JP2013102318A - Device for detecting state of secondary battery, and fault diagnosis method for device for detecting state of secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device for detecting a state of a secondary battery which performs an accurate fault diagnosis of AD converters even if a fault diagnostic voltage varies.SOLUTION: The device for detecting a state of a secondary battery which has a plurality of AD converters (18-20) for converting analog values detected for state detection of the secondary battery to digital values includes: a fault diagnostic power supply (15) for inputting a fault diagnostic voltage into the plurality of AD converters simultaneously at a fault diagnosis of the plurality of AD converters; and a computing section (16) for comparing output values of the plurality of AD converters with one another to make a fault determination.

Description

  The present invention calculates a secondary battery state based on a charging current and a discharging current flowing in a chargeable / dischargeable battery (hereinafter referred to as a secondary battery), a voltage between terminals of the secondary battery, and a temperature sensed by a temperature sensor. The present invention relates to a failure diagnosis of a battery state detection device, particularly an AD converter that converts analog values of the current, voltage, and temperature into digital values.

  A secondary battery state detection device using a secondary battery as a voltage source is an AD converter for charging and discharging current flowing in a chargeable / dischargeable secondary battery, voltage between terminals of the secondary battery, and temperature detected by a temperature sensor. The state of the secondary battery is calculated based on the current, the voltage, and the temperature.

  Normally, a secondary battery state detection device using a secondary battery as a voltage source detects the charge rate of the secondary battery, and when the control device has a low charge rate of the secondary battery based on the detected value. Control that reduces the charging rate of the secondary battery by stopping the operation of the electrical load or reducing the power consumption, or conversely, increases the charging rate of the secondary battery by operating the generator or charger, etc. I do.

  When the AD converter fails, the secondary battery state detection device using the secondary battery as a voltage source calculates the secondary battery charge rate based on the incorrect output from the AD converter. Cannot be calculated accurately. For this reason, if the secondary battery is deteriorated or the secondary battery is mounted on an automobile, the engine may be unable to start due to a decrease in the charging rate.

  Therefore, a secondary battery state detection device using a secondary battery as a voltage source and an AD converter failure diagnosis function are proposed. Conventionally, for example, as a method of diagnosing a fault in an AD converter, a value obtained by digitally converting the voltage for failure diagnosis by the AD converter and a value stored in advance corresponding to the value obtained by digitally converting the voltage for fault diagnosis by the AD converter are mutually converted. There has been a method of diagnosing a fault by comparing and determining (see, for example, Patent Document 1 below).

JP 59-198365 A

  However, in the case of the conventional method described above, when the voltage for failure diagnosis fluctuates due to noise or the like in a state where the AD converter has not failed, the AD converter is diagnosed as having a failure depending on the magnitude of the fluctuation. Thus, at the time of failure diagnosis, there has been a problem that if the voltage for failure diagnosis fluctuates due to noise or the like, the AD converter is diagnosed as a failure even if the AD converter is not broken. If the failure diagnosis is wrong, the secondary battery state detection device cannot accurately calculate the state of the secondary battery.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a state detection device for a secondary battery that accurately performs failure diagnosis of an AD converter even when the failure diagnosis voltage fluctuates. .

  The present invention provides a state detection device for a secondary battery including a plurality of AD converters that convert analog values detected for detecting a state of the secondary battery into digital values, and at the time of failure diagnosis of the plurality of AD converters. A power supply for fault diagnosis for simultaneously inputting a voltage for fault diagnosis to the plurality of AD converters, and an arithmetic unit for determining a fault by comparing output values of the plurality of AD converters with each other. It exists in the state detection apparatus of the secondary battery characterized.

  According to the present invention, it is possible to provide a state detection device for a secondary battery that accurately performs failure diagnosis of an AD converter even when a voltage for failure diagnosis fluctuates.

It is a block diagram of the part which concerns on the fault diagnosis of the AD converter especially of the state detection apparatus of the secondary battery by Embodiment 1 of this invention. 3 is an operation flowchart in the state detection device for a secondary battery according to the present invention. It is a block diagram of the part which concerns on the fault diagnosis of the AD converter especially of the state detection apparatus of the secondary battery by Embodiment 2 of this invention. It is a figure for demonstrating the timing of the fault diagnosis of the AD converter in the state detection apparatus of the secondary battery by Embodiment 3 of this invention. It is an operation | movement flowchart at the time of the fault diagnosis of the AD converter in the state detection apparatus of the secondary battery by Embodiment 4 of this invention. It is a figure for demonstrating the timing of the fault diagnosis of the AD converter in the state detection apparatus of the secondary battery by Embodiment 4 of this invention.

  Hereinafter, a state detection apparatus for a secondary battery according to the present invention will be described with reference to the drawings according to each embodiment. In each embodiment, the same or corresponding parts are denoted by the same reference numerals, and redundant description is omitted.

Embodiment 1 FIG.
FIG. 1 is a block diagram of a portion relating to failure diagnosis of an AD converter, in particular, of a secondary battery state detection device according to Embodiment 1 of the present invention. As shown in FIG. 1, a secondary battery state detection device 12 using a secondary battery 11 as a voltage source includes, for example, a current AD converter 18, a voltage AD converter 19, and a temperature AD converter 20 configured as an integrated circuit 13. And a multiplexer 17 provided in each of these AD converters, a temperature sensor 14, a failure diagnosis power supply 15, an arithmetic unit 16, and a current detection resistor R1. In addition, the state detection apparatus of the secondary battery of FIG. 1 has shown the case where it mounts in a vehicle.

The AD converter 18 for current is an analog signal value obtained by using the current value of the secondary battery 11 as the voltage across the current detection resistor R1 inserted in the state detection device 12 of the secondary battery 11 and the power supply line to the vehicle. The voltage value is converted into a digital signal value for detection.
The voltage AD converter 19 converts the voltage between the terminals of the rechargeable battery 11 that can be charged and discharged into a digital signal value from the analog signal value of the state detection device 12 of the secondary battery 11 and the power supply line to the vehicle. It is provided as a role to detect.
The temperature AD converter 20 outputs a voltage value of an analog signal value corresponding to the temperature output from the state sensor 12 or the temperature sensor 14 provided outside the state detector 12 in order to detect a temperature change of the secondary battery 11. It is provided as a role to detect by converting to a digital signal value.

  The failure diagnosis power supply 15 is provided to supply a failure diagnosis voltage to each of the AD converters at the time of failure diagnosis of the current AD converter 18, the voltage AD converter 19, and the temperature AD converter 20. The multiplexer 17 is provided as an input switching unit for switching from a normal detection voltage to a failure diagnosis voltage at a predetermined timing.

  A converter (not shown) for converting the input voltage level from the power supply line of the secondary battery 11 to a desired level may be provided on the input side of the multiplexer 17 of the current AD converter 18 and the voltage AD converter 19. Good.

  For example, the calculation unit 16 from the microprocessor normally outputs the detected current, voltage, and temperature output values of the secondary battery 11 from, for example, the current AD converter 18, the voltage AD converter 19, and the temperature AD converter 20. The state of the secondary battery 11 is calculated on the basis of it, and the switching control of the multiplexer 17 is performed at the time of failure diagnosis, and the current AD converter 18 by the failure diagnosis voltage simultaneously input from the same failure diagnosis power supply 15 and the voltage AD By comparing and determining the output values from the converter 19 and the temperature AD converter 21 with each other, failure diagnosis of the current AD converter 18, the voltage AD converter 19, and the temperature AD converter 21 is performed.

  A control procedure will be described in accordance with an operation flowchart of the arithmetic unit 16 shown in FIG. The arithmetic unit 16 normally has a voltage value obtained by converting a charging current and a discharging current flowing in the chargeable / dischargeable secondary battery 11 from the current AD converter 18 by a current detection resistor (current-voltage converter) R1, and a voltage AD converter. The voltage value between the terminals of the secondary battery 11 that can be charged and discharged from 19 and the voltage value corresponding to the temperature sensed by the temperature sensor 14 from the temperature AD converter 20 are detected as digital values, respectively (step S10).

  Then, the state of the secondary battery 11 is calculated based on the digital value (step S11).

  Then, it is determined whether or not failure diagnosis of the AD converter is necessary (step S12). If necessary, the process proceeds to step S13, and if not necessary, the process proceeds to step S10.

  In step S13, the arithmetic unit 16 controls each multiplexer 17 to switch the voltage input to the AD converter 18-20 from the normal detection voltage to the failure diagnosis voltage supplied from the failure diagnosis power supply 15, and at the same time The fault diagnosis voltage is input to the current AD converter 18, the voltage AD converter 19, and the temperature AD converter 20. Then, the digital values from the current AD converter 18, the voltage AD converter 19, and the temperature AD converter 20 are compared with each other to determine a failure. By comparing the digital values with each other, it is possible to determine a failure that is not affected by the noise of the failure diagnosis voltage.

  In step S14, the arithmetic unit 16 performs a fault diagnosis of the current AD converter 18, the voltage AD converter 19, and the temperature AD converter 20. If the fault is diagnosed, the process proceeds to step S15. Control goes to step S16.

  In step S15, a fault signal S1 indicating that the AD converter of the secondary battery state detection device 12 is faulty is output. In step S16, the normal signal S1 which shows that the AD converter of the state detection apparatus 12 of a secondary battery is normal is output.

  Steps S10 and S11 constitute the secondary battery state detection means, and steps S12-16 constitute the AD converter failure diagnosis means.

  As described above, the current AD converter 18, the voltage AD converter 19, and the temperature AD converter 20 which are normally used for detection for calculating the state (detection) of the secondary battery are simultaneously the same at the time of failure diagnosis. By inputting the failure diagnosis voltage and comparing the obtained digital values with each other, it is possible to realize a state detection device that performs failure diagnosis with high accuracy even if the failure diagnosis voltage fluctuates due to noise or the like.

  Further, the state (detection) calculation of the secondary battery and the determination at the time of failure diagnosis may be performed by a calculation unit or the like (not shown) outside the state detection device 12.

  In this embodiment, as shown in FIG. 1, the current value flowing through the secondary battery is converted into a voltage value by a current-voltage converter, and the AD value is detected as a digital value. The present invention is also applied to a secondary battery state detection device 12 including two or more AD converters in total, that is, at least one AD converter that detects digital values. This embodiment is also applied to the case where the failure diagnosis power source and the temperature sensor are outside the state detection device 12 or when a power source different from the secondary battery 11 is used as a voltage source.

  As described above, according to the present invention, at the time of failure diagnosis of a plurality of AD converters, a failure diagnosis voltage is simultaneously input to the plurality of AD converters from the same failure diagnosis power supply, and the output values of the plurality of AD converters are mutually converted. By comparing and determining, it is possible to improve the fault diagnosis accuracy of the AD converter.

Embodiment 2. FIG.
FIG. 3 is a block diagram of a portion relating to failure diagnosis of the AD converter, in particular, of the secondary battery state detection device according to Embodiment 2 of the present invention. In the second embodiment, the failure diagnosis power source of the first embodiment is an internal power source 22 which is an existing power source for driving a circuit provided in an integrated circuit 13 provided with an AD converter. At the time of failure diagnosis, a voltage obtained by dividing the output voltage of the internal power supply 22 is used as a failure diagnosis voltage.

  A failure diagnosis method according to the second embodiment will be described with reference to FIG. At the time of failure diagnosis of the AD converter, a voltage obtained by dividing the voltage supplied from the internal power supply 22 by the voltage dividing circuit 21 provided at the position of FIG. 3 is simultaneously input to the AD converter 18-20 as a failure diagnosis voltage. A failure diagnosis of the AD converter is performed by comparing the output digital values. The internal power supply 22 includes, for example, an AD converter power supply 23 for the AD converter 18-20, a microprocessor power supply 24 for the calculation unit 16 (which may be a calculation unit (not shown) only for secondary battery state detection), There is an AD converter reference power supply 25 in the case where the AD converter 18-20 is a ΣΔ AD converter described later. FIG. 3 shows a configuration in the case where the output from the AD converter power supply 23 is a failure diagnosis voltage.

  Alternatively, the internal power supply 22 may be a single AD converter power supply 23, and a voltage obtained by dividing the output voltage of the AD converter power supply 23 may be used as a failure diagnosis voltage. The internal power supply 22 may be a single microprocessor power supply 24, and a voltage obtained by dividing the output voltage of the microprocessor power supply 24 may be used as a failure diagnosis voltage. Further, the AD converter 18-20 is a ΣΔ type ΣΔ AD converter in which the integrated circuit 13 is mounted, and is a single unit that supplies an AD converter reference voltage serving as a digital conversion reference voltage in a plurality of ΣΔ type AD converters. An AD converter reference power supply 25 may be provided, the internal power supply 22 may be a single AD converter reference power supply 25, and a voltage obtained by dividing the AD converter reference voltage may be used as a failure diagnosis voltage.

  Further, the internal power supply 22 may be an existing internal power supply that supplies power to a circuit for detecting the state of the secondary battery, for example, and is used for driving a circuit provided in the integrated circuit 13. It doesn't matter.

  In the above description, the output voltage of the internal power supply 22 is divided in order to obtain a voltage suitable for failure diagnosis of the AD converter. However, the voltage may be reduced by means other than voltage division. It is an example of the voltage transformation part which carries out pressure | voltage fall or voltage-dividing. If the output voltage of the internal power supply 22 is a voltage suitable for fault diagnosis of the AD converter, the transformer is not necessary.

  As described above, in the second embodiment, by using an existing internal power supply, it is not necessary to newly provide a power supply for failure diagnosis necessary for failure diagnosis. A state detection device can be realized.

  As described above, according to the present invention, when diagnosing a plurality of AD converters, a plurality of internal power supplies, that is, existing power supplies (AD converter power supply, microprocessor power supply, AD converter reference when the AD converter is a ΣΔ AD converter) One of the power supplies, etc.) is used as a fault diagnosis power supply, and the voltage obtained by dividing and stepping down the output voltage as needed is used as a fault diagnosis voltage, thereby newly adding a voltage source for the fault diagnosis voltage. Since it is not necessary, it is possible to realize a secondary battery state detection device that performs failure diagnosis at low cost.

Embodiment 3 FIG.
In the state detection device for a secondary battery according to still another embodiment of the present invention, the timing of fault diagnosis of the AD converter is determined. The configuration of the secondary battery state detection device is basically the same as that of each of the above embodiments. With reference to FIG. 4, the timing of fault diagnosis of the AD converter will be described. FIG. 4 shows the magnitude I of the charge / discharge current flowing through the secondary battery 11 in the key-off state, the key switch-on state, and the starter activation state in the vehicle. The key-off state is a key-off period in which the key switch is turned off. Generally, in the key-off state, the charge / discharge current I flowing through the secondary battery 11 is very small, and the discharge current to the secondary battery 11, the charge current or the combined current of both, and between the terminals of the secondary battery 11 that can be charged / discharged. Even if there is a period during which the voltage, the state detection device 12 or the temperature sensed by the temperature sensor 14 installed outside the state detection device 12 cannot be digitally converted, the decrease in the state calculation accuracy is minor and often does not cause a problem.

  The key switch on state is a key switch on period from when the key switch is turned on until the starter starting current flows. By performing failure diagnosis of the plurality of AD converters 18-20 during this period, failure diagnosis of the AD converter can be performed before the operation of the engine in which a large amount of current flows into and out of the secondary battery due to the generator and the electric load.

  The arithmetic unit 16 can obtain the current I of the charge / discharge current flowing through the secondary battery 11 shown in FIG. 4 from the output of the current AD converter 18. For example, based on this output in step S 12 of FIG. The key switch ON period is judged to determine the timing of failure diagnosis of the AD converter 18-20. More specifically, for example, the calculation unit 16 stores in advance a threshold value for determining a key-off period and a key switch-on period (which may be a common threshold value or each threshold value) in the storage unit, and the secondary battery 11 Is determined to be a key-off period or a key switch-on period when the charge / discharge current I is equal to or less than the threshold value or for a predetermined time or less.

  In order to determine a key-off period, a key switch-on period, and a starter activation period, the calculation unit 16 inputs a key state signal S2 indicating the above-described state of the key from, for example, an ECU (not shown) of the vehicle. Alternatively, the failure diagnosis timing may be determined from a combination of this input and the output of the current AD converter 18 described above.

  As described above, according to the present invention, failure diagnosis of a plurality of AD converters is performed during a key-off period when the key switch is turned off, or during a key switch-on period from when the key switch is turned on until the starter starting current flows. Thus, failure diagnosis can be performed with a slight decrease in the accuracy of state calculation of the secondary battery.

Embodiment 4 FIG.
In the secondary battery state detection device according to still another embodiment of the present invention, the timing of fault diagnosis of the AD converter is determined by another configuration. The configuration of the secondary battery state detection device is basically the same as that of each of the above embodiments. In the fourth embodiment, based on the temperature of the plurality of AD converters 18-20 or the temperature of the integrated circuit 13, it is determined whether or not failure diagnosis of the AD converter is necessary.

  FIG. 5 shows an operation flowchart of a timing determination procedure for performing a fault diagnosis of the AD converter in the arithmetic unit 16 in this embodiment. The computing unit 16 detects the temperature of the plurality of AD converters 18-20 or the temperature of the integrated circuit 13 (step S20).

For example, the temperature sensor 14 is provided in the state detection device 12 to detect the temperature of the plurality of AD converters 18-20 or the temperature of the integrated circuit 13, that is, the temperature in the vicinity of the plurality of AD converters 18-20. In this case, the temperature sensor 14 is an AD converter temperature sensor, and the temperature can be obtained from the output of the temperature AD converter 20. Further, the signal S3 from the temperature sensor 14 may be directly input to the calculation unit 16. In addition, a temperature sensor (not shown) for detecting the temperature of the plurality of AD converters 18-20 and the integrated circuit 13 may be separately provided in the state detection device 12, and in this case, the signal S3 from the temperature sensor is directly To the arithmetic unit 16. On the other hand, when the temperature sensor 14 is provided outside the state detection device 12 and detects a temperature at which the temperatures of the plurality of AD converters 18-20 and the integrated circuit 13 are not directly reflected, the temperature of the AD converter 18-20 is detected. Alternatively, a signal S3 from another AD converter temperature sensor (not shown) for detecting the temperature of the integrated circuit 13 is input. The output of the temperature sensor signal S3 may be directly input by the calculation unit 16, or may be input via an input circuit including a multiplexer and a temperature A / D converter, as with the temperature sensor.
Thus, the temperature sensor value for AD converters 18-20 or the integrated circuit 13, that is, the vicinity of the plurality of AD converters 18-20, is obtained by the AD sensor temperature sensor configured as described above.

Referring back to FIG. 5, a predetermined temperature diagnosis value “T _THn ” (n = 1, 2,...) Is set (for example, stored in the storage unit) in the arithmetic unit 16 in advance. When the temperature of the AD converter 18-20 or the temperature of the integrated circuit 13 passes the temperature diagnostic value “T _THn ” or reaches the temperature diagnostic value “T _THn ” (step S21), the process proceeds to step S22. On the other hand, if it is determined in step S21 that the temperature of the AD converter 18-20 or the temperature of the integrated circuit 13 has not passed the temperature diagnosis value T _THn or has not reached the temperature diagnosis value “T _THn ”, step S23 Migrate to

  In step S22, since it is determined that a failure is diagnosed, a failure diagnosis of the AD converter is required in step S12 of FIG. In step S23, since it is determined that failure diagnosis is not performed, it is determined in step S12 of FIG. 2 that failure diagnosis is unnecessary, and the process proceeds to step S10.

FIG. 6 shows a specific example of setting the temperature diagnostic value “T _THn ”. When the arithmetic unit 16 determines that the temperature of the AD converter or the integrated circuit has passed _TTH1 , the arithmetic unit 16 performs failure diagnosis of the plurality of AD converters 18-20. When the detected temperature passes T _TH2 (T _TH1 <T _TH2 ), failure diagnosis is performed again. The above procedure is continued and failure diagnosis is performed according to the temperature of the AD converter or the temperature of the integrated circuit. In general, the lifetime of electronic parts largely depends on the temperature environment in which they are used. Therefore, by diagnosing the presence or absence of a fault in the AD converter according to the temperature of the AD converter or the temperature of the integrated circuit, the fault diagnosis can be performed with a slight decrease in the state calculation accuracy of the secondary battery.

  The calculation unit 16 normally calculates the state of the secondary battery 11 and performs failure diagnosis of the AD converter 18-20 at failure diagnosis, but does not calculate (detect) the state of the secondary battery 11 ( A calculation unit for calculating the state of the secondary battery is separately connected), and it may be dedicated for fault diagnosis of the AD converter that performs fault diagnosis of the AD converter 18-20 at any of the timings described above.

  Each AD converter 18-20 is not limited to an integrated circuit.

  In addition, the secondary battery state detection device of each of the above embodiments has a failure diagnosis power source and a temperature sensor outside the state detection device, or a power source other than the secondary battery as a voltage source. Furthermore, the present invention is also applicable when the state detection device does not use a secondary battery as a voltage source.

  Further, in each of the above embodiments, the fault diagnosis voltage is simultaneously sent to a plurality of AD converters from the same fault diagnosis power supply. However, by sending the same fault diagnosis voltage from the same fault diagnosis power supply at the same time, Fault diagnosis accuracy is improved.

  Further, the present invention is not limited to the above-described embodiments, and it is needless to say that all possible combinations of the features of the respective embodiments are included.

  DESCRIPTION OF SYMBOLS 11 Secondary battery, 12 State detection apparatus, 13 Integrated circuit, 14 Temperature sensor, 15 Power supply for fault diagnosis, 16 Calculation part, 17 Multiplexer, 18 Current A / D converter, 19 Voltage A / D converter, 20 Temperature A / D converter, 21 voltage divider circuit (transformer), 22 internal power supply, 23 AD converter power supply, 24 microprocessor power supply, 25 AD converter reference power supply, R1 current detection resistor, S1 fault signal (normal signal), S2 Key status signal, S3 Temperature sensor signal.

The present invention provides a state detection device for a secondary battery including a plurality of AD converters that convert analog values detected for detecting a state of the secondary battery into digital values, and at the time of failure diagnosis of the plurality of AD converters. includes a fault trouble diagnosis supply for inputting a diagnostic voltage simultaneously to the plurality of AD converters, and a calculation unit for judging failure compared to each other the output values of the plurality of AD converters, each An input switching unit for switching an input on the input side of the AD converter between each analog value for detecting the state of the secondary battery and the failure diagnosis voltage from the failure diagnosis power supply; According to the current value of the secondary battery obtained from the AD converter, the starter starting current is applied during the key-off period when the key switch is turned off or after the key switch is turned on. It is in the state detecting device such as a secondary battery, characterized in that switching the input switching unit to perform a fault diagnosis of the plurality of AD converters in the key switch-on period until.
Further, in the secondary battery state detection device including a plurality of AD converters that convert analog values detected for detecting the state of the secondary battery into digital values, a failure diagnosis is performed when the plurality of AD converters are diagnosed. A failure diagnosis power source for simultaneously inputting the operation voltage to the plurality of AD converters, and an arithmetic unit for determining a failure by comparing output values of the plurality of AD converters with each other. A temperature sensor for AD converter for detecting the temperature in the vicinity of the converter is provided, and an input at the input side of each AD converter is an analog value for detecting the state of the secondary battery and the fault diagnosis from the power supply for fault diagnosis An input switching unit for switching between the input voltage and the calculation unit, wherein the arithmetic unit switches the input switching unit based on a temperature detection value of the AD converter temperature sensor. Rikae controlled to, in the state detecting device such as a secondary battery and determines the timing of the fault diagnosis of the plurality of AD converters.

The AD converter 18 for current is an analog signal value obtained by using the current value of the secondary battery 11 as the voltage across the current detection resistor R1 inserted in the state detection device 12 of the secondary battery 11 and the power supply line to the vehicle. The voltage value is converted into a digital signal value for detection.
AD converter 19 for voltage, the voltage between the terminals of the rechargeable secondary battery 11, the power supply lines to the state detection device 12 and the vehicle battery 11, which is an analog signal value, a digital signal a voltage value It is provided as a role to detect by converting to a value.
The temperature AD converter 20 outputs a voltage value of an analog signal value corresponding to the temperature output from the state sensor 12 or the temperature sensor 14 provided outside the state detector 12 in order to detect a temperature change of the secondary battery 11. It is provided as a role to detect by converting to a digital signal value.

Then, the state of the secondary battery 11 is calculated based on the digital value (step S11).

Claims (10)

  In a secondary battery state detection device including a plurality of AD converters that convert analog values detected for detecting the state of the secondary battery into digital values, a failure diagnosis voltage is provided at the time of failure diagnosis of the plurality of AD converters. A fault diagnosis power source for simultaneously inputting the power to the plurality of AD converters, and an arithmetic unit for determining a fault by comparing the output values of the plurality of AD converters with each other. Secondary battery status detection device.   The secondary battery status detection device includes an existing internal power supply for secondary battery status detection, the internal power supply is used as the failure diagnosis power supply, and the output voltage of the internal power supply is used as the failure diagnosis voltage. The state detection apparatus for a secondary battery according to claim 1.   The secondary battery state detection device according to claim 2, wherein the internal power source is an AD converter power source that drives the plurality of AD converters.   The secondary battery state detection device according to claim 2, wherein the internal power source is a microprocessor power source that drives a microprocessor provided in the secondary battery state detection device.   3. The state detection device for a secondary battery according to claim 2, wherein the plurality of AD converters are ΣΔ type AD converters, and the internal power source is an AD converter reference power source for the ΣΔ type AD converter.   An input switching unit for switching an input on the input side of each AD converter between a respective analog value for detecting a state of a secondary battery and the failure diagnosis voltage from the failure diagnosis power supply; According to the current value of the secondary battery obtained from the AD converter, during the key-off period when the key switch is turned off, or during the key switch-on period from when the key switch is turned on until the starter starting current flows. The secondary battery state detection device according to claim 1, wherein the input switching unit is switched so as to perform a fault diagnosis of the AD converter.   A temperature sensor for AD converter that detects temperatures in the vicinity of the plurality of AD converters is provided, and an input is input from each analog value for detecting the state of the secondary battery and the power source for failure diagnosis on the input side of each AD converter. An input switching unit that switches between the fault diagnosis voltages, and the arithmetic unit switches and controls the input switching unit based on a temperature detection value of the AD converter temperature sensor, and the plurality of AD converters The state detection device for a secondary battery according to any one of claims 1 to 5, wherein the timing of failure diagnosis is determined.   The state of the secondary battery according to any one of claims 1 to 7, wherein the secondary battery state detection device including the power supply for fault diagnosis uses the secondary battery as a voltage source. Detection device.   The secondary voltage according to any one of claims 2 to 5, wherein the output voltage of the internal power supply is stepped down by a voltage transformer or a method other than voltage division to obtain the fault diagnosis voltage. Battery state detection device.   In a secondary battery state detection apparatus including a plurality of AD converters that convert analog values detected for detecting the state of secondary batteries into digital values, the same failure diagnosis is performed when the plurality of AD converters are diagnosed. A state detection device for a secondary battery, wherein a failure diagnosis voltage is simultaneously input from a power supply to the plurality of AD converters, and output values of the plurality of AD converters are compared with each other to determine a failure. For fault diagnosis.

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