JP2015102336A - Battery monitoring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect abnormality of a cell balance circuit with an inexpensive circuit configuration.SOLUTION: In a cell balance circuit 104, a cell-balance switch FET1 to a cell-balance switch FETn short-circuit both ends of respective cells 10-1 to 10-n for electric discharge. CR differential circuits 120-1 to 120-n convert voltages of the cell-balance switch FET1 to the cell-balance switch FETn to a reference voltage level, respectively. A detection IC 121 detects a voltage across a resistance R and outputs a binary electric signal representing an ON/OFF operation of each of the cell-balance switch FET1 to the cell-balance switch FETn to a microcomputer 108.

Description

  The present invention relates to a battery monitoring device for monitoring a battery that operates an electric vehicle such as an electric vehicle (EV) and a hybrid electric vehicle (Hybrid EV; HEV), and particularly detects an abnormality of a cell balance circuit.

  The EV and HEV employ a lithium ion battery as a driving power source. A lithium ion battery is composed of a battery having a voltage of about 4 V called a cell, and a module in which 8 to 10 cells are collected is called a module. 10 to 20 modules are connected in series to form a total battery of 300 to 400V, which is used as a driving power source for EVs and HEVs.

  In order to ensure the soundness of this lithium ion battery, a battery monitoring device is mounted on the vehicle. The battery monitoring device monitors (measures) voltage and temperature, which are important parameters for calculating the state of charge and deterioration of the lithium ion battery.

  Lithium ion batteries vary in the amount of charge in each cell due to individual differences in cells and aging. If the lithium ion battery is used in this state, it may be overcharged or overdischarged, leading to deterioration of the battery and ignition. In order to avoid this, the battery monitoring device is equipped with a cell balance circuit that discharges and equalizes cells with a large amount of charge.

  A conventional cell balance circuit includes a discharge resistor connected to a cell and a switching element such as a field effect transistor (FET) that short-circuits the cell via the discharge resistor, and a battery monitoring IC (Integrated Circuit) is an FET. In general, a cell balance operation is performed such that a current is passed through a discharge resistor to discharge a cell (see, for example, Patent Document 1). When the battery monitoring IC is abnormal, or when the FET is opened or short-circuited, the cell balance operation does not function normally. Therefore, an abnormality diagnosis of the cell balance circuit is necessary.

  Since the module has a structure in which a large number of cells are connected in series, a high voltage is applied to the FET that discharges the high potential side cell. Therefore, in order to detect an abnormality in the cell balance circuit, the drain of the FET of the high potential side cell cannot be directly connected to the voltage detection IC having a low voltage tolerance.

Thus, for example, in Patent Document 1, the voltage between the source and drain of the FET and the reference voltage connected to each cell are compared by a comparator, and an external short circuit of the FET, a short circuit of the discharge resistance, and Openness was detected individually.
For example, there is a method of detecting an abnormality in the cell balance circuit using an IC having a special function such as level shift and insulation processing.

JP 2007-85847 A

  However, the conventional method has a problem that the circuit configuration is complicated, the number of parts is large, and the cost is high.

  The present invention has been made to solve the above-described problems, and detects an abnormality of a cell balance circuit with an inexpensive circuit configuration without using an IC having a special function such as level shift and insulation processing. For the purpose.

  The battery monitoring device according to the present invention is connected between a switch and a discharge resistor for each cell, the switch operates, a cell balance circuit that discharges the cell through the discharge resistor, and is installed between the switch and the discharge resistor, An abnormality detection unit having a CR differentiation circuit that converts a switch voltage into a differential waveform of a reference voltage level and outputs the waveform, and an abnormality diagnosis unit that diagnoses an abnormality of the cell balance circuit based on the output of the abnormality detection unit. is there.

  According to the present invention, since the CR differential circuit (coupling capacitor and resistor) is installed to convert the switch voltage to the reference voltage level, an IC having a special function such as level shift and insulation processing is used. Therefore, the abnormality of the cell balance circuit can be detected with an inexpensive circuit configuration.

It is a circuit diagram which shows the periphery structure of a cell balance circuit among the battery monitoring apparatuses which concern on Embodiment 1 of this invention. It is a block diagram which shows the whole structure of the battery monitoring apparatus which concerns on Embodiment 1. FIG. It is an example of the block diagram of the electric vehicle drive system to which the battery monitoring apparatus which concerns on Embodiment 1 is applied. 3 is a graph showing waveforms of respective parts of the battery monitoring device according to Embodiment 1. It is a circuit diagram which shows the periphery structure of a cell balance circuit among the battery monitoring apparatuses which concern on Embodiment 2 of this invention. 6 is a graph showing waveforms of respective parts of the battery monitoring device according to Embodiment 2. It is a circuit diagram which shows the periphery structure of a cell balance circuit among the battery monitoring apparatuses which concern on Embodiment 3 of this invention. 10 is a graph showing waveforms of respective parts of the battery monitoring device according to Embodiment 3. It is a circuit diagram which shows the periphery structure of a cell balance circuit among the battery monitoring apparatuses which concern on Embodiment 4 of this invention. FIG. 10 is a circuit diagram showing a modification of the cell balance circuit of FIG. 9.

Embodiment 1 FIG.
FIG. 1 is a circuit diagram showing a peripheral structure of the cell balance circuit 104 in the battery monitoring apparatus 100 according to the first embodiment. FIG. 2 is a block diagram showing the overall configuration of the battery monitoring apparatus 100. As shown in FIG. FIG. 3 is an example of a block diagram of an electric vehicle drive system to which the battery monitoring device 100 is applied. A battery 1 mounted on an electric vehicle such as EV and HEV is composed of a lithium ion battery, and is modularized for each of eight cells 11 to 18 connected in series, and a battery monitoring device 100 is connected to each module 10. Has been. In FIG. 2 and FIG. 3, one module 10 is composed of eight cells 11 to 18, but the number of cells is not limited to this. In FIG. 1, one module is composed of n cells 10-1 to 10-n (n is an arbitrary number).

  As shown in FIG. 2, the battery monitoring device 100 is separated into a high voltage side that receives power supply from the module 10 of the battery 1 and a low voltage side that receives power supply from an auxiliary battery (not shown). . Both areas are electrically connected via an isolator 109.

  On the high voltage side of the battery monitoring device 100, the high voltage side power supply circuit 101 generates, for example, a 5V power source using the module 10 of the battery 1 as a power source, and an EEPROM (Electrically Erasable Programmable Read-Only Memory) 102 and a microcomputer (hereinafter, referred to as a power source). (Microcomputer) 108. The EEPROM 102 is a storage element that stores various parameters of the battery monitoring apparatus 100. The module voltage measurement circuit 103 divides the voltage of the module 10 and inputs it to the microcomputer 108.

  The cell balance circuit 104 discharges the cells 11 to 18 individually to equalize the charge amount. Further, the cell balance circuit 104 outputs an abnormality detection result described later to the microcomputer 108. The battery monitoring IC 105 measures the voltages of the cells 11 to 18 and outputs them to the microcomputer 108. The temperature measurement circuit 106 converts the temperature of the cells 11 to 18 into an electrical signal using the temperature sensor 20 and inputs it to the microcomputer 108.

  The microcomputer 108 controls the battery monitoring IC 105 to measure the voltages of the cells 11 to 18 or detects an abnormality of the cell balance circuit 104 via the battery monitoring IC 105. The microcomputer 108 also measures the voltage measurement result of the module 10 by the module voltage measurement circuit 103, the voltage measurement result of the cells 11 to 18 by the battery monitoring IC 105, the temperature measurement result by the temperature measurement circuit 106, and the abnormality detection result by the cell balance circuit 104. Is transmitted to the battery management device 2 via a CAN (Controller Area Network). The watchdog circuit 107 resets the microcomputer 108 when the microcomputer 108 runs away.

  On the other hand, on the low voltage side of the battery monitoring device 100, the low voltage side power supply circuit 110 generates, for example, a 5V power source using an auxiliary battery (not shown) as a power source and supplies it to the CAN communication I / F 111. The CAN communication I / F 111 communicates with the battery management device 2 and other battery monitoring devices 100 via the CAN. The automatic numbering circuit 112 detects the connection order of its own device among the plurality of battery monitoring devices 100 connected to the CAN, and sets it in the EEPROM 102.

Here, the details of the cell balance circuit 104 will be described with reference to FIG.
The basic configuration of the cell balance circuit 104 is cell balance switches FET1 to FETn and discharge resistors R1 to Rn provided for the cells 10-1 to 10-n.

  In the cells 10-1 to 10-n, the charge amount is not always uniform due to the influence of manufacturing variations, self-discharge variations, and aging, and individual differences occur depending on the cells. Therefore, when the cell voltages of the cells 10-1 to 10-n vary, the microcomputer 108 operates the cell balance circuit 104 via the battery monitoring IC 105 to selectively select the cells 10-1 to 10-n. To charge the cells 10-1 to 10-n with the least amount of cells.

  As shown in FIG. 1, in order to measure the cell voltage of the cell 10-1, both electrodes of the cell 10-1 are connected to the cell voltage measurement terminals C0 and C1 of the battery monitoring IC 105. The cell voltage measurement result is transmitted from the battery monitoring IC 105 to the microcomputer 108 by SPI (Serial Peripheral Interface) communication or the like.

  The source of the cell balance switch FET1 is connected to the positive electrode (high potential V1 side) of the cell 10-1, and the drain of the cell balance switch FET1 is connected to the negative electrode (low) of the cell 10-1 via the discharge resistor R1. Potential V0 side). The gate of the cell balance switch FET1 is connected to the cell balance control terminal S1 of the battery monitoring IC 105. When the cell balance operation of the cell 10-1 is performed, a cell balance control signal (ON / OFF signal) is transmitted from the microcomputer 108 to the battery monitoring IC 105 by SPI communication or the like. The battery monitoring IC 105 turns on the cell balance control terminal S1 according to the cell balance control signal, and varies the gate voltage of the cell balance switch FET1. Then, the cell balance switch FET1 is turned on, both ends of the cell 10-1 are short-circuited, and a current flows through the discharge resistor R1 to discharge. When the cell balance operation is not executed, no current flows through the discharge resistor R1 because the cell balance switch FET1 is OFF.

  Similarly to the cell 10-1, the cells 10-2 to 10-n are connected to the cell balance control terminals S2 to Sn of the battery monitoring IC 105. In the cell balance operation, the cell balance switches FET2 to FETn connected in parallel to the cells 10-2 to 10-n are turned on, and the cells 10-2 to 10-n are connected via the discharge resistors R2 to Rn. Will short circuit and discharge.

  Since the module 10 has a structure in which a large number of cells 10-1 to 10-n are connected in series, the voltage levels applied to the cell balance switches FET1 to FETn are different, and the cell balance switch FETn on the high potential side etc. A high voltage is applied to. Therefore, in order to detect an abnormality in the cell balance circuit 104, the drain of the cell balance switch FETn or the like having a high voltage level is connected to a voltage detection IC having a low voltage tolerance (for example, the detection IC 121 or the microcomputer 108 shown in FIG. 1). You cannot connect directly to.

Therefore, in the first embodiment, in order to detect an abnormality in the cell balance switch FET1 and the cell balance control terminal S1 of the cell 10-1, a CR differentiation circuit 120-1 in which a coupling capacitor C and a resistor R are connected in series. Has been added. Similarly to the cell 10-1, the cells 10-2 to 10-n are additionally provided with CR differentiating circuits 120-2 to 120-n. Then, the detection IC 121 detects a change in the voltage across the resistors R of the CR differentiation circuits 120-1 to 120-n, and represents a binary value (High / Low) indicating the ON / OFF operation of each of the cell balance switches FET1 to FETn. ) And output to the microcomputer 108.
The CR differentiation circuits 120-1 to 120-n and the detection IC 121 constitute an abnormality detection unit, and the battery monitoring IC 105 and the microcomputer 108 constitute an abnormality diagnosis unit.

Hereinafter, the CR differentiating circuit 120-1 will be described as a representative of the CR differentiating circuits 120-1 to 120-n.
One end of the coupling capacitor C is connected between the cell balance switch FET1 and the discharge resistor R1, and the other end is connected to the resistor R and the detection IC 121. The resistor R has one end connected to the coupling capacitor C and the detection IC 121, and the other end connected to a reference voltage (here, the same potential as the low potential V0 of the module 10).
As a result, the voltage levels of the cell balance switches FET1 to FETn can be lowered to the reference voltage level by the CR differentiation circuits 120-1 to 120-n and input to the detection IC 121.

  4A shows the waveform of the ON / OFF signal output from the cell balance control terminal S1 to the cell balance switch FET1, and FIG. 4B shows the voltage across the resistor R of the CR differentiation circuit 120-1. The waveform is shown. When the cell balance switch FET1 is switched ON / OFF, the coupling capacitor C is charged and discharged, and the voltage across the resistor R varies. The detection IC 121 outputs High when the positive peak of the voltage across the resistor R is detected (or when the voltage across the positive voltage exceeds the positive threshold), and outputs Low otherwise.

In this circuit configuration, when the microcomputer 108 switches the cell balance operation of the cell 10-1 from OFF to ON, that is, an ON signal is output to the cell balance control terminal S1 of the battery monitoring IC 105 to turn on the cell balance switch FET1. In this case, the voltage across the resistor R of the CR differentiating circuit 120-1 fluctuates when the cell balance switch FET1 is switched ON / OFF, and the electrical signal output from the detection IC 121 becomes High.
On the other hand, while the cell balance operation is OFF, the voltage across the resistor R of the CR differentiation circuit 120-1 does not fluctuate, so the electrical signal output from the detection IC 121 remains low.

Therefore, when the cell balance control terminal S1 and the cell balance switch FET1 for the cell 10-1 are normal, the electric signal of the detection IC 121 changes from Low to High when the cell balance operation is executed.
On the other hand, when an abnormality occurs in one or both of the cell balance control terminal S1 for the cell 10-1 and the cell balance switch FET1, the electric signal of the detection IC 121 is low even if the cell balance operation is executed. Or the electric signal of the detection IC 121 changes from Low to High even though the cell balance operation is not executed.
Therefore, the microcomputer 108 can diagnose the abnormality of the cell balance circuit 104 by comparing the ON / OFF signal of the cell balance control terminals S1 to Sn and the high / low electric signal of the detection IC 121.

  Furthermore, the time constant of the CR differentiation circuit 120-1 is changed by adjusting the capacitance of the coupling capacitor C and the resistance value of the resistor R, and the voltage across the resistor R is changed as shown by the two-dot chain line in FIG. You may comprise so that a fluctuation | variation may be converged quickly. As a result, the abnormality diagnosis of the cell balance circuit 104 can be performed at a faster response speed. In addition, since the number of abnormality diagnoses that can be performed per unit time can be increased by increasing the response speed, for example, the microcomputer 108 repeats the ON / OFF operation of the cell balance switch 100 times for one cell. Diagnosis is performed, and when the number of normal diagnoses exceeds 80, the final diagnosis result is determined to be normal. For example, the diagnostic accuracy can be improved.

  The microcomputer 108 detects the abnormality of the cell balance circuit 104, the measurement result of the cell voltage measured by the battery monitoring IC 105, the measurement result of the module voltage measured by the module voltage measurement circuit 103, and the temperature measurement measured by the temperature measurement circuit 106. The result is output from the CAN communication I / F 111 to the battery management device 2 (shown in FIG. 3) via the isolator 109 together with the unique number of the battery monitoring device 100 set by the automatic numbering circuit 112. The battery management device 2 confirms the state of the module 10 of the battery 1 based on the measurement result, and outputs the confirmation result to the vehicle control device 3 via the CAN as necessary.

  The battery management device 2 is a so-called BMU (Battery Management Unit) that manages the battery 1. For example, the battery management device 2 diagnoses the remaining capacity of the battery 1 based on the voltage measurement result notified from the battery monitoring device 100. Further, the battery management device 2 outputs various measurement results notified from the battery monitoring device 100 to the vehicle control device 3, and receives the notification from the vehicle control device 3 to control the operation of the battery monitoring device 100.

  The vehicle control device 3 is a so-called ECU (Electronic Control Unit) that performs integrated control of the entire electric vehicle, and is connected to a vehicle drive motor 4, a charging connector (not shown), an ignition switch, a display, and the like. For example, the vehicle control device 3 detects on / off of an ignition switch to control the power supply from the battery 1 to each part of the vehicle, or displays information such as the remaining capacity of the battery 1 notified from the battery management device 2 on the display. It is displayed or the battery management device 2 is notified that the connection to the charging connector has been detected and the state has shifted to the chargeable state.

  As described above, according to the first embodiment, the battery monitoring device 100 includes the cell balance switches FET1 to FETn and the discharge resistors R1 to Rn connected to the cells 10-1 to 10-n, and the cell balance switches FET1 to FET1. The FETn operates and is disposed between the cell balance circuit 104 for discharging the cells 10-1 to 10-n through the discharge resistors R1 to Rn, and the cell balance switches FET1 to FETn and the discharge resistors R1 to Rn, respectively. An abnormality detection unit having CR differentiation circuits 120-1 to 120-n for converting the voltage of the cell balance switches FET1 to FETn into a differential waveform of a reference voltage level (V0 in FIG. 1) and outputting the differential waveform; An abnormality diagnosis unit (microcomputer 108) for diagnosing an abnormality in the cell balance circuit 104 based on the output is provided. Therefore, an abnormality in the cell balance circuit 104 can be detected with an inexpensive circuit configuration in which the coupling capacitor C and the resistor R are added. In addition, since no direct current flows into the coupling capacitor C, no current is consumed during diagnosis and there is no influence on the discharge current.

  Further, according to the first embodiment, the abnormality detection unit detects a voltage output from the CR differentiation circuits 120-1 to 120-n, and represents a binary value representing the ON / OFF operation of the cell balance switches FET1 to FETn. The detection IC 121 is configured to output the electrical signal. Since this detection IC 121 converts the ON / OFF information of the cell balance circuit 104 into an electrical signal and outputs it, the microcomputer 108 can easily perform abnormality diagnosis.

  In the first embodiment, the detection IC 121 detects voltage fluctuations of the resistors R of the CR differentiation circuits 120-1 to 120-n. However, when the microcomputer 108 capable of high-speed processing is used, The detection IC 121 may be omitted, and the microcomputer 108 may be configured to detect the voltage fluctuation of each resistor R.

  Further, according to the first embodiment, the abnormality diagnosis unit (the microcomputer 108) repeats the ON / OFF operation of the cell balance switches FET1 to FETn for the set number of times, performs abnormality diagnosis for the number of times, and is normal or The final diagnosis is made according to the number of times diagnosed as abnormal. For this reason, diagnostic accuracy can be improved.

Embodiment 2. FIG.
FIG. 5 is a circuit diagram showing the peripheral structure of cell balance circuit 104 in battery monitoring apparatus 100 according to Embodiment 2 of the present invention. 6A shows the waveform of the ON / OFF signal output from the cell balance control terminal S1 to the cell balance switch FET1, and FIG. 6B shows the voltage across the resistor R of the CR differentiation circuit 120-1. FIG. 6C is a graph showing the waveform of the output voltage of the rectifier diode D1.
5 and 6, the same or corresponding parts as those in FIGS. 1 to 4 are denoted by the same reference numerals and description thereof is omitted.

In the second embodiment, rectifier diodes D1 to Dn are connected between the CR differentiating circuits 120-1 to 120-n and the detection IC 122, and the negative voltage generated by the CR differentiating circuits 120-1 to 120-n is obtained. It removes with the rectifier diodes D1-Dn.
Thereby, a logic IC, a microcomputer, etc. which handle only a positive voltage input can be used as the detection IC 122.

  As described above, according to the second embodiment, the abnormality detection unit has the rectifier diodes D1 to Dn connected between the CR differentiation circuits 120-1 to 120-n and the detection IC 122. For this reason, since the rectifier diodes D1 to Dn remove the negative voltage output from the CR differentiation circuits 120-1 to 120-n, it is possible to use an inexpensive detection IC 122 such as a logic IC or a microcomputer that handles only positive voltage input. it can.

Embodiment 3 FIG.
FIG. 7 is a circuit diagram showing a peripheral structure of cell balance circuit 104 in battery monitoring apparatus 100 according to Embodiment 3 of the present invention. FIG. 8A shows the waveform of the ON / OFF signal output from the cell balance control terminal S1 to the cell balance switch FET1, and FIG. 8B shows the voltage across the resistor R of the CR differentiation circuit 120-1. 8C shows the waveform of the output voltage of the rectifier diode D1, FIG. 8D shows the output waveform of the output terminal Q of the detection IC 123-1, and FIG. It is a graph which shows the input waveform (reset signal) of the reset terminal R of detection IC123-1.
7 and 8, the same or corresponding parts as those in FIGS. 1 to 6 are denoted by the same reference numerals and description thereof is omitted.

  In the third embodiment, logic ICs such as RS latches are used as the detection ICs 123-1 to 123-n that detect the output voltages of the CR differentiation circuits 120-1 to 120-n. For example, when the detection IC 123-1 detects the fluctuation edge of the voltage across the resistor R of the CR differentiation circuit 120-1 that is input to the set terminal S via the rectifier diode D1, the detection IC 123-1 outputs it to the microcomputer 108 from the output terminal Q. Latch the electrical signal high. Further, when a reset signal is input from the microcomputer 108 to the reset terminal R, the detection IC 123-1 releases the latch and sets the electrical signal to Low.

  For example, the microcomputer 108 measures the electrical signals of the detection ICs 123-1 to 123-n at a timing when a predetermined time has elapsed after switching the cell balance operation of the cells 10-1 to 10-n from OFF to ON, and detects the detection IC 123. A reset signal is output to each of -1 to 123-n. Thereby, even the low-speed microcomputer 108 can reliably measure the electrical signals of the detection ICs 123-1 to 123-n. In addition, since the microcomputer 108 does not need to individually measure the timing of electrical signal output from the detection ICs 123-1 to 123-n, the load on the microcomputer 108 can be reduced.

In the third embodiment, the detection ICs 123-1 to 123n are installed for each of the cells 10-1 to 10-n, so that abnormality diagnosis of a plurality of cells can be performed simultaneously.
Moreover, even if abnormality diagnosis of a plurality of cells is performed simultaneously and the abnormality diagnosis is performed at high speed by changing the time constant of the CR differentiation circuits 120-1 to 120-n as described in the first embodiment, Since the consumption current of the CR differentiation circuits 120-1 to 120-n is extremely small, the influence on the discharge current is small.

  As described above, according to the third embodiment, the detection ICs 123-1 to 123-n of the abnormality detection unit detect the rising edges of the voltages output from the CR differentiation circuits 120-1 to 120-n and latch the electric signals. It was configured to be. For this reason, the load on the microcomputer 108 can be reduced, and the low-speed microcomputer 108 can be used.

Embodiment 4 FIG.
FIG. 9 is a circuit diagram showing a peripheral structure of cell balance circuit 104 in battery monitoring apparatus 100 according to Embodiment 4 of the present invention. In FIG. 9, the same or corresponding parts as those in FIGS. 1 to 8 are denoted by the same reference numerals and description thereof is omitted.
In the fourth embodiment, an AD (analog / digital) converter is used as the detection IC 124 that detects the output voltages of the CR differentiation circuits 120-1 to 120-n.

  Further, when an AD converter is used for the detection IC 124, the variation amount of the voltage across each resistor R of the CR differentiation circuits 120-1 to 120-n may be measured and output to the microcomputer 108. In that case, in order to accurately measure the voltage fluctuation amount of the resistor R, it is preferable to use an AD converter having a sample and hold function.

Hereinafter, the cell 10-1 will be described on behalf of the cells 10-1 to 10-n.
The microcomputer 108 estimates the cell voltage of the cell 10-1 from the voltage fluctuation amount of the resistor R measured by the detection IC 124, using preset values of the discharge resistor R1, the coupling capacitor C, and the resistor R. To do. Since the voltage across the resistor R of the CR differentiating circuit 120-1 is directly proportional to the cell voltage of the cell 10-1, the cell voltage of the cell 10-1 estimated from the voltage fluctuation amount of the resistor R and the cell voltage measuring terminals C0, It is possible to diagnose an abnormality of the cell balance circuit 104 by comparing the cell voltage of the cell 10-1 calculated from the potential difference of C1.

  Specifically, when an abnormality occurs in the battery monitoring IC 105, the cell voltage measurement terminals C0, C1, etc., the cell voltage of the cell 10-1 estimated from the voltage fluctuation amount of the resistor R and the cell voltage measurement terminals C0, C1 Since the deviation of the cell voltage of the cell 10-1 calculated from the potential difference of the cell 10-1 becomes large, an abnormality on the path for measuring the cell voltage of the cell 10-1 can be found.

In addition, when abnormality occurs in the discharge resistor R1, the cell voltage of the cell 10-1 estimated from the voltage fluctuation amount of the resistor R is deviated from the assumed cell voltage of the cell 10-1. Is discoverable.
In addition, although the example of FIG. 9 shows the case where there is one discharge resistor R1, as shown in FIG. 10, even when a plurality of discharge resistors R1 are connected in parallel, they occurred in any one of the discharge resistors R1. Anomalies can be found.

  As described above, according to the fourth embodiment, the abnormality detection unit includes the detection IC 124 that measures the fluctuation amount of the voltage output from the CR differentiation circuits 120-1 to 120-n and outputs the measurement value. Since the fluctuation amount of the voltage across the resistors R of the CR differentiating circuits 120-1 to 120-n is directly proportional to the cell voltage, the cell voltage can be calculated from the fluctuation amount measured by the detection IC 124. Therefore, the disconnection of the discharge resistors R1 to Rn can be diagnosed.

  In the first to fourth embodiments, an FET is used as the cell balance switch of the cell balance circuit 104. However, a switching element such as a transistor may be used.

  In addition to the above, within the scope of the present invention, the present invention can be freely combined with each embodiment, modified any component of each embodiment, or omitted any component in each embodiment. Is possible.

  DESCRIPTION OF SYMBOLS 1 Battery (battery), 2 Battery management apparatus, 3 Vehicle control apparatus, 4 Vehicle drive motor, 10 module, 11-18, 10-1-10-n cell, 20 Temperature sensor, 100 Battery monitoring apparatus, 101 High voltage Side power supply circuit, 102 EEPROM, 103 module voltage measurement circuit, 104 cell balance circuit, 105 battery monitoring IC (abnormality diagnosis unit), 106 temperature measurement circuit, 107 watchdog circuit, 108 microcomputer (abnormality diagnosis unit), 109 isolator, 110 Low voltage side power supply circuit, 111 CAN communication I / F, 112 automatic numbering circuit, 120-2 to 120-n CR differentiation circuit (abnormality detection unit), 121, 122, 123-1 to 123-n, 124 detection IC (Abnormality detection unit), C coupling capacitor, C0 to Cn cell voltage measurement terminal, D1 Dn rectifier diode, FET1～FETn cell balancing switch, R resistor, R1 to Rn discharge resistor, S1 to Sn cell balance control terminal.

Claims (6)

A battery monitoring device for monitoring a battery in which a plurality of cells are connected in series,
A switch and a discharge resistor are connected for each cell, and the switch operates to discharge the cell via the discharge resistor,
An anomaly detector having a CR differentiation circuit that is installed between the switch and the discharge resistor, converts the voltage of the switch into a differential waveform of a reference voltage level, and outputs the differential waveform;
A battery monitoring apparatus comprising: an abnormality diagnosis unit that diagnoses an abnormality of the cell balance circuit based on an output of the abnormality detection unit.   The said abnormality detection part has a detection IC which detects the voltage which the said CR differentiation circuit outputs, and outputs the binary electric signal showing ON / OFF operation | movement of the said switch. Battery monitoring device.   3. The battery monitoring apparatus according to claim 2, wherein the detection IC detects a rising edge of a voltage output from the CR differentiation circuit and latches the electric signal.   The battery monitoring device according to claim 1, wherein the abnormality detection unit includes a detection IC that measures a fluctuation amount of a voltage output from the CR differentiation circuit and outputs a measurement value.   5. The battery monitoring device according to claim 2, wherein the abnormality detection unit includes a rectifier diode connected between the CR differentiation circuit and the detection IC.   The abnormality diagnosis unit repeats the ON / OFF operation of the switch for a set number of times, performs abnormality diagnosis for the number of times, and makes a final diagnosis according to the number of times diagnosed as normal or abnormal The battery monitoring device according to any one of claims 1 to 5.

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