 from MCU 101 becomes the potential of the power supply Vcc, while during the period when the cell lower limit voltage warning signal is transmitted, the input potential of signal line 104 from MCU 101 becomes 0. When the input potential from signal line 104 drops from the potential of the power supply Vcc to 0, MCU 101 detects the cell lower limit voltage warning signal and controls the power converter PCS to reduce the discharge power of string St.

[0108] The cell upper voltage warning signal and the cell lower voltage warning signal do not necessarily have to be H-level signals; they can also be L-level signals. In this case, during the period when the cell upper voltage warning signal or the cell lower voltage warning signal is not transmitted, the input potential of signal line 103 or signal line 104 from MCU101 becomes 0 (L-level), while during the period when the cell upper voltage warning signal or the cell lower voltage warning signal is transmitted, the input potential of signal line 103 or signal line 104 from MCU101 becomes the potential of power supply Vcc. When the input potential rises from 0 to the potential of power supply Vcc, MCU101 detects the cell upper voltage warning signal or the cell lower voltage warning signal and controls the power converter PCS to reduce the charging power or discharging power of string St.

[0109] Figure 6 This is a diagram illustrating the communication method of the battery control device according to the comparative example. Similar to the battery control device 2 of the above-described embodiment, the comparative example battery control device includes a power storage system controller (PSC), a string system controller (SSC), a string controller (SC), a power converter (PCS), and a module interface (M). I / FAnd the unit monitoring device (CMU). However, the battery control device of the comparative example differs from the battery control device 2 of the above embodiment in that the unit upper voltage warning signal and the unit lower voltage warning signal are not emitted from the module interface M. I / F The MCU100 transmits data to the MCU101 of the power converter PCS.

[0110] In the comparative example battery control device, when standard slope control and shortest slope control are executed, the string charge / discharge power command value of each string St is transmitted from the string system controller SSC to the string controller SC (charge / discharge power command), and the control signal based on the string charge / discharge power command value of each string St is transmitted from the string controller SC to the power converter PCS.

[0111] On the other hand, when performing standard slope control and minimum slope control, the cell voltage information is transmitted from the cell monitoring unit (CMU) to the module interface (M). I / F And via module interface M I / F Calculate the voltage of battery module M. The calculated battery voltage of module M is transmitted from module interface M. I / F The voltage is transmitted to the string controller SC, which determines whether the voltage is between the upper and lower limits (voltage limit over-limit determination). Then, when the voltage exceeds the upper limit, the string controller SC transmits a signal to the power converter PCS indicating a reduction in charging power; and when the voltage is below the lower limit, the string controller SC transmits a signal to the power converter PCS indicating a reduction in discharging power (charge / discharge power reduction).

[0112] Here, in standard slope control, the string charge / discharge power command value can gradually change from the current value to the target value over multiple (e.g., 20) cycles, and the power converter PCS can complete control within any period (e.g., 100ms) from the start of the charge / discharge power command. Therefore, when executing standard slope control, the change in string St charge / discharge power per unit time is small. Thus, there is sufficient margin for the time from when the cell voltage exceeds the upper threshold to when the cell voltage rises to the upper threshold voltage (maximum allowable cell voltage), and for the time from when the cell voltage falls below the lower threshold to when the cell voltage drops to the lower threshold voltage (minimum allowable cell voltage). Therefore, as... Figure 6 As shown, through periodic processing from the cell monitoring unit (CMU) to the string controller (SC), the cell voltage can be maintained between the upper and lower limits.

[0113] In contrast, in shortest slope control, the string charge / discharge power command value changes from the current value to the target value in one cycle, and the power converter PCS needs to complete the control within a short period (e.g., 60ms). Therefore, when executing shortest slope control, the change in string St charge / discharge power per unit time is large. Consequently, there is no margin for the time from when the cell voltage exceeds the upper threshold to when the cell voltage rises to the upper threshold voltage (maximum allowable cell voltage), and the time from when the cell voltage falls below the lower threshold to when the cell voltage drops to the lower threshold voltage (minimum allowable cell voltage). Therefore, as... Figure 6 As shown, it is difficult to maintain the cell voltage between the upper and lower limits through the periodic processing from the cell monitoring device (CMU) to the string controller (SC).

[0114] Therefore, in the battery control device 2 of this embodiment, the cell upper limit voltage warning signal and the cell lower limit voltage warning signal are transmitted from the module interface M. I / F The MCU100 transmits the data to the MCU101 of the power converter PCS. This shortens the time from the transmission of unit voltage information from the unit monitoring device (CMU) to the power converter PCS's charge / discharge power reduction control response.

[0115] Figure 7 It means Figure 1 and Figure 2 A diagram illustrating the communication method of the battery control device 2 is shown. In the battery control device 2 of this embodiment, similar to the comparative example, when standard slope control and minimum slope control are executed, the string charge / discharge power command value is transmitted from the string system controller SSC to the string controller SC (charge / discharge power command), and a control signal based on the string charge / discharge power command value is transmitted from the string controller SC to the power converter PCS. When standard slope control is executed, control is completed within any period (e.g., 100 ms) from the start of the charge / discharge power command. In contrast, when minimum slope control is executed, the power converter PCS completes control within a short period (e.g., 60 ms) from the start of the charge / discharge power command.

[0116] On the other hand, when performing standard slope control and minimum slope control, the cell voltage information is transmitted from the cell monitoring unit (CMU) to the module interface (M). I / F And module interface M I / F Determine if the cell voltage is between the upper and lower thresholds (voltage over-limit determination). When the cell voltage exceeds the upper threshold, a cell upper limit voltage warning signal and a GND signal are emitted from the module interface M. I / F Transmitted to the power converter PCS. When the cell voltage falls below the lower threshold, a cell lower threshold voltage warning signal and a GND signal are transmitted from the module interface M. I / F Transmitted to the power converter PCS.

[0117] Therefore, compared to the comparative example, the time from transmitting unit voltage information from the unit monitoring device (CMU) to the power converter (PCS) for charging / discharging power reduction control response can be shortened. Thus, not only when performing standard slope control, but also when performing minimum slope control, the unit voltage can be maintained between the upper and lower limits.

[0118] Figure 8 It includes graphs showing the charge / discharge power command values ​​and the actual charge / discharge power progression, as well as timing diagrams showing the ON / OFF timings of the cell upper limit voltage warning signal and the cell lower limit voltage warning signal, respectively. For example... Figure 8 As shown in the chart, the actual charging and discharging power of each string group St changes after the commanded charging and discharging power value of each string group St changes. During charging, the actual charging power of each string group St changes to approach the commanded charging power value, and during discharging, the actual discharging power of each string group St changes to approach the commanded discharging power value. The commanded charging power value is set below the upper limit of the charging and discharging power of each string group St, and the commanded discharging power value is set above the lower limit of the charging and discharging power of each string group St.

[0119] When string St is charging, if the cell voltage of module M in string St exceeds the upper limit threshold, a cell upper limit voltage warning signal is emitted from module interface M. I / F Transmission. Here, the upper limit threshold for the cell voltage is set to a value lower than the upper limit value for the cell voltage (hereinafter referred to as the cell upper limit voltage). Therefore, when the cell voltage approaches the cell upper limit voltage, a cell upper limit voltage warning signal is emitted from the module interface M before the cell voltage exceeds the cell upper limit voltage. I / F transmission.

[0120] During the period when MCU101 detects a cell upper voltage warning signal, the charging power of string St is reduced by power converter PCS. When MCU101 does not detect a cell upper voltage warning signal, the charging power of string St is increased by power converter PCS to approach the charging power command value.

[0121] When string St discharges, if the cell voltage of module M in string St falls below the lower threshold, a cell lower threshold voltage warning signal is emitted from module interface M. I / F Transmission. Here, the lower limit threshold of the cell voltage is set to a value higher than the lower limit value of the cell voltage (hereinafter referred to as the lower limit voltage). Therefore, when the cell voltage approaches the lower limit voltage, a lower limit voltage warning signal is emitted from the module interface M before the cell voltage falls below the lower limit voltage. I / F transmission.

[0122] During the period when MCU101 detects a cell lower limit voltage warning signal, the discharge power of string St is reduced by power converter PCS. When MCU101 does not detect a cell lower limit voltage warning signal, the discharge power of string St is increased by power converter PCS to approach the discharge power command value.

[0123] Figure 9 It means Figure 1 and Figure 2 The flowchart illustrates the charging control process of the battery control device 2. As shown in the flowchart, when the charging control of the power storage system 1 begins, the MCU 101 of the power converter PCS determines whether a cell upper limit voltage warning signal has been received (step S11). In this step, the MCU 101 determines whether the input potential from the signal line 103 is 0 (L level).

[0124] When MCU101 does not receive a cell upper limit voltage warning signal (step S11 is no), MCU101 controls the power converter PCS to bring the charging power of string St close to the charging power command value (charging power control in step S12). Conversely, when MCU101 receives a cell upper limit voltage warning signal (step S11 is yes), MCU101 controls the power converter PCS to reduce the charging power of string St (charging power reduction in step S13).

[0125] By repeating steps S11 to S13 above, the charging power of string St is repeatedly increased in a manner close to the charging power command value, and the charging power of string St is reduced in order to make the cell voltage lower than the cell upper limit voltage.

[0126] Figure 10 It means Figure 1 and Figure 2 The flowchart illustrates the discharge control process of the battery control device 2. As shown in the flowchart, when the discharge control of the power storage system 1 begins, the MCU 101 of the power converter PCS determines whether a cell lower limit voltage warning signal has been received (step S101). In this step, the MCU 101 determines whether the input potential from the signal line 104 is 0 (L level).

[0127] When MCU101 does not receive a cell lower limit voltage warning signal (step S101 is negative), MCU101 controls the power converter PCS to bring the discharge power of string St close to the discharge power command value (discharge power control in step S102). Conversely, when MCU101 receives a cell lower limit voltage warning signal (step S101 is positive), MCU101 controls the power converter PCS to reduce the discharge power of string St (discharge power reduction in step S103).

[0128] By repeating steps S101 to S103, the string St discharge power is repeatedly increased in a manner close to the discharge power command value, and the string St discharge power is reduced in order to make the cell voltage higher than the cell lower limit voltage.

[0129] As described above, in the battery control device 2 of this embodiment, the module interface M I / F The MCU100 receives the cell voltage detection signal from the cell monitoring device (CMU) and, when the cell voltage is equal to or greater than the upper limit threshold, transmits a charge reduction signal to the MCU101 of the power converter PCS to reduce the charging power of the string St. The MCU101 receives a control signal from the string controller SC corresponding to the charging power command value and does not receive a control signal from the module interface M. I / F During the charging decrease signal period of MCU100, the control power converter PCS brings the charging power of string St close to the charging power command value. Conversely, MCU101 receives control signals from string controller SC and from module interface M... I / F During the charging reduction signal of the MCU100, the power converter PCS is controlled to reduce the charging power of the string St.

[0130] Therefore, it is possible to prevent communication delay between the transmission of cell voltage information executed by the cell monitoring device (CMU) and the charging power reduction control response executed by the power converter (PCS). Thus, in the power storage system 1 where the performance of battery cells C in the string St varies, it is possible to control the charging of the string St while maintaining the cell voltage below the upper limit.

[0131] In the battery control device 2 of this embodiment, the module interface M I / F The MCU100 receives the cell voltage detection signal from the cell monitoring device (CMU) and, when the cell voltage is equal to or greater than the lower threshold, transmits a discharge reduction signal to the MCU101 of the power converter (PCS) to reduce the discharge power of the string St. The MCU101 receives a control signal from the string controller (SC) corresponding to the discharge power command value and does not receive a control signal from the module interface (M). I / F During the discharge reduction signal period of MCU100, the control power converter PCS brings the discharge power of string St close to the discharge power command value. Conversely, MCU101 receives control signals from string controller SC and from module interface M... I / F During the discharge reduction signal of the MCU100, the power converter PCS is controlled to reduce the discharge power of the string St.

[0132] Therefore, communication delay can be prevented between the transmission of cell voltage information executed by the cell monitoring device (CMU) and the response of the discharge power reduction control executed by the power converter (PCS). Thus, in the power storage system 1 where the performance of battery cells C in the string St varies, the discharge of the string St can be controlled while maintaining the cell voltage above a lower limit.

[0133] The battery control device 2 in this embodiment includes: a first optocoupler PC1, which is disposed at the connection module interface M. I / F The signal line 103 of the MCU100 and the MCU101 of the power converter PCS; and resistor R1, which acts as a pull-up resistor, is connected in the signal line 103 between the first optocoupler PC1 and the MCU101. Thus, while electrically isolating the MCU100 from the MCU101, a cell upper limit voltage warning signal can be transmitted from the MCU100 to the first optocoupler PC1.

[0134] The battery control device 2 in this embodiment includes: a second optocoupler PC2, which is disposed at the connection module interface M. I / F The signal line 104 of the MCU100 and the MCU101 of the power converter PCS is connected; and resistor R2, which acts as a pull-up resistor, is connected between the second optocoupler PC2 and the MCU101 in the signal line 103. Thus, the lower limit voltage warning signal of the unit can be transmitted from the MCU100 to the second optocoupler PC2 while electrically isolating the MCU100 from the MCU101.

[0135] Although the present invention has been described above based on the above embodiments, the present invention is not limited to the above embodiments. Modifications may be made without departing from the spirit of the present invention, or well-known or publicly known techniques may be appropriately combined.

[0136] For example, in the above implementation, module interface M I / F The MCU100 and the MCU101 of the power converter PCS can be isolated from each other via the first optocoupler PC1 and the second optocoupler PC2, but this is not mandatory. Furthermore, although separate optocouplers (first optocoupler PC1 and second optocoupler PC2) and separate signal lines 103 and 104 are used to transmit the upper and lower limit voltage warning signals, the invention is not limited to this; a single optocoupler and a single signal line can be used to transmit both the upper and lower limit voltage warning signals. In this case, the MCU101 receives the upper and lower limit voltage warning signals, but because the MCU101 knows which of the charging and discharging processes it is controlling, it can perform charge / discharge power reduction control.

[0137] In the above embodiment, the string system controller SSC transmits string charge / discharge power command values ​​to the string controller SC. However, the power storage system controller PSC and the string system controller SSC can be integrated into a single controller, and this integrated controller can transmit string charge / discharge power command values ​​to the string controller SC. Furthermore, any one of the multiple string controllers SC can act as the master controller, while the others can act as slave controllers, and the master controller can transmit string charge / discharge power command values ​​to the slave controllers.

[0138] Hereinafter, the features of the embodiments of the battery control device and energy storage system of the present invention will be briefly summarized and listed in the following [1] to [4].

[0139] [1] A battery control device (2) for controlling a power storage system (1), the power storage system (1) comprising a string (St, St1 to Stx) containing a plurality of battery modules (M, M1 to Mn) connected in series, and a power converter (PCS, PCS1 to PCSx) configured to convert the charging and discharging power of the string (St, St1 to Stx), the battery modules (M, M1 to Mn) each comprising a plurality of battery cells (C) connected in series, and a cell voltage detection device (CMU, CMU1 to CMUn) configured to detect the voltage of each of the battery cells (C), the battery control device (2) comprising:

[0140] Multiple module control devices (100) are respectively provided for the battery modules (M, M1 to Mn) and configured to control the battery modules (M, M1 to Mn);

[0141] A power converter control device (101) configured to control the power converters (PCS, PCS1 to PCSx); and

[0142] A string control unit (SC, SC1 to SCx), corresponding to the string (St, St1 to Stx), is configured to communicate with the plurality of module control units (100), the power converter control unit (101), and the main control unit (SSC), and to send control signals to the power converter control unit (101) to control the power converter (PCS, PCS1 to PCSx) so that the charging power of the string (St, St1 to Stx) is close to the charging power command value received from the main control unit (SSC), wherein,

[0143] Each of the module control devices (100) is configured to receive a detection signal of the voltage of the battery cell (C) from the cell voltage detection devices (CMU, CMU1 to CMUn), and when the voltage of the battery cell (C) is equal to or greater than an upper limit threshold, send a charge reduction signal to the power converter control device (101) to reduce the charging power of the string (St, St1 to Stx), and

[0144] The power converter control device (101) is configured to control the power converter (PCS, PCS1 to PCSx) to bring the charging power of the string (St, St1 to Stx) close to the charging power command value during the period when it receives the control signal from the string control device (SC, SC1 to SCx) but not from the module control device (100), and to control the power converter (PCS, PCS1 to PCSx) to reduce the charging power of the string (St, St1 to Stx) during the period when it receives the control signal from the string control device (SC, SC1 to SCx) and the charging power reduction signal from the module control device (100).

[0145] [2] A battery control device (2) for controlling a power storage system (1), the power storage system (1) comprising strings (St, St1 to Stx) of multiple battery modules (M, M1 to Mn) connected in series, and power converters (PCS, PCS1 to PCSx) configured to convert the charging and discharging power of the strings (St, St1 to Stx), each battery module (M, M1 to Mn) comprising multiple battery cells (C) connected in series, and cell voltage detection devices (CMU, CMU1 to CMUn) configured to detect the voltage of each battery cell (C), the battery control device (2) comprising:

[0146] Multiple module control devices (100) are respectively provided for the battery modules (M, M1 to Mn) and configured to control the battery modules (M, M1 to Mn);

[0147] A power converter control device (101) configured to control the power converters (PCS, PCS1 to PCSx); and

[0148] A string control unit (SC, SC1 to SCx), corresponding to the string (St, St1 to Stx), is configured to communicate with the plurality of module control units (100), the power converter control unit (101), and the main control unit (SSC), and to send control signals to the power converter control unit (101) to control the power converters (PCS, PCS1 to PCSx) so that the discharge power of the string (St, St1 to Stx) is close to the discharge power command value received from the main control unit (SSC), wherein,

[0149] Each of the module control devices (100) is configured to receive a detection signal of the voltage of the battery cell (C) from the cell voltage detection devices (CMU, CMU1 to CMUn), and when the voltage of the battery cell (C) is equal to or less than a lower threshold, send a discharge reduction signal to the power converter control device (101) to reduce the discharge power of the string (St, St1 to Stx), and

[0150] The power converter control device (101) is configured to control the power converter (PCS, PCS1 to PCSx) to bring the discharge power of the string (St, St1 to Stx) close to the discharge power command value during the period when it receives the control signal from the string control device (SC, SC1 to SCx) but not from the module control device (100), and to control the power converter (PCS, PCS1 to PCSx) to reduce the discharge power of the string (St, St1 to Stx) during the period when it receives the control signal from the string control device (SC, SC1 to SCx) and the discharge reduction signal from the module control device (100).

[0151] [3] The battery control device (2) according to [1] or [2] further includes:

[0152] Optical couplers (PC1, PC2) are disposed on signal lines (103, 104) connecting the module control device (100) and the power converter control device (101); and

[0153] Pull-up resistors (R1, R2) are connected on the signal lines (103, 104) between the optocoupler (PC1, PC2) and the power converter control device (101).

[0154] [4] An electric power storage system (1), comprising:

[0155] A string (St, St1 to Stx) comprising multiple battery modules (M, M1 to Mn) connected in series;

[0156] A power converter (PCS, PCS1 to PCSx) configured to convert the charging and discharging power of the strings (St, St1 to Stx), each of the battery modules (M, M1 to Mn) including a plurality of battery cells (C) connected in series, and a cell voltage detection device (CMU, CMU1 to CMUn) configured to detect the voltage of each of the battery cells (C); and

[0157] According to the battery control device (2) described in [1] or [2].

[0158] Although the invention has been described in detail with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention.

[0159] This application is based on Japanese Patent Application No. 2024-001574, filed on January 10, 2024, the contents of which are incorporated herein by reference.

[0160] According to the present invention, a battery control device and a power storage system are provided that can maintain the voltage of the battery cells in a battery module within an appropriate range, regardless of performance differences among the battery cells in a string. The present invention, having this effect, is useful for battery control devices and power storage systems.

[0161] Figure Labels

[0162] 1: Power storage system

[0163] 2: Battery control device

[0164] 100: MCU (Microcontroller Unit)

[0165] 101: MCU (Microcontroller Unit)

[0166] 103: Signal line

[0167] 104: Signal line

[0168] C: Battery unit

[0169] CMU: Unit Monitoring Unit (Unit Voltage Detection Device)

[0170] CMU1: Unit Monitoring Unit (Unit Voltage Detection Device)

[0171] CMU2: Unit Monitoring Unit (Unit Voltage Detection Device)

[0172] CMUn: Unit Monitoring Unit (Unit Voltage Detection Device)

[0173] M: Module (Battery Module)

[0174] M1: Module (Battery Module)

[0175] M2: Module (Battery Module)

[0176] Mn: Module (Battery Module)

[0177] PC1: First optical coupler (optical coupler)

[0178] PC2: Second optical coupler (optical coupler)

[0179] PCS: Power Converter

[0180] PCS1: Power Converter

[0181] PCS2: Power Converter

[0182] PCSx: Power Converter

[0183] R1: Resistor (Pull-up resistor)

[0184] R2: Resistor (Pull-up resistor)

[0185] SC: String Controller (String Control Device)

[0186] SC1: String Controller (String Control Device)

[0187] SC2: String Controller (String Control Device)

[0188] SCx: String Controller (String Control Device)

[0189] SSC: String System Controller (Main Control Unit)

[0190] St: string

[0191] St1: String

[0192] St2: String

[0193] Stx: string

Claims

1. A battery control device for controlling a power storage system, the power storage system comprising a string of multiple battery modules connected in series, and a power converter configured to convert the charging and discharging power of the string, each battery module comprising multiple battery cells connected in series, and a cell voltage detection device configured to detect the voltage of each battery cell, the battery control device comprising: Multiple module control devices are provided, each corresponding to the battery module, and configured to control the battery module; A power converter control device configured to control the power converter; as well as A string control device, configured to correspond to the string and communicate with the plurality of module control devices, the power converter control device, and the main control device, sends control signals to the power converter control device to control the power converter so that the charging power of the string approaches the charging power command value received from the main control device. Each of the module control devices is configured to receive a voltage detection signal of the battery cell from the unit voltage detection device, and when the voltage of the battery cell is equal to or greater than an upper limit threshold, send a charge reduction signal to the power converter control device to reduce the charging power of the string. The power converter control device is configured to control the power converter to bring the charging power of the string close to the charging power command value during a period when it receives the control signal from the string control device but not from the module control device, and to control the power converter to reduce the charging power of the string during a period when it receives the control signal from the string control device and the charging power reduction signal from the module control device.

2. A battery control device for controlling a power storage system, the power storage system comprising a string of multiple battery modules connected in series, and a power converter configured to convert the charging and discharging power of the string, each battery module comprising multiple battery cells connected in series, and a cell voltage detection device configured to detect the voltage of each battery cell, the battery control device comprising: Multiple module control devices are provided, each corresponding to the battery module, and configured to control the battery module; A power converter control device configured to control the power converter; as well as A string control device, configured to correspond to the string and communicate with the plurality of module control devices, the power converter control device, and the main control device, sends control signals to the power converter control device to control the power converter so that the discharge power of the string approaches the discharge power command value received from the main control device. Each of the module control devices is configured to receive a voltage detection signal of the battery cell from the unit voltage detection device, and when the voltage of the battery cell is equal to or less than a lower threshold, send a discharge reduction signal to the power converter control device to reduce the discharge power of the string. The power converter control device is configured to control the power converter to bring the discharge power of the string close to the discharge power command value during a period when it receives the control signal from the string control device but not from the module control device, and to control the power converter to reduce the discharge power of the string during a period when it receives the control signal from the string control device and the discharge reduction signal from the module control device.

3. The battery control device according to claim 1 or 2, further comprising: An optocoupler is disposed on the signal line connecting the module control device and the power converter control device; as well as A pull-up resistor is connected on the signal line between the optocoupler and the power converter control device.

4. An energy storage system, comprising: A string, which includes multiple battery modules connected in series; A power converter configured to convert the charging and discharging power of the string, each of the battery modules including a plurality of battery cells connected in series and a cell voltage detection device configured to detect the voltage of each of the battery cells; as well as The battery control device according to claim 1 or 2.

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