JP2018160960A - Power storage device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power storage device for preventing overcurrent caused by a reflux current which flows to battery modules connected in parallel, from flowing to the battery modules connected in parallel.SOLUTION: Control parts 3 and 5 of a power storage device 1 comprising battery modules 2 that are connected in parallel acquire a first reflux current value indicating a reflux current to flow to any other battery module 2 than a battery module 2 which is recovered normal from abnormality after charge/discharge stop, assume that a connection part SW1 of the battery module 2 recovered normal is brought into a conducted state after the charge/discharge stop, estimate a second reflux current value indicating a reflux current that flows to the battery module 2 recovered normal and the other battery module 2, estimate a first estimate current value by adding the first and second reflux current values, keep a cutoff state of the connection part SW1 of the battery module 2 recovered normal from the abnormality in a case where any first estimate current value is equal to a threshold or more, and bring the connection part SW1 of the battery module 2 recovered normal into the conducted state in a case where each of the first estimate current values is smaller than the threshold.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a power storage device having battery modules connected in parallel.

A technique for controlling so that an overcurrent does not flow through battery modules connected in parallel is known.
As related techniques, for example, there are Patent Document 1, Patent Document 2, and Patent Document 3.

JP 2009-212020 A JP 2014-103822 A JP2016-119839A

However, after charging / discharging, the voltage difference between the batteries included in the battery module and the battery in a no-load state in which the battery module connected in parallel and the load are not connected or no current flows from the battery module to the load. A reflux current is generated in the battery module due to the internal resistance of the battery module. Therefore, in the following cases (1) and (2), there is a possibility that an overcurrent caused by the return current flows in the battery modules connected in parallel.
(1) When the battery module disconnected from the parallel connection returns to normal due to the occurrence of an abnormality, and the battery module that has returned to normal from the abnormality is connected in parallel again while the return current is flowing through the battery module. (2) Start charging When the power supply from the charging device to the battery module is started while the reflux current is flowing through the battery modules connected in parallel before, the object according to one aspect of the present invention is to flow through the battery modules connected in parallel. An object of the present invention is to provide a power storage device that prevents an overcurrent caused by a reflux current from flowing to battery modules connected in parallel.

  A power storage device according to one aspect of the present invention includes a battery module connected in parallel, a connection part connected in series to the battery of the battery module, and a connection part of the battery module in which an abnormality occurs when an abnormality occurs And a control unit that brings the connection unit into a conductive state when the normal state is restored from the abnormality.

  The control unit has a first reflux current value indicating a reflux current that flows to other battery modules other than the battery module that has returned to normal from the abnormality when the connection part of the battery module that has returned to normal from the abnormality is in a cut-off state after charging and discharging are stopped. To get.

  In addition, the control unit assumes that the connection portion of the battery module that has returned to normal from the abnormality is in a conductive state after stopping charging and discharging, and indicates the return current that flows between the battery module that has returned to normal from the abnormality and another battery module. The second reflux current value is estimated.

  Subsequently, the control unit adds the first return current value and the second return current value to obtain a first estimated current value indicating a current flowing through the battery module that has returned to normal from the abnormality and the other battery module. presume.

  Then, if any of the first estimated current values is equal to or greater than a threshold value for determining whether or not it is an overcurrent, the control unit leaves the connection part of the battery module that has returned to normal from the abnormality in a disconnected state. When each of the estimated current values is smaller than the threshold value, the connection part of the battery module that has returned to normal from the abnormality is brought into a conductive state.

  In addition, the control unit sets a third current indicating a reflux current that flows between the battery module that has returned to normal from the abnormality and another battery module after the connection of the battery module that has returned to normal from the abnormality is in a conductive state before the start of charging. To obtain the reflux current value.

Moreover, a control part calculates | requires the charging current value which shows the charging current which flows into the battery module and other battery modules which returned normally from abnormality at the time of charge before charge start.
Subsequently, the control unit adds the third reflux current value and the charging current value, and estimates a second estimated current value indicating a current flowing through the battery module that has returned to normal from the abnormality during charging and another battery module. To do.

The control unit does not start charging when any of the second estimated current values is equal to or greater than the threshold value, and starts charging when each of the second estimated current values is smaller than the threshold value.
A power storage device according to another embodiment of the present invention includes battery modules connected in parallel and a control unit that controls the battery modules.

The control unit acquires a return current value indicating a return current flowing through the battery modules connected in parallel before starting charging.
In addition, before starting charging, the control unit obtains a charging current value indicating a charging current flowing through the battery modules connected in parallel, adds the reflux current value and the charging current value, and adds them to the battery modules connected in parallel at the time of charging. An estimated current value indicating a flowing current is estimated.

  Subsequently, the control unit does not start charging when any of the estimated current values is equal to or greater than a threshold value for determining whether or not the current is an overcurrent, and starts charging when each of the estimated current values is smaller than the threshold value. To do.

The power storage device has a connection portion connected in series to the battery of the battery module.
When an abnormality occurs, the control unit puts the connection part of the battery module in which the abnormality has occurred into a cut-off state, and brings the connection part into a conductive state when the abnormality is restored from the abnormality.

  In addition, the control unit obtains a reflux current value indicating a reflux current flowing through the battery modules connected in parallel before the charging is started and the connection portion of the battery module that has returned to normal from the abnormality is brought into a conductive state.

Moreover, a control part calculates | requires the charging current value which shows the charging current which flows into the battery module connected in parallel before charge start.
Subsequently, the control unit adds the reflux current value and the charging current value, and estimates an estimated current value indicating a current flowing through the battery modules connected in parallel during charging.

  Then, the control unit does not start charging when any of the estimated current values is equal to or greater than a threshold value for determining whether or not the current is an overcurrent, and starts charging when each of the estimated current values is smaller than the threshold value. .

  It is possible to prevent an overcurrent caused by the reflux current flowing through the battery modules connected in parallel from flowing into the battery modules connected in parallel.

It is a figure which shows one Example of an electrical storage apparatus. It is a figure for demonstrating the case of (1). It is a figure for demonstrating the case of (2-2). It is a figure which shows one Example of operation | movement of an electrical storage apparatus.

Hereinafter, embodiments will be described in detail with reference to the drawings.
FIG. 1 is a diagram illustrating an example of a power storage device 1. The power storage device 1 includes a battery module 2 (battery B1, fuse F1, switch SW1 (connection unit), monitoring circuit 3 (control unit), ammeter 4), control circuit 5 (control unit), switch SW2, and connector 6. . For example, the power storage device 1 may be a battery pack mounted on a vehicle (for example, PHV: Plug-in Hybrid Vehicle, EV: Electric Vehicle, electric forklift, etc.).

  The battery module 2 indicates the battery module 2a, the battery module 2b, the battery module 2c, the battery module 2d, and the battery module 2e shown in FIG. 1, and the battery modules 2a, 2b, 2c, 2d, and 2e are connected in parallel to each other. The battery module 2a includes a battery B1a, a switch SW1a, a fuse F1a, a monitoring circuit 3a, and an ammeter 4a shown in FIG. The battery module 2b includes a battery B1b, a switch SW1b, a fuse F1b, a monitoring circuit 3b, and an ammeter 4b. The battery module 2c includes a battery B1c (not shown), a switch SW1c, a fuse F1c, a monitoring circuit 3c, and an ammeter 4c. The battery module 2d includes a battery B1d (not shown), a switch SW1d, a fuse F1d, a monitoring circuit 3d, and an ammeter 4d. The battery module 2e includes a battery B1e, a switch SW1e, a fuse F1e, a monitoring circuit 3e, and an ammeter 4e. Note that the battery module 2 is not limited to five.

  Further, the battery module 2 may be provided with a thermometer for measuring the temperature of the battery B1 and the ambient temperature. In this case, the monitoring circuit 3 and the thermometer are connected so that the monitoring circuit 3 can receive a signal or information indicating the temperature transmitted from the thermometer.

  Further, the battery module 2 monitors the state (for example, voltage value, current value, charging rate, temperature, etc.) of the battery B1, and transmits state information indicating the state of the monitored battery module 2 to the control circuit 5. Further, the battery module 2 controls each part of the battery module 2 based on the state of each part of the battery module 2 or control information for controlling each part of the battery module 2 transmitted from the control circuit 5.

  The battery B1 indicates the batteries B1a, B1b, B1c (not shown), B1d (not shown), and B1e shown in FIG. The battery B1 is a secondary battery provided in a battery pack or the like, for example, a secondary battery such as a nickel metal hydride battery or a lithium ion battery, or a storage element. The battery B1 may be an assembled battery in which one or a plurality of batteries are connected.

  The switch SW1 indicates the switches SW1a, SW1b, SW1c (not shown), SW1d (not shown), and SW1e shown in FIG. The switch SW1 is connected in series with the battery B1. The switch SW1 is in a conductive state when the battery module 2 is normal, and is in a cutoff state when the battery module 2 is abnormal. For example, the switch SW1 may be a relay or a semiconductor element.

  Here, the battery module 2 is abnormal, for example, the battery B1 is in an overcharged state or an overdischarged state, an overcurrent stopped state in which an overcurrent has flown into the battery B1, and the temperature of the battery B1 has increased. A high temperature state, a communication abnormal state in which the monitoring circuit 3 and the control circuit 5 cannot communicate, a state in which the switch SW1 or the fuse F1, the monitoring circuit 3 or the ammeter 4 cannot be used, or a state in which the wiring is disconnected can be considered.

  The fuse F1 indicates the fuses F1a, F1b, F1c (not shown), F1d (not shown), and F1e shown in FIG. The fuse F1 is connected in series with the battery B1. The fuse F1 is blown when an overcurrent flows through the battery B1.

  The monitoring circuit 3 includes monitoring circuits 3a, 3b, 3c (not shown), 3d (not shown), and 3e. The monitoring circuit 3 may be, for example, a circuit configured using a CPU (Central Processing Unit), a multi-core CPU, and a programmable device (FPGA (Field Programmable Gate Array), PLD (Programmable Logic Device), etc.). The monitoring circuit 3 includes a storage unit inside or outside, and reads and executes a program that controls each unit of the battery module 2 stored in the storage unit.

  The monitoring circuit 3 includes a circuit that controls each part of the battery module 2, a circuit that communicates with the control circuit 5, and a circuit (voltmeter) that measures the voltage of the battery B1. The voltmeter may be provided outside the monitoring circuit 3.

  The monitoring circuit 3 is, for example, a signal or information indicating the voltage of the battery B1 measured by a voltmeter included in the monitoring circuit 3 or a voltmeter provided outside the monitoring circuit 3, and a current value flowing through the battery B1 measured by the ammeter 4. Signal or information indicating the temperature of the battery B1 measured by a thermometer (not shown) or the ambient temperature is acquired, and the above-described state information of the battery module 2 is generated based on the acquired signal or information. The generated state information is transmitted to the control circuit 5 via the communication line. The monitoring circuit 3 receives the control information transmitted from the control circuit 5 via the communication line, and controls conduction and interruption of the switch SW1.

  When the abnormality occurs in the battery module 2, the monitoring circuit 3 turns off the switch SW1 of the battery module 2 in which the abnormality has occurred, and turns on the switch SW1 when the battery module 2 returns to normal from the abnormality.

  The ammeter 4 includes ammeters 4a, 4b, 4c (not shown), 4d (not shown), and 4e shown in FIG. The ammeter 4 measures the current flowing through the battery B1. The ammeter 4 may be, for example, a shunt resistor or a Hall element.

  For example, the control circuit 5 may be a circuit configured using a CPU, a multi-core CPU, a programmable device, or a PLD. The control circuit 5 includes a storage unit inside or outside, and reads and executes a program for controlling each unit of the power storage device 1 stored in the storage unit.

  The control circuit 5 performs communication with the monitoring circuit 3 and controls the battery module 2 and the switch SW2. In addition, the control circuit 5 communicates with the monitoring circuit 3, and when an abnormality occurs in the battery module 2, the switch SW1 of the battery module 2 in which the abnormality has occurred is turned off, and the battery module 2 has returned to normal from the abnormality. In some cases, the switch SW1 may be controlled to be in a conductive state.

  When the connector 6 and the charging connector 7 connected to the charging device CHG are connected and the control circuit 5 supplies power from the charging device CHG to the power storage device 1 (when charging the battery B1), the control circuit 5 The battery module 2 is controlled to be charged by communicating with the charging device CHG via the battery. When power storage device 1 is mounted on the vehicle, control circuit 5 communicates with an ECU (Electronic Control Unit) mounted on the vehicle, and based on communication with ECU, each part of power storage device 1 You may control.

  In addition, the control circuit 5 is connected to the connector 6 and the discharge connector 8 connected to the load LD, and supplies power to the load LD from the power storage device 1 (when discharging from the battery B1). The battery module 2 is controlled to be discharged by communicating with the load LD via.

  When charging, connector 6 is connected to charging connector 7 connected to charging device CHG via a power line, and supplies power from charging device CHG to battery B1 of power storage device 1. Further, when discharging, the connector 6 is connected to a charging connector 8 connected to the load LD via a power line, and supplies power from the power storage device 1 to the load LD to the battery B1.

  Switch SW2 is controlled by control circuit 5, power storage device 1 and charging device CHG are connected (connector 6 and charging connector 7 are connected), and before power supply from power storage device CHG to power storage device 1 is started ( The battery is in a conductive state before charging is started, and is cut off after power supply from the charging device CHG to the power storage device 1 is completed (after charging is completed). Switch SW2 is controlled by control circuit 5 to connect power storage device 1 and load LD (connector 6 and discharge connector 8 are connected) before power supply from power storage device 1 to load LD is started. It enters a conductive state (before the start of discharge) and enters a cut-off state after power supply from the power storage device 1 to the load LD is finished (after the discharge is finished). For example, the switch SW2 may be a relay or a semiconductor element. Further, the connector 6 may be provided separately for the charging device CHG and the load LD.

A circuit configuration of the power storage device 1 will be described.
The terminal PI of the monitoring circuit 3a of the battery module 2a is connected to the output terminal of the ammeter 4a. The terminals PV1, PV2, PV3... PVn of the monitoring circuit 3a are connected to the positive terminal or the negative terminal of each battery constituting the battery B1a. The terminal cnt of the monitoring circuit 3a is connected to the terminal Pa of the control circuit 5. The positive terminal (+) of the battery B1a is connected to one terminal of the ammeter 4a, and the negative terminal (−) of the battery B1a is connected to one terminal of the switch SW1a. The other terminal of the switch SW1a is connected to one terminal of the fuse F1a.

  The terminal PI of the monitoring circuit 3b of the battery module 2b is connected to the output terminal of the ammeter 4b. The terminals PV1, PV2, PV3... PVn of the monitoring circuit 3b are connected to the positive terminal or the negative terminal of each battery constituting the battery B1b. The terminal cnt of the monitoring circuit 3b is connected to the terminal Pb of the control circuit 5. The positive terminal (+) of the battery B1b is connected to one terminal of the ammeter 4b, and the negative terminal (−) of the battery B1b is connected to one terminal of the switch SW1b. The other terminal of the switch SW1b is connected to one terminal of the fuse F1b.

  The terminal PI of the monitoring circuit 3e of the battery module 2e is connected to the output terminal of the ammeter 4e. The terminals PV1, PV2, PV3... PVn of the monitoring circuit 3e are connected to the positive terminal or the negative terminal of each battery constituting the battery B1e. The terminal cnt of the monitoring circuit 3e is connected to the terminal Pe of the control circuit 5. The positive terminal (+) of the battery B1e is connected to one terminal of the ammeter 4e, and the negative terminal (−) of the battery B1e is connected to one terminal of the switch SW1e. The other terminal of the switch SW1e is connected to one terminal of the fuse F1e.

The circuit configuration (not shown) of the battery modules 2c, 2d is the same circuit configuration as the battery modules 2a, 2b, 2e.
The other terminal of the ammeter 4a, the other terminal of the ammeter 4b, the other terminal of the ammeter 4c not shown, the other terminal of the ammeter 4d not shown, and the other terminal of the ammeter 4e Connected to the terminal 6P1, the terminal 6P2 of the connector 6 is connected to one terminal of the switch SW2. The other terminal of the switch SW2 is connected to the other terminal of the fuse F1a, the other terminal of the fuse F1b, the other terminal of the fuse F1c (not shown), the other terminal of the fuse F1d (not shown), and the other terminal of the fuse F1e. Is done.

  The terminal Ps2 of the control circuit 5 is connected to the control terminal of the switch SW2, the terminal Pchg of the control circuit 5 is connected to the terminal 6P3 of the connector 6, and the terminal Pecu of the control circuit 5 is used for communication and control with the ECU. Connected to terminal cnt.

  When charging, the terminal 6P1 of the connector 6 is connected to one terminal 7P1 of the connector 7 connected to the positive terminal (+) of the charging device CHG via the power line, and the terminal 6P2 of the connector 6 is connected to the power line via the power line. , Connected to the other terminal 7P2 of the connector 7 connected to the negative terminal (−) of the charging device CHG, and the terminal 6P3 of the connector 6 is connected to a terminal cnt used for communication / control of the charging device CHG via a communication line. Connected to the terminal 7P3 of the connector 7 to be connected. When discharging, the terminal 6P1 of the connector 6 is connected to one terminal 8P1 of the connector 8 connected to the positive terminal (+) of the load LD via the power line, and the terminal 6P2 of the connector 6 is connected to the positive terminal (+) of the load LD, Connected to the other terminal 8P2 of the discharge connector 8 connected to the negative terminal (−) of the load LD, the terminal 6P3 of the connector 6 is connected to a terminal cnt used for communication / control of the load LD via a communication line. It is connected to the terminal 8P3 of the connector 8.

  The position where the ammeter 4 is provided is not limited to that in FIG. 1 and may be provided on the negative electrode terminal side of the battery B1. Further, the positions where the switches SW1, SW2 and the fuse F1 are provided are not limited to those in FIG. 1, and may be provided on the positive terminal side of the battery B1.

The control unit will be described.
As the control unit, for example, a circuit configuration using the monitoring circuit 3 or the control circuit 5 or the monitoring circuit 3 and the control circuit 5 can be considered. The controller prevents the overcurrent caused by the return current from flowing through the battery modules 2 connected in parallel.

  When the battery module 2 is in a no-load state in which the battery module 2 connected in parallel and the load LD are not connected after charging / discharging, or the current does not flow from the battery module to the load. It is generated in the battery module 2 due to the voltage difference between the batteries B1 and the internal resistance of the battery B1. Therefore, (1) When the battery module 2 disconnected from the parallel connection due to the occurrence of abnormality returns to normal, and the battery module 2 that has returned to normal from the abnormality is connected in parallel while the return current flows through the battery module 2 (2) When the supply of power from the charging device CHG to the battery module 2 is started while the return current is flowing through the battery module 2, an overcurrent caused by the return current is connected to the battery modules 2 connected in parallel. May flow.

  There are two cases of (2). (2-1) When all of the battery modules 2 are normal or there is no battery module 2 that returns to normal from the abnormality, while the return current flows through the battery module 2, the charging device CHG transfers to the battery module 2. When power supply is started, and (2-2) the battery module 2 that has returned to normal is connected again in parallel, and power is supplied from the charging device CHG to the battery module 2 while the reflux current is flowing through the battery module 2. This is the case.

The case of (1) will be described.
A case where the power storage device 1 is mounted on a vehicle will be described. Since an abnormality has occurred in one or more battery modules 2, it is assumed that the switch SW1 of the battery module 2 in which an abnormality has occurred is cut off and the battery module 2 in which the abnormality has occurred is disconnected from the parallel connection. Under such an assumption, when the vehicle stops traveling, the control unit turns off the switch SW2 and enters a no-load state in which the battery module 2 and the load LD are not connected. Then, a reflux current is generated between the batteries B1 of the battery modules 2 (other battery modules) that are not disconnected. Then, when the battery module 2 that has returned to normal from the abnormality is connected in parallel again while the return current is flowing through the battery module 2, the battery module 2 that has returned to normal from the abnormality and the other battery modules 2 other than that return to normal There is a possibility that a new reflux current will be generated between them, and an overcurrent caused by the new reflux current may flow through the battery modules 2 connected in parallel. Therefore, the control unit controls the battery modules 2 connected in parallel so that no overcurrent caused by the return current flows.

  FIG. 2 is a diagram for explaining the case (1). 2A shows the voltage or charging rate of the batteries B1a, B1b, B1c, B1d, and B1e when the switches SW1a, SW1b, and SW1c are in a conductive state and the switches SW1d and SW1e are in a disconnected state. (B) shows the reflux current that flows through the battery module 2 when the switches SW1a, SW1b, and SW1c are in the conductive state and the switches SW1d and SW1e are in the cut-off state. In FIG. This shows that a current flows into the battery module 2.

  When the switches SW1d and SW1e of the battery modules 2d and 2e that have returned to normal after the charge / discharge stop and the switches SW1d and SW1e are in the cut-off state, the control unit recirculates current values I2 (I2a, I2b, I2c: first reflux current value) is acquired.

  For example, as shown in FIG. 2 (A), the voltage value of the battery B1 of the battery module 2 (dot range in FIG. 2 (A)) has a relationship of voltage V2d = voltage V2e> voltage V2b> voltage V2c> voltage V2a. In this case, due to the voltage difference between the batteries B1a, B1b, B1c and the internal resistance of the batteries B1a, B1b, B1c, as shown in the shaded range of FIG. A reflux current of I2b and I2c flows. That is, before the battery modules 2d and 2e that have returned to normal from the abnormality are connected in parallel again, a reflux current flows from the battery module 2b to the battery modules 2a and 2c, and a reflux current flows from the battery module 2c to the battery module 2a. In this case, the relationship between the reflux current value (the shaded range in FIG. 2B) is: current value I2a (charging direction)> current value I2c (discharging direction is larger than the charging current, so that the discharging direction)> current Value I2b (discharge direction). Note that the current values I2d and I2e do not flow through the battery modules 2d and 2e.

  In addition, the control unit assumes that the switches SW1d and SW1e of the battery modules 2d and 2e that have returned to normal after the charge / discharge stop are in a conductive state, and the battery modules 2d and 2e that have returned to normal from the error and other battery modules. A reflux current value I2 ′ (I2a ′, I2b ′, I2c ′, I2d ′, I2e ′: second reflux current value) indicating the reflux current flowing through 2a, 2b, and 2c is estimated.

  FIG. 2C shows the reflux current estimated to flow to the battery B1 when the switches SW1a, SW1b, and SW1c are in a conductive state and the switches SW1d and SW1e are in a conductive state due to normal recovery.

  For example, as shown in FIG. 2A, when the voltage value of the battery B1 of the battery module 2 satisfies the relationship of voltage V2d = voltage V2e> voltage V2b> voltage V2c> voltage V2a, the voltage difference between the batteries B1 and Due to the internal resistance of the battery B1, a reflux current flows through the battery module 2 as shown in FIG. That is, assuming that the battery modules 2d and 2e that have returned to normal from the abnormality are connected in parallel again, it is estimated that a reflux current flows from the battery modules 2d and 2e to the battery modules 2a, 2b, and 2c. It should be noted that the relationship between the return current value (the thick frame range in FIG. 2C) is: current value I2a ′ (charge direction) = current value I2d ′ (discharge direction) = I2e ′ (discharge direction)> current value I2b ′ ( (Charging direction) = current value I2c ′ (charging direction) is estimated.

  Here, the second return current value I2 ′ is obtained using the open circuit voltage of the battery B1 of the battery module 2 and the internal resistance. Note that the open circuit voltage of the battery B1 in which the switch SW1 connected in series is conductive is estimated from the closed circuit voltage.

  Subsequently, the control unit adds the return current value I2 and the return current value I2 ′ to estimate the current flowing through the battery modules 2d and 2e and the other battery modules 2a, 2b, and 2c that have returned to normal from the abnormality. Current values I2 + I2 ′ (I2a + I2a ′, I2b + I2b ′, I2c + I2c ′, I2d (= 0) + I2d ′, I2e (= 0) + I2e ′: first estimated current value) are estimated.

  Subsequently, the control unit cuts off the switches SW1d and SW1e of the battery modules 2d and 2e that have returned to normal from the abnormality when any of the estimated current values I2 + I2 ′ is equal to or greater than a threshold value Vth for determining whether or not the current is an overcurrent. Leave the state.

  As the threshold value Vth, for example, a value smaller than a current value at which the fuse F1 is blown and a value smaller than a current value at which the battery B1 is considered to deteriorate may be used. The threshold value Vth is stored in the storage unit.

  Further, when each of the estimated current values I2 + I2 ′ is smaller than the threshold value Vth, the control unit turns on the switches SW1d and SW1e of the battery modules 2d and 2e that have returned to normal from the abnormality.

  In FIG. 2D, since the estimated current value I2a + I2a ′ is equal to or greater than the threshold value Vth, it is considered that an overcurrent flows through the battery module 2a. Therefore, the control unit switches the switch SW1 of the battery modules 2d and 2e that have returned to normal from the abnormality. Is left shut off.

  However, the voltage difference between the battery modules 2a, 2b, and 2c decreases with the passage of time, and the reflux current values I2a, I2b, and I2c decrease, so the estimated current value I2 + I2 ′ also decreases. Therefore, waiting for each of the estimated current values I2 + I2 ′ to become smaller than the threshold value Vth, the switches SW1d and SW1e of the battery modules 2d and 2e that have returned to normal from the abnormality are turned on.

  As described above, until the estimated current value I2 + I2 ′ becomes smaller than the threshold value Vth, the battery modules 2 that have returned to normal from the abnormality are not connected in parallel again. Therefore, the overcurrent caused by the reflux current flowing in the battery modules 2 connected in parallel is The flow to the module 2 can be prevented.

  Moreover, since it is possible to prevent an overcurrent caused by the reflux current flowing through the battery modules 2 connected in parallel from flowing into the battery module 2, it is possible to prevent the deterioration of the battery B1 and the fusing of the fuse F1 due to the overcurrent caused by the reflux current. .

The case (2) will be described separately for the cases (2-1) and (2-2).
(2-1) When all the battery modules 2 are normal or there is no battery module 2 that returns to normal from the abnormality, the charging device CHG and the power storage device 1 Is connected to the battery module 2 and the battery module 2 is connected in parallel with the current obtained by adding the charging current to the reflux current flowing in the battery module 2 connected in parallel. When flowing to the module 2, there is a possibility that an overcurrent caused by the reflux current and the charging current flows to the battery modules 2 connected in parallel. Therefore, the control unit controls the battery modules 2 connected in parallel so that no overcurrent caused by the return current flows.

  In the case of (2-1), the control unit acquires a return current value indicating a return current flowing through the battery modules 2 connected in parallel before starting charging. Moreover, a control part calculates | requires the charging current value which shows the charging current which flows into the battery module 2 connected in parallel before charge start. Subsequently, the control unit adds the reflux current value and the charging current value, and estimates an estimated current value indicating the current flowing through the battery modules 2 connected in parallel during charging. Then, the control unit does not start charging when any of the estimated current values is equal to or greater than a threshold value for determining whether or not the current is an overcurrent, and starts charging when each of the estimated current values is smaller than the threshold value. .

  (2-2) The case where the battery modules 2 that have returned to normal from the abnormality are connected in parallel again and power supply from the charging device CHG to the battery module 2 is started while the return current flows through the battery module 2 will be described. .

  FIG. 3 is a diagram for explaining the case (2-2). FIG. 3A shows that when any of the battery modules 2a, 2b, 2c, 2d, and 2e returns to normal from the abnormality and the switches SW1a, SW1b, SW1c, SW1d, and SW1e are in a conductive state, they are connected in parallel. The reflux current flowing through the battery module 2 is shown. In the following description, the battery modules 2d and 2e will be described as the battery module 2 that has returned to normal from the abnormality.

  The control unit turns on the switch SW1 of the battery module 2 that has returned to normal from the abnormality before the start of charging, and then returns a reflux current value I2 ″ indicating the reflux current flowing through the battery modules 2a, 2b, 2c, 2d, and 2e. (I2a ″, I2b ″, I2c ″, I2d ″, I2e ″: third reflux current value) is acquired.

  FIG. 3 (A) shows a case where the reflux current flows before the charging starts and after the connection part SW1 of the battery module 2 that has returned to normal from the abnormality is turned on and then flows into the battery modules 2 connected in parallel. The relationship between the values (the shaded range in FIG. 3A) is: current value I2a ″ (charge direction)> current value I2c ′ (charge direction)> I2e ′ (discharge direction)> current value I2b ′ (discharge direction)> A case where the current value is I2d ′ (discharge direction) is shown.

  Subsequently, the control unit obtains a charging current value Ichg indicating a charging current flowing from the charging device CHG to the battery module 2 during charging before starting charging. For example, the control unit obtains the charging current value Ichg based on the current command value transmitted to the charging device CHG.

  Subsequently, the control unit adds the return current value I2 ″ and the charging current value Ichg, and estimates the currents flowing in the battery modules 2d and 2e and the other battery modules 2a, 2b, and 2c that have returned to normal from the abnormality during charging. Current value I2 ″ + Ichg (I2a ″ + Ichg, I2b ″ + Ichg, I2c ″ + Ichg, I2d ″ + Ichg, I2e ″ + Ichg: second estimated current value) is estimated.

  Subsequently, when any of the estimated current values I2 ″ + Ichg is equal to or greater than the threshold value Vth, the control unit does not start charging the battery module 2 from the charging device CHG, and each of the current values I2 ″ + Ichg is less than the threshold value Vth. If it is smaller, charging from the charging device CHG to the battery module 2 is started.

In FIG. 3B, since the estimated current value I2a ″ + Ichg is equal to or greater than the threshold value Vth, it is considered that an overcurrent flows through the battery module 2a, and therefore the control unit does not start charging.
However, the voltage difference between the battery modules 2 decreases with the passage of time, and the return current value I2 ″ decreases, so the estimated current value I2 ″ + Ichg also decreases. Therefore, the control unit waits for each estimated current value I2 ″ + Ichg to become smaller than the threshold value Vth, and the control unit starts charging.

  As described above, charging is not started until the estimated current value I2 ″ + Ichg becomes smaller than the threshold value Vth, so that the recirculation current flowing in the battery modules 2 connected in parallel and the overcurrent caused by the charging current flow in the battery module 2. Can be prevented.

  Further, since it is possible to prevent the overcurrent caused by the reflux current and the charge current flowing through the battery modules 2 connected in parallel from flowing into the battery module 2, the deterioration of the battery B1 and the fuse due to the overcurrent caused by the reflux current and the charge current are prevented. F1 can be prevented from fusing.

The operation of the power storage device 1 will be described.
FIG. 4 is a diagram illustrating an example of the operation of the power storage device.
In FIG. 4, the cases (1) and (2) will be described together. In step S1, the control unit determines whether or not charging / discharging is stopped, and when charging / discharging is stopped (Yes), the process proceeds to step S2 and charging / discharging is not stopped (No). In step S1, a charge / discharge stop is awaited.

  In step S <b> 2, the control unit obtains a first return current value indicating a return current flowing through the other battery module 2 when the switch SW <b> 1 of the battery module 2 that has returned to normal from the abnormality is in an interrupted state.

  In step S <b> 3, the control unit assumes that the switch SW <b> 1 of the battery module 2 that has returned to normal from the abnormality is in a conductive state after stopping charging and discharging, and estimates a second return current value indicating the return current flowing through the battery module 2. To do. Here, the second return current value is obtained by using the open circuit voltage of the battery B1 of the battery module 2 and the internal resistance. Further, when the switch SW1 is in a conductive state, the open circuit voltage is estimated from the closed circuit voltage. The closed circuit voltage may be estimated from the charging rate or the current integrated value.

Note that the order of step S2 and step S3 may be reversed.
In step S <b> 4, the control unit adds the first return current value and the second return current value to estimate a first estimated current value indicating the current flowing through the battery module 2.

  In step S5, the control unit determines whether or not each of the first estimated current values is smaller than a threshold value Vth for determining whether or not each of the first estimated current values is an overcurrent, and when each of the first estimated current values is small (Yes). The process proceeds to step S6. In step S5, if any of the first estimated current values is greater than or equal to the threshold value Vth (No), the control unit proceeds to step S2, and each of the first estimated current values becomes smaller than the threshold value Vth. Wait for.

In step S <b> 6, when each of the first estimated current values is smaller than the threshold value Vth, the control unit sets the switch SW <b> 1 of the battery module 2 that has returned to normal from the abnormality to a conductive state.
Thus, according to step S1 to step S6, until the first estimated current value becomes smaller than the threshold value Vth, the battery modules 2 that have returned to normal from the abnormality are not connected in parallel again, and therefore flow to the battery modules 2 connected in parallel. It is possible to prevent an overcurrent caused by the reflux current from flowing to the battery module 2.

  Moreover, since it is possible to prevent an overcurrent caused by the reflux current flowing through the battery modules 2 connected in parallel from flowing into the battery module 2, it is possible to prevent the deterioration of the battery B1 and the fusing of the fuse F1 due to the overcurrent caused by the reflux current. .

  In step S7, the control unit turns on the switch SW1 of the battery module 2 that has returned to normal from the abnormality before the start of charging, and then returns to the battery module 2 and other battery modules 2 that have returned to normal from the abnormality. A third reflux current value indicating is obtained. In other words, the control unit acquires a reflux current value indicating a reflux current flowing through the battery modules 2 connected in parallel before starting charging.

  In step S <b> 8, the control unit obtains a charging current value indicating a charging current flowing through the battery module 2 that has returned to normal from the abnormality during charging and the other battery modules 2 before starting charging. For example, the control unit obtains a charging current value Ichg based on a current command value transmitted to the charging device CHG. In other words, the control unit obtains a charging current value indicating a charging current flowing through the battery modules 2 connected in parallel.

Note that the order of step S7 and step S8 may be reversed.
In step S9, the control unit adds the third return current value and the charging current value, and the second estimated current indicating the current flowing in each of the battery module 2 that has returned to normal from the abnormality during charging and the other battery modules 2 Estimate the value. In other words, the control unit adds the reflux current value and the charging current value, and estimates an estimated current value indicating the current flowing through the battery modules 2 connected in parallel during charging.

  In step S10, the control unit determines whether each of the second estimated current values is smaller than a threshold value Vth for determining whether each of the second estimated current values is an overcurrent, and when each of the second estimated current values is small (Yes). To step S11. In step S10, if any of the second estimated current values is greater than or equal to the threshold value Vth (No), the control unit proceeds to step S7 and determines that each of the second estimated current values is smaller than the threshold value Vth. wait.

In step S11, the control unit starts charging when each of the second estimated current values is smaller than the threshold value.
Thus, according to step S7 to step S11, since charging is not started until the second estimated current value becomes smaller than the threshold value Vth, the third reflux current and the charging current flowing through the battery modules 2 connected in parallel are set. The resulting overcurrent can be prevented from flowing into the battery module 2.

  Further, since it is possible to prevent the overcurrent caused by the reflux current and the charge current flowing through the battery modules 2 connected in parallel from flowing into the battery module 2, the deterioration of the battery B1 and the fuse due to the overcurrent caused by the reflux current and the charge current are prevented. F1 can be prevented from fusing.

  The present invention is not limited to the above-described embodiment, and various improvements and modifications can be made without departing from the gist of the present invention.

1 Power storage device 2, 2a, 2b, 2c, 2d, 2e Battery module 3, 3a, 3b, 3c, 3d, 3e Monitoring circuit 4, 4a, 4b, 4c, 4d, 4e Ammeter 5 Control circuit 6 Connector 7 Charging connector 8 Discharge Connector B1, B1a, B1b, B1c, B1d, B1e Battery CHG Charger F1, F1a, F1b, F1c, F1d, F1e Fuse LD Load SW1, SW1a, SW1b, SW1c, SW1d, SW1e Switch SW2 Switch

Claims (4)

Battery modules connected in parallel;
A connection part connected in series to the battery of the battery module;
A control unit that, when an abnormality occurs, sets the connection part of the battery module in which an abnormality has occurred to a cut-off state, and sets the connection part to a conductive state when the abnormality is restored from the abnormality,
The controller is
A first reflux current value indicating a reflux current that flows through the other battery modules other than the battery module that has returned to normal from the abnormality when the connection portion of the battery module that has returned to normal after the charge / discharge stop is in a disconnected state Get
Assuming that the connection part of the battery module that has returned to normal after an abnormality has been made conductive after stopping charging and discharging, a second current indicating a return current that flows between the battery module that has returned to normal from the abnormality and the other battery module Estimate the reflux current value,
Adding the first return current value and the second return current value, estimating a first estimated current value indicating a current flowing through the battery module and the other battery module that has returned to normal from an abnormality,
If any of the first estimated current value is equal to or higher than a threshold for determining whether or not it is an overcurrent, the connection part of the battery module that has returned to normal from the abnormality is left in a disconnected state,
When each of the first estimated current values is smaller than the threshold value, the connection portion of the battery module that has returned to normal from an abnormality is brought into a conductive state.
A power storage device. The power storage device according to claim 1,
The controller is
A third recirculation that indicates a recirculation current that flows between the battery module that has returned to normal from the abnormality and the other battery module after the connection portion of the battery module that has returned to normal from the abnormality is in a conductive state before the start of charging. Get the current value
Before starting charging, obtain a charging current value indicating a charging current flowing through the battery module and other battery modules that have returned to normal from an abnormality during charging,
Adding the third reflux current value and the charging current value, estimating a second estimated current value indicating a current flowing through the battery module and other battery modules that have returned to normal from an abnormality during charging;
If any of the second estimated current value is greater than or equal to the threshold, charging is not started,
When each of the second estimated current values is smaller than the threshold value, charging is started.
A power storage device. Battery modules connected in parallel;
A power storage device having a control unit for controlling the battery module,
The controller is
Before starting charging, obtain a reflux current value indicating the reflux current flowing in the battery modules connected in parallel,
Before starting charging, obtain a charging current value indicating the charging current flowing through the battery modules connected in parallel,
Adding the reflux current value and the charging current value, estimating an estimated current value indicating a current flowing through the battery modules connected in parallel during charging;
If any of the estimated current values is greater than or equal to a threshold for determining whether or not an overcurrent, charging is not started,
When each of the estimated current values is smaller than the threshold value, charging is started.
A power storage device. The power storage device according to claim 3,
Having a connection part connected in series with the battery of the battery module;
The controller is
When an abnormality occurs, the connection part of the battery module in which an abnormality has occurred is cut off, and when the abnormality is restored from the abnormality, the connection part is turned on.
Before the start of charging and after the connection part of the battery module that has returned to normal from the abnormality is made conductive, the return current value indicating the return current flowing through the battery modules connected in parallel is obtained,
Before the start of charging, obtain the charging current value indicating the charging current flowing through the battery modules connected in parallel,
Adding the reflux current value and the charging current value, estimating the estimated current value indicating the current flowing through the battery modules connected in parallel during charging,
If any of the estimated current values is equal to or greater than the threshold for determining whether or not an overcurrent, charging is not started,
When each of the estimated current values is smaller than the threshold value, charging is started.
A power storage device.

Images