Battery monitoring device

Abstract

To provide a battery monitoring device for detecting the cell voltage of each cell of a plurality of battery cells connected in series, in which it is made possible to more elaborately identify the cause of faults detected as broken wire.SOLUTION: Provided is a battery monitoring device 1 for detecting the cell voltage Vc of each cell of a plurality of battery cells connected in series, said battery monitoring device comprising a connection line 2 connected to the electrode of each battery cell C, a discharge path 5 provided to each battery cell C for letting the battery cell C to discharge electricity, a filter circuit 4 provided to the middle region of the connection line 2, and a control processing unit 8 for determining a fault. The control processing unit 8 identifies in which of the battery cell C, the connection line 2, and the filter circuit 4 there is occurrence of broken wire, on the basis of the voltage of the discharge path 5, a cell average voltage representing the average value of a plurality of cell voltages, and a cell voltage.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a battery monitoring device. [Background technology]

[0002] For example, Patent Document 1 discloses a voltage detection device for a battery pack. The voltage detection device disclosed in Patent Document 1 performs fault diagnosis using the individual cell voltages and the total voltage of the cells. The voltage detection device disclosed in Patent Document 1 eliminates the need to provide two unit voltage detection circuits for each unit battery, thereby reducing the number of components. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-134675 Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, a battery monitoring device that detects the state of battery cells, such as the voltage detection device disclosed in Patent Document 1, can detect a disconnection by comparing the cell voltages of each battery cell. This disconnection detection is performed by comparing the cell voltage of a target battery cell with the cell voltages of other battery cells adjacent to that battery cell. However, the cell voltages of two adjacent battery cells can fluctuate significantly due to faults in the transmission line connected to the electrodes of the battery cells, as well as faults in the filter circuit connected to the transmission line or faults in the battery cells themselves. Therefore, it is not possible to determine the type of fault that caused the disconnection simply by comparing the cell voltages of the two battery cells.

[0005] The present invention has been made in consideration of the above-mentioned problems, and aims to enable a battery monitoring device that detects the cell voltage of each of multiple battery cells connected in series to identify in more detail the cause of a failure that is detected as an open circuit. [Means for solving the problem]

[0006] The present invention employs the following configuration as a means for solving the above problems.

[0007] A first aspect of the present invention is a battery monitoring device that detects the cell voltage of each of a plurality of battery cells connected in series, and includes a transmission line connected to the electrodes of each of the battery cells, a discharge unit provided in each of the battery cells to discharge the battery cell, a filter circuit provided midway along the transmission line, and a fault determination unit that determines whether a fault has occurred, based on the voltage of the discharge unit, a cell average voltage which is the average value of a plurality of cell voltages, and the cell voltage. [Effects of the Invention]

[0008] According to the present invention, the fault in the battery cell, the transmission line, or the filter circuit is identified based on the voltage of the discharge section, the average cell voltage which is the average of multiple cell voltages, and the cell voltage, making it possible to identify in more detail the cause of the fault detected as an open circuit. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic configuration diagram of a battery monitoring device according to an embodiment of the present invention; [Figure 2] 1 is an explanatory diagram illustrating a state in which a filter circuit fails in a battery monitoring device according to an embodiment of the present invention. FIG. [Figure 3] FIG. 10 is a schematic diagram showing a voltage change when a filter circuit fails. [Figure 4]1 is an explanatory diagram illustrating a state in which a battery cell has failed in a battery monitoring device according to an embodiment of the present invention; [Figure 5] FIG. 4 is a schematic diagram showing a voltage change when a battery cell fails. [Figure 6] 1 is an explanatory diagram illustrating a state in which a connection line has failed in a battery monitoring device according to an embodiment of the present invention; [Figure 7] FIG. 10 is a schematic diagram showing a voltage change when a connection line breaks down. [Figure 8] 4 is a flowchart illustrating the operation of the battery monitoring device according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a battery monitoring device according to the present invention will be described below with reference to the drawings.

[0011] FIG. 1 is a schematic diagram of a battery monitoring device 1 according to this embodiment. The battery monitoring device 1 according to this embodiment is mounted on an electric vehicle or an electric hybrid vehicle that uses a motor as a power source. The battery monitoring device 1 is mounted on the electric vehicle together with a battery module M, and detects the state of the battery module M. The battery monitoring device 1 also outputs the detected state of the battery module M to a higher-level control device, and performs necessary processing such as discharging based on the detected state of the battery module M.

[0012] The battery module M, which is the detection target of the battery monitoring device 1 of this embodiment, has a plurality of battery cells C connected in series. The battery module M is a secondary battery that supplies DC power to an external load with an output voltage (battery voltage) that is the sum of the electromotive voltages of the plurality of battery cells C. The battery module M is, for example, a lithium ion battery.

[0013] In this embodiment, for convenience of explanation, the battery module M is assumed to include three battery cells C. However, the number of battery cells C included in the battery module M is not limited to this. In other words, the battery module M may include four or more battery cells C. In the following explanation, of the three battery cells C, the battery cell C with the highest potential will be referred to as the first battery cell C1, the battery cell C with the next highest potential after the first battery cell C1 will be referred to as the second battery cell C2, and the battery cell C with the lowest potential will be referred to as the third battery cell C3. The negative terminal of the third battery cell C3 is connected to ground.

[0014] As shown in FIG. 1, the battery monitoring device 1 of this embodiment includes a connection line 2 (transmission path), a fuse 3, a filter circuit 4, a discharge path 5 (discharge section), a power supply path 6, a voltage detection IC 7, and a control processing section 8.

[0015] The connection lines 2 are transmission paths that transmit voltage information of the battery cells C from the battery cells C to the voltage detection IC 7, with one end connected to an electrode of the battery cell C and the other end connected to the voltage detection IC 7. In this embodiment, the connection lines 2 include a first connection line 2a connected to the positive terminal of the first battery cell C1, a second connection line 2b connected to the negative terminal of the first battery cell C1 and the positive terminal of the second battery cell C2, and a third connection line 2c connected to the negative terminal of the second battery cell C2 and the positive terminal of the second battery cell C2. The number of connection lines 2 varies depending on the number of battery cells C. In other words, as the number of battery cells C included in the battery module M increases, the number of connection lines 2 also increases.

[0016] The fuses 3 are provided in the middle of each of the connection wires 2. When an excessive current flows through the connection wires 2, the fuses 3 melt and cut off the connection wires 2, electrically disconnecting the connection wires 2. As shown in FIG. 1, the fuses 3 are provided in the same number as the connection wires 2.

[0017] The filter circuit 4 is provided in a midpoint of each connecting line 2. In this embodiment, the filter circuit 4 is provided closer to the voltage detection IC 7 than the fuse 3. Each filter circuit 4 is a low-pass filter that removes high-frequency components flowing through the connecting line 2, and includes a resistor 41 and a ceramic capacitor 42.

[0018] The discharge path 5 is a path that has a discharge resistor 51, and is connected to the connection line 2 and the voltage detection IC 7. In this embodiment, one end of the discharge path 5 is connected to the connection line 2 between the fuse 3 and the filter circuit 4. A discharge path 5 is provided for each connection line 2. In other words, the discharge paths 5 include a first discharge path 5a connected to the first connection line 2a, a second discharge path 5b connected to the second connection line 2b, and a third discharge path 5c connected to the third connection line 2c.

[0019] The first discharge path 5a and the second discharge path 5b are connected via a switch provided inside the voltage detection IC 7. When the first discharge path 5a and the second discharge path 5b are electrically connected, a current flows from the positive terminal to the negative terminal of the first battery cell C1 via the first discharge path 5a and the second discharge path 5b, thereby discharging the first battery cell C1.

[0020] The second discharge path 5b and the third discharge path 5c are connected via a switch provided inside the voltage detection IC 7. When the second discharge path 5b and the third discharge path 5c are electrically connected, a current flows from the positive terminal to the negative terminal of the second battery cell C2 via the second discharge path 5b and the third discharge path 5c, thereby discharging the second battery cell C2.

[0021] The third discharge path 5c is connected to ground via a switch provided inside the voltage detection IC 7. When the third discharge path 5c is connected to ground, a current flows from the positive terminal to the negative terminal of the third battery cell C3 via the third discharge path 5c, thereby discharging the third battery cell C3.

[0022] Alternatively, a connection line (fourth connection line) may be provided that connects the negative electrode of the third battery cell C3 to the voltage detection IC 7, and a discharge path (fourth discharge path) connected to this connection line. In this case, the third discharge path 5c and the fourth discharge path are connected via a switch inside the voltage detection IC 7.

[0023] The power supply path 6 connects the first connection line 2a and the voltage detection IC 7, and is a path for supplying power from the battery module M to the voltage detection IC 7 connected to ground. As shown in FIG. 1, a filter circuit 4 is also provided midway along the power supply path 6.

[0024] The voltage detection IC 7 is an integrated circuit that detects the voltage (cell voltage Vc) of each battery cell C of the battery module M. As shown in FIG. 1, the voltage detection IC 7 has multiple cell voltage detection units 71 that detect the cell voltage Vc based on the potential difference between two connection lines 2. For example, the cell voltage detection unit 71 connected to the first connection line 2a and the second connection line 2b detects the cell voltage of the first battery cell C1. Meanwhile, the cell voltage detection unit 71 connected to the second connection line 2b and the third connection line 2c detects the cell voltage of the second battery cell C2.

[0025] The voltage detection IC 7 also has a plurality of discharge path voltage detection units 72 that detect the voltages of the discharge paths 5 (discharge path voltages Vr). Here, the discharge path voltages Vr of the discharge paths 5 refer to the potential difference between the two discharge paths 5 that are connected. That is, the discharge path voltage detection units 72 detect the potential difference between the two discharge paths 5 as the discharge path voltage Vr. For example, the discharge path voltage detection unit 72 connected to the first discharge path 5a and the second discharge path 5b detects the potential difference between the first discharge path 5a and the second discharge path 5b as the discharge path voltage Vr. Furthermore, the discharge path voltage detection unit 72 connected to the second discharge path 5b and the third discharge path 5c detects the potential difference between the second discharge path 5b and the third discharge path 5c as the discharge path voltage Vr.

[0026] Furthermore, the voltage detection IC7 detects the output voltage (module voltage Vm) of the battery module M. The voltage detection IC7 detects the potential difference between the power supply path 6 and the ground as the module voltage Vm.

[0027] As described above, the voltage detection IC 7 has switches connected to the two discharge paths 5. For example, the voltage detection IC 7 opens and closes the switches under the control of the control processing unit 8 to cause the battery cell C to discharge.

[0028] The control processing unit 8 performs processing based on the detection result of the voltage detection IC 7. The control processing unit 8 is, for example, a microprocessor, a microcomputer, a CPU (Central Processing Unit), or a DSP (Digital Signal Processor). The control processing unit 8 is capable of executing computer programs and performs operations by executing the computer programs.

[0029] 1, the control processing unit 8 has, as functional units, a fault detection unit 81, a disconnection detection unit 82, and a fault location identification unit 83. In addition to the above functional units, the control processing unit 8 also has a discharge processing unit (not shown) and the like.

[0030] The fault detection unit 81 detects that a fault has occurred in a part of the battery module M or the battery monitoring device 1. For example, the fault detection unit 81 determines that a fault has occurred when a certain cell voltage Vc fluctuates significantly with respect to the other cell voltages Vc. Note that the method of fault detection in the fault detection unit 81 is not particularly limited.

[0031] When a failure is detected by the failure detection unit 81, the disconnection detection unit 82 determines whether the cause of the failure is a disconnection. Note that a disconnection here means a state in which power supply from each battery cell C to the voltage detection IC 7 has stopped. For example, the disconnection detection unit 82 executes a predetermined process, and if the cause of the failure is, for example, the voltage detection IC, determines that the cause of the failure is not a disconnection.

[0032] When a disconnection is detected by the disconnection detection unit 82, the failure location identification unit 83 identifies the cause of the disconnection. In this embodiment, when a disconnection is detected, the failure location identification unit 83 identifies whether the failure has occurred in the battery cell C, the connection line 2, or the filter circuit 4. Furthermore, in this embodiment, the failure location identification unit 83 identifies whether the failure has occurred in the battery cell C, the connection line 2, or the filter circuit 4 based on the discharge path voltage Vr, the cell average voltage Vave which is the average value of multiple cell voltages, and the cell voltage Vc. The cell average voltage Vave is calculated, for example, by dividing the module voltage Vm by the number of battery cells C (3 in this embodiment).

[0033] Here, we will explain the case where an abnormality is found in the cell voltage Vc of the second battery cell C2 and an open circuit is detected. For example, as shown in Figure 2, assume that the cause of the open circuit is the ceramic capacitor 42 of the filter circuit 4 provided in the second connection line 2b. In this case, as shown in Figure 3, the cell voltage Vc of the first battery cell C1 detected by the voltage detection IC7 increases from the time the failure occurs, and the cell voltage Vc of the second battery cell C2 detected by the voltage detection IC7 decreases from the time the failure occurs.

[0034] On the other hand, if the cause of the disconnection is the ceramic capacitor 42 of the filter circuit 4 provided on the second connection line 2b, the discharge path voltage Vr based on the second discharge path 5b connected to the positive electrode of the second battery cell C2 (i.e., the second connection line 2b) and the third discharge path 5c connected to the negative electrode of the second battery cell C2 (i.e., the third connection line 2c) will not change from the time when the failure occurred. In addition, the cell average voltage Vave will also not change from the time when the failure occurred. Therefore, if the cause of the disconnection is the ceramic capacitor 42 of the filter circuit 4 provided on the second connection line 2b, a large difference will occur between the cell voltage Vc of the second battery cell C2 and the discharge path voltage Vr.

[0035] For example, suppose the cause of the disconnection is a failure of the second battery cell C2, as shown in FIG. 4. In this case, as shown in FIG. 5, the cell voltage Vc of the second battery cell C2 detected by the voltage detection IC drops from the time the failure occurs. Note that the cell voltage Vc of the first battery cell C1 does not drop. Furthermore, the discharge path voltage Vr based on the second discharge path 5b connected to the positive electrode of the second battery cell C2 (i.e., the second connection line 2b) and the third discharge path 5c connected to the negative electrode of the second battery cell C2 (i.e., the third connection line 2c) also drops from the time the failure occurs. As a result, there is no significant difference between the cell voltage Vc of the second battery cell C2 and the discharge path voltage Vr. Furthermore, due to the failure of the second battery cell C2, the module voltage Vm drops by the amount of one battery cell.

[0036] In this way, when the second battery cell C2 fails, there is no large difference between the cell voltage Vc of the second battery cell C2 and the discharge path voltage Vr. On the other hand, when the second battery cell C2 fails, there is a large difference between the cell voltage Vc of the second battery cell C2 and the cell average voltage Vave.

[0037] Also, for example, as shown in FIG. 6, suppose the cause of the disconnection is a failure of the second connection line 2b. In this case, as shown in FIG. 7, the cell voltage Vc of the second battery cell C2 detected by the voltage detection IC drops from the time the failure occurs. Note that the cell voltage Vc of the first battery cell C1 rises from the time the failure occurs. Also, the discharge path voltage Vr based on the second discharge path 5b connected to the positive electrode of the second battery cell C2 (i.e., the second connection line 2b) and the third discharge path 5c connected to the negative electrode of the second battery cell C2 (i.e., the third connection line 2c) also drops from the time the failure occurs. As a result, there is no significant difference between the cell voltage Vc of the second battery cell C2 and the discharge path voltage Vr. Also, the module voltage Vm does not change due to the failure of the second battery cell C2.

[0038] In this way, when the second connection line 2b fails, there is no large difference between the cell voltage Vc of the second battery cell C2 and the discharge path voltage Vr. On the other hand, when the second connection line 2b fails, there is an even larger difference between the cell voltage Vc of the second battery cell C2 and the average cell voltage Vave than when the second battery cell C2 fails.

[0039] As described above, when comparing the cases where the filter circuit 4 fails, the second battery cell C2 fails, and the second connection line 2b fails, a difference occurs between the cell voltage Vc of the second battery cell C2 and the discharge path voltage Vr only when the filter circuit 4 fails. Therefore, the failure point identification unit 83 compares the cell voltage Vc with the discharge path voltage Vr, and if there is a difference between them that is greater than a predetermined threshold (first threshold), it determines that the filter circuit 4 has failed.

[0040] On the other hand, if there is no difference between the cell voltage Vc of the second battery cell C2 and the discharge path voltage Vr, the fault is determined to be in the second battery cell C2 or the second connection line 2b. Therefore, if there is no difference between the cell voltage Vc of the second battery cell C2 and the discharge path voltage Vr, the fault location identification unit 83 determines that there is a fault in the second battery cell C2 or the second connection line 2b.

[0041] Furthermore, when comparing the case where the second battery cell C2 fails with the case where the second connection line 2b fails, the difference between the second battery cell C2 and the cell average voltage Vave is larger when the second battery cell C2 fails than when the second connection line 2b fails. Therefore, the failure location identification unit 83 determines that the second battery cell C2 has failed when there is no difference between the cell voltage Vc and the discharge path voltage Vr of the second battery cell C2 and the difference between the second battery cell C2 and the cell average voltage Vave is larger than the threshold value (second threshold value). On the other hand, when there is no difference between the cell voltage Vc and the discharge path voltage Vr of the second battery cell C2 and the difference between the second battery cell C2 and the cell average voltage Vave is smaller than the threshold value (second threshold value), the failure location identification unit 83 determines that the second connection line 2b has failed.

[0042] Next, the operation of the battery monitoring device 1 of this embodiment will be described with reference to Fig. 8. Fig. 8 is a flowchart for explaining the process (identification process) for the battery monitoring device 1 of this embodiment to identify the fault location.

[0043] As shown in Fig. 8, this process starts when the failure detection unit 81 of the control processing unit 8 detects a failure. When the failure detection unit 81 detects a failure in any of the battery cells C, the control processing unit 8 sets the battery cell C in which the failure is detected as a target battery cell C and determines whether or not an open circuit has been detected (step S1). Here, the control processing unit 8 determines that an open circuit has been detected if the open circuit detection unit 82 detects an open circuit. On the other hand, the control processing unit 8 determines that an open circuit has not been detected if the open circuit detection unit 82 does not detect an open circuit.

[0044] If no open circuit is detected in step S1, the fault is not one for which the fault location can be identified by this identification process, so the control processing unit 8 determines that the fault is not subject to the identification process and terminates this process. On the other hand, if an open circuit is detected in step S1, the control processing unit 8 causes the fault location identification unit 83 to compare the cell voltage Vc of the target battery cell C with the potential difference (discharge path voltage Vr) between the discharge path 5 connected to the positive electrode of the target battery cell C and the discharge path 5 connected to the negative electrode of the target battery cell C (step S3).

[0045] Next, the control processing unit 8 determines whether the difference between the cell voltage Vc of the target battery cell C and the discharge path voltage Vr exceeds a first threshold value by using the failure location identification unit 83 (step S4). As a result, if the difference between the cell voltage Vc of the target battery cell C and the discharge path voltage Vr exceeds the first threshold value, the failure location identification unit 83 determines that the fault is in the filter circuit 4 connected to the positive electrode of the target battery cell C (step S5).

[0046] On the other hand, if the difference between the cell voltage Vc of the target battery cell C and the discharge path voltage Vr does not exceed the first threshold value in step S4, the control processing unit 8 causes the fault location identification unit 83 to compare the cell voltage Vc of the target battery cell C with the cell average voltage Vave (step S6).

[0047] Next, the control processing unit 8 determines whether or not the difference between the cell voltage Vc of the target battery cell C and the average cell voltage Vave exceeds a second threshold value using the failure location identification unit 83 (step S7). As a result, if the difference between the cell voltage Vc of the target battery cell C and the average cell voltage Vave exceeds the second threshold value, the failure location identification unit 83 determines that the target battery cell C is faulty (step S8).

[0048] On the other hand, if the difference between the cell voltage Vc of the target battery cell C and the average cell voltage Vave does not exceed the second threshold value in step S7, the fault location identification unit 83 determines that there is a fault in the connection line 2 connected to the positive electrode of the target battery cell C (step S9).

[0049] As described above, the battery monitoring device 1 of this embodiment detects the cell voltage Vc of each of the multiple battery cells C connected in series. The battery monitoring device also includes a connection line 2, a discharge path 5, a filter circuit 4, and a control processing unit 8. The connection line 2 is connected to the electrodes of each battery cell C. The discharge path 5 is provided in each battery cell C and allows discharge to the battery cell C. The filter circuit 4 is provided in a location along the connection line 2. The control processing unit 8 determines whether a fault has occurred. The control processing unit 8 also identifies whether a fault has occurred in the battery cell C, the connection line 2, or the filter circuit 4 based on the voltage of the discharge path 5 (discharge path voltage Vr), the cell average voltage Vave which is the average value of the multiple cell voltages Vc, and the cell voltage Vc.

[0050] The battery monitoring device 1 of this embodiment identifies whether a fault has occurred in the battery cell C, the connection line 2, or the filter circuit 4 based on the discharge path voltage Vr, the cell average voltage Vave, which is the average value of multiple cell voltages Vc, and the cell voltage Vc. Therefore, the battery monitoring device 1 of this embodiment can identify in more detail the cause of the fault detected as a disconnection.

[0051] Furthermore, in the battery monitoring device 1 of this embodiment, the control processing unit 8 determines that a fault has occurred in the filter circuit 4 when there is a difference between the cell voltage Vc of a target battery cell C, which is one of the multiple battery cells C, and the discharge path voltage Vr provided in the target battery cell C.

[0052] As described above, a failure in the filter circuit 4 can be determined based on the difference between the cell voltage Vc of the target battery cell C and the discharge path voltage Vr of the discharge path 5 connected to the target battery cell C. Therefore, according to the battery monitoring device 1 of this embodiment, a failure in the filter circuit 4 can be detected more reliably.

[0053] Furthermore, in the battery monitoring device 1 of this embodiment, when there is a difference between the cell voltage Vc of a target battery cell C, which is one of the multiple battery cells C, and the cell average voltage Vave, the control processing unit 8 determines that a fault has occurred in the target battery cell C or the connection line 2 connected to the target battery cell C.

[0054] As described above, if the target battery cell C is not faulty, by checking that there is a difference between the cell voltage Vc of the target battery cell C and the average cell voltage Vave, it can be determined that a fault has occurred in the target battery cell C or the connection line 2 connected to the target battery cell C. Therefore, according to the battery monitoring device 1 of this embodiment, it is possible to more reliably determine that a fault has occurred in the target battery cell C or the connection line 2 connected to the target battery cell C.

[0055] Furthermore, in the battery monitoring device 1 of this embodiment, the control processing unit 8 determines that a fault has occurred in the target battery cell C when the difference between the cell voltage Vc of the target battery cell C and the average cell voltage Vave is smaller than a predetermined threshold. Furthermore, the control processing unit 8 determines that a fault has occurred in the connection line 2 connected to the target battery cell C when the difference between the cell voltage Vc of the target battery cell C and the average cell voltage Vave is larger than the threshold.

[0056] As described above, when the difference between the cell voltage Vc of the target battery cell C and the average cell voltage Vave is relatively small, it can be determined that a fault has occurred in the target battery cell C. On the other hand, when the difference between the cell voltage Vc of the target battery cell C and the average cell voltage Vave is relatively large, it can be determined that a fault has occurred in the connection line 2 connected to the target battery cell C. Therefore, the battery monitoring device 1 of this embodiment makes it possible to reliably determine whether a fault has occurred in the target battery cell C or in the connection line 2 connected to the target battery cell C.

[0057] Furthermore, in the battery monitoring device 1 of this embodiment, the control processing unit 8 determines, based on the cell voltage Vc, whether or not a disconnection has occurred, which is a state in which power supply has stopped from a target battery cell C that is one of the multiple battery cells C. Furthermore, if the control processing unit 8 determines that a disconnection has occurred, it identifies whether the fault has occurred in the battery cell C, the connection line 2, or the filter circuit 4.

[0058] According to the battery monitoring device 1 of this embodiment, the process of identifying the fault location is performed only when a disconnection is detected. Therefore, the processing load on the control processing unit 8 can be reduced compared to when the process of identifying the fault location is performed all the time.

[0059] While the preferred embodiments of the present invention have been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to the above-described embodiments. The shapes and combinations of the components shown in the above-described embodiments are merely examples, and various modifications can be made based on design requirements, etc., without departing from the spirit of the present invention.

[0060] For example, in the above embodiment, the control processing unit 8 has been described as having the functional units of the failure detection unit 81, the disconnection detection unit 82, and the failure location identification unit 83. However, the present invention is not limited to this. For example, it is also possible to adopt a configuration in which the voltage detection IC 7 has some or all of the failure detection unit 81, the disconnection detection unit 82, and the failure location identification unit 83. It is also possible to adopt a configuration in which a control unit higher than the control processing unit 8 has some or all of the failure detection unit 81, the disconnection detection unit 82, and the failure location identification unit 83.

[0061] The above embodiment can also be described as follows, for example:

[0062] (Appendix 1) A battery monitoring device that detects the cell voltage of each of a plurality of battery cells connected in series, a transmission line connected to an electrode of each of the battery cells; a discharge unit provided in each of the battery cells to discharge the battery cells; a filter circuit provided in a middle portion of the transmission line; a failure determination unit for determining a failure; Equipped with The failure determination unit determines whether a failure has occurred in the battery cell, the transmission line, or the filter circuit based on the voltage of the discharge unit, an average cell voltage that is an average value of a plurality of cell voltages, and the cell voltage. A battery monitoring device characterized by:

[0063] (Appendix 2) The battery monitoring device described in Appendix 1, characterized in that the failure determination unit determines that a failure has occurred in the filter circuit when there is a difference between the cell voltage of a target battery cell, which is one of the multiple battery cells, and the voltage of the discharge unit provided in the target battery cell.

[0064] (Appendix 3) The battery monitoring device described in Appendix 2, characterized in that the fault determination unit determines that a fault has occurred in the target battery cell or the transmission line connected to the target battery cell when there is a difference between the cell voltage of the target battery cell, which is one of the multiple battery cells, and the average cell voltage.

[0065] (Appendix 4) The failure determination unit determining that a fault has occurred in the target battery cell when a difference between the cell voltage of the target battery cell and the average cell voltage is smaller than a predetermined threshold value; When the difference between the cell voltage of the target battery cell and the average cell voltage is greater than the threshold value, it is determined that a fault has occurred in the transmission line connected to the target battery cell. 4. The battery monitoring device according to claim 3.

[0066] (Appendix 5) The failure determination unit determining whether or not a disconnection has occurred, in which power supply from a target battery cell that is one of the plurality of battery cells has stopped, based on the cell voltage; When it is determined that the disconnection has occurred, it is determined whether the failure has occurred in the battery cell, the transmission line, or the filter circuit. 5. The battery monitoring device according to any one of claims 1 to 4. [Explanation of symbols]

[0067] 1... Battery monitoring device, 2... Connection line (transmission path), 2a... First connection line, 2b... Second connection line, 2c... Third connection line, 3... Fuse, 4... Filter circuit, 41... Resistor, 42... Ceramic capacitor, 5... Discharge path (discharge section), 5a... First discharge path, 5b... Second discharge path, 5c... Third discharge path, 6... Power supply path, 7... Voltage detection IC, 8... Control processing section (failure determination section), 81... Fault detection section, 82... Open circuit detection section, 83... Fault location identification section, C... Battery cell, C1... First battery cell, C2... Second battery cell, C3... Third battery cell, M... Battery module

Claims

1. A battery monitoring device that detects the cell voltage of each of a plurality of battery cells connected in series, a transmission line connected to an electrode of each of the battery cells; a discharge unit provided in each of the battery cells to discharge the battery cells; a filter circuit provided in a middle portion of the transmission line; a failure determination unit for determining a failure; Equipped with The failure determination unit determines whether a failure has occurred in the battery cell, the transmission line, or the filter circuit based on the voltage of the discharge unit, an average cell voltage that is an average value of a plurality of cell voltages, and the cell voltage. A battery monitoring device characterized by:

2. The battery monitoring device according to claim 1, characterized in that the failure determination unit determines that a failure has occurred in the filter circuit when there is a difference between the cell voltage of a target battery cell, which is one of the plurality of battery cells, and the voltage of the discharge unit provided in the target battery cell.

3. The battery monitoring device according to claim 2, characterized in that the fault determination unit determines that a fault has occurred in the target battery cell or the transmission line connected to the target battery cell when there is a difference between the cell voltage of the target battery cell, which is one of the plurality of battery cells, and the average cell voltage.

4. The failure determination unit determining that a fault has occurred in the target battery cell when a difference between the cell voltage of the target battery cell and the average cell voltage is smaller than a predetermined threshold value; When the difference between the cell voltage of the target battery cell and the average cell voltage is greater than the threshold value, it is determined that a fault has occurred in the transmission line connected to the target battery cell.

4. The battery monitoring device according to claim 3.

5. The failure determination unit determining whether or not a disconnection has occurred, in which power supply from a target battery cell that is one of the plurality of battery cells has stopped, based on the cell voltage; When it is determined that the disconnection has occurred, it is determined whether the failure has occurred in the battery cell, the transmission line, or the filter circuit.

5. The battery monitoring device according to claim 1, wherein the battery monitoring device is a power supply.

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