JP2014206453A - Battery monitoring device - Google Patents

Abstract

An abnormality of a cell balance circuit is detected by a simple and inexpensive circuit configuration.
In a cell balance circuit 104, cell balance switches FET1 to FET8 are discharged by short-circuiting both ends of each cell 11-18, and photocouplers PC1 to PC8 are operated by the discharge current. Based on the input signals from the light receiving elements Q1 to Q8 of the photocouplers PC1 to PC8 to the input terminal Vin, the microcomputer 108 detects the abnormality of the cell balance control terminals VB1 to VB8 that are the cause of the abnormality of the cell balance circuit 104 and the cell balance. The open and short circuits of the switches FET1 to FET8 are detected.
[Selection] Figure 1

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.

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 abnormality detection method disclosed in Patent Document 1 requires a reference voltage source, a comparator, and the like, which complicates the circuit configuration and increases the number of parts. Further, the special IC as described above is expensive.

  Thus, the conventional method has a problem that a circuit for detecting an abnormality of the cell balance circuit cannot be configured simply and inexpensively.

  The present invention has been made to solve the above-described problems, and an object thereof is to detect an abnormality of a cell balance circuit with a simple and inexpensive circuit configuration.

  The battery monitoring device according to the present invention includes a cell balance circuit in which a switch and a discharge resistor are connected to each cell, the switch short-circuits both ends of the cell via the discharge resistor, and light emission that emits light by the discharge current of the cell. Comprising an element and a light receiving element that receives the emitted light and outputs a signal, and includes an abnormality detecting unit provided for each switch, and an abnormality diagnosing unit that diagnoses an abnormality in the cell balance circuit based on a signal from the light receiving element It is.

  According to the present invention, it is possible to detect an abnormality in the cell balance circuit with a simple and inexpensive circuit configuration using a light emitting element and a light receiving element.

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. 6 is a diagram for explaining a method for detecting an abnormality of the cell balance circuit according to the first embodiment; FIG. 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. FIG. 10 is a diagram for explaining an abnormality detection method for a cell balance circuit according to the second embodiment. 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. 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. It is a circuit diagram which shows the periphery structure of a cell balance circuit among the battery monitoring apparatuses which concern on Embodiment 5 of this invention.

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 the illustrated example, one module 10 is composed of eight cells 11 to 18, but the number of cells is not limited to this.

  The battery monitoring apparatus 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, details of the cell balance circuit 104 and the battery monitoring IC 105 will be described.
The basic configuration of the cell balance circuit 104 is cell balance switches FET1 to FET8 and discharge resistors R1 to R8 provided for the cells 11 to 18, respectively. In the first embodiment, in order to detect an abnormality in the cell balance circuit 104 including the cell balance switches FET1 to FET8 and the discharge resistors R1 to R8, the photocouplers PC1 to PC1 connected in parallel to the discharge resistors R1 to R8 are used. A PC 8 and current limiting resistors R11 to R18, and a 5V power source and a pull-up resistor R21 supplied from the high voltage side power supply circuit 101 are added.
Photocouplers PC1 to PC8 constitute an abnormality detection unit, and battery monitoring IC 105 and microcomputer 108 constitute an abnormality diagnosis unit.

  In the cells 11 to 18, the amount of charge is not necessarily uniform due to variations in manufacturing, variations in self-discharge, and aging, and individual differences occur depending on the cells. Therefore, when variation occurs in the cell voltages of the cells 11 to 18, the microcomputer 108 operates the cell balance circuit 104 via the battery monitoring IC 105 to selectively discharge the cells 11 to 18. Match the charge of 18 to the smallest cell.

  As shown in FIG. 1, in order to measure the cell voltage of the cell 11, both electrodes of the cell 11 are connected to the cell voltage measurement terminals C <b> 1 and C <b> 2 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 of the cell 11, and the drain of the cell balance switch FET1 is connected to the negative electrode of the cell 11 via the discharge resistor R1. The gate of the cell balance switch FET1 is connected to the cell balance control terminal VB1 of the battery monitoring IC 105. When the cell balance operation of the cell 11 is performed, a cell balance control 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 VB1 in accordance with the cell balance control signal, and applies a voltage to the gate of the cell balance switch FET1. Then, the cell balance switch FET1 is turned on, both ends of the cell 11 are short-circuited, and a current flows through the discharge resistor R1 to perform 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 11, the cells 12 to 18 are connected to the cell voltage measurement terminals C <b> 2 to C <b> 9 of the battery monitoring IC 105. In the cell balance operation, the cell balance switches FET2 to FET8 connected in parallel to the cells 12 to 18 are turned on, and the cells 12 to 18 are short-circuited and discharged through the discharge resistors R2 to R8.
In the illustrated example, the FET is used for the cell balance switch, but the present invention is not limited to this.

  In this cell balance circuit 104, in order to detect an abnormality in the cell balance switch FET1 and the cell balance control terminal VB1, the photocoupler PC1 is arranged in parallel with the discharge resistor R1, and the photocoupler PC1 is operated with a discharge current. In the illustrated example, a photodiode is used as the light emitting element D1 of the photocoupler PC1, and a phototransistor is used as the light receiving element Q1.

  The light-emitting element D1 of the photocoupler PC1 is connected to the drain of the cell balance switch FET1 via the current limiting resistor R11, and the photocoupler PC1 operates by the ON operation of the cell balance switch FET1. The collector of the light receiving element Q1 of the photocoupler PC1 is connected to a 5V power supply via a pull-up resistor R21, and the emitter of the light receiving element Q1 is grounded. Further, the connection point between the collector of the light receiving element Q1 and the pull-up resistor R21 is connected to the input terminal Vin of the microcomputer 108, and the input signal to the input terminal Vin is pulled up to High while the photocoupler PC1 is OFF. When the photocoupler PC1 operates, the input signal to the input terminal Vin changes to Low.

  In this circuit configuration, when the cell balance operation of the cell 11 is OFF, the input signal to the microcomputer 108 becomes High. When the cell balance operation is turned on, a discharge current flows from the cell 11 to the discharge resistor R1, the photocoupler PC1 operates with the discharge current, and the input signal to the microcomputer 108 changes to Low.

Here, an abnormality detection method of the cell balance circuit 104 will be described with reference to the list of FIG.
When the cell balance operation of the cell 11 is OFF, the setting of the cell balance switch FET1 is OFF (that is, the cell balance control terminal VB1 of the battery monitoring IC 105 is OFF), and no current flows through the discharge resistor R1, and the photocoupler PC1 Since it does not operate, the input signal to the input terminal Vin of the microcomputer 108 becomes High.
On the other hand, when the cell balance operation of the cell 11 is ON, the setting of the cell balance switch FET1 is ON (that is, the cell balance control terminal VB1 of the battery monitoring IC 105 is ON), and both ends of the cell 11 are short-circuited to discharge resistance. As current flows through R1, the photocoupler PC1 operates and the input signal to the input terminal Vin of the microcomputer 108 becomes Low.

  Therefore, when the cell balance control terminal VB1 for the cell 11 and the cell balance switch FET1 are normal, when the cell balance operation is executed, the input signal to the microcomputer 108 changes from High to Low.

  On the other hand, when an abnormality occurs in the cell balance control terminal VB1 for the cell 11 and the cell balance control terminal VB1 is always turned off or always turned on, the input signal to the microcomputer 108 is not subject to the cell balance operation. It does not change and always remains High or Low, and the microcomputer 108 can detect this abnormality.

  If an abnormality occurs in which the cell balance switch FET1 is opened (fixed to OFF), the input signal to the microcomputer 108 remains high regardless of the cell balance operation regardless of whether the cell balance control terminal VB1 is ON or OFF. The microcomputer 108 can detect this abnormality.

  If an abnormality occurs in which the cell balance switch FET1 is short-circuited (fixed to ON), the input signal to the microcomputer 108 remains low regardless of the cell balance operation, regardless of whether the cell balance control terminal VB1 is ON or OFF. Therefore, the microcomputer 108 can detect this abnormality.

  Similarly to the cell 11, the cells 12 to 18 include photocouplers PC2 to PC8 and current limiting resistors R12 to R18 connected in parallel to the discharge resistors R2 to R8, respectively, and the discharge resistor R2 when the cell balance operation is turned on. As the current flows through .about.R8, the photocouplers PC2 to PC8 operate, and the input signal to the microcomputer 108 changes from High to Low. Therefore, the abnormality of the cell balance control terminals VB2 to VB8 and the opening and shorting of the cell balance switches FET2 to FET8 can be detected as shown in FIG.

In the example of FIG. 1, a photodiode is used as the light emitting element of the photocoupler and a phototransistor is used as the light receiving element. However, the present invention is not limited to these.
Further, as shown in FIG. 1, the signal lines connecting the collectors of the light receiving elements Q1 to Q8 are shared, and the collectors of the eight light receiving elements Q1 to Q8 are commonly connected to one input terminal Vin. Therefore, when any one of the photocouplers PC1 to PC8 operates, the input signal changes to Low. Therefore, when the cells 11 to 18 are simultaneously subjected to the cell balance operation, it cannot be specified where the abnormality occurs in the cell balance switches FET1 to FET8 and the cell balance control terminals VB1 to VB8. In order to specify an abnormality on a cell basis, it is necessary to detect the abnormality by sequentially turning on / off the cell balance control terminals VB1 to VB8 to perform a cell balance operation.

  The microcomputer 108 displays the abnormality detection result of the cell balance circuit 104, the voltage measurement result of the cells 11 to 18, the voltage measurement result of the module 10 measured by the module voltage measurement circuit 103, and the temperature measurement result measured by the temperature measurement circuit 106. Along with the unique number of the battery monitoring device 100 set by the automatic numbering circuit 112, the data is output from the CAN communication I / F 111 to the battery management device 2 (shown in FIG. 3) via the isolator 109. 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.

  Note that the abnormality detection of the cell balance circuit 104 may be performed at any time. For example, abnormality detection may be performed before the ignition switch is turned on and power supply to each part of the vehicle is started, or abnormality detection may be performed simultaneously when the microcomputer 108 executes the cell balance operation.

  As described above, according to the first embodiment, in the battery monitoring device 100, the cell balance switches FET1 to FET8 and the discharge resistors R1 to R8 are connected to the cells 11 to 18, respectively, and the cell balance switches FET1 to FET8 are connected to the discharge resistors. The cell balance circuit 104 that short-circuits both ends of the cells 11 to 18 via R1 to R8, the light emitting elements D1 to D8 that emit light by the discharge current of the cells 11 to 18 and the light emission, and outputs an input signal Comprising photocouplers PC1 to PC8 provided for each cell balance switch, and an abnormality diagnosis unit for diagnosing an abnormality of the cell balance circuit 104 based on signals from the light receiving elements Q1 to Q8. It was configured as follows. For this reason, abnormality of the cell balance circuit 104 can be detected with a simple and inexpensive circuit configuration using the light emitting elements D1 to D8 and the light receiving elements Q1 to Q8.

  Moreover, according to Embodiment 1, since it was set as the structure which connected the light emitting elements D1-D8 and discharge resistance R1-R8 in parallel, it becomes possible to flow a big electric current through discharge resistance R1-R8, and the cells 11-18. Can be discharged quickly.

  Further, according to the first embodiment, since the microcomputer 108 constituting the abnormality diagnosis unit is configured to connect the light receiving elements Q1 to Q8 in common to one input terminal Vin, it is inexpensive. Further, there is an advantage that abnormality of the cell balance control terminals VB1 to VB8 and the cell balance switches FET1 to FET8 of the battery monitoring IC 105 can be easily diagnosed by the battery monitoring device 100 alone.

Embodiment 2. FIG.
FIG. 5 is a circuit diagram showing a peripheral structure of the cell balance circuit 104 in the battery monitoring apparatus 100 according to the second embodiment. 5 that are the same as or equivalent to those in FIG. 1 are denoted by the same reference numerals and description thereof is omitted. FIG. 6 is a diagram for explaining an abnormality detection method of the cell balance circuit 104 according to the second embodiment.

  In the second embodiment, the light emitting element D1 of the photocoupler PC1 is connected in series with the discharge resistor R1. Accordingly, when the cell balance operation of the cell 11 is performed, when the battery monitoring IC 105 turns on the cell balance control terminal VB1 and applies a voltage to the gate of the cell balance switch FET1, the cell balance switch FET1 is turned on and the cell 11 is short-circuited, a current flows through the discharge resistor R1, and discharge is performed. At the same time, the photocoupler PC1 operates and the input signal to the input terminal Vin of the microcomputer 108 becomes Low. When the cell balance operation is not performed, since the cell balance switch FET1 is OFF, no current flows through the discharge resistor R1, and therefore the photocoupler PC1 does not operate, and the input signal to the input terminal Vin becomes High.

  Similarly to the photocoupler PC1, the light emitting elements D2 to D8 of the photocouplers PC2 to PC8 are also connected in series to the discharge resistors R2 to R8, respectively. When the cell balance switches FET2 to FET8 are turned on, the discharge resistors R2 to R8 are connected. As the current flows through the photocouplers PC2 to PC8, the input signal to the input terminal Vin of the microcomputer 108 changes from High to Low.

  Since the abnormalities of the cell balance control terminals VB1 to VB8, which are the cause of the abnormality of the cell balance circuit 104, and the open and short circuits of the cell balance switches FET1 to FET8 can be detected in the same manner as in the first embodiment, the explanation will be given. Omitted.

  Furthermore, in the second embodiment, it is possible to detect the opening of the discharge resistors R1 to R8 that are the cause of the abnormality of the cell balance circuit 104. For example, if an abnormality occurs in which the discharge resistor R1 is opened, no current flows through the discharge resistor R1 and the photocoupler PC1 does not operate regardless of whether the cell balance control terminal VB1 is ON or OFF, so that the input signal to the microcomputer 108 is High. Therefore, the microcomputer 108 can detect this abnormality.

  As described above, according to the second embodiment, since the light emitting elements D1 to D8 and the discharge resistors R1 to R8 are connected in series, the cell balance control terminals VB1 to VB8 of the battery monitoring IC 105 and the cell balance switch Along with the opening and short-circuiting of FET1 to FET8, the opening of the discharge resistors R1 to R8 can also be diagnosed.

Embodiment 3 FIG.
FIG. 7 is a circuit diagram showing a peripheral structure of the cell balance circuit 104 in the battery monitoring apparatus 100 according to the third embodiment. 7 that are the same as or equivalent to those in FIG. 1 are assigned the same reference numerals, and descriptions thereof are omitted.

In the third embodiment, the connection point between the pull-up resistor R21 of the 5V power supply and the collector of the light receiving element Q1 of the photocoupler PC1 is connected to the input terminal Vin1 of the microcomputer 108, and the microcomputer 108 receives an input signal to the input terminal Vin1. Based on the above, the abnormality of the cell balance control terminal VB1 and the cell balance switch FET1 is detected.
Similarly, each connection point between the pull-up resistors R22 to R28 of the 5V power source and the collectors of the light receiving elements Q2 to Q8 of the photocouplers PC2 to PC8 is connected to the input terminals Vin2 to Vin8 of the microcomputer 108, and the microcomputer 108 is the input terminal. Based on each input signal to Vin2 to Vin8, each abnormality of the cell balance control terminals VB2 to VB8 and the cell balance switches FET2 to FET8 is detected.

  As described above, since the input signal for detecting the abnormality of the cell balance circuit 104 is input to the microcomputer 108 for each of the cells 11 to 18, the cell balance switches FET1 to FET8 and the cell balance control are provided for each of the cells 11 to 18. An abnormality of the terminals VB1 to VB8 can be detected. Therefore, the cells 11 to 18 can be simultaneously cell-balanced to detect simultaneously the abnormality of the cell balance control terminals VB1 to VB8 and the opening and short-circuiting of the cell balance switches FET1 to FET8.

  In FIG. 7, the light emitting elements D1 to D8 of the photocouplers PC1 to PC8 are connected in parallel to the discharge resistors R1 to R8, but may be connected in series.

  As described above, according to the third embodiment, the microcomputer 108 constituting the abnormality diagnosis unit is configured to connect the plurality of light receiving elements Q1 to Q8 to the plurality of input terminals Vin1 to Vin8, respectively. 104 abnormalities can be detected in units of cells.

Embodiment 4 FIG.
FIG. 8 is a circuit diagram showing a peripheral structure of the cell balance circuit 104 in the battery monitoring apparatus 100 according to the fourth embodiment. 8 that are the same as or equivalent to those in FIG. 1 are denoted by the same reference numerals and description thereof is omitted.

  In the fourth embodiment, the connection point between the collector of the light receiving element Q1 of the photocoupler PC1 and the pull-up resistor R21 connected to the 5V power supply is connected to the input terminal Vin of the battery monitoring IC 105, and one microcomputer 108 is connected. In this configuration, a plurality of battery monitoring ICs 105 (two in the illustrated example) are monitored and controlled. The upper battery monitoring IC 105 is directly connected to the microcomputer 108 by SPI communication or the like, and the lower battery monitoring IC 105 is connected to the upper battery monitoring IC 105 by inter-IC communication or the like. The upper battery monitoring IC 105 measures the input signal of the input terminal Vin of its own device and transmits it to the microcomputer 108 by SPI communication or the like, and also the measurement result of the input signal received from the lower battery monitoring IC 105 by inter-IC communication or the like. It transmits to the microcomputer 108.

  In the case of this configuration, an abnormality in the cell balance circuit 104 of the plurality of modules 10 can be detected by a single microcomputer 108. Further, since it is not necessary to provide the microcomputer 108 for each module 10, the number of the microcomputers 108 is reduced, and the cost can be reduced.

  In FIG. 8, the light emitting elements D1 to D8 of the photocouplers PC1 to PC8 are connected in parallel with the discharge resistors R1 to R8, but may be connected in series.

  As described above, according to the fourth embodiment, the battery monitoring apparatus 100 includes the battery monitoring IC 105 in which the plurality of light receiving elements Q1 to Q8 are commonly connected to one input terminal Vin, and the light reception received from the battery monitoring IC 105. The microcomputer 108 is configured to diagnose abnormality of the cell balance circuit 104 based on the signals of the elements Q1 to Q8. For this reason, it is possible to diagnose abnormality of the plurality of cell balance circuits 104 controlled by the plurality of battery monitoring ICs 105 with one microcomputer 108. Further, since the number of microcomputers 108 is reduced, there is a merit of cost reduction.

Embodiment 5. FIG.
FIG. 9 is a circuit diagram showing a peripheral structure of the cell balance circuit 104 in the battery monitoring apparatus 100 according to the fifth embodiment. In FIG. 9, the same or corresponding parts as in FIG.

  In the fifth embodiment, the connection points of the pull-up resistors R21 to R28 of the 5V power source and the collectors of the light receiving elements Q1 to Q8 of the photocouplers PC1 to PC8 are connected to the input terminals Vin1 to Vin8 of the battery monitoring IC 105, In this configuration, a single microcomputer 108 monitors and controls a plurality of battery monitoring ICs 105 (two in the illustrated example). Communication between the upper and lower battery monitoring ICs 105 and communication between the upper battery monitoring IC 105 and the microcomputer 108 are performed in the same manner as in the fourth embodiment.

  In the case of this configuration, an abnormality in the cell balance circuit 104 of the plurality of modules 10 can be detected by a single microcomputer 108. Further, since it is not necessary to provide the microcomputer 108 for each module 10, the number of the microcomputers 108 is reduced, and the cost can be reduced. Furthermore, the abnormality of the cell balance circuit 104 can be detected in units of cells.

  In FIG. 9, the light emitting elements D1 to D8 of the photocouplers PC1 to PC8 are connected in parallel to the discharge resistors R1 to R8, but may be connected in series.

  As described above, according to the fifth embodiment, the battery monitoring apparatus 100 receives from the battery monitoring IC 105 and the battery monitoring IC 105 in which the plurality of light receiving elements Q1 to Q8 are commonly connected to the plurality of input terminals Vin1 to Vin8. The microcomputer 108 for diagnosing abnormality of the cell balance circuit 104 based on the signals of the received light receiving elements Q1 to Q8 is used. For this reason, it is possible to diagnose abnormality of the plurality of cell balance circuits 104 controlled by the plurality of battery monitoring ICs 105 with one microcomputer 108. Further, since the number of microcomputers 108 is reduced, there is a merit of cost reduction. Further, since the plurality of light receiving elements Q1 to Q8 are respectively connected to the plurality of input terminals Vin1 to Vin8, the abnormality of the cell balance circuit 104 can be detected in units of cells.

  8 and FIG. 9, the configuration is such that a plurality of battery monitoring ICs 105 are connected to one microcomputer 108, but the present invention is not limited to this, and one battery monitoring IC 105 is connected to one microcomputer 108. May be connected. In this way, by outputting the signals of the light receiving elements Q1 to Q8 to the microcomputer 108 via the battery monitoring IC 105, in the system configuration in which the battery monitoring IC 105 and the microcomputer 108 are insulated, the signals of the light receiving elements Q1 to Q8 are output. There is no need to insulate and input to the microcomputer 108, and the insulation circuit can be simplified.

  In addition to the above, within the scope of the invention, the invention of the present application 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 modules, 11-18 cells, 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, C1 to C9 cell voltage measurement terminal, D1 to D8 light emitting element, FET1 to FET8 cell balance switch, PC1 to PC8 photocoupler (abnormality detection unit), Q1 to Q8 light receiving element, R1-R8 discharge resistance, R11-R18 current limit Anti, R21 to R28 pullup resistor, VB1～VB8 cell balance control terminal, Vin, Vin1~Vin8 input terminal.

Claims (7)

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 to each cell, and a cell balance circuit in which the switch short-circuits both ends of the cell via the discharge resistor and discharges,
An abnormality detection unit provided for each switch, comprising a light emitting element that emits light with a discharge current of the cell and a light receiving element that receives the emitted light and outputs a signal;
A battery monitoring apparatus comprising: an abnormality diagnosis unit that diagnoses an abnormality of the cell balance circuit based on a signal of the light receiving element.   The battery monitoring apparatus according to claim 1, wherein the light emitting element and the discharge resistor are connected in parallel.   The battery monitoring device according to claim 1, wherein the light emitting element and the discharge resistor are connected in series.   The abnormality diagnosis unit is a microcomputer in which a plurality of the light receiving elements are commonly connected to one input terminal and diagnoses an abnormality of the cell balance circuit based on a signal of the light receiving element input to the input terminal. The battery monitoring device according to any one of claims 1 to 3, wherein the battery monitoring device is provided.   The abnormality diagnosis unit is a microcomputer in which a plurality of the light receiving elements are respectively connected to a plurality of input terminals, and the abnormality of the cell balance circuit is diagnosed based on a signal of the light receiving elements input to the input terminals. The battery monitoring device according to claim 1, wherein the battery monitoring device is a battery monitoring device.   The abnormality diagnosis unit includes a battery monitoring IC in which a plurality of light receiving elements are commonly connected to one input terminal, and an abnormality of the cell balance circuit based on a signal of the light receiving element received from the battery monitoring IC. 4. The battery monitoring apparatus according to claim 1, further comprising a microcomputer for diagnosing the battery.   The abnormality diagnosis unit includes a battery monitoring IC in which a plurality of light receiving elements are connected to a plurality of input terminals, and an abnormality of the cell balance circuit based on a signal of the light receiving elements received from the battery monitoring IC. The battery monitoring apparatus according to claim 1, further comprising a microcomputer for diagnosis.

Images