JP6657779B2 - Power storage device and abnormality detection method - Google Patents

Description

  The present invention relates to a power storage device and an abnormality detection method.

When the battery module included in the power storage device is charged by the charging device, the power storage device may be configured to monitor the charging device for an abnormality (failure).
Specifically, for example, the power storage device outputs a current command value indicating a current value required for charging the battery module to the charging device. Then, the power storage device detects the charging current detection value based on the current value flowing through the battery module as the current value output by the charging device according to the current command value. However, the charging current detection value may have an error with respect to the current command value. Therefore, a predetermined abnormality detection threshold larger than the assumed maximum error is set so that the abnormality of the charging device is not erroneously detected due to the error present in the charging current detection value. Then, the power storage device compares the difference between the current command value and the charging current detection value with the set abnormality detection threshold, and outputs a current corresponding to the current command value output to the charging device from the charging device. Is determined. When the difference between the current command value and the charging current detection value exceeds the abnormality detection threshold, the power storage device detects an abnormality (failure) of the charging device.

  As related techniques, for example, techniques described in Patent Documents 1 to 3 are known.

JP 2008-005593 A JP 2014-027803 A JP 2009-081948 A

However, as described above, when an abnormality detection threshold value that is larger than the assumed maximum error is set, there is a possibility that the detection of an abnormality in the charging device may be omitted.
An object according to one aspect of the present invention is to provide a power storage device in which a failure in detecting an abnormality in a charging device when charging a battery module is suppressed.

A power storage device according to one embodiment of the present invention includes at least one or more battery modules, a calculation unit, a setting unit, and a detection unit.
The calculation unit calculates a current command value indicating a current value that instructs a charging device to output to charge the battery module. The setting unit sets an abnormality detection threshold according to at least one of the number of connected battery modules and the current command value. The detection unit determines a difference between the current command value and a charging current detection value detected based on a current value input to the battery module as a current value output by the charging device according to the current command value, based on the abnormality detection threshold. If it exceeds, the abnormality of the charging device is detected.

  According to the power storage device according to the embodiment, it is possible to suppress a failure in detecting an abnormality of the charging device when charging the battery module.

FIG. 3 is a diagram illustrating a configuration example of a power storage device according to the embodiment. FIG. 4 is an exemplary flowchart of a method for detecting abnormality of the charging device, which is executed by the power storage device according to the embodiment; FIG. 5 is a diagram illustrating an example of an abnormality detection threshold set by the power storage device according to the 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. As shown in FIG. 1, the power storage device 1 includes at least one or more battery modules 11, a battery control unit (ECU: Electronic Control Unit) 12, a switch 13, a voltage sensor 14, a current sensor 15, and a connection connector 16. .

  As shown in the example of FIG. 1, when there are N (N is an integer of 2 or more) battery modules 11-1 to 11 -N as the battery module 11, the N battery modules 11-1 to 11-11 are provided. -N are connected in parallel. Although FIG. 1 shows each battery module 11 in which a plurality of cells are connected in series, the number and connection relationship of the cells constituting the battery module 11 may be arbitrary.

  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 calculation unit 121, a setting unit 122, and a detection unit 123. Battery control unit 12 monitors the state of battery module 11 and controls the operation of power storage device 1 as a whole. The battery control unit 12 operates, for example, as described below. FIG. 2 is an exemplary flowchart of an abnormality detection method of the charging device, which is executed by the power storage device according to the embodiment.

  When the power storage device 1 is connected to the charging device 2 via the connection connector 16 on the power storage device 1 side and the connection connector 21 on the charging device 2 side and charging of the battery module 11 is started, the calculation unit 121 outputs the current command value. Calculation is performed (step S1). The current command value indicates a current value at which power storage device 1 instructs charging device 2 to output to charge battery module 11.

  The current command value is determined according to, for example, the voltage of each battery module 11 being charged, the number of connected battery modules 11, and the outputable current value of the charging device 2. Each voltage of the battery modules 11-1 to 11-N is measured by the corresponding N voltage sensors 14 (14-1 to 14-N), and acquired by the battery control unit 12. The number of connected battery modules 11 is the number of battery modules 11 in which the corresponding switches 13 (13-1 to 13-N) connected in series to the battery modules 11-1 to 11-N are closed, respectively. 13 is obtained by the battery control unit 12 that controls the opening and closing of the battery 13. The switch 13 is, for example, a relay. Each switch 13 is closed under the control of the battery control unit 12 when the corresponding battery module 11 is normal, and is opened under the control of the battery control unit 12 when the corresponding battery module 11 is abnormal. The outputable current value of the charging device 2 is obtained by the battery control unit 12 from the charging device 2 via the communication line Lc.

  Calculation unit 121 outputs the calculated current command value to charging device 2 via communication line Lc. Charging device 2 outputs a current according to a current command value input via communication line Lc. The output current from the charging device 2 is input to each battery module 11 with the corresponding switch 13 closed via the power line Lp, and each battery module 11 is charged.

  The setting unit 122 sets the abnormality detection threshold according to at least one of the number of connected battery modules 11 and the current command value (Step S2). A specific example of a method of setting the abnormality detection threshold by the setting unit 122 will be described later with reference to FIG.

  The detection unit 123 detects a charging current detection value based on the current value input to the battery module 11 as the current value output by the charging device 2 according to the current command value (Step S3). Specifically, the current values flowing through the battery modules 11 with the switch 13 closed are respectively measured by the corresponding current sensors 15 (15-1 to 15-N). Then, the detection unit 123 detects the charging current detection value from the sum of the measured current values.

  The detecting unit 123 determines whether or not the difference between the current command value and the charging current detection value exceeds an abnormality detection threshold (Step S4). When the difference (absolute value) between the current command value and the charging current detection value exceeds the abnormality detection threshold ("YES" in step S4), detection section 123 detects an abnormality in charging device 2 (step S5). Note that the detection unit 123 may notify the charging device 2 of the detected abnormality of the charging device 2 via the communication line Lc. In addition, the detection unit 123 instructs the charging device 2 to stop charging via the communication line Lc, or opens the switch 13 to stop the current flowing into the battery module 11, and the like. 11 may be stopped.

  The battery control unit 12 repeatedly performs the abnormality detection processing described above with reference to FIG. 2 at an arbitrary timing (for example, a predetermined time interval) while the battery module 11 is being charged by the charging device 2.

  A specific example of a method of setting the abnormality detection threshold by the setting unit 122 will be described with reference to FIG. FIG. 3 is a diagram illustrating an example of an abnormality detection threshold set by the power storage device according to the embodiment. In FIG. 3, the horizontal axis represents the current command value, and the vertical axis represents the difference between the current command value and the charging current detection value.

  As can be understood from FIG. 3, the charging current detection value has an error with respect to the current command value. The cause of the error includes, for example, the control accuracy of the charging device 2 that controls to output a current corresponding to the input current command value. A factor that causes the error includes, for example, the measurement accuracy of the current sensor 15 that measures the current flowing through the corresponding battery module 11.

  In order to prevent the abnormality of the charging device 2 from being erroneously detected due to the error added to the charging current detection value, for example, the error is larger than the maximum errors such as the first maximum error E1 and the second maximum error E2. It is desirable to set an abnormality detection threshold. The first maximum error E1 indicates a maximum error assumed according to a change in the current command value when the number of connected battery modules 11 is α (α is an integer of 1 or more and N or less). The second maximum error E2 indicates a maximum error assumed according to a change in the current command value when the number of connected battery modules 11 is β (β is an integer greater than α and equal to or less than N).

  However, as can be understood by comparing the first maximum error E1 and the second maximum error E2, the error added to the charging current detection value due to the factors described above is caused by an increase in the number of connections of the battery module 11. It increases in proportion to. For example, an error caused by the measurement accuracy of the current sensor 15 increases as the number of measurements of the current sensor 15 increases in accordance with the number of connections of the battery module 11. Further, as indicated by the slopes of the first maximum error E1 and the second maximum error E2, the error added to the charging current detection value due to the above-described factors increases in proportion to the increase in the current command value. For example, even if the error (unit: amperage) due to the accuracy error of the current sensor 15 is an error (unit: percentage) within an allowable range specified for the current sensor 15, the current of the measurement target increases as the current command value increases. It increases as the value increases. Similarly, for example, if the charging device 2 controls the output current value using a current sensor (not shown), the error caused by the control accuracy of the charging device 2 causes the output of the control target to increase as the current command value increases. It increases as the current value increases.

  Therefore, if a certain abnormality detection threshold is set in advance, such as a fixed type abnormality detection threshold Thc, the set abnormality detection threshold corresponds to the current number of connections of the battery module 11 and the current current command value. It may deviate from the maximum error, and there is a possibility that an abnormality in the detection of the abnormality of the charging device may be missed by the deviation. The constant type abnormality detection threshold Thc is set to be constant according to the maximum error corresponding to the maximum number of connected battery modules 11 included in power storage device 1 and the maximum current command value output from power storage device 1 to charging device 2. FIG.

  Therefore, the setting unit 122 sets the abnormality detection threshold so as to change following at least one of the number of connected battery modules 11 and the current command value. For example, like the first abnormality detection threshold Th1 and the second abnormality detection threshold Th2, the setting unit 122 detects abnormality so as to increase as at least one of the number of connected battery modules 11 and the current command value increases. Set the threshold. In addition, the setting unit 122 sets the abnormality detection threshold so as to decrease as at least one of the number of connected battery modules 11 and the current command value decreases. The first abnormality detection threshold Th1 indicates an abnormality detection threshold that is set to increase or decrease in accordance with an increase or decrease in the current command value when the number of connected battery modules 11 is α. The second abnormality detection threshold Th2 indicates an abnormality detection threshold that is set to increase or decrease in accordance with an increase or decrease in the current command value when the number of connected battery modules 11 is β.

  If the abnormality detection threshold is set so as to change following at least one of the number of connections of the battery module 11 and the current command value, the set abnormality detection threshold becomes the current number of connections of the battery module 11 and the current number of connections. Does not deviate from the maximum error corresponding to the current command value. Therefore, according to the power storage device according to the embodiment, omission of detection of abnormality of the charging device can be suppressed.

  The setting unit 122 may set the above-described abnormality detection threshold using a threshold function having at least one of the number of connected battery modules 11 and the current command value as a variable. The threshold function is, for example, a straight line having the number of connected battery modules 11 as a predetermined value and the current command value as a variable, as indicated by the first abnormality detection threshold Th1 or the second abnormality detection threshold Th2. The setting unit 122 holds such a threshold function in advance.

  The setting unit 122 may set the abnormality detection threshold using a threshold table in which an abnormality detection threshold corresponding to at least one of the number of connected battery modules 11 and the current command value is recorded. The threshold value table is a table in which, for example, a correspondence relationship between a current command value and an abnormality detection threshold value at an arbitrary number of connections of the battery module 11 is recorded. The setting unit 122 holds such a threshold table in advance.

  If the abnormality detection threshold is set according to a threshold function or a threshold table in which the abnormality detection threshold changes following at least one of the number of connections of the battery modules 11 and the current command value, the set abnormality detection threshold is determined by the battery module 11 does not deviate from the maximum error corresponding to the current number of connections and the current current command value. Therefore, according to the power storage device according to the embodiment, omission of detection of abnormality of the charging device can be suppressed.

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

1 power storage device 11 (11-1 to 11-N) battery module 12 battery control unit 121 calculation unit 122 setting unit 123 detection unit 13 (13-1 to 13-N) switch 14 (14-1 to 14-N) voltage Sensor 15 (15-1 to 15-N) Current sensor 16 Connector 2 Charger 21 Connector Lc Communication line Ld Power line

Claims (5)

At least one or more battery modules;
A current sensor that measures a current value input to each of the battery modules;
A calculating unit that calculates a current command value indicating a current value that instructs a charging device to output to charge the battery module;
A setting unit that sets an abnormality detection threshold according to the number of connections of the battery module,
When a difference between the current command value and a charging current detection value detected based on a current value measured by the current sensor as a current value output by the charging device according to the current command value exceeds the abnormality detection threshold. A power storage device including: a detection unit that detects an abnormality of the charging device. The power storage device according to claim 1,
The power storage device, wherein the setting unit sets the abnormality detection threshold so as to increase as the number of connected battery modules increases and decrease as the number of connected battery modules decreases. The power storage device according to claim 1 or 2,
The power storage device, wherein the setting unit sets the abnormality detection threshold using a threshold function having the number of connections of the battery modules as a variable. The power storage device according to claim 1 or 2,
The power storage device, wherein the setting unit sets the abnormality detection threshold using a threshold table in which abnormality detection thresholds corresponding to the number of connected battery modules are recorded. Calculating a current command value indicating a current value that instructs a charging device to output to charge at least one or more battery modules;
Setting an abnormality detection threshold according to the number of connections of the battery module,
A charging current detection value detected based on the current command value and a current value measured by a current sensor that measures a current value input to each of the battery modules as a current value output by the charging device according to the current command value. An abnormality detection method executed by the power storage device, the method including detecting an abnormality of the charging device when a difference between the power storage device and the battery exceeds the abnormality detection threshold.

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