JP2015070681A - Battery monitoring device, power storage device, and battery monitoring method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To determine the presence or absence of an abnormality in a discharge circuit while suppressing the reduction of cell voltage detection accuracy.SOLUTION: A CPU 15 alternately supplies an open instruction signal and a close instruction signal to a switch 41. The CPU 15 detects a variation of an AC voltage. The CPU 15 compares the variation of an AC voltage with an abnormality criterion value stored in advance in a memory 16, to determine whether or not each switch 41-43 is abnormal. This enables the detection of an abnormal switch connected in parallel with a cell, while suppressing the deterioration of the cell voltage detection accuracy, in comparison with a configuration using a resistor for diagnosis.

Description

  The present invention relates to a technique for determining whether there is an abnormality in a discharge circuit connected in parallel to a cell.

  Conventionally, there is a battery monitoring device that monitors the voltage of a battery cell. The battery monitoring device includes a plurality of battery cells connected in series, a plurality of diagnostic resistors, a plurality of equalizing discharge circuits, and a monitoring circuit. Each diagnostic resistor is connected between the positive side of each battery cell and the monitoring device, and each equalizing discharge circuit is connected in parallel to each battery cell via each diagnostic resistor. The monitoring circuit detects the cell voltage of each battery cell through a diagnostic resistor, turns on the equalization discharge circuit based on the comparison result between the detected value and a predetermined threshold value, and starts diagnosis from each battery cell. A current flowing through the resistor is supplied to the negative electrode side of the battery cell.

  In addition, the battery monitoring device includes a configuration for determining whether the equalization discharge circuit is abnormal. Specifically, the monitoring circuit gives a command to turn on the equalization circuit, and determines that the equalization discharge circuit is abnormal by using a drop voltage generated across the diagnostic resistor.

JP 2011-76778 A

  However, in the battery monitoring device, a diagnostic resistor is indispensable for determining whether the equalization discharge circuit is abnormal, and the monitoring circuit is forced to detect the cell voltage via the diagnostic resistor. . For this reason, there exists a possibility that the detection accuracy of the voltage of a battery cell may fall under the influence of the drop voltage of diagnostic resistance. As described above, various problems may occur in the battery monitoring device using the diagnostic resistor.

  In the present specification, a technique capable of determining the presence or absence of abnormality in a discharge circuit without using a diagnostic resistor is disclosed.

  A battery monitoring device disclosed in the present specification is connected between a cell and a discharge circuit that switches between a state in which the current from the cell can be discharged and a state in which the battery cannot be discharged, and the cell and the discharge circuit. A connected reactance element; a voltage detection unit that detects an AC voltage generated by the reactance element through the reactance element; and a control unit, wherein the control unit detects the discharge circuit from a change in the AC voltage. An abnormality determination process for determining whether or not there is an abnormality is executed.

  In the battery monitoring device, it is possible to determine whether there is an abnormality in the discharge circuit without using a diagnostic resistor.

Block diagram of a battery pack according to an embodiment Change diagram of AC component of reactance back electromotive force Diagram showing current flowing through cell monitoring device Each switch state and back electromotive force amplitude (variation) Flowchart of switch abnormality judgment processing Flow chart of open mode abnormality judgment processing Open mode error identification process flowchart Flow chart of short mode abnormality judgment processing Flow chart of short mode abnormality identification processing

(Outline of the embodiment)
A battery monitoring device disclosed in the present specification is connected between a cell and a discharge circuit that switches between a state in which the current from the cell can be discharged and a state in which the battery cannot be discharged, and the cell and the discharge circuit. A connected reactance element; a voltage detection unit that detects an AC voltage generated by the reactance element through the reactance element; and a control unit, wherein the control unit detects the discharge circuit from a change in the AC voltage. An abnormality determination process for determining whether or not there is an abnormality is executed.

  According to this battery monitoring apparatus, the AC voltage is detected via the reactance element. Thereby, the presence or absence of abnormality of a discharge circuit can be determined based on the change of an alternating voltage, without using a diagnostic resistance.

  The battery monitoring device includes a bypass circuit that is connected in parallel to the cell and allows an AC component current to flow, and the voltage detection unit is configured so that the discharge circuit is between the dischargeable state and the undischargeable state. The amplitude of the AC voltage generated by the reactance element when switching is detected, and the control unit gives a switching signal for switching between the dischargeable state and the discharge impossible state to the discharge circuit A switching process may be performed, and the abnormality determination process may determine whether or not the discharge circuit is abnormal based on the detection result of the voltage detection unit based on the amplitude of the AC voltage when the switching process is performed. .

  In this battery monitoring device, the amplitude of the AC voltage when a switching signal is given to the discharge circuit is generated by the reactance element and the bypass circuit, and differs depending on whether the discharge circuit is normal or abnormal. Therefore, according to the battery monitoring device, it is possible to detect the presence or absence of abnormality in the discharge circuit based on the amplitude.

  In the battery monitoring device, a plurality of the cells are connected in series, a plurality of the discharge circuits and reactance elements are provided corresponding to the plurality of cells, and the control unit is configured to perform the switching process. The switching signal may be applied to one of the plurality of discharge circuits.

  According to this battery monitoring device, it is possible to suppress the influence due to an increase in the load of the control unit and a shift in switching timing, compared to a configuration in which switching signals are given to all the discharge circuits.

  In the battery monitoring device, when the control unit gives the switching signal to the one discharge circuit, the discharge circuit is in a state where the discharge is possible or a state where the discharge is not possible. A command process for giving a command signal for performing the processing may be executed.

  According to this battery monitoring device, since the command signal is given to the other discharge circuit other than the one discharge circuit, the control unit is in an abnormal state in which any one of the discharge circuits is not in a dischargeable state, or cannot be discharged. It can be determined that the abnormality is not in a state.

  In the battery monitoring device, the control unit may perform the switching process on the discharge circuit connected to the cell having the lowest potential among the plurality of discharge circuits.

  According to this battery monitoring device, the amplitude is increased under the influence of the amplitude of the AC voltage generated by more reactance elements, compared with the configuration in which the switching process is performed by the discharge circuit having the highest potential, and therefore the accuracy is high. Switch abnormality can be detected.

  In the battery monitoring device, when the control unit provides the switching signal to the one discharge circuit, the control unit executes the command process on all other discharge circuits other than the one discharge circuit, The command signal different from the command signal given in the command processing may be given to any one of the discharge circuits.

  According to this battery monitoring device, a failed discharge circuit can be identified.

  In the battery monitoring device, the voltage detection unit may detect an amplitude of the AC voltage generated at both ends of the plurality of discharge circuits.

  According to this battery monitoring device, since the amplitude of the voltage at both ends becomes larger than the configuration for detecting the amplitude of the alternating voltage generated at both ends of one discharge circuit, the abnormality of the discharge circuit can be detected with high accuracy. Can do.

  Further, a power storage device including a power storage element and a battery monitoring device may be used.

  The invention disclosed in this specification is realized in various modes such as a battery monitoring device, an electronic monitoring method, a computer program for realizing the functions of these methods or devices, and a recording medium on which the computer program is recorded. can do.

<One Embodiment>
A battery pack 11 according to an embodiment will be described with reference to FIGS. The battery pack 11 of this embodiment is an example of a power storage device, and includes an assembled battery module 12 and a cell monitoring device 13. The battery pack 11 is mounted on, for example, an electric vehicle or a hybrid vehicle, and supplies power to various devices in the vehicle.

(Electric configuration of battery pack)
As shown in FIG. 1, the assembled battery module 12 is an assembled battery in which three first cells C1 to C3 are connected in series. The assembled battery module 12 may have a configuration in which one, two, or four or more cells are connected in series. Moreover, each cell C1-C3 is secondary batteries, such as a lithium ion battery, for example. However, each cell C1-C3 should just be an electrical storage element, and a capacitor etc. may be sufficient as it. In the following description, the cell voltage of each of the cells C1 to C3 is about 2.5 to 4.2 V when the cells C1 to C3 are not abnormal such as disconnection, overdischarge, and overcharge. And In addition, each cell C1-C3 is an example of an electrical storage element.

  Each of the cells C1 to C3 is connected to the cell monitoring unit 14 of the cell monitoring device 13 through four voltage detection lines 21 to 24. Inductive reactances L1 to L3 are connected to the voltage detection lines 22 to 24, respectively, and no reactance is connected to the voltage detection line 21. The reactances L1 to L3 are examples of reactance elements.

  Hereinafter, each of the three reactances L1 to L3 may be referred to as a first reactance L1, a second reactance L2, and a third reactance L3. It should be noted that the reactance values of the three reactances L1 to L3 indicate that even if the cell voltage of each of the cells C1 to C3 changes according to the environment, the cell monitoring unit 14 determines that the switch is abnormal from the reactance values of the three reactances L1 to L3. It is optimally determined so that detection can be performed without problems.

  In the following, “switch failure” refers to either the case where the switch is continuously in an abnormal state or the case where the switch is temporarily in an abnormal state due to the surrounding environment such as noise. Including.

  The cell monitoring device 13 includes equalization circuits 31 to 33, filters F1 to F3, an AC voltmeter AV, and a cell monitoring unit 14. The equalization circuits 31 to 33 are connected in parallel to the cells C1 to C3, respectively. Reactances L1 to L3 are connected between the cells C1 to C3 and the equalization circuits 31 to 33, respectively.

  Each equalization circuit 31 to 33 is a series circuit in which switches 41 to 43 and discharge resistors 51 to 53 are connected in series. Each of the switches 41 to 43 is on / off controlled by receiving an on (close) command signal or an off (open) command signal from the cell monitoring unit 14. Note that the switches 41 to 43 are normally in an open state given an open command signal from the cell monitoring unit 14. The cell monitoring device 13 is an example of a battery monitoring device, the equalization circuit 31 is an example of a discharge circuit (one discharge circuit), and the equalization circuits 32 and 33 are discharge circuits (other discharge circuits). ).

  Each of the switches 41 to 43 may be, for example, a semiconductor switch element such as an FET, a contactor (electromagnetic contactor), or the like, or a switch unit that controls current in the IC. Hereinafter, the switches 41 to 43 may be referred to as the first switch 41, the second switch 42, and the third switch 43 in association with the cells C1 to C3.

  Each of the switches 41 to 43 is supplied with an on (close) command signal or an off (open) command signal from the cell monitoring unit 14 so that each of the switches 41 to 43 is turned on from the off state (open state or open state). (Closed state, closed state), and the cells C1 to C3 are discharged. Thereby, the cell voltage of each cell C1-C3 can be made uniform, and it can be made to correspond with the cell voltage of the cell corresponding to it. The off state (open state, open state) is an example of a discharge impossible state, and the on state (closed state, closed state) is an example of a dischargeable state.

  The filters F1 to F3 have resistors R1 to R3 and capacitors CAP1 to CAP3. The resistors R1 to R3 are connected between the reactances L1 to L3 and the cell monitoring unit 14 on the voltage detection lines 22 to 24. The capacitors CAP1 to CAP3 are connected in parallel to the equalization circuits 31 to 33, respectively. Each of the capacitors CAP1 to CAP3 is a bypass circuit that allows an alternating current to flow.

  The AC voltmeter AV detects the amplitude of the AC voltage generated by the reactances L1 to L3 at the detection point P, and gives the detection result to the CPU 15. The detection point P is a connection point to which the equalization circuit 33 is connected on the voltage detection line 24. That is, the configuration is such that the amplitude of the AC voltage across the equalization circuits 31 to 33, more specifically, the amplitude of the AC voltage between the voltage detection line 21 and the voltage detection line 24 is detected. The filters F1 to F3 are examples of bypass circuits, and the AC voltmeter AV is an example of a voltage detection unit.

  The cell monitoring unit 14 includes a cell voltage detection circuit 17 and a control unit 18. The cell voltage detection circuit 17 is connected to the cells C1 to C3 via the reactances L1 to L3. The cell voltage detection circuit 17 individually detects the voltages of the cells C <b> 1 to C <b> 3 and gives the detection result to the control unit 18. The control unit 18 monitors the states of the cells C1 to C3 from the detection result of the cell voltage detection circuit 17. In addition, the state of each cell C1-C3 includes the voltage, charge state, internal resistance, etc. of each cell C1-C3.

  The control unit 18 includes a central processing unit (hereinafter referred to as CPU) 15 and a memory 16. Various programs (including a switch abnormality determination program) for controlling the operation of the cell monitoring unit 14 are stored in the memory 16, and the CPU 15 executes each unit of the cell monitoring unit 14 according to the program read from the memory 16. To control. The memory 16 has a RAM and a ROM. The medium for storing the various programs may be a non-volatile memory such as a CD-ROM, a hard disk device, or a flash memory in addition to the RAM.

(Determining if there is an abnormality in the discharge circuit)
The CPU 15 determines whether there is an abnormality in the discharge circuit as described below. In the following, a switch abnormality will be described as an example of a discharge circuit abnormality.

  When the CPU 15 alternately applies a switching command signal, that is, an open command signal and a close command signal to the switch 41, the back electromotive force of the reactances L1 to L3 at the detection point P is an AC component as shown in FIG. Occur. In FIG. 2, the waveforms are obtained when the CPU 15 gives a switching command signal to the switch 41 and gives an open command signal to the switch 42 and the switch 43. Hereinafter, the counter electromotive voltage of reactances L1 to L3 is referred to as an AC voltage.

  It should be noted that the detection point P should be the detection point on the voltage connection line 24 having the highest potential among the voltage connection lines of the cell monitoring device 13 so that the influence of all the switches 41 to 43 can be seen. desirable. The switch to which the CPU 15 gives the switching command signal is preferably the switch 41 connected to the voltage detection line 21 having the lowest potential in the cell monitoring device 13.

  In FIG. 2, the vertical axis represents the AC voltage, and the horizontal axis represents time. Time t0 is the time when the CPU 15 gives the close command signal to the switch 41 and the switch 41 is in the closed state. Thereafter, at time t3, the CPU 15 gives an open command signal to the switch 41, and the switch 41 is in an open state. At time t5, the CPU 15 gives a close command signal to the switch 41, and the switch 41 is again closed. Thus, the AC voltage fluctuates as the switch 41 changes state between the open state and the closed state.

  FIG. 4 shows the states of the switches 41 to 43 and the maximum value, minimum value, and difference of the AC voltage, that is, the amplitude of the AC voltage. In the state of each of the switches 41 to 43 in FIG. 4, “open” means that the state of each of the switches 41 to 43 is open, and “closed” means that the state of each of the switches 41 to 43 is closed. The switching indicates that the switch 41 is alternately switched between an open state and a closed state. Hereinafter, the amplitude of the AC voltage is referred to as a change amount of the AC voltage.

  As shown in FIG. 4, the current flowing in the cell monitoring device 13 changes between when the switch 42 and the switch 43 are in the open state and when the switch 42 and the switch 43 are in the closed state. The magnitude of the voltage waveform changes. Even when one of the switch 42 and the switch 43 is in the open state and the other is in the closed state, the current flowing in the cell monitoring device 13 changes, and the waveform of the AC voltage changes.

  As shown in FIG. 3, even when the switches 42 and 43 are in the open state and the switch 41 is alternately switched between the open state and the closed state, the capacitors CAP1 to CAP3 have the respective switches 41 to 43. Are connected in parallel with each other, the current path in the cell monitoring device 13 is not instantaneously interrupted.

  When the switch 42 and the switch 43 are in the open state, the change amount of the AC voltage is the smallest, and when the switch 42 and the switch 43 are in the closed state, the change amount of the AC voltage is the largest. Further, when one of the switch 42 and the switch 43 is in an open state and the other is in a closed state, the amount of change in the AC voltage is different.

  For this reason, for example, the CPU 15 gives a close command signal to the switch 42 and the switch 43, and when the switch 42 and the switch 43 are in the closed state, gives a switching command signal to the switch 41 and opens the switch 41. Switch alternately between state and closed state. At this time, if the CPU 15 determines that the amount of change in the AC voltage in FIG. 4 has been reduced, it can determine that there is an open mode abnormality switch. The open mode abnormality is an abnormality in which the switch does not enter the closed state even when the CPU 15 gives the close command signal to the switch.

  Further, for example, the CPU 15 gives an open command signal to the switch 42 and the switch 43, and when the switch 42 and the switch 43 are in the open state, gives a switching command signal to the switch 41 to open the switch 41. Switch alternately between closed and closed state. At this time, if the CPU 15 determines that the amount of change in the AC voltage in FIG. 4 has been exceeded, it can determine that there is a short mode abnormality switch. The short mode abnormality is an abnormality in which the switch does not enter the open state even when the CPU 15 gives an open command signal to the switch.

  Furthermore, for example, when the CPU 15 determines that there is a switch that is abnormal in the open mode or determines that there is a switch that is abnormal in the short mode, it gives an open command signal to either the switch 42 or the switch 43. An open state is set, and a close command signal is given to the other to set a close state. Then, the CPU 15 is abnormal by determining that the change amount of the AC voltage at that time does not match the change amount of the AC voltage in FIG. 4 or does not exist within a predetermined range (for example, several tens of mV). A switch can be specified.

  For example, when the switch 41 is in an open mode abnormality or a short mode abnormality, even if the CPU 15 gives a switching command signal to the switch 41, the state of the switch 41 does not change. For this reason, since the switch 41 is in one of the open state and the closed state, no AC voltage is generated. At this time, the amount of change in the AC voltage is approximately 0 mV. That is, if the CPU 15 determines that the amount of change in the AC voltage is approximately 0 mV, it can determine that the switch 41 is in the open mode abnormality or the short mode abnormality.

  Note that “the CPU 15 determines that the change amount of the AC voltage is approximately 0 mV” is not only the case where the change amount of the AC voltage matches 0 mV, but the change amount of the AC voltage is within a predetermined range (for example, , Several tens of mV).

  In the above description, for the sake of simplicity, it has been described that the waveform of the AC voltage changes at the timing when the CPU 15 gives the switching command signal to the switch 41. However, the waveform of the AC voltage changes because of the CPU 15 However, the timing is not limited to exactly the same timing as the timing at which the switching command signal is given to the switch 41, and may be slightly different timing. In short, it suffices if the change amount of the AC voltage due to the CPU 15 giving the switching command signal to the switch 41 can be specified.

(Switch abnormality judgment processing)
When determining that the execution condition is satisfied, the CPU 15 executes a switch abnormality determination process shown in FIG. Examples of execution conditions are that the power of the vehicle has been turned off by the user operating the ignition key, or that the CPU 15 has determined that the reference time has elapsed since the last switch abnormality determination process when the system was stopped. Etc. Hereinafter, the switch 41 may be referred to as a first switch, the switch 42 as a second switch, and the switch 43 as a third switch.

  The CPU 15 first determines whether or not the vehicle or system is stopped (S1). Specifically, the CPU 15 determines whether the vehicle or the system is stopped by determining whether charging / discharging of the assembled battery module 12 is stopped. When the CPU 15 determines that the vehicle or the system is not stopped (S1: NO), the CPU 15 stands by, and when it is determined that the vehicle or the system is stopped (S1: YES), the switch 41 which is the first switch. Is determined to be abnormal (S2).

  “The charging / discharging of the assembled battery module 12 has stopped” is not limited to the case where the assembled battery module 12 has completely stopped charging / discharging, but a load (not shown) to which the assembled battery module 12 is connected. ) Or when a dark current flows through the cell monitoring device 13 (for example, less than several hundred μA).

  In S2, the CPU 15 gives a switching command signal to the switch 41, and causes the AC voltmeter AV to detect the AC voltage at the detection point P. When the CPU 15 determines that the change amount of the AC voltage is not changed (approximately 0 mV) (S2: YES), the CPU 15 determines that the switch 41 is in the open mode abnormality or the short mode abnormality, and sets an error flag. Error processing is executed (S3), and the switch abnormality determination processing is terminated. The switching command signal is an example of a switch signal.

  On the other hand, when the CPU 15 determines that the change amount of the AC voltage is changed (S2: NO), the CPU 15 executes an open mode abnormality determination process shown in FIG. 6 (S4).

(Open mode error judgment processing)
The open mode abnormality determination process is a process in which the CPU 15 causes the AC voltmeter AV to detect the AC voltage at the detection point P and determines whether any of the switches is abnormal in the open mode. Specifically, the CPU 15 alternately gives a switching command signal, that is, an open command signal and a close command signal to the switch 41, and gives an open command signal to the switch 42 and the switch 43. In this state, the CPU 15 causes the AC voltmeter AV to detect the AC voltage at the detection point P. In the following description, it is assumed that the impedance of the assembled battery module 12 with respect to the high-frequency signal is high and can be ignored in the present embodiment.

  CPU15 gives an open command signal to switch 42 and switch 43 except switch 41 which is the 1st switch (S21). Next, the CPU 15 gives a switching command signal to the switch 41 (S22). Specifically, the CPU 15 alternately gives an open command signal and a close command signal to the switch 41. More specifically, the CPU 15 alternately gives an open command signal and a close command signal to the switch 41 at an operating frequency of, for example, 500 kHz. Note that the process of S21 is an example of a command process, and the process of S22 is an example of a switching process. The open command signal given to the switch 42 and the switch 43 in S21 is an example of a command signal.

  The CPU 15 causes the AC voltmeter AV to detect the amplitude (change amount) of the back electromotive force of the reactances L1 to L3 at the detection point P (S23). Specifically, the CPU 15 causes the cell voltage detection circuit 17 to detect the maximum voltage value and the minimum voltage value of the AC voltage at the detection point P, and detects the difference between the AC voltages. Thereafter, the CPU 15 stores the amount of change in the AC voltage in the memory (S24).

  The CPU 15 stops the switching command signal to the switch 41 (S25), and ends the open mode abnormality determination process.

  The CPU 15 compares the change amount of the AC voltage detected in S23 with the open mode abnormality reference value stored in the memory 16 in advance (S5). The CPU 15 determines whether or not at least one of the switches 41 to 43 is in the open mode abnormality by the process of S5. When the CPU 15 determines that the change amount of the AC voltage is smaller than the open mode abnormality reference value (S5: YES), the CPU 15 initializes the switch number to 2 (S6), and performs the open mode abnormality specifying process shown in FIG. Execute (S7). Note that the process of S5 is an example of an abnormality determination process.

(Open mode error identification processing)
This open mode abnormality specifying process is a process in which the CPU 15 causes the AC voltmeter AV to detect the AC voltage at the detection point P and specifies which switch is in the open mode abnormality. Specifically, the CPU 15 alternately gives a switching command signal, that is, an open command signal and a close command signal to the switch 41, and gives an open command signal to the Nth switch. In this state, the CPU 15 causes the AC voltmeter AV to detect the AC voltage at the detection point P.

  First, the CPU 15 gives an open command signal to the switch 41 as the first switch and the switch 42 as the second switch, and gives a close command signal to the other switches (S31). Thereafter, the CPU 15 gives a switching command signal to the switch 41 which is the first switch (S32). Specifically, the CPU 15 alternately gives an open command signal and a close command signal to the switch 41 at an operating frequency of, for example, 500 kHz. Note that the process of S32 is an example of a switching process.

  The CPU 15 causes the cell voltage detection circuit 17 to detect the change amount of the AC voltage at the detection point P (S33). Specifically, the CPU 15 causes the cell voltage detection circuit 17 to detect the maximum voltage value and the minimum voltage value of the AC voltage at the detection point P, and detects the difference between the AC voltages. Thereafter, the CPU 15 stores the amount of change in the AC voltage in the memory (S34).

  CPU15 stops the switching command signal to switch 41 (S35), and complete | finishes an open mode abnormality specific process.

  The CPU 15 compares the change amount of the AC voltage detected in S33 with the open mode abnormality reference value stored in the memory 16 in advance (S8). When the CPU 15 determines that the change amount of the AC voltage is smaller than the open mode abnormality reference value (S8: YES), the switch 42 determines that the open mode is abnormal, and executes error processing such as setting an error flag. (S9), go to S10. Note that the process of S8 is an example of an abnormality determination process.

  When the CPU 15 determines that the change amount of the AC voltage is equal to or greater than the open mode abnormality reference value (S8: NO), the CPU 15 proceeds to S10.

  The CPU 15 determines whether or not the switch number N is the total number of switches (S10). If the CPU 15 determines that the switch number N is not equal to the total number of switches (S10: NO), the CPU 15 increases the switch number N by 1 (S11), and returns to S7. When the CPU 15 determines that the switch number N is equal to the total number of switches (S10: YES), the switch abnormality determination process ends.

  On the other hand, when the CPU 15 determines that the change amount of the AC voltage is equal to or greater than the open mode abnormality reference value (S5: NO), the CPU 15 determines that all the switches 41 to 43 are not in the open mode abnormality, and is illustrated in FIG. Short mode abnormality determination processing is executed (S12).

(Short mode abnormality judgment processing)
This short mode abnormality determination process is a process in which the CPU 15 causes the AC voltmeter AV to detect the AC voltage at the detection point P and determines whether any of the switches is abnormal in the short mode. Specifically, the CPU 15 gives a switching command signal to the switch 41 and gives a closing command signal to the switch 42 and the switch 43. In this state, the CPU 15 causes the AC voltmeter AV to detect the AC voltage at the detection point P.

  CPU15 gives a close command signal to switch 42 and switch 43 except switch 41 which is the 1st switch (S41). Next, the CPU 15 gives a switching command signal to the switch 41 (S42). Specifically, the CPU 15 alternately gives an open command signal and a close command signal to the switch 41. More specifically, the CPU 15 alternately gives an open command signal and a close command signal to the switch 41 at an operating frequency of, for example, 500 kHz. Note that the process of S41 is an example of a command process, and the process of S42 is an example of a switching process. The close command signal given to the switch 42 and the switch 43 in S41 is an example of a command signal.

  The CPU 15 gives a switching command signal to the switch 41 in the process of S42. For this reason, an alternating voltage is generated at the detection point P as a waveform similar to the waveform shown in FIG.

  CPU15 makes cell voltage detection circuit 17 detect the variation | change_quantity of the alternating voltage of reactance L1-L3 in the detection point P (S43). Specifically, the CPU 15 causes the cell voltage detection circuit 17 to detect the maximum voltage value and the minimum voltage value of the AC voltage at the detection point P, and detects the difference between the AC voltages. Thereafter, the CPU 15 stores the amount of change in the AC voltage in the memory (S44).

  The CPU 15 stops the switching command signal to the switch 41 (S45), and ends the short mode abnormality determination process.

  The CPU 15 compares the change amount of the AC voltage detected in S33 with the short mode abnormality reference value stored in the memory 16 in advance (S13). The CPU 15 determines whether or not at least one of the switches 41 to 43 is in the short mode abnormality by the process of S13. When the CPU 15 determines that the change amount of the AC voltage is smaller than the short mode abnormality reference value (S13: NO), the CPU 15 determines that all the switches 41 to 43 are not in the short mode abnormality and performs the switch abnormality determination processing. finish. Note that the process of S13 is an example of an abnormality determination process.

  When the CPU 15 determines that the change amount of the AC voltage is equal to or greater than the short mode abnormality reference value (S13: YES), the switch number N is initialized to 2 (S14), and the short mode abnormality identification process shown in FIG. 9 is executed. (S15).

(Short mode abnormality identification processing)
This short mode abnormality specifying process is a process in which the CPU 15 causes the AC voltmeter AV to detect the AC voltage at the detection point P and specifies which switch is in the short mode abnormality. Specifically, the CPU 15 alternately gives a switching command signal, that is, an open command signal and a close command signal to the switch 41, and gives a close command signal to the Nth switch. In this state, the CPU 15 causes the AC voltmeter AV to detect the AC voltage at the detection point P.

  First, the CPU 15 gives an open command signal to the second switch 42, and gives a close command signal to the other switches (S51). Thereafter, the CPU 15 gives a switching command signal to the switch 41 which is the first switch (S52). Specifically, the CPU 15 alternately gives an open command signal and a close command signal to the switch 41. More specifically, the CPU 15 alternately gives an open command signal and a close command signal to the switch 41 at an operating frequency of, for example, 500 kHz. Note that the process of S32 is an example of a switching process.

  The CPU 15 causes the cell voltage detection circuit 17 to detect the change amount of the AC voltage at the detection point P (S53). Specifically, the CPU 15 causes the AC voltmeter AV to detect the maximum voltage value and the minimum voltage value of the AC voltage at the detection point P, and detects the difference between the AC voltages. Thereafter, the CPU 15 stores the amount of change in the AC voltage in the memory (S54).

  CPU15 stops the switching command signal to switch 41 (S55), and complete | finishes a short mode abnormality specific process.

  The CPU 15 compares the change amount of the AC voltage detected in S53 with the short mode abnormality reference value stored in the memory 16 in advance (S16). When the CPU 15 determines that the amount of change in the AC voltage is equal to or greater than the short mode abnormality reference value (S16: YES), the switch 42 determines that the short mode is abnormal and performs error processing such as setting an error flag. (S17), the process proceeds to S18. Note that the process of S14 is an example of an abnormality determination process.

  If the CPU 15 determines that the change amount of the AC voltage is smaller than the short mode abnormality reference value (S16: NO), the CPU 15 proceeds to S18.

  The CPU 15 determines whether or not the switch number N is the total number of switches (S18). When determining that the switch number N is not equal to the total number of switches (S18: NO), the CPU 15 increases the switch number N by one (S19), and returns to S15. When determining that the switch number N is equal to the total number of switches (S18: YES), the CPU 15 ends the switch abnormality determination process.

(Effect of this embodiment)
The CPU 15 alternately gives an open command signal and a close command signal to the switch 41. And CPU15 detects the variation | change_quantity of alternating voltage. CPU15 judges whether each switch 41-43 is abnormal by comparing the variation | change_quantity of alternating voltage, and the abnormal reference value previously memorize | stored in the memory 16. FIG. As a result, it is possible to detect an abnormality of the switch connected in parallel to the cell while suppressing deterioration in the voltage detection accuracy of the cell as compared with the configuration using the diagnostic resistor.

<Other embodiments>
The technology disclosed in the present specification is not limited to the embodiments described with reference to the above description and drawings, and includes, for example, the following various aspects.

  In the above embodiment, the control unit 34 has one CPU and a memory. However, the control unit is not limited to this, and may include a configuration including a plurality of CPUs, a configuration including a hardware circuit such as ASIC (Application Specific Integrated Circuit), or a configuration including both the hardware circuit and the CPU. For example, a configuration in which part or all of the switch abnormality determination processing is executed by a separate CPU or hardware circuit may be used. Further, the order of these processes may be changed as appropriate.

  In the said embodiment, each cell C1-C3 gave the example which is secondary batteries, such as a lithium ion battery, for example. However, the present invention is not limited thereto, and the cells C1 to C3 may be primary batteries.

  In the above embodiment, the first reactance L1, the second reactance L2, and the third reactance L3 are given as examples of reactance elements. However, the present invention is not limited to this, and a configuration in which a coupling filter is placed over the current path may be used. In short, any configuration that generates a reactance component may be used.

  In the embodiment described above, the CPU 15 has given an example in which an open command signal and a close command signal are alternately given to the switch 41 at an operating frequency of, for example, 500 kHz. However, the present invention is not limited to this, and any potential difference may occur between the first reactance L1, the second reactance L2, and the third reactance L3 before and after the open command signal and the close command signal are alternately applied. The operating frequency may be used.

  In the above embodiment, the filters F1 to F3 are configured to connect the capacitors CAP1 to CAP3 in parallel with the cells C1 to C3, respectively. However, the present invention is not limited to this, and instead of the capacitors CAP1 to CAP3, switches and resistors connected in series may be connected in parallel to the cells C1 to C3, respectively.

  In the above embodiment, the assembled battery module 12 has a configuration in which three first cells C1 to C3 are connected in series. However, the present invention is not limited to this, and the assembled battery module 12 may have a configuration in which one, two cells, or four or more cells are connected in series. Further, the number of switches may be appropriately changed according to the number of cells. In this case, the CPU 15 may be configured to give a switching command signal only to the switch 41 connected to the voltage detection line 21 having the lowest potential in the cell monitoring device 13. For example, the CPU 15 divides a group into a plurality of cells, A configuration may be adopted in which a switching command signal is given to a switch connected to a voltage detection line having the lowest potential in the group, and a switch abnormality determination process is executed for each group.

  In the above embodiment, the detection point P is a connection point on the voltage detection line 24 having the highest potential in the cell monitoring device 13, and the switch to which the CPU 15 gives the switching command signal is in the cell monitoring device 13. The switch 41 is connected to the voltage detection line 21 having the lowest potential. In order to determine the detection point P, the CPU 15 may execute the following processing. That is, when all the switches 41 to 43 are in the open state, the CPU 15 executes the voltage detection process at the detection point P, and compares the obtained amount of change in the AC voltage. Then, the CPU 15 may determine the detection point that is determined to have the largest change amount of the AC voltage as the detection point P.

  In the above embodiment, the detection point P is a connection point on the voltage detection line 24 having the highest potential in the cell monitoring device 13, and the switch to which the CPU 15 gives the switching command signal is in the cell monitoring device 13. The switch 41 is connected to the voltage detection line 21 having the lowest potential. However, the present invention is not limited to this, and the detection point P may be any connection point having a higher potential than the switch to which the CPU 15 gives a switching command signal.

  In the above embodiment, inductive reactances L1 to L3 are connected to the voltage detection lines 22 to 24, respectively. However, the present invention is not limited to this, and in addition to reactances L1 to L3, resistors may be provided in series with the reactances L1 to L3. This resistor only needs to have a relatively small resistance value with respect to the impedance of each reactance L1 to L3.

  The reactance components of the first reactance L1, the second reactance L2, and the third reactance L3 may be substantially the same or different, and the resistance components of the resistor R1, the resistor R2, and the resistor R3 are substantially the same. It may be good or different.

  The switches 41 to 43 may be semiconductor elements such as bipolar transistors and MOSFETs, and may be a normally closed type that is normally closed and is open only when an open command signal is given.

  In the above embodiment, the CPU 15 gives a switching command signal to the switch 41 to generate the back electromotive force of the reactances L1 to L3 at the detection point P as an AC component. However, the present invention is not limited thereto, and an AC component may be generated by providing a completely different AC generation source on the voltage detection line 22 between the reactance L1 and the resistor R1. The position where the AC generation source is provided is not limited to the above, and may be provided between the reactance L2 and the resistor R2 on the voltage detection line 23, or between the reactance L3 and the resistor R3 on the voltage detection line 24. May be provided. Moreover, although the alternating current generation source should just be provided in the said any one place, the said any two places may be sufficient and may be provided in all.

  DESCRIPTION OF SYMBOLS 11: Battery pack 13: Cell monitoring apparatus 14: Cell monitoring part 15: CPU 16: Memory 17: Cell voltage detection circuit 18: Control part 31-33: Equalization circuit 41-43: Switch C1-C3: Cell L1-L3 : Reactance F1 to F3: Filter AV: AC voltmeter

Claims (9)

A discharge circuit connected in parallel to the cell and switching between a state in which the current from the cell can be discharged and a state in which the current cannot be discharged;
A reactance element connected between the cell and the discharge circuit;
A voltage detection unit for detecting an alternating voltage generated by the reactance element via the reactance element;
A control unit;
With
The battery monitoring apparatus, wherein the control unit executes an abnormality determination process for determining whether or not the discharge circuit is abnormal based on a change in the AC voltage. The battery monitoring device according to claim 1,
A bypass circuit connected in parallel to the cell and flowing an AC component current;
The voltage detection unit detects an amplitude of the alternating voltage generated by the reactance element when the discharge circuit is switched between the dischargeable state and the non-dischargeable state;
The controller is
Performing a switching process for providing the discharge circuit with a switching signal for switching between the dischargeable state and the non-dischargeable state;
In the abnormality determination process, the battery monitoring device determines whether or not there is an abnormality in the discharge circuit based on a detection result of the voltage detection unit based on an amplitude of the AC voltage when the switching process is executed. The battery monitoring device according to claim 2,
A plurality of the cells are connected in series;
A plurality of the discharge circuit and the reactance element corresponding to each of the plurality of cells;
The control unit is a battery monitoring device that provides the switching signal to one of the plurality of discharge circuits in the switching process. The battery monitoring device according to claim 2 or claim 3,
The controller is
A command process for providing a command signal for setting the dischargeable state or the non-dischargeable state to a discharge circuit other than the one discharge circuit when the switching signal is applied to the one discharge circuit; A battery monitoring device to execute. The battery monitoring device according to any one of claims 2 to 4,
The said control part is a battery monitoring apparatus which performs the said switching process about the said discharge circuit connected to the said cell with the lowest electric potential among several said discharge circuits. The battery monitoring device according to claim 4 or 5, wherein
The controller is
When giving the switching signal to the one discharge circuit, after executing the command processing to all of the other discharge circuits other than the one discharge circuit, to any one of the other discharge circuits, A battery monitoring device that gives the command signal different from the command signal given in the command processing. The battery monitoring device according to any one of claims 1 to 6,
The battery monitoring device is configured to detect the amplitude of the AC voltage generated at both ends of the plurality of discharge circuits. A storage element;
A power storage device comprising: the battery monitoring device according to any one of claims 1 to 7. A discharge circuit connected in parallel to the cell and switching between a state in which the current from the cell can be discharged and a state in which the current cannot be discharged;
A reactance element connected between the cell and the discharge circuit;
A voltage monitoring unit for detecting an alternating voltage generated by the reactance element via the reactance element, and a battery monitoring method for a battery monitoring device comprising:
A battery monitoring method comprising: an abnormality determination step of determining whether or not the discharge circuit is abnormal based on a change in the AC voltage.

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