Storage battery control device, and power storage system

Abstract

To keep voltages of storage battery cells in a storage battery module within an appropriate range regardless of whether there is variation in the performance of the storage battery cells in a string.SOLUTION: An MCU 100 of a module interface MI / F receives a detection signal of a cell voltage from a cell monitoring unit CMU, and when the cell voltage is an upper threshold value or more, it transmits a charge suppressing signal for suppressing a charging power of a string to an MCU 101 of a power converter PCS. While the MCU 101 receives a control signal from a string controller SC, and does not receive the charge suppressing signal from the MCU 100, it controls the power converter PCS so that the charging power of the string approaches a charging power instruction value, and while it receives the control signal from the string controller SC, and receives the charge suppressing signal from the MCU 100, it controls the power converter so that the charging power of the string approaches the charging power instruction value.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a battery control device and a power storage system.

Background Art

[0002] As a power storage system including a string in which a plurality of battery modules are connected in series, a power storage system including a bypass mechanism for bypassing each battery module is known (see, for example, Patent Documents 1 and 2). In the power storage systems described in Patent Documents 1 and 2, charging and discharging can be continued by bypassing a battery module that has been fully charged or fully discharged by a bypass mechanism. Therefore, it is possible to mix battery modules having different charge and discharge capacities due to differences in degradation states and types.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] For a new battery module with reduced variations in performance during manufacturing, or a battery module that has reached an equivalent state of deterioration by being used in the same environment and under the same conditions, if the total voltage and total current of the string are monitored to control the charge and discharge of the string, the voltages of all the battery cells within the string can be kept within an appropriate range. However, for a battery module with variations in performance during manufacturing, or a battery module with different states of deterioration due to not being used in the same environment and under the same conditions, the performance of the battery cells within the battery module often varies as well. When battery modules with variations in the performance of battery cells are mixed, it is difficult to control the voltages of all the battery cells so that they do not exceed the upper limit value or fall below the lower limit value by simply monitoring the total voltage and total current of the string and controlling the charge and discharge of the string.

[0005] Therefore, in a power storage system equipped with a string in which battery modules with variations in the performance of battery cells are mixed, it is necessary to monitor the voltage of the battery cells (hereinafter referred to as cell voltage) to control the charge and discharge of the string. However, if cell voltage information is transmitted from a cell voltage monitoring unit to a controller that controls the charge and discharge of the string via the interface of the battery module, and the controller determines whether the cell voltage is within the range between the upper limit value and the lower limit value and transmits a control signal based on the determination result to the power converter of the string, the delay in a series of communications will increase, and during that time, there is a possibility that the cell voltage may exceed the upper limit value or fall below the lower limit value.

[0006] In view of the above circumstances, an object of the present invention is to provide a battery control device and a power storage system that can keep the voltages of the battery cells within a battery module within an appropriate range regardless of whether there are variations in the performance of the battery cells within the string.

Means for Solving the Problem

[0007] The battery control device of the present invention includes a string including a plurality of serially connected battery modules, and a power converter that converts the charge and discharge power of the string. The battery module includes a plurality of serially connected battery cells and a cell voltage detection unit that detects the voltage of the battery cells. The battery control device controls a power storage system, and includes a plurality of module control units respectively provided corresponding to the battery modules to control the battery modules, a power converter control unit that controls the power converter, and a string control unit provided corresponding to the string, which communicates with the plurality of module control units, the power converter control unit, and a host control unit, and transmits a control signal for controlling the power converter so that the charging power of the string approaches a charging power instruction value received from the host control unit. The module control unit receives a detection signal of the voltage of the battery cells from the cell voltage detection unit, and when the voltage of the battery cells is equal to or higher than an upper threshold value, transmits a charging suppression signal for suppressing the charging power of the string to the power converter control unit. The power converter control unit controls the power converter so that the charging power of the string approaches the charging power instruction value while receiving the control signal from the string control unit and not receiving the charging suppression signal from the module control unit, and controls the power converter so as to suppress the charging power of the string while receiving the control signal from the string control unit and receiving the charging suppression signal from the module control unit.

[0008] The battery control device of the present invention includes a string including a plurality of battery modules connected in series, and a power converter that converts the charge and discharge power of the string. The battery module includes a plurality of battery cells connected in series, and a cell voltage detection unit that detects the voltage of the battery cell. The battery control device controls a power storage system, and includes a plurality of module control units respectively provided corresponding to the battery modules to control the battery modules, a power converter control unit that controls the power converter, and a string control unit provided corresponding to the string. The string control unit communicates with the plurality of module control units, the power converter control unit, and a host control unit, and transmits a control signal for controlling the power converter so that the discharge power of the string approaches a discharge power instruction value received from the host control unit. The module control unit receives a detection signal of the voltage of the battery cell from the cell voltage detection unit, and when the voltage of the battery cell is equal to or lower than a lower threshold value, transmits a discharge suppression signal for suppressing the discharge power of the string to the power converter control unit. The power converter control unit controls the power converter so that the discharge power of the string approaches the discharge power instruction value while receiving the control signal from the string control unit and not receiving the discharge suppression signal from the module control unit, and controls the power converter so as to suppress the discharge power of the string while receiving the control signal from the string control unit and receiving the discharge suppression signal from the module control unit.

[0009] The power storage system of the present invention includes a string including a plurality of battery modules connected in series, and a power converter that converts the charge and discharge power of the string. The battery module includes a plurality of battery cells connected in series, and a cell voltage detection unit that detects the voltage of the battery cell. The power storage system includes the battery control device according to claim 1 or 2.

Advantages of the Invention

[0010] According to the present invention, regardless of whether there are variations in the performance of the battery cells in the string, the voltage of the battery cells in the battery module can be kept within an appropriate range.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Embodiments for Carrying Out the Invention

[0012] Hereinafter, the present invention will be described in accordance with preferred embodiments. Note that the present invention is not limited to the embodiments shown below, and the embodiments can be appropriately changed without departing from the gist of the present invention. Also, in the embodiments shown below, there are some places where the illustration and description of some configurations are omitted. For the details of the omitted technologies, well-known or widely known technologies are appropriately applied within the range where there is no contradiction with the content described below.

[0013] FIG. 1 is a circuit diagram showing the circuit configuration of a power storage system 1 including a power storage battery control device 2 according to an embodiment of the present invention. The power storage system 1 shown in this figure is a stationary power source and includes a string system 10 and a power storage system controller PSC.

[0014] The power storage system controller PSC is the highest-level control device in the power storage system 1, communicates with a host server 7 (see FIG. 2) and a string system controller SSC, and controls a power storage system compensator 3 (see FIG. 2). Further, the power storage system controller PSC includes a display input device such as a touch panel having a display function and an input function (not shown).

[0015] The string system 10 includes a plurality of strings St1 to Stx, a string bus 6, a string system controller SSC, and a plurality of string controllers SC1 to SCx. The string system controller SSC and the string controllers SC1 to SCx will be described later. When it is not necessary to distinguish and describe each of the strings St1 to Stx, the strings St1 to Stx are described as string St. Also, when it is not necessary to distinguish and describe each of the string controllers SC1 to SCx, the string controllers SC1 to SCx are described as string controller SC.

[0016] A plurality of strings St are connected in parallel to a string bus 6. The string bus 6 is connected to an external system (not shown). Each string St includes power converters PCS1 to PCSx, a plurality of modules M1 to Mn, and a plurality of module interfaces M I / F 1 to M I / F n. The module interfaces M I / F 1 to M I / F n will be described later. When it is not necessary to distinguish each of the power converters PCS1 to PCSx for description, the power converters PCS1 to PCSx are referred to as the power converter PCS. Also, when it is not necessary to distinguish each of the modules M1 to Mn for description, the modules M1 to Mn are referred to as the module M. Further, when it is not necessary to distinguish each of the module interfaces M I / F 1 to M I / F n for description, the module interfaces M I / F 1 to M I / F n are referred to as the module interface M I / F for description.

[0017] The module M includes a storage battery composed of a plurality of storage battery cells C connected in series, a bypass mechanism B, and cell monitoring units CMU1 to CMUn. In the string St, a plurality of storage batteries are connected in series, and a bypass mechanism B is provided for each storage battery. Also, the string St includes a current sensor 11 that measures the total current of the string St and a voltage sensor (not shown) that measures the total voltage of the string St (hereinafter referred to as the string total voltage), etc.

[0018] The storage battery cell C is a secondary battery cell such as a lithium-ion battery or a lithium-ion capacitor, and is charged by receiving power from an external system through the power converter PCS, and discharges the charged power to supply power to the external system through the power converters PCS1 to PCSx. Although not particularly limited, the storage battery of the module M in the present embodiment is a recycled used storage battery, and there are differences in the degree of deterioration and differences in the performance of the storage battery cells.

[0019] The bypass mechanism B includes a bypass line BL and switches S1 and S2. The bypass line BL is a power line that bypasses the storage battery. The switch S1 is provided on the bypass line BL. This switch S1 is, for example, a mechanical switch, a semiconductor switch, or a relay. The switch S2 is provided between the positive electrode of the storage battery and one end of the bypass line BL. This switch S2 is, for example, a mechanical switch, a semiconductor switch, or a relay.

[0020] The storage batteries of the starting module M1 and the ending module Mn are connected to an external system via a power converter PCS and a string bus 6. When the switch S1 is turned OFF and the switch S2 is turned ON in all the bypass mechanisms B, all the storage batteries of the string St are connected in series to the external system. On the other hand, when the switch S2 is turned OFF and the switch S1 is turned ON in any one of the bypass mechanisms B, the storage battery corresponding to the bypass mechanism B is bypassed.

[0021] The power converter PCS is a bidirectional converter and is connected to the string bus 6. Also, the positive electrode of the storage battery of the starting module M1 and the negative electrode of the storage battery of the ending module Mn are respectively connected to the power converter PCS.

[0022] During the charging of the string St, the power converter PCS converts the voltage input from the string bus 6 and outputs it to the storage batteries of the plurality of modules M. Here, the voltage on the string St side changes according to the bypass state of the plurality of modules M (the number of modules M in which the storage battery is bypassed) and the charging state of the storage batteries of the plurality of modules M. Therefore, during the charging of the string St, the power converter PCS converts the voltage input from the string bus 6 into the voltage on the string St side and outputs it to the storage batteries of the plurality of modules M.

[0023] The power converter PCS converts the voltage input from the batteries of a plurality of modules M during the discharge of the string St and outputs it to the string bus 6. Here, the input voltage of the power converter PCS during discharge varies according to the bypass states of the plurality of modules M and the charge states of the batteries of the plurality of modules M. As a result, variations occur in the input voltage of the power converter PCS between the strings St during discharge. Therefore, the power converter PCS converts the input voltage into a voltage that matches that of other strings St and outputs it to the string bus 6 during the discharge of the string St. When the current flowing through the string bus 6 is alternating current, the power converter PCS is provided with synchronization means for following the change in the instantaneous value.

[0024] The cell monitoring units CMU1 to CMUn are connected between the positive and negative terminals of each battery cell C, detect the voltage across the terminals of each battery cell C (cell voltage), and transmit a detection signal to the module interface M. I / F Also, the cell monitoring units CMU1 to CMUn have a cell balancing function and equalize the cell voltages of the module M. When it is not necessary to distinguish each of the cell monitoring units CMU1 to CMUn for explanation, the cell monitoring units CMU1 to CMUn are described as the cell monitoring unit CMU.

[0025] The module interface M I / F has a function of controlling the switches S1 and S2 of the bypass mechanism B and a function of communicating with the string controller SC and the power converter PCS. These functions will be described later.

[0026] FIG. 2 is a block diagram showing the control configuration of the power storage system 1 shown in FIG. 1. As shown in this figure, 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, a plurality of string controllers SC, and a plurality of module interfaces M. I / Fand a plurality of cell monitoring units CMU and a plurality of MCUs (Micro Control Unit) 101. The cell monitoring unit CMU is provided for each module M, and the MCU 101 is provided for each power converter PCS.

[0027] The power storage system controller PSC, the string system controller SSC, the string controller SC, and the module interface M I / F are provided for each hierarchy. The power storage system controller PSC corresponds to the hierarchy of the top-level power storage system 1. The string system controller SSC corresponds to the hierarchy of the string system 10 following the hierarchy of the power storage system 1. The string controller SC corresponds to the hierarchy of the string St following the hierarchy of the string system 10. The module interface M I / F corresponds to the hierarchy of the module M following the hierarchy of the string St.

[0028] The power storage system controller PSC communicates with the upper server 7 and the string system controller SSC, and controls and manages the power storage system compensator 3. The upper server 7 is provided in facilities of the aggregator, power receiving facilities such as buildings and factories, etc. This upper server 7 calculates a charge / discharge power instruction value for the entire power storage system 1 (hereinafter, the power storage system charge / discharge power instruction value) according to the state of the power storage system 1 and the power demand on the demand side, and transmits it to the power storage system controller PSC.

[0029] Examples of the power storage system compensator 3 include a temperature sensor that detects the temperature of the installation environment (e.g., a container, etc.) of the power storage system 1, a fire extinguishing facility, etc. (both are not shown). When the detected value of the temperature sensor exceeds the threshold value, the power storage system controller PSC determines that the temperature of the installation environment of the power storage system 1 is abnormal, and transmits an abnormality notification to the display input device. In addition, the power storage system controller PSC monitors the operating state of the fire extinguishing facility.

[0030] The power storage system controller PSC receives information about the state of the string St (hereinafter referred to as string state information) and information about the state of the string system 10 (hereinafter referred to as string system state information) from the string system controller SSC, and transmits them to the upper server 7 and the display input device.

[0031] Examples of the state of the string St include operating states such as charging, discharging, resting, and maintenance, string current, string total voltage, SOC (State of Charge) of the string St (hereinafter referred to as string SOC), SOH (State of Health) of the string St (hereinafter referred to as string SOH), and limit values of the charge and discharge power (or charge and discharge current) of the string St (hereinafter referred to as string charge and discharge power limit values).

[0032] Examples of the state of the string system 10 include the current of the string bus 6 (see FIG. 1) (hereinafter referred to as string bus current), the voltage of the string bus 6 (hereinafter referred to as string bus voltage), SOC of the string system 10 (hereinafter referred to as string system SOC), SOH of the string system 10 (hereinafter referred to as string system SOH), and limit values of the charge and discharge power (or charge and discharge current) of the string system 10 (hereinafter referred to as string system charge and discharge power limit values).

[0033] The power storage system controller PSC estimates the state of the power storage system 1 based on the string state information and the string system state 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, resting, and maintenance, SOC of the power storage system 1 (hereinafter referred to as power storage system SOC), SOH of the power storage system 1 (hereinafter referred to as power storage system SOH), and the like. The power storage system controller PSC outputs information about the estimated state of the power storage system 1 to the display input device as necessary. In this embodiment where the string system 10 is singular, 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.

[0034] The power storage system controller PSC transmits information required for the processing of the upper server 7 to the upper server 7. Examples of the information required for the processing of the upper server 7 include the state of charge (SOC) of the power storage system, the state of health (SOH) of the power storage system, the charge / discharge power limit value of the string system, and the like. Here, based on the "information required for the processing of the upper server 7" received from the power storage system controller PSC, the upper server 7 determines a charge / discharge instruction corresponding to the power storage system 1 and transmits it to the power storage system controller PSC. Examples of this charge / discharge instruction include, in addition to the charge / discharge power instruction value of the power storage system, control quantities such as the constant voltage (CV) mode, the constant current (CC) mode, and the constant power (CP) mode, and operation modes such as independent operation / system connection.

[0035] The power storage system controller PSC transmits various instruction information input by an operator or the like using a display input device to the string system controller SSC. Examples of the various instruction information that can be input using the display input device include information such as an instruction to execute a maintenance / stop mode (hereinafter referred to as a maintenance / stop instruction), an instruction to forcibly execute charge / discharge, and an instruction to forcibly execute state estimation.

[0036] Examples of the maintenance / stop instruction include an instruction to forcibly operate the compensators of the string St such as the power storage system compensator 3, the string system compensator 4, and the power converter PCS. By forcibly operating the power storage system compensator 3, the string system compensator 4, and the compensators of the string St, it becomes possible to confirm the operation of the power storage system compensator 3, the string system compensator 4, and the compensators of the string St.

[0037] Examples of the instruction to forcibly execute charge / discharge include an instruction to specify a predetermined charge / discharge amount and forcibly execute charge / discharge on the power storage system 1. By specifying a predetermined charge / discharge amount and forcibly executing charge / discharge on the power storage system 1, it becomes possible to confirm whether the power storage system 1 can charge / discharge the specified predetermined charge / discharge amount.

[0038] Examples of an instruction to force the execution of state estimation include an instruction to force the power storage system 1 to execute state estimation by designating a predetermined state estimation item. By forcing the power storage system 1 to execute state estimation by designating a predetermined state estimation item, it becomes possible to obtain state estimation items such as the string system SOH and the power storage system SOH at an arbitrary point in time.

[0039] The string system controller SSC communicates with the power storage system controller PSC and a plurality of string controllers SC, and controls and manages the string system compensator 4. Examples of the string system compensator 4 include a temperature sensor that detects the ambient temperature, a cooling device within the string system 10, a cutoff device for the string bus 6, a current sensor that detects the string bus current, a voltage sensor that detects the string bus voltage, etc. (all are not shown in the figure).

[0040] The string system controller SSC receives string state information from a plurality of string controllers SC. Examples of the state of the string St include operating states such as charging, discharging, standby, and maintenance, string current, string total voltage, string SOC, string SOH, string charge / discharge power limit value, the state of the string system compensator 4, etc. Examples of the state of the string system compensator 4 include the string bus current, the string bus voltage, etc.

[0041] The string system controller SSC estimates the state of the string system 10 based on the string state information received from a plurality of string controllers SC. Examples of the state of the string system 10 include the string bus current, the string bus voltage, the string system SOC, the string system SOH, the string system charge / discharge power limit value, etc. Note that the state of the string system 10 may be estimated by the power storage system controller PSC.

[0042] When the detection values of, for example, a temperature sensor, a current sensor, and a voltage sensor, or the estimated values of the state of the string system 10 deviate from the threshold range, the string system controller SSC determines the presence or absence of an abnormality in the string system 10, and stops the operation of the string system 10 or transmits an abnormality notification to the power storage system controller PSC.

[0043] The string system controller SSC transmits, to the power storage system controller PSC, information that is necessary for the processing of the power storage system controller PSC among the information received from a plurality of string controllers SC and the information estimated by itself. Examples of the information necessary for the processing of the power storage system controller PSC include the string system SOC, the string system SOH, and the string system charge / discharge power limit value.

[0044] Here, the power storage system controller PSC determines an instruction corresponding to the string system 10 based on the "information required for the processing of the power storage system controller PSC" received from the string system controller SSC, and transmits the instruction information to the string system controller SSC. Such instructions include charge / discharge instructions for the string system 10 in the charge / discharge mode, instructions for individually controlling each part of the string system 10 in the maintenance mode (hereinafter referred to as individual control instructions), state estimation instructions for the string system 10 in the state estimation mode, and the like. Examples of the charge / discharge instructions for the string system 10 in the charge / discharge mode include, in addition to the string charge / discharge power instruction value assigned to each string St, control amounts in the slope control mode, constant voltage (CV) mode, constant current (CC) mode, and constant power (CP) mode described later, and instructions for the operation mode such as independent operation / grid connection. Note that the charge / discharge instructions for the string system 10 in the charge / discharge mode are transmitted from the power storage system controller PSC to the string controller SC via the string system controller SSC. Examples of the individual control instructions for the string system 10 in the maintenance mode include instructions for individually controlling the power converter PCS, the switches S1 and S2 of the bypass mechanism B, and the string system compensator 4. Examples of the state estimation instructions for the string system 10 in the state estimation mode include execution instructions for predetermined control necessary for performing state estimation of the string St.

[0045] The string system controller SSC receives an instruction corresponding to the above-described string system 10 from the power storage system controller PSC, and determines whether it is necessary to update the operating state of the string system 10 by comparing the currently received instruction with the previously received instruction. If it is necessary to update the operating state of the string system 10, the string system controller SSC determines the operating mode of the string St, the permission for the bypass request from the string controller SC, and the string charge and discharge power instruction value assigned to the string St. Examples of the operating mode of the string St include a charge and discharge mode, a state estimation mode, a maintenance / stop mode, and the like.

[0046] The string controller SC communicates with the string system controller SSC and a plurality of module interfaces M I / F and controls and manages accessories of the string St such as the power converter PCS. Examples of the accessories of the string St include, in addition to the power converter PCS, a current sensor 11 (see FIG. 1) for detecting the string current, a voltage sensor (not shown) for detecting the total string voltage, and a switch (not shown) for connecting / disconnecting the string St.

[0047] The string controller SC receives information about the state of the module M (hereinafter referred to as module state information) from the module interface M I / F . Examples of the module state include the temperature, current, voltage, cell voltage, state of the bypass mechanism B, etc. of the module M.

[0048] The string controller SC estimates the SOC, SOH, charge and discharge power limit value, etc. of the battery of the module M based on the module state information received from the module interface M I / F . Note that the estimation of the SOC, SOH, charge and discharge power limit value, etc. of the battery of the module M may be performed by the module interface M I / F . In this case, the module interface M I / F may simply transmit the estimation result to the string controller SC.

[0049] The string controller SC estimates the state of the string St based on the module state information received from the module interface M I / F The states of the string St include string SOH, string SOC, string charge / discharge power limit value, etc. Note that the estimation of the state of the string St may be performed by the string system controller SSC. In this case, the string controller SC may transmit the module state information and the estimation result of the state of the battery to the string system controller SSC.

[0050] When the cell voltage, the total string current, the estimated value of the state of the string St, etc. are out of the threshold range, the string controller SC determines an abnormality in the string St. In this case, the string controller SC may stop the operation of the string St or transmit an abnormality notification to the string system controller SSC.

[0051] The string controller SC transmits the information received from the module interface M I / F and the information estimated by itself that is required for the processing of the string system controller SSC to the string system controller SSC. The information required for the processing of the string system controller SSC includes the temperature, current, voltage, SOC, SOH, charge / discharge power limit value of the battery of the module M, the cell voltage, the state of the bypass mechanism B, the string SOC, the string SOH, the string charge / discharge power limit value, etc.

[0052] Here, the string system controller SSC determines an instruction for each string St based on the "information required for the processing of the string system controller SSC" received from the string controller SC, and transmits the instruction information to the string controller SC. Examples of such instructions include charge / discharge instructions for the string St in the charge / discharge mode, individual control instructions for the string St in the maintenance mode, state estimation instructions for the string St in the state estimation mode, and the like. Examples of the items of the charge / discharge instruction for the string St in the charge / discharge mode include, in addition to the string charge / discharge power instruction value, the control amounts in the constant voltage mode, constant current mode, and constant power mode, and the operation modes such as independent operation / system connection. Examples of the items of the individual control instruction for the string St in the maintenance mode include instructions for individually controlling the bypass mechanism B. Examples of the items of the state estimation instruction in the state estimation mode include performing charge / discharge at a constant current and recording the voltage of the storage battery at that time.

[0053] The string controller SC receives the above-mentioned instruction information for each string St from the string system controller SSC, and determines whether it is necessary to update the bypass schedule of the string St by comparing the currently received instruction information with the previously received instruction information. The bypass schedule of the string St is a plan regarding the bypass of the storage battery by the bypass mechanism B, and is determined based on a predetermined criterion. The string controller SC determines whether the switching from charge to discharge or from discharge to charge is performed in the string St, and determines that it is necessary to update the bypass schedule when such switching is performed. When it is necessary to update the bypass schedule, the string controller SC I / F determines the bypass schedule of the storage battery based on the storage battery state information received from the module interface M and the estimation result of the state of the storage battery.

[0054] On the other hand, the string controller SC is the module interface M I / FBased on the comparison between the module state information received from and the estimation results of the battery state for this time and the previous time, it is determined whether control of the string charge and discharge power is necessary. When control of the string charge and discharge power is required, the string controller SC transmits a control signal corresponding to the string charge and discharge power instruction value received from the string system controller SSC to the MCU101, which is the control device of the power converter PCS.

[0055] Here, the MCU101 of the power converter PCS and the MCU100 which is the control device provided in the module interface M I / F are connected by dedicated signal lines 102, 103, and 104 (see Fig. 5). When the cell voltage exceeds the upper threshold value, a charge suppression signal (a cell upper voltage warning signal described later) for instructing the suppression of the charging power is transmitted from the MCU100 of the module interface M I / F to the MCU101 of the power converter PCS. Also, when the cell voltage falls below the lower threshold value, a discharge suppression signal (a cell lower voltage warning signal described later) for instructing the suppression of the discharge power is transmitted from the MCU100 of the module interface M I / F to the MCU101 of the power converter PCS.

[0056] The MCU101 of the power converter PCS controls the power converter PCS so that the charge and discharge power of the string St approaches the string charge and discharge power instruction value according to the above control signal. However, when the above charge suppression signal or the above discharge suppression signal is transmitted while the above control signal is being transmitted, the MCU101 of the power converter PCS gives priority to the charge suppression signal or the discharge suppression signal and controls the power converter PCS so that the charge and discharge power of the string St is suppressed. Then, when the transmission of the above charge suppression signal or the above discharge suppression signal stops, the MCU101 of the power converter PCS controls the power converter PCS so that the charge and discharge power of the string St approaches the string charge and discharge power instruction value according to the above control signal.

[0057] When the string controller SC receives a maintenance / stop instruction from the string system controller SSC, it analyzes the received maintenance / stop instruction and determines the type of maintenance to be executed. Examples of this type of maintenance include individual control, self-diagnosis, battery replacement (hereinafter referred to as battery replacement), etc.

[0058] Examples of individual control include controlling the cooling device, etc. within the string St to be individually turned on / off. Examples of self-diagnosis include anomaly determination for anomalies that were difficult to determine during operation in the state estimation mode or charge / discharge mode. Examples of such anomaly determination include performing special control on the power converter PCS, etc. and the switches S1, S2 of the bypass mechanism B, and acquiring the response with various sensors to determine the presence or absence of anomalies. Examples of battery replacement include guiding the battery replacement for the module M in which deterioration has progressed or a failure has occurred, etc. During 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 the string St targeted for battery replacement are executed in the power storage system 1.

[0059] When the string controller SC receives a state estimation instruction from the string system controller SSC, it compares the currently received string charge / discharge power instruction value with the previously received string charge / discharge power instruction value and determines whether there has been a change. When the string controller SC receives a state estimation instruction from the string system controller SSC and there is a change in the string charge / discharge power instruction value between the previous and current times, it controls the switches S1, S2 of the power converter PCS and the bypass mechanism B in a predetermined method so that the state estimation of the string St is possible. Examples of the control method of the power converter PCS, etc. during the execution of the state estimation mode include the method of controlling the power converter PCS with a constant current. Examples of the control method of the switches S1, S2 of the bypass mechanism B during the execution of the state estimation mode include the method of sequentially bypassing the batteries of the modules M that have been fully discharged during discharge.

[0060] The string controller SC records the module status information received from the module interface M I / F In addition, the string controller SC updates, as necessary, the parameters used when performing state estimation based on the module status information received from the module interface M I / F Examples of such parameters include the SOH of the battery of module M, the map of charge and discharge limit values of the battery of module M, the SOC-OCV (Open Circuit Voltage) characteristics, and the like.

[0061] The module interface M I / F communicates with the string controller SC and the cell monitoring unit CMU. The MCU100 controls the switches S1, S2 of the bypass mechanism B, the cell monitoring unit CMU, and the like. The module interface M I / F receives module status information from the cell monitoring unit CMU and the like. Examples of the module status information include the total voltage of the battery of module M, the temperature of module M, the cell voltage, and the like. The cell monitoring unit CMU receives detection signals from various sensors (not shown) such as a module voltage sensor that detects the voltage of the battery of module M, a cell voltage sensor that detects the cell voltage, and a module temperature sensor that detects the temperature of module M. Note that the cell monitoring unit CMU may be configured as a single unit, or may be configured using a battery cell monitoring IC (Integrated Circuit) within the module interface M I / F

[0062] The module interface M I / F receives module status information from the cell monitoring unit CMU, and the MCU100 estimates the state of the battery of module M based on the received information. Examples of the state of the battery of module M to be estimated include the SOC, SOH, charge and discharge power limit values, and the like of the battery of module M. Note that the state of the battery of module M may be estimated by the string controller SC.

[0063] ​Module Interface M I / F determines an abnormality of the module M when, for example, the detected values of a module voltage sensor, a cell voltage sensor, a module temperature sensor, or the estimated value of the state of charge of the battery of the module M is out of a threshold range. And the module interface M I / F either shuts off with the switch S2 of the bypass mechanism B of the module M for which the abnormality determination has been made, or transmits an abnormality notification to the string controller SC. When the cell voltage exceeds the upper threshold value or falls below the lower threshold value, the cell upper voltage warning signal or the cell lower voltage warning signal described later is transmitted from the module interface M I / F to the MCU101 of the power converter PCS.

[0064] Module Interface M I / F transmits to the string controller SC the information received from the cell monitoring unit CMU and the information estimated by itself that is required for the processing of a higher-level controller such as the string controller SC. Examples of the information required for the processing of the string controller SC include the temperature, current, voltage, SOC, SOH, charge / discharge power limit value of the battery of the module M, the cell voltage, and the states of the switches S1 and S2 of the bypass mechanism B.

[0065] Here, based on the "information required for the processing of the string controller SC" received from the module interface M I / F the string controller SC determines an instruction for each module M and transmits the instruction information to the module interface M I / F Examples of this instruction include bypass control of the module M by the switches S1 and S2 of the bypass mechanism B and cutoff control of the battery of the module M by the switch S2 of the bypass mechanism B.

[0066] Module Interface M I / FWhen there is a change in the instruction information received by the MCU100 from the string controller SC between this time and the previous time, it controls the switches S1 and S2 of the bypass mechanism B to execute the above-mentioned bypass control or cutoff control. Also, the module interface M I / F When there is a change in the information received from the cell monitoring unit CMU and the information estimated by itself, it executes exception control that does not depend on the instruction from the upper controller as necessary. Also, the module interface M I / F sends an instruction to the cell monitoring unit CMU to execute cell balancing of the battery of the module M.

[0067] Figures 3 and 4 are graphs for explaining the update of the charge / discharge power instruction value of the energy storage system and the string charge / discharge power instruction value assigned to each string St. As shown in these graphs, the update of the charge / discharge power instruction value of the energy storage system is performed so as to change from the current value to the target value over a predetermined period (the slope control period of the charge / discharge power of the energy storage system in the figure).

[0068] Also, after the update of the charge / discharge power instruction value of the energy storage system, while the charge / discharge power instruction value of the energy storage system is maintained, the string charge / discharge power instruction value of each string St is updated. The update of the string charge / discharge power instruction value of each string St is performed so as to gradually change to the target value over a predetermined period (the slope control period of the string charge / discharge power in the figure). The update of the string charge / discharge power instruction value of each string St after the update of the charge / discharge power instruction value of the energy storage system is performed for the purpose of adjusting the balance of the charge / discharge power between the strings St.

[0069] The graph in Figure 3 shows the relationship between the charge / discharge power instruction value of the energy storage system, the string charge / discharge power instruction value of each string St, and time when controlling to suppress the response speed of the update of the charge / discharge power instruction value of the energy storage system (hereinafter, standard slope control) is executed. The standard slope control is executed for the purpose of suppressing a sudden change in the charge / discharge power of the energy storage system when the charge / discharge power instruction value of the energy storage system is updated.

[0070] The graph in Fig. 4 shows the relationship between the charge / discharge power instruction value of the power storage system, the string charge / discharge power instruction value of each string St, and time during the execution of control (hereinafter referred to as the shortest slope control) for increasing the response speed of the update of the charge / discharge power instruction value of the power storage system. The shortest slope control is executed for the purpose of high-speed response when updating the charge / discharge power instruction value of the power storage system.

[0071] As shown in the graph of Fig. 3, when the standard slope control is executed, the charge / discharge power instruction value of the power storage system changes from the current value to the target value over a long slope control period (for example, 1.3 to 30 s) compared to when the shortest slope control is executed. During this slope control period, the update of the string charge power instruction value of each string St is performed so as to gradually change from the current value to the target value.

[0072] Here, the charge / discharge power instruction value of the power storage system is the sum of the string charge / discharge power instruction values of each string St. Therefore, the string system controller SSC determines the string charge / discharge power instruction value of each string St so that the string charge / discharge power instruction value of each string St gradually changes from the current value to the target value, and the sum of the string charge / discharge power instruction values of each string St gradually changes from the current value to the target value of the charge / discharge power instruction value of the power storage system.

[0073] The string system controller SSC determines the target value of the individual string charge / discharge power instruction value for each string St before the start of the slope control period of the charge / discharge power of the power storage system. Also, the string system controller SSC individually calculates the change amount ΔP1 of the string charge / discharge power instruction value for each string St at a predetermined period (for example, a period of several seconds). The change amount ΔP1 is a value obtained by equally dividing the difference between the current value and the target value of the string charge / discharge power instruction value of 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 predetermined period.

[0074] During the slope control period of the charge / discharge power of the energy storage system, the string system controller SSC calculates the string charge / discharge power instruction value for each string St at each of the above-mentioned predetermined cycles, and transmits it to each string controller SC by unicast communication. This string charge / discharge power instruction value is a value obtained by adding the above change amount ΔP1 to the assumed current value (hereinafter referred to as the assumed current value).

[0075] After the string system controller SSC transmits the string charge / discharge power instruction value to all the string controllers SC, it transmits a flag (hereinafter referred to as the PCS control update flag) for updating the control of the power converter PCS to all the string controllers SC by broadcast communication.

[0076] When the standard slope control is executed, when the charge / discharge power instruction value of the energy storage system converges to the target value, the string charge / discharge power instruction value of each string St also converges to the target value. In the subsequent slope control period of the string charge / discharge power, for the purpose of balancing the string charge / discharge power of each string St, the string charge / discharge power instruction value of each string St gradually changes.

[0077] When the charge / discharge power instruction value of the energy storage system converges to the target value, the string system controller SSC determines the target value of the string charge / discharge power instruction value of each string St for the purpose of balancing the charge / discharge power of each string St. Also, at the same time, the string system controller SSC individually calculates the change amount ΔP2 of the string charge / discharge power instruction value for each string St at each predetermined cycle (for example, a cycle of several seconds). The calculation method of the change amount ΔP2 is the same as that of the above change amount ΔP1.

[0078] During the slope control period of the string charge / discharge power, the string system controller SSC transmits the string charge / discharge power instruction value of each string St to each string controller SC by unicast communication at each of the above-mentioned predetermined cycles. This string charge / discharge power instruction value is a value obtained by adding the above change amount ΔP2 to the assumed current value.

[0079] After the string system controller SSC unicasts the string charge / discharge power instruction value to all string controllers SC, it broadcasts the PCS control update flag to all string controllers SC.

[0080] As shown in the graph of FIG. 4, when the shortest slope control is executed, the charge / discharge power instruction value of the energy storage system changes from the current value to the target value over a shorter slope control period (for example, 200 ms to 2 s) compared to when the standard slope control is executed. During this slope control period, the update of the string charge power instruction value of each string St is performed so as to change from the current value to the intermediate target value in one cycle.

[0081] Also, after the update of the charge / discharge power instruction value of the energy storage system, while the charge / discharge power instruction value of the energy storage system is maintained, the string charge / discharge power instruction value of each string St is updated. The update of the string charge / discharge power instruction value of each string St is performed so as to gradually change from the intermediate target value to the final target value over the slope control period of the string charge / discharge power.

[0082] Here, the charge / discharge power instruction value of the energy storage system is the sum of the string charge / discharge power instruction values of each string St. Therefore, the string system controller SSC determines the string charge / discharge power instruction value of each string St so that the string charge / discharge power instruction value of each string St changes from the current value to the intermediate target value in one cycle, and the sum of the string charge / discharge power instruction values of each string St changes from the current value to the target value of the charge / discharge power instruction value of the energy storage system in one cycle.

[0083] Before the start of the slope control period of the power charge and discharge of the energy storage system, the string system controller SSC uniformly determines the intermediate target value of the string charge and discharge power instruction values of all strings St to be the same value. During the slope control period of the power charge and discharge of the energy storage system, the string system controller SSC transmits the intermediate target value of the string charge and discharge power instruction value to all string controllers SC through broadcast communication. After that, the string system controller SSC transmits the PCS control update flag to all string controllers SC through broadcast communication. Note that the transmission of the PCS control update flag by the string system controller SSC to all string controllers SC through broadcast communication is not essential.

[0084] The string controller SC controls the power converter PCS according to the received intermediate target value of the string charge and discharge power instruction value, and updates the charge and discharge power. Here, for the string St whose intermediate target value of the string charge and discharge power instruction value exceeds the charge and discharge power upper limit value, the corresponding string controller SC restricts the charge and discharge power to be less than the intermediate target value and not more than the charge and discharge power upper limit value. In this case, the total value of the charge and discharge power of each string St becomes less than the target value of the power charge and discharge of the energy storage system. Therefore, in this case, the string system controller SSC corrects the target value of the power charge and discharge instruction value of the battery system in advance considering the charge and discharge power upper limit value received from the string controller SC.

[0085] When the shortest slope control is executed, when the power charge and discharge instruction value of the energy storage system converges to the target value, the string charge and discharge power instruction values of all strings St converge to the intermediate target value. Since there is a deviation between this intermediate target value and the final target value, after the power charge and discharge instruction value of the energy storage system converges to the target value, the slope control of the string charge and discharge power is executed. During the slope control period of the string charge and discharge power, for the purpose of adjusting the balance of the string charge and discharge power of each string St, the string charge and discharge power instruction value of each string St gradually changes from the intermediate target value to the final target value.

[0086] When the charge / discharge power instruction value of the energy storage system converges to the target value, the string system controller SSC determines the final target value of the charge / discharge power instruction value of each string St for the purpose of balancing the charge / discharge power of each string St. At the same time, the string system controller SSC individually calculates the change amount ΔP3 of the string charge / discharge power instruction value for each string St every predetermined period (for example, a period of several seconds). The change amount ΔP3 is a value obtained by equally dividing the difference between the intermediate target value and the final target value of the string charge / discharge power instruction value of each string St, and is determined by the resolution.

[0087] During the slope control period of the string charge / discharge power, the string system controller SSC transmits the string charge / discharge power instruction value of each string St to all string controllers SC by unicast communication every predetermined period. This string charge / discharge power instruction value is a value obtained by adding the change amount ΔP3 to the assumed current value.

[0088] After transmitting the string charge / discharge power instruction value to all string controllers SC by unicast communication, the string system controller SSC transmits the PCS control update flag to all string controllers SC by broadcast communication.

[0089] FIG. 5 is a circuit diagram showing a communication circuit for performing communication between the string controller SC, the power converter PCS, and the module interface M shown in FIGS. 1 and 2. As shown in this figure, the MCU100 of the module interface M is connected to the string controller SC via the signal line 105 and is connected to the MCU101 of the power converter PCS via the dedicated signal lines 103 and 104. Also, the MCU100 of the module interface M is connected to GND (ground) via the signal line 102. I / F As shown in this figure, the MCU100 of the module interface M is connected to the string controller SC via the signal line 105 and is connected to the MCU101 of the power converter PCS via the dedicated signal lines 103 and 104. I / F Also, the MCU100 of the module interface M is connected to GND (ground) via the signal line 102. I / F Also, the MCU100 of the module interface M is connected to GND (ground) via the signal line 102.

[0090] Module interface M I / FIt includes a first photocoupler PC1 and a second photocoupler PC2. The light-emitting diode of the first photocoupler PC1 is connected to MCU100 and GND. Also, the phototransistor of the first photocoupler PC1 is connected to MCU101 of the power converter PCS via signal line 103 and is connected to GND via signal line 102. Further, the light-emitting diode of the second photocoupler PC2 is connected to MCU100 and GND, and the phototransistor of the second photocoupler PC2 is connected to MCU101 of the power converter PCS via signal line 104 and is connected to GND via signal line 102.

[0091] Module interface M I / F When the cell voltage transmitted from the cell monitoring unit CMU exceeds the upper threshold value, the MCU100 of the module interface M transmits a cell upper voltage warning signal to the light-emitting diode of the first photocoupler PC1. Also, the MCU100 of the module interface M I / F When the cell voltage transmitted from the cell monitoring unit CMU is lower than the lower threshold value, the MCU100 of the module interface M transmits a cell lower voltage warning signal to the light-emitting diode of the second photocoupler PC2.

[0092] When a cell upper voltage warning signal is transmitted from MCU100, the first photocoupler PC1 causes the light-emitting diode to emit light and conducts the phototransistor. In contrast, when no cell upper voltage warning signal is transmitted from MCU100, the first photocoupler PC1 insulates the input-side MCU100 and the output-side MCU101.

[0093] When a cell lower voltage warning signal is transmitted from MCU100, the second photocoupler PC2 causes the light-emitting diode to emit light and conducts the phototransistor. In contrast, when no cell lower voltage warning signal is transmitted from MCU100, the second photocoupler PC2 insulates the input-side MCU100 and the output-side MCU101.

[0094] The signal line 103 is connected to the power supply Vcc via a resistor R1 which is a pull-up resistor. The resistor R1 is connected between the connection point of the first photocoupler PC1 on the signal line 103 and the connection point of the MCU101. Also, the cell upper limit voltage warning signal is an H-level signal. Therefore, while the cell upper limit voltage warning signal is not being transmitted, the input potential from the signal line 103 of the MCU101 becomes the potential of the power supply Vcc, and while the cell upper limit voltage warning signal is being transmitted, the input potential from the signal line 103 of the MCU101 becomes 0 (L-level). The MCU101 detects the cell upper limit voltage warning signal when the input potential from the signal line 103 drops from the potential of the power supply Vcc to 0, and controls the power converter PCS so that the charging power of the string St is suppressed.

[0095] Similarly, the signal line 104 is connected to the power supply Vcc via a resistor R2 which is a pull-up resistor. The resistor R2 is connected between the connection point of the second photocoupler PC2 on the signal line 104 and the connection point of the MCU101. Also, the cell lower limit voltage warning signal is an H-level signal. Therefore, while the cell lower limit voltage warning signal is not being transmitted, the input potential from the signal line 104 of the MCU101 becomes the potential of the power supply Vcc, and while the cell lower limit voltage warning signal is being transmitted, the input potential from the signal line 104 of the MCU101 becomes 0. The MCU101 detects the cell lower limit voltage warning signal when the input potential from the signal line 104 drops from the potential of the power supply Vcc to 0, and controls the power converter PCS so that the discharging power of the string St is suppressed.

[0096] Note that the cell upper voltage warning signal and the cell lower voltage warning signal do not have to be H-level signals, and may be L-level signals. In that case, while the cell upper voltage warning signal or the cell lower voltage warning signal is not being transmitted, the input potential from the signal line 103 or the signal line 104 of the MCU 101 becomes 0 (L-level), and while the cell upper voltage warning signal or the cell lower voltage warning signal is being transmitted, the input potential from the signal line 103 or the signal line 104 of the MCU 101 becomes the potential of the power supply Vcc. Then, when the input potential rises from 0 to the potential of the power supply Vcc, the MCU 101 detects the cell upper voltage warning signal or the cell lower voltage warning signal, and controls the power converter PCS so that the charging power or the discharging power of the string St is suppressed.

[0097] FIG. 6 is a chart for explaining a communication method of a battery control device according to a comparative example. The battery control device according to this comparative example includes a power storage system controller PSC, a string system controller SSC, a string controller SC, a power converter PCS, a module interface M, I / F and a cell monitoring unit CMU, similar to the battery control device 2 according to the above-described embodiment. However, the battery control device according to the comparative example is different from the battery control device 2 according to the above-described embodiment in that it does not transmit the cell upper voltage warning signal and the cell lower voltage warning signal from the MCU 100 of the module interface M I / F to the MCU 101 of the power converter PCS.

[0098] In the battery control device according to the comparative example, during the execution of the standard slope control and the shortest slope control, the string charge / discharge power instruction value of each string St is transmitted from the string system controller SSC to the string controller SC (charge / discharge power instruction), and a control signal corresponding to the string charge / discharge power instruction value of each string St is transmitted from the string controller SC to the power converter PCS.

[0099] On the other hand, during the execution of the standard slope control and the shortest slope control, the cell voltage information is transmitted from the cell monitoring unit CMU to the module interface MI / F is transmitted, and the voltage of the storage battery of module M is calculated by module interface M I / F . The calculated voltage of the storage battery of module M is transmitted from module interface M I / F to string controller SC, and string controller SC determines whether the voltage is within the upper and lower limit values (judgment of exceeding upper and lower limit voltages). When it is determined that the voltage exceeds the upper limit value, a signal for instructing suppression of charging power is transmitted from string controller SC to power converter PCS. When it is determined that the voltage is lower than the lower limit value, a signal for instructing suppression of discharging power is transmitted from string controller SC to power converter PCS (suppression of charge and discharge power).

[0100] Here, in the standard slope control, the string charge and discharge power instruction value gradually changes in a plurality of cycles (for example, 20 times) from the current value to the target value, and the power converter PCS may complete the control in an arbitrary period (for example, 100 ms) from the charge and discharge power instruction. Therefore, when the standard slope control is executed, the change amount per unit time of the charge and discharge power of string St is small. As a result, there is a margin in the time from when the cell voltage exceeds the upper limit threshold to when it rises to the cell upper limit voltage (the maximum allowable cell voltage), and in the time from when the cell voltage falls below the lower limit threshold to when it drops to the cell lower limit voltage (the minimum allowable cell voltage). Therefore, it is possible to keep the cell voltage between the upper and lower limit values by the periodic processing between the cell monitoring unit CMU and the string controller SC as shown in FIG. 6.

[0101] On the other hand, in the shortest slope control, the string charge / discharge power instruction value changes from the current value to the target value in one cycle process, and the power converter PCS needs to complete the control in a short period (for example, 60 ms). Therefore, when the shortest slope control is executed, the change amount of the charge / discharge power of the string St per unit time is large. As a result, there is no margin in the time from when the cell voltage exceeds the upper threshold value until it rises to the cell upper limit voltage (cell maximum allowable voltage), and the time from when the cell voltage falls below the lower threshold value until it drops to the cell lower limit voltage (cell minimum allowable voltage). Therefore, it is difficult to keep the cell voltage between the upper limit value and the lower limit value by the cycle process between the cell monitoring unit CMU and the string controller SC as shown in FIG. 6.

[0102] Therefore, in the battery control device 2 according to the present embodiment, the module interface M I / F transmits the cell upper limit voltage warning signal and the cell lower limit voltage warning signal from the MCU100 of the module interface M to the MCU101 of the power converter PCS. Thereby, the time from the transmission of the cell voltage information of the cell monitoring unit CMU to the response of the charge / discharge power suppression control of the power converter PCS is shortened.

[0103] FIG. 7 is a chart for explaining the communication method of the battery control device 2 shown in FIGS. 1 and 2. In the battery control device 2 according to the present embodiment, similar to the above comparative example, when the standard slope control and the shortest slope control are executed, the string charge / discharge power instruction value is transmitted from the string system controller SSC to the string controller SC (charge / discharge power instruction), and a control signal corresponding to the string charge / discharge power instruction value is transmitted from the string controller SC to the power converter PCS. When the standard slope control is executed, the control is completed in an arbitrary period (for example, 100 ms) from the charge / discharge power instruction. On the other hand, when the shortest slope control is executed, the power converter PCS completes the control in a short period (for example, 60 ms) from the charge / discharge power instruction.

[0104] On the other hand, when the standard slope control and the shortest slope control are executed, the cell voltage information is transmitted from the cell monitoring unit CMU to the module interface MI / F is transmitted to the module interface M I / F where a determination is made as to whether the cell voltage is within the upper and lower threshold values (upper and lower voltage excess determination). When the cell voltage exceeds the upper threshold value, a cell upper voltage warning signal and a GND signal are transmitted from the module interface M I / F to the power converter PCS. Also, when the cell voltage is below the lower threshold value, a cell lower voltage warning signal and a GND signal are transmitted from the module interface M I / F to the power converter PCS.

[0105] Thereby, compared with the above comparative example, the time from the transmission of the cell voltage information of the cell monitoring unit CMU to the response of the charge / discharge power suppression control of the power converter PCS can be shortened. Therefore, it is possible to keep the cell voltage between the upper limit value and the lower limit value not only when the standard slope control is executed but also when the shortest slope control is executed.

[0106] FIG. 8 is a graph showing the transition of the charge / discharge power instruction value and the actual charge / discharge power, and a timing chart showing the ON / OFF timing of the cell upper voltage warning signal and the cell lower voltage warning signal. As shown in the graph of FIG. 8, the actual charge / discharge power of each string St changes with a delay in the change of the string charge / discharge power instruction value of each string St. During charging, the actual charging power of each string St changes so as to approach the charging power instruction value, and during discharging, the discharging power of each string St changes so as to approach the discharging power instruction value. The charging power instruction value is set to a value lower than the charge / discharge upper limit power of each string St, and the discharging power instruction value is set to a value higher than the charge / discharge lower limit power of each string St.

[0107] During charging of the string St, when the cell voltage of the module M in the string St exceeds the upper threshold value, the module interface M I / FA cell upper voltage warning signal is sent from [the module interface M]. Here, the upper threshold value of the cell voltage is set to a value lower than the upper limit value of the cell voltage (hereinafter referred to as the cell upper voltage). Therefore, when the cell voltage approaches the cell upper voltage, before the cell voltage exceeds the cell upper voltage, the module interface M I / F sends a cell upper voltage warning signal.

[0108] While the cell upper voltage warning signal is being detected by the MCU101, the charging power of the string St is decreased by the power converter PCS. Then, when the cell upper voltage warning signal is no longer detected by the MCU101, the charging power of the string St is increased by the power converter PCS so as to approach the charging power instruction value.

[0109] During discharging of the string St, when the cell voltage of the module M in the string St drops below the lower threshold value, the module interface M I / F sends a cell lower voltage warning signal. Here, the lower threshold value of the cell voltage is set to a value higher than the lower limit value of the cell voltage (hereinafter referred to as the cell lower voltage). Therefore, when the cell voltage approaches the cell lower voltage, before the cell voltage drops below the cell lower voltage, the module interface M I / F sends a cell lower voltage warning signal.

[0110] While the cell lower voltage warning signal is being detected by the MCU101, the discharging power of the string St is decreased by the power converter PCS. Then, when the cell lower voltage warning signal is no longer detected by the MCU101, the discharging power of the string St is increased by the power converter PCS so as to approach the discharging power instruction value.

[0111] FIG. 9 is a flowchart for explaining the charging control of the battery control device 2 shown in FIGS. 1 and 2. As shown in this flowchart, when the charging control of the power storage system 1 is started, the MCU101 of the power converter PCS determines whether or not it has received a cell upper voltage warning signal (step S11). In this step, the MCU101 determines whether or not the input potential from the signal line 103 is 0 (L level).

[0112] When the MCU 101 does not receive the cell upper limit voltage warning signal (NO in step S11), it controls the power converter PCS so that the charging power of the string St approaches the charging power indication value (charging power control in step S12). On the contrary, when the MCU 101 receives the cell upper limit voltage warning signal (YES in step S11), it controls the power converter PCS so that the charging power of the string St is suppressed (charging power suppression in step S13).

[0113] By repeating the above steps S11 to S13, the charging power of the string St increases so as to approach the charging power indication value, and the charging power of the string St decreases to keep the cell voltage below the cell upper limit voltage, and this is repeated.

[0114] FIG. 10 is a flowchart for explaining the discharge control of the battery control device 2 shown in FIGS. 1 and 2. As shown in this flowchart, when the discharge control of the power storage system 1 is started, the MCU 101 of the power converter PCS determines whether or not it has received the cell lower limit voltage warning signal (step S101). In this step, the MCU 101 determines whether or not the input potential from the signal line 104 is 0 (L level).

[0115] When the MCU 101 does not receive the cell lower limit voltage warning signal (NO in step S101), it controls the power converter PCS so that the discharge power of the string St approaches the discharge power indication value (discharge power control in step S102). On the contrary, when the MCU 101 receives the cell lower limit voltage warning signal (YES in step S101), it controls the power converter PCS so that the discharge power of the string St is suppressed (discharge power suppression in step S103).

[0116] By repeating the above steps S101 to S103, the discharge power of the string St increases so as to approach the discharge power indication value, and the discharge power of the string St decreases to keep the cell voltage higher than the cell lower limit voltage, and this is repeated.

[0117] As described above, in the battery control device 2 according to the present embodiment, the MCU100 of the module interface M I / F receives the cell voltage detection signal from the cell monitoring unit CMU, and when the cell voltage is equal to or higher than the upper threshold value, transmits a charge suppression signal for suppressing the charging power of the string St to the MCU101 of the power converter PCS. The MCU101 receives the control signal corresponding to the charging power instruction value from the string controller SC, and while not receiving the charge suppression signal from the MCU100 of the module interface M I / F , controls the power converter PCS so that the charging power of the string St approaches the charging power instruction value. On the other hand, the MCU101 receives the above control signal from the string controller SC, and while receiving the charge suppression signal from the MCU100 of the module interface M I / F , controls the power converter PCS so that the charging power of the string St is suppressed.

[0118] Thereby, the communication delay from the transmission of the cell voltage information by the cell monitoring unit CMU to the response of the charge power suppression control by the power converter PCS can be suppressed. Therefore, in the power storage system 1 in which there are variations in the performance of the battery cells C in the string St, the charging of the string St can be controlled while maintaining the cell voltage below the upper limit value.

[0119] Also, in the battery control device 2 according to the present embodiment, the MCU100 of the module interface M I / F receives the cell voltage detection signal from the cell monitoring unit CMU, and when the cell voltage is equal to or higher than the lower threshold value, transmits a discharge suppression signal for suppressing the discharge power of the string St to the MCU101 of the power converter PCS. The MCU101 receives the control signal corresponding to the discharge power instruction value from the string controller SC, and while not receiving the discharge suppression signal from the MCU100 of the module interface M I / FWhile not receiving the discharge suppression signal from the MCU100, the power converter PCS is controlled so that the discharge power of the string St approaches the discharge power indication value. On the other hand, the MCU101 receives the control signal from the string controller SC and, moreover, the module interface M I / F While receiving the discharge suppression signal from the MCU100 of I / F , the power converter PCS is controlled so that the discharge power of the string St is suppressed.

[0120] Thereby, the communication delay from the transmission of the cell voltage information by the cell monitoring unit CMU to the response of the discharge power suppression control by the power converter PCS can be suppressed. Therefore, in the power storage system 1 in which the performance of the battery cells C in the string St varies, the discharge of the string St can be controlled while maintaining the cell voltage higher than the lower limit value.

[0121] Further, the battery control device 2 according to the present embodiment includes a first photocoupler PC1 provided on a signal line 103 connecting the MCU100 of the module interface M I / F and the MCU101 of the power converter PCS, and a resistor R1 as a pull-up resistor connected between the first photocoupler PC1 and the MCU101 in the signal line 103. Thereby, after electrically insulating the MCU100 and the MCU101, a cell upper limit voltage warning signal can be transmitted from the MCU100 to the first photocoupler PC1.

[0122] Further, the battery control device 2 according to the present embodiment includes a second photocoupler PC2 provided on a signal line 104 connecting the MCU100 of the module interface M I / F and the MCU101 of the power converter PCS, and a resistor R2 as a pull-up resistor connected between the second photocoupler PC2 and the MCU101 in the signal line 103. Thereby, after electrically insulating the MCU100 and the MCU101, a cell lower limit voltage warning signal can be transmitted from the MCU100 to the second photocoupler PC2.

[0123] The present invention has been described based on the above-described embodiments. However, the present invention is not limited to the above-described embodiments, and modifications may be made without departing from the spirit of the present invention, or known and well-known technologies may be appropriately combined.

[0124] For example, in the above-described embodiment, the first photocoupler PC1 and the second photocoupler PC2 insulate the MCU100 of the module interface M I / F from the MCU101 of the power converter PCS, but this is not essential. Also, although the cell upper limit voltage warning signal and the cell lower limit voltage warning signal are transmitted using different photocouplers (the first photocoupler PC1 and the second photocoupler PC2) and different signal lines 103, 104, the present invention is not limited to this, and they may be transmitted using one photocoupler and one signal line. In this case, the MCU101 will receive the cell upper and lower limit voltage warning signals. However, since the MCU101 knows whether it is controlling charging or discharging, it can perform charge and discharge power suppression control.

[0125] Also, in the above-described embodiment, the string system controller SSC transmits the string charge and discharge power instruction value to the string controller SC. However, the power storage system controller PSC and the string system controller SSC may be integrated, and the integrated controller may transmit the string charge and discharge power instruction value to the string controller SC. Also, any one of the plurality of string controllers SC may be a master controller, and the others may be slave controllers, and the master controller may transmit the string charge and discharge power instruction value to the slave controllers.

Explanation of Reference Numerals

[0126] 1: Power storage system 2: Battery control device 100: MCU (module control unit) 101: MCU (power converter control unit) 103: Signal line 104: Signal line C: Battery cell CMU: Cell monitoring unit (cell voltage detection unit) CMU1: Cell monitoring unit (cell voltage detection unit) CMU2: Cell monitoring unit (cell voltage detection unit) CMUn: Cell monitoring unit (cell voltage detection unit) M: Module (battery module) M1: Module (battery module) M2: Module (battery module) Mn: Module (battery module) PC1: First photocoupler (photocoupler) PC2: Second photocoupler (photocoupler) PCS: Power converter PCS1: Power converter PCS2: Power converter PCSx: Power converter R1: Resistor (pull-up resistor) R2: Resistor (pull-up resistor) SC: String controller (string control unit) SC1: String controller (string control unit) SC2: String controller (string control unit) SCx: String controller (string control unit) SSC: String system controller (upper control unit) St: String St1: String St2: String Stx: String

Claims

1. A battery control device for controlling a power storage system including a string including a plurality of serially connected battery modules and a power converter that converts charge and discharge power of the string, wherein the battery module includes a plurality of serially connected battery cells and a cell voltage detection unit that detects a voltage of the battery cell, a plurality of module control units respectively provided corresponding to the battery modules and controlling the battery modules, a power converter control unit that controls the power converter, a string control unit provided corresponding to the string, communicating with the plurality of module control units, the power converter control unit, and a host control unit, and transmitting a control signal for controlling the power converter so that the charging power of the string approaches a charging power instruction value received from the host control unit is provided, the module control unit receives a detection signal of the voltage of the battery cell from the cell voltage detection unit, and when the voltage of the battery cell is equal to or higher than an upper threshold value, transmits a charge suppression signal for suppressing the charging power of the string to the power converter control unit, the power converter control unit receives the control signal from the string control unit and controls the power converter so that the charging power of the string approaches the charging power instruction value while not receiving the charge suppression signal from the module control unit, and controls the power converter so as to suppress the charging power of the string while receiving the control signal from the string control unit and receiving the charge suppression signal from the module control unit Battery control device.

2. A battery control device for controlling a power storage system including a string including a plurality of serially connected battery modules and a power converter that converts charge and discharge power of the string, wherein the battery module includes a plurality of serially connected battery cells and a cell voltage detection unit that detects a voltage of the battery cell, a plurality of module control units respectively provided corresponding to the battery modules and controlling the battery modules, a power converter control unit that controls the power converter, A string control unit that is provided corresponding to the string, communicates with the plurality of module control units, the power converter control unit, and the upper control unit, and transmits a control signal for controlling the power converter to the power converter control unit so that the discharge power of the string approaches the discharge power instruction value received from the upper control unit comprising The module control unit receives a detection signal of the voltage of the battery cell from the cell voltage detection unit, and when the voltage of the battery cell is equal to or lower than a lower threshold value, transmits a discharge suppression signal for suppressing the discharge power of the string to the power converter control unit. The power converter control unit controls the power converter to bring the discharge power of the string close to the discharge power instruction value while receiving the control signal from the string control unit and not receiving the discharge suppression signal from the module control unit, and controls the power converter to suppress the discharge power of the string while receiving the control signal from the string control unit and receiving the discharge suppression signal from the module control unit Battery control device.

3. A photocoupler provided on a signal line connecting the module control unit and the power converter control unit, A pull-up resistor connected between the photocoupler and the power converter control unit in the signal line The battery control device according to claim 1 or 2, comprising.

4. A power storage system comprising a string including a plurality of battery modules connected in series and a power converter that converts the charge and discharge power of the string, wherein the battery module includes a plurality of battery cells connected in series and a cell voltage detection unit that detects the voltage of the battery cell. A power storage system comprising the battery control device according to claim 1 or 2.

Images