JP6583034B2 - Power storage device and battery module control method - Google Patents

Description

  The present invention relates to a power storage device and a battery module control method.

  The plurality of battery cells included in the battery module are restrained by a restraining member. For example, the following method is used to determine whether or not the restraint load applied to the battery module due to restraint of the restraint member exceeds the restraint load limit when the battery cell expands due to deterioration. That is, assuming that each battery cell included in the battery module deteriorates on average, the restraint load of the battery module depends on whether or not the deterioration state of the battery cell that has progressed most exceeds the deterioration threshold. It is determined whether the limit is exceeded.

  In addition, the technique of patent documents 1-3 is known as a related technique.

JP 2002-027681 A JP 2012-234629 A JP 2003-045387 A

  However, in the above-described determination method, if there is variation in the deterioration state of each battery cell, it may be determined that the restraint load of the battery module does not actually exceed the restraint load limit but exceeds it. There is. As a result, use of the battery module may be stopped unnecessarily.

  An object according to one aspect of the present invention is to use a battery module by accurately determining whether or not the restraint load of the battery module exceeds the restraint load limit even if the deterioration states of the plurality of battery cells vary. It is providing the electrical storage apparatus which controls appropriately.

A power storage device according to one aspect of the present invention includes a plurality of battery cells, a storage unit, an acquisition unit, a calculation unit, a determination unit, and a restriction unit.
The storage unit stores a cell deterioration state / cell expansion amount correspondence map. The acquisition unit acquires the deterioration states of the plurality of battery cells. The calculation unit acquires cell expansion amounts corresponding to the deterioration states of the plurality of battery cells from the cell deterioration state / cell expansion amount correspondence map, and calculates the plurality of batteries from the sum of the acquired cell expansion amounts. The module expansion amount of the battery module composed of cells is calculated.

  The determination unit determines whether or not the module expansion amount exceeds a module expansion threshold. The restriction unit restricts currents input to and output from the plurality of battery cells when the module expansion amount exceeds the module expansion threshold.

  According to the power storage device according to the embodiment, even if there is variation in the deterioration state of the plurality of battery cells included in the battery module, it is accurately determined whether or not the restraint load of the battery module exceeds the restraint load limit. By doing so, it is possible to appropriately control the use of the battery module.

It is a figure which shows the structural example of the electrical storage apparatus according to embodiment. It is the schematic of the structural example of the battery module contained in the electrical storage apparatus according to embodiment. It is a flowchart of the 1st example of the control method of the battery module according to embodiment. It is a flowchart of the 2nd example of the control method of the battery module according to embodiment.

Hereinafter, embodiments will be described in detail with reference to the drawings.
FIG. 1 is a diagram illustrating a configuration example of a power storage device according to the embodiment. In the example illustrated in FIG. 1, the power storage device 1 includes a battery module 11, a battery control unit (ECU: Electronic Control Unit) 12, a switch 13, a voltage sensor 14, a current sensor 15, a temperature sensor 16, and a connection connector 17.

  The battery module 11 includes a plurality of battery cells 111-1 to 111 -N (N is an integer of 2 or more). The plurality of battery cells 111-1 to 111 -N may have the same type and structure as each other, and are connected in series. FIG. 2 is a schematic diagram of a configuration example of a battery module included in the power storage device according to the embodiment. In the configuration example illustrated in FIG. 2, the battery module 11 includes five (N = 5) battery cells 111-1 to 111-5. Battery cells 111-1 to 111-5 are sandwiched between a pair of end plates 112. The battery cells 111-1 to 111-5 are constrained between the end plates 112 by tightening the end plates 112 with the through bolts 113 and the nuts 114 that pass through the four corners of the end plate 112, respectively. The end plate 112, the through bolt 113, and the nut 114 are examples of restraining members. The battery module 11 is subjected to a restraining load in the direction in which the battery cells 111-1 to 111-5 are arranged, that is, the direction in which the pair of end plates 112 face each other.

In the example illustrated in FIG. 1, one battery module 11 is included in the power storage device 1, but a plurality of battery modules 11 may be included in the power storage device 1.
The battery control unit 12 is, for example, a processor such as a CPU (Central Processing Unit), an FPGA (Field Programmable Gate Array), or a PLD (Programmable Logic Device). The battery control unit 12 includes a storage unit 121, an acquisition unit 122, a calculation unit 123, a determination unit 124, and a restriction unit 125.

  The battery control unit 12 monitors the state of the battery module 11 and controls the operation of the entire power storage device 1. The battery control unit 12 operates as described below, for example. FIG. 3 is a flowchart of a first example of the battery module control method executed by the power storage device according to the embodiment. The control method as shown in FIG. 3 may be repeatedly executed at an arbitrary timing (for example, a predetermined time interval).

  The storage unit 121 stores a cell deterioration state / cell expansion amount correspondence map in advance. For example, the plurality of battery cells 111-1 to 111 -N may have the same type and structure, and the correspondence relationship between the deterioration state (cell deterioration state) and the expansion amount (cell expansion amount) of such battery cells The map shown is stored in the storage unit 121. The correspondence relationship between the cell deterioration state and the cell expansion amount is acquired by, for example, a prior experiment using a battery cell having the same type and structure as the battery cells 111-1 to 111 -N.

  The acquisition unit 122 acquires the deterioration states of the plurality of battery cells 111-1 to 111-N, respectively (step S11). The deterioration state may be acquired based on the full charge capacity of each of the battery cells 111-1 to 111-N. Moreover, a deterioration state may be acquired based on each internal resistance value of the battery cells 111-1 to 111-N. The full charge capacity or the internal resistance value is, for example, a voltage value measured by the voltage sensor 14 (14-1 to 14-N), a current value measured by the current sensor 15, and a temperature measured by the temperature sensor 16. And can be detected.

  The calculating unit 123 acquires the cell expansion amounts corresponding to the deterioration states of the plurality of battery cells 111-1 to 111-N from the cell deterioration state / cell expansion amount correspondence map stored in the storage unit 121 (step S12). ). Then, the calculation unit 123 calculates a module expansion amount from the sum of the acquired cell expansion amounts (step S13). The module expansion amount is an expansion amount of the battery module 11 including the plurality of battery cells 111-1 to 111 -N.

  The determination unit 124 determines whether or not the calculated module expansion amount exceeds the module expansion threshold (step S14). The module expansion threshold is an expansion limit value of the battery module 11 that is allowed in order that the battery module 11 does not fail or break, and corresponds to the constraint load limit of the battery module 11. The module expansion threshold is acquired by, for example, a prior experiment using a battery module having the same type and structure as the battery module 11 and is held in the determination unit 124 in advance.

  When the module expansion amount exceeds the module expansion threshold (“YES” in step S14), the limiting unit 125 enters the plurality of battery cells 111-1 to 111-N to limit or stop the use of the battery module 11. The output current is limited (step S16). Specifically, for example, the limiting unit 125 turns off the switch 13 that connects the plurality of battery cells 111-1 to 111 -N to the load 2 via the power lines Lp 1 and Lp 2, thereby the plurality of battery cells 111. Stops the current input to and output from −1 to 111-N. In addition, for example, the restriction unit 125 restricts the currents input to and output from the plurality of battery cells 111-1 to 111 -N by notifying the load 2 of the power use restriction via the communication line Lc. The switch 13 is a relay, for example, and is installed on the power line Lp1 as a voltage line. The load 2 is, for example, a hybrid car, an electric vehicle, and an electric forklift. The load 2 is connected via the connection connector 17 on the power storage device 1 side and the connection connector 21 on the load 2 side. Instead of the load 2, a charging device (not shown) may be connected to the power storage device 1.

  Thus, the module expansion amount of the battery module 11 is calculated based on the respective deterioration states of the plurality of battery cells 111-1 to 111 -N. Then, it is determined whether or not the calculated module expansion amount exceeds a module expansion threshold value corresponding to the constraint load limit of the battery module 11. Therefore, according to the power storage device according to the embodiment, it is possible to accurately determine whether or not the restraint load of the battery module exceeds the restraint load limit even if there is variation in the deterioration state of the plurality of battery cells. Can be controlled appropriately.

  When the module expansion amount does not exceed the module expansion threshold (“NO” in step S14), the determination unit 124 determines whether the maximum cell expansion amount among the cell expansion amounts acquired in step S12 exceeds the cell expansion allowable value. It is further determined whether or not (step S15). The cell expansion allowable value is an expansion limit value allowed for each battery cell so that the battery cell or an adjacent battery cell does not fail or break due to expansion. The cell expansion allowable value is acquired by a prior experiment using a battery cell having the same type and structure as the battery cells 111-1 to 111 -N, and is held in the determination unit 124 in advance.

  When the maximum cell expansion amount exceeds the cell expansion allowable value (“YES” in step S15), the limiting unit 125 is configured to limit or stop the use of the battery module 11 to have a plurality of battery cells 111-1 to 111-. The current that is input to and output from N is limited (step S16). Specific examples of the current limiting method have been described above.

  As described above, even when the restraining load of the battery module 11 does not exceed the restraining load limit, the battery module 11 is used when the expansion amount of at least one battery cell included in the battery module 11 exceeds the cell expansion allowable value. Limited. Therefore, according to the power storage device according to the embodiment, it is possible to appropriately control the use of the battery module even if the deterioration states of the plurality of battery cells vary.

In addition, this invention is not limited to the above embodiment, A various improvement and change are possible within the range which does not deviate from the summary of this invention.
For example, in step S12, the calculation unit 123 may perform the following process. That is, the deterioration state of each of the battery cells 111-1 to 111 -N acquired in step S <b> 11 is a predicted (estimated) value based on the detected full charge capacity or internal resistance value. Errors can be included. In step S12, the calculation unit 123 adds a predetermined error (for example, 3 to 5%) set in advance based on the prediction accuracy of the deterioration state of the battery cell to the deterioration state acquired in step S11. Also good. Specifically, for example, the calculation unit 123 adds a plus-side error to the acquired deterioration state, and adds a minus-side error to the acquired deterioration state. The calculation unit 123 acquires each cell expansion amount corresponding to the deterioration state to which the plus side error is added. Further, the calculation unit 123 acquires the cell expansion amount corresponding to the deterioration state to which the minus side error is added. The calculation unit 123 selects a cell expansion amount having a large value from the two cell expansion amounts acquired for each battery cell. If such a process is performed, it can be determined more accurately whether or not the restraint load of the battery module exceeds the restraint load limit.

  Further, the battery control unit 12 may execute a control method as shown in FIG. 4 instead of the control method shown in FIG. It is a flowchart of the 2nd example of the control method of the battery module according to embodiment. The control method as shown in FIG. 4 may be repeatedly executed at an arbitrary timing (for example, a predetermined time interval).

  The storage unit 121 further stores in advance a module expansion amount / restraint load correspondence map. The module expansion amount / restraint load correspondence map is a map showing a correspondence relationship between the module expansion amount and the restraint load applied to the battery module 11. The correspondence relationship between the module expansion amount and the restraint load is acquired by, for example, a prior experiment using a battery module having the same type and structure as the battery module 11.

  In steps S21 to S23, the same processes as those described above in steps S11 to S13 may be performed. In step S24, the calculation unit 123 further acquires a constraint load corresponding to the module expansion amount calculated in step S23 from the module expansion amount / constraint load correspondence map stored in the storage unit 121.

  The determination unit 124 determines whether or not the acquired restraint load exceeds the restraint load threshold (step S25). The restraint load threshold value is a restraint load limit value of the battery module 11 that is allowed so that the battery module 11 does not fail or break. The restraining load threshold is acquired by, for example, a prior experiment using a battery module having the same type and structure as the battery module 11 and is held in the determination unit 124 in advance.

  When the acquired restraint load exceeds the restraint load threshold (“YES” in step S25), the restriction unit 125 restricts or stops the use of the battery module 11 to a plurality of battery cells 111-1 to 111-N. The input / output current is limited (step S27). A specific example of the current limiting method has been described above with respect to step S16.

  When the acquired restraint load does not exceed the restraint load threshold (“NO” in step S25), the determination unit 124 determines that the maximum cell expansion amount among the cell expansion amounts acquired in step S22 is the cell expansion allowable value. It is further determined whether or not it exceeds (step S26). When the maximum cell expansion amount exceeds the cell expansion allowable value (“YES” in step S26), the limiting unit 125 is configured to limit or stop the use of the battery module 11 to have a plurality of battery cells 111-1 to 111-. The current that is input to and output from N is limited (step S27). A specific example of the current limiting method has been described above with respect to step S16.

  The effect similar to that of the first example of the control method described above with reference to FIG. 3 can be obtained by the second example of the control method as shown in FIG.

DESCRIPTION OF SYMBOLS 1 Power storage device 11 Battery module 111-1 to 111-N Battery cell 112 End plate 113 Through bolt 114 Nut 12 Battery control unit 121 Storage part 122 Acquisition part 123 Calculation part 124 Determination part 125 Limiting part 13 Switch 14 (14-1 to 14-1 14-N) Voltage sensor 15 Current sensor 16 Temperature sensor 17 Connector 2 Load 21 Connector 21 Lc Communication line Lp1, Lp2 Power line

Claims (5)

A plurality of battery cells;
A storage unit for storing a cell degradation state / cell expansion amount correspondence map;
An acquisition unit that acquires the deterioration states of the plurality of battery cells, respectively.
Each cell expansion amount corresponding to the deterioration state of the plurality of battery cells is acquired from the cell deterioration state / cell expansion amount correspondence map, and the plurality of battery cells are configured from the obtained sum of the cell expansion amounts. A calculation unit for calculating a module expansion amount of the battery module,
A determination unit for determining whether or not the module expansion amount exceeds a module expansion threshold;
A power storage device comprising: a limiting unit that limits currents input to and output from the plurality of battery cells when the module expansion amount exceeds the module expansion threshold. The power storage device according to claim 1,
The storage unit further stores a module expansion amount / restraint load correspondence map,
The calculation unit further obtains a constraint load corresponding to the module expansion amount from the module expansion amount / constraint load correspondence map,
Instead of determining whether the module expansion amount exceeds the module expansion threshold, the determination unit determines whether the constraint load exceeds a constraint load threshold,
The limiting unit is a power storage device that limits the current when the constraint load exceeds the constraint load threshold instead of limiting the current when the module expansion amount exceeds the module expansion threshold. The power storage device according to claim 1 or 2,
The determination unit further determines whether or not the maximum cell expansion amount among the acquired cell expansion amounts exceeds a cell expansion allowable value,
The limiting unit is a power storage device that limits the current when the maximum cell expansion amount exceeds the cell expansion allowable value. The power storage device according to any one of claims 1 to 3,
The said calculating part is an electrical storage apparatus which adds the error set based on the prediction accuracy of the degradation state of a battery cell to the acquired said degradation state, respectively. Obtain the degradation status of multiple battery cells,
From the cell deterioration state / cell expansion amount correspondence map, cell expansion amounts corresponding to the deterioration states of the plurality of battery cells are obtained,
From the obtained sum of the cell expansion amount, the module expansion amount of the battery module composed of the plurality of battery cells is calculated,
Determining whether the module expansion amount exceeds a module expansion threshold;
A battery module control method executed by a power storage device, comprising: limiting currents input to and output from the plurality of battery cells when the module expansion amount exceeds the module expansion threshold.

Images