JP2007085843A - Failure detector for electric current sensor and its method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a failure detector for an electric current sensor and its method for rapidly and accurately detecting failure in the current sensor while being used for cost cutting. <P>SOLUTION: A battery pack 11 formed by serially connecting a plurality of cells 10 is equipped with a plurality of voltage detection circuits 16 severally provided on the plurality of cells to detect voltages of the cells and a current sensor 17 for detecting a current value of the battery pack. The battery pack 11 is structured to detect a failure in the current sensor based on the comparison of cell voltage values detected in the detection circuits with a certain threshold voltage and on the current value when the current value detected by the current sensor is a steady value outputted within a prescribed range. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a current sensor failure detection apparatus and method used for determining a failure of a current sensor that detects a current of an assembled battery configured by connecting a plurality of cells in series.

2. Description of the Related Art Conventionally, a device for detecting a failure of a current sensor that detects a charge / discharge current of a battery, in particular, an intermediate sticking failure is known (see, for example, Patent Document 1). This device is a device for determining a failure of a current sensor that detects a charge / discharge current of a battery that supplies power to an electric load, and a voltage sensor that detects the voltage of the battery, and a voltage value detected by the voltage sensor The current sensor failure is determined when the current fluctuation amount detected by the current sensor corresponding to the reference fluctuation amount is equal to or less than the reference value.
JP-A-10-253682

  However, the conventional device requires a high-accuracy voltage sensor to detect the fluctuation amount of the battery voltage, so that the device becomes expensive and the circuit configuration becomes large. In addition, the conventional apparatus has a problem that it takes time to detect a failure because the amount of change in the voltage value and current value of the battery is calculated. In addition, when the voltage sensor fails, there is a problem that the current sensor cannot be detected.

  The present invention is intended to solve the above-described problems and to provide a current sensor failure detection apparatus and method that can quickly and accurately detect a failure of a current sensor and can reduce costs.

  In the assembled battery configured by connecting a plurality of cells in series, the failure detection device for the current sensor of the present invention includes a plurality of voltage detection circuits provided for each of the plurality of cells and detecting the voltage of the cells, A current sensor for detecting a current value of the assembled battery, and a cell voltage value detected by the voltage detection circuit when the current value detected by the current sensor outputs a constant value within a predetermined range; The present invention is characterized in that a failure of the current sensor is detected based on the comparison with the threshold voltage and the current value.

  Further, according to the current sensor failure detection method of the present invention, a failure of a current sensor for detecting a current of an assembled battery configured by connecting a plurality of cells in series is obtained using the above-described current sensor failure detection device. It is characterized by this.

  In the present invention, in an assembled battery configured by connecting a plurality of cells in series, a plurality of voltage detection circuits provided for each of the plurality of cells to detect a voltage of the cell, and a current value of the assembled battery are detected. A cell voltage value detected from the voltage detection circuit when the current value detected by the current sensor outputs a constant value within a predetermined range and compared with a certain threshold voltage Since the current sensor failure is detected based on the current value, it is possible to make a failure determination based on a threshold flag variation instead of reading the voltage value with the voltage sensor. For this reason, it is not necessary to calculate an accurate voltage fluctuation amount, and a high-accuracy voltage sensor is not required, so that the cost can be reduced. In addition, since it is not necessary to calculate an accurate voltage fluctuation amount and software calculation processing is facilitated, failure detection can be accelerated.

  As a preferred example of the current sensor failure detection apparatus of the present invention, one or more threshold voltages may be set. With this configuration, it becomes possible to confirm a more accurate variation in the cell voltage value, and the failure determination becomes quick and accurate.

  As a preferred example of the current sensor failure detection device of the present invention, the threshold voltage is changed by the remaining capacity of the assembled battery calculated by the CPU, and the threshold voltage is changed by the total voltage of the assembled battery. The threshold voltage may be changed depending on the temperature of the assembled battery detected by the temperature sensor. In any case, with such a configuration, the threshold voltage can be freely changed, and the change in the cell voltage value can be confirmed quickly, so that the failure determination can be performed quickly and accurately.

Embodiments of the present invention will be described below in detail with reference to the drawings.
FIG. 1 is a block diagram showing an example of the overall configuration of an assembled battery equipped with a current sensor failure detection device of the present invention. In the example shown in FIG. 1, the assembled battery 11 is a battery in which a plurality of cells 10 are connected in series (here, three in series), and a load 13 is connected to the assembled battery 11 via a conductor 12. . The conducting wire 12 is provided with a relay 14 that turns on and off the supply of current from the assembled battery 11 to the load 13. It is assumed that the relay 14 is turned on / off under the control of the CPU 15.

  The CPU 15 samples the total voltage and input / output current of the assembled battery 11 at a predetermined cycle based on the input signal from the voltage detection circuit 16 of each cell 10 and the input signal from the current sensor 17. Calculate the remaining capacity. In the voltage detection circuit 16, the voltage value of each cell 10 and the threshold voltage Vref are compared by a cell voltage comparison unit 19 including an OP amplifier, and a comparison signal is input from the cell voltage comparison unit 19 to the CPU 15. Further, an input signal is sent from the CPU 15 to the variable resistor 20 that adjusts the threshold voltage based on the remaining battery capacity calculated by the CPU 15, the total voltage of the assembled battery 11, and the temperature of the assembled battery 11 measured by the temperature sensor 18. The threshold voltage Vref can be changed by the CPU 15. The threshold voltage Vref is set between the overdischarge threshold and the overcharge threshold of the cell 10. Vcc is a threshold voltage reference power source.

  FIG. 2 is a diagram for explaining an example of a current sensor failure detection method in the configuration of the present invention shown in FIG. In the example shown in FIG. 2, it can be understood that the state of charge is obtained when the output of the current sensor shows a constant output on the (−) side at the predetermined time t1. At that time, the voltage value output from a certain cell 10 is compared with the threshold voltage Vref in the voltage detection circuit 16. After the determination with the threshold value, the flag is set to High if the determination result is high, and the flag is set to Low if the determination result is low. Here, since the voltage of the cell 10 increases in the charged state, the flag cannot change from High to Low (voltage value decrease) within t1, and in this case, it is determined that the current sensor has failed.

  At a predetermined time t2, it can be understood that the discharge state is obtained when the output of the current sensor shows a constant output on the (+) side. Similarly, when the state of the flag is examined, at a predetermined time t2, there is no change in the flag from Low to High (voltage value increase) within t2 in the discharge state, and in this case, it is determined that the current sensor has failed.

  At a predetermined time t3, the output of the current sensor is a constant output of 0A, so that it can be understood that charging / discharging is stopped. In FIG. 2, when the t2 state, that is, the low flag state in which the cell voltage is lower than the threshold value, changes to the t3 state (charge / discharge stop state), the cell voltage does not change, so there is no possibility that the flag changes from High → Low and Low → High. In that case, it is determined as a failure. Also, since it starts from the Low flag state, the High flag cannot be displayed. That is, flag fluctuation from the initial value is determined as a failure.

  In the above-described example, the threshold voltage Vref is a constant value once determined. However, as described above, the remaining capacity of the assembled battery 11 calculated by the CPU 15, the total voltage of the assembled battery 11, and the temperature sensor 18. The threshold voltage Vref can be changed according to the temperature of the assembled battery 11 detected by the above. For example, when the cell voltage is low or the SOC is low, the threshold voltage Vref can be controlled to be lowered.

  Table 1 below shows a current sensor failure detection correspondence table based on the flag in FIG. 2 showing the configuration of an example of the present invention.

  FIG. 3 is a block diagram showing another example of the overall configuration of an assembled battery provided with the current sensor failure detection device of the present invention. In the example shown in FIG. 3, the same members as those in the example shown in FIG. 3 is different from the example shown in FIG. 1 in the configuration of the voltage detection circuit 16. That is, in the voltage detection circuit 16 shown in FIG. 3, two cell voltage comparison sections 19 are provided corresponding to each cell 10, and two threshold voltages Vref1 and Vref2 are set for comparison with the voltage value of each cell 10. is doing.

  FIG. 4 is a diagram for explaining an example of a current sensor failure detection method in the configuration of the present invention shown in FIG. 3. In the example shown in FIG. 4, at the predetermined time t <b> 1, when the output of the current sensor shows a constant output on the (−) side, it can be understood that the state of charge is present. At that time, the voltage value output from a certain cell 10 is compared with two threshold voltages Vref1 and Vref2 in the voltage detection circuit 16. After the determination with the threshold, if the determination result is higher than Vref1, the flag is set to High.If the determination result is between Vref1 and Vref2, the flag is set to Mid.If the determination result is lower than Vref2, the flag is set to Low. To do. Here, since the voltage of the cell 10 rises in the charged state, the flag cannot change between High → Mid and Mid → Low (voltage value drop) within t1, and in this case, it is determined that the current sensor has failed.

  At a predetermined time t2, it can be understood that the discharge state is obtained when the output of the current sensor shows a constant output on the (+) side. Similarly, when the state of the flag is examined, at a predetermined time t2, there is no possibility that the flag changes from Low → Mid or Mid → High (voltage value increase) within t2 in the discharging state.

  At a predetermined time t3, the output of the current sensor is a constant output of 0A, so that it can be understood that charging / discharging is stopped. In FIG. 4, when the t2 state, that is, the low flag state where the cell voltage is lower than the threshold value Vref1, is changed to the t3 state (charge / discharge stop state), the cell voltage does not change, and therefore the flag changes from High → Mid, Low → Mid, etc. Since there is no possibility of voltage fluctuation, it is determined that there is a failure. Also, since it starts from the Low flag state, the High flag cannot be displayed.

  Also in this example, the threshold voltages Vref1 and Vref2 are constant values once determined. However, as described above, the remaining capacity of the assembled battery 11, the total voltage of the assembled battery 11, and the temperature calculated by the CPU 15 are used. The threshold voltages Vref1 and Vref2 can be changed according to the temperature of the assembled battery 11 detected by the sensor 18. For example, when the cell voltage is low or the SOC is low, the threshold voltages Vref1 and Vref2 can be controlled to be lowered.

  Table 2 below shows a current sensor failure detection correspondence table based on flags in FIG. 4 showing the configuration of another example of the present invention.

  In the example described above, the fault detection of the current sensor in the assembled battery including a plurality of cells has been described, but it goes without saying that the present invention can be applied to the fault detection of the current sensor in a battery including a single cell.

  The present invention is an application for detecting a failure of a current sensor in various loads such as an assembled battery that supplies electric power to a rotating electric machine, and is suitable for an application for detecting a failure of the current sensor in a short time with a simple configuration. Can be used.

It is a block diagram which shows an example of the whole structure of the assembled battery provided with the failure detection apparatus of the current sensor of this invention. In the structure of this invention shown in FIG. 1, it is a figure for demonstrating an example of the failure detection method of a current sensor. It is a block diagram which shows the other example of the whole structure of the assembled battery provided with the failure detection apparatus of the current sensor of this invention. FIG. 4 is a diagram for explaining an example of a current sensor failure detection method in the configuration of the present invention shown in FIG. 3.

Explanation of symbols

10 cells 11 batteries 12 conductors 13 loads 14 relays 15 CPU
16 Voltage detection circuit 17 Current sensor 18 Temperature sensor 19 Cell voltage comparison unit 20 Variable resistance

Claims (6)

  In the assembled battery configured by connecting a plurality of cells in series, a plurality of voltage detection circuits that are provided for each of the plurality of cells and detect a voltage of the cell, and a current sensor that detects a current value of the assembled battery When the current value detected by the current sensor outputs a constant value within a predetermined range, the cell voltage value detected from the voltage detection circuit is compared with a certain threshold voltage, and the current value A failure detection device for a current sensor, wherein the failure detection device is configured to detect a failure of the current sensor based on the above.   The current sensor failure detection apparatus according to claim 1, wherein one or more threshold voltages are set.   The current sensor failure detection device according to claim 1, wherein the threshold voltage is changed according to a remaining capacity of the assembled battery calculated by a CPU.   The current sensor failure detection device according to claim 1, wherein the threshold voltage is changed according to a total voltage of the assembled battery.   3. The current sensor failure detection apparatus according to claim 1, wherein the threshold voltage is changed according to a temperature of the assembled battery detected by the temperature sensor.   Using the current sensor failure detection device according to any one of claims 1 to 5, detecting a failure of a current sensor that detects a current of an assembled battery configured by connecting a plurality of cells in series. A fault detection method for a current sensor, characterized by:

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