JP2015155858A - Battery abnormality determination apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery abnormality determination apparatus capable of suppressing cost increase by reducing a storage area of a storage part for storing current and voltage used for estimating internal resistance of a battery, and of preventing deterioration in determination accuracy of abnormality of the battery.

SOLUTION: The battery abnormality determination apparatus comprises: a current detection unit 3 detecting current flowing through a battery 2; a voltage detection unit 4 detecting a voltage of the battery; and a control unit 7 estimating an internal resistance of the battery 2 from a difference between currents detected twice by the current detection unit 3 and a difference between voltages detected twice by the voltage detection unit 4, and determining that the battery 2 is abnormal when an internal resistance equal to or greater than an abnormal threshold is detected for the number of times of determining abnormality or more.

COPYRIGHT: (C)2015,JPO&INPIT

Description

  The disclosed technique relates to a technique for determining battery abnormality based on internal resistance of a battery.

  A technique for realizing a high voltage battery by connecting a plurality of rechargeable batteries in series has been put into practical use. In recent years, this type of battery has attracted attention in mounting on a vehicle such as an electric forklift, a hybrid car, or an electric vehicle.

Moreover, it is performed to determine the abnormality of the battery based on the internal resistance of the battery. For example, see Patent Document 1.
As an estimation method of the internal resistance of the battery, for example, as shown in FIG. 6, a large number of currents flowing through the battery and the voltage of the battery at that time are obtained, and an approximate straight line is obtained by using the least square method or the like by using the current and the voltage. Some have obtained and estimated the slope of the approximate line as the internal resistance of the battery.

JP 2007-8214 A

  However, as described above, when the internal resistance is estimated from a large number of currents and voltages, the storage unit for storing the currents and voltages requires a large number of storage areas, which increases the cost accordingly. End up.

  In addition, as described above, when the internal resistance is estimated from a large number of currents and voltages, it takes a lot of time to acquire a large number of currents and voltages. If the voltage of the battery fluctuates due to the influence of the above, the estimation accuracy of the internal resistance deteriorates, and the abnormality determination accuracy of the battery deteriorates.

  Therefore, the present invention reduces the storage area of the storage unit for storing the current and voltage used when estimating the internal resistance of the battery, and suppresses an increase in cost while improving the accuracy of battery abnormality determination. It aims at providing the battery abnormality determination apparatus which can suppress deterioration.

The battery abnormality determination device according to the embodiment includes a current detection unit, a voltage detection unit, and a control unit.
The current detection unit detects a current flowing through the battery.
A voltage detection part detects the voltage of a battery.

  The control unit estimates the internal resistance of the battery from the difference between the current detected twice by the current detection unit and the difference between the voltages detected twice by the voltage detection unit, and the internal resistance equal to or greater than the abnormality threshold When this is the case, it is determined that the battery is abnormal.

  As described above, in the battery abnormality determination device of the embodiment, since the internal resistance of the battery is estimated based on the difference between the currents detected twice and the difference between the voltages detected twice, as described above, Compared to the case where the internal resistance is estimated from the current and voltage, the storage area of the storage unit for storing the current and voltage can be reduced, and the increase in cost can be suppressed.

  Further, in the battery abnormality determination device of the embodiment, when the internal resistance equal to or greater than the abnormality threshold is equal to or greater than the number of abnormality determinations, it is determined that the battery is abnormal, so that the reliability of the internal resistance abnormality determination can be improved. And deterioration of battery abnormality determination accuracy can be suppressed.

  According to the present invention, it is possible to reduce the storage area of the storage unit for storing the current and voltage used when estimating the internal resistance of the battery, thereby suppressing the increase in cost and improving the battery abnormality determination accuracy. Deterioration can be suppressed.

It is a figure which shows an example of the battery abnormality determination apparatus of embodiment. It is a flowchart which shows an example of operation | movement of a control part. It is a flowchart which shows an example of operation | movement of a control part. It is a figure which shows an example of the information memorize | stored in a memory | storage part. (A) is a figure which shows the relationship between SOC of a battery, and internal resistance, (b) is a figure which shows the relationship between the temperature of a battery, and internal resistance. It is a figure which shows an example of the approximate line calculated | required from the electric current which flows into the battery in charging / discharging, and the voltage of the battery at that time.

FIG. 1 is a diagram illustrating an example of a battery abnormality determination device according to an embodiment.
The battery abnormality determination device shown in FIG. 1 determines whether or not the battery 2 that supplies power to the load 1 is abnormal, and includes a current detection unit 3, a voltage detection unit 4, and a temperature detection unit 5. And a storage unit 6 and a control unit 7. The load 1 is, for example, a motor mounted on a vehicle such as an electric forklift, a hybrid car, or an electric vehicle, and an inverter circuit that drives the motor.

The current detection unit 3 is an ammeter, for example, and detects a current flowing through the battery 2.
The voltage detection unit 4 is, for example, a voltmeter or the like, and detects the voltage of the battery 2.
The temperature detector 5 is a thermistor to which a constant voltage is applied, for example, and detects the temperature of the battery 2.

  The storage unit 6 is, for example, a RAM (Random Access Memory) or a ROM (Read Only Memory), and information used to estimate the internal resistance of the battery 2 or information used to determine abnormality of the battery 2. Memorize etc.

  The control unit 7 estimates the internal resistance of the battery 2 using the current detected by the current detection unit 3, the voltage detected by the voltage detection unit 4, and the like. Further, the control unit 7 uses the estimated internal resistance, the ratio of the current charge capacity to the full charge capacity of the battery 2 (SOC (State Of Charge)), the temperature detected by the temperature detection unit 5, and the like. It is determined whether 2 is abnormal. The control unit 7 includes, for example, a CPU (Central Processing Unit), a multi-core CPU, and a programmable device (FPGA (Field Programmable Gate Array), PLD (Programmable Logic Device, etc.)) and is stored in the storage unit 6. The CPU, the multi-core CPU, or the programmable device reads and executes the program being executed, and as described above, the operation for estimating the internal resistance of the battery 2 and the determination of whether or not the battery 2 is abnormal are performed. Operation is realized.

2 and 3 are flowcharts illustrating an example of the operation of the control unit 7. Note that the flowcharts shown in FIGS. 2 and 3 are performed at regular intervals (for example, 1 [second]).
First, in FIG. 2, the control unit 7 stores the current acquired from the current detection unit 3 in the storage unit 6 as the current current, and stores the voltage acquired from the voltage detection unit 4 as the current voltage in the storage unit 6. (S1). For example, as shown in FIG. 4, the control unit 7 stores “15” as the current [A] in the storage unit 6 and “3.95” as the current voltage [V] in the storage unit 6. Remember.

  Next, the control unit 7 determines whether or not the resistance calculation permission condition is satisfied (S2). For example, the control unit 7 determines that “the SOC is within a predetermined SOC range”, “the temperature detected by the temperature detection unit 5 is within the predetermined temperature range”, and “from the battery 2 to the load 1 as a motor”. A state in which the ripple current included in the supplied power is less than or equal to a predetermined current, a state in which the output of the load 1 as a motor is less than or equal to a predetermined value, or a state in which the load 1 as a motor is driven with low rotation and high torque "Is determined, it is determined that the resistance calculation permission condition is satisfied. In addition, the control unit 7 may determine that the resistance calculation permission condition is satisfied when at least one of the above states has occurred.

  When the control unit 7 determines that the resistance calculation permission condition is not satisfied (S2: NO), the control unit 7 clears the previous current and the previous voltage stored in the storage unit 6 and sets the previous value normal substitution flag to OFF. (S3) The operation shown in the flowcharts of FIGS. 2 and 3 is terminated, and the next operation shown in the flowcharts of FIGS. 2 and 3 is executed. That is, the state of the SOC of the battery 2, the temperature of the battery 2, the output of the battery 2 (the state of the ripple current included in the power supplied from the battery 2 to the load 1), or the output of the load 1 to which the battery 2 is supplied The internal resistance is not estimated according to the torque.

Further, when determining that the resistance calculation permission condition is satisfied (S2: YES), the control unit 7 determines whether or not the previous value normal substitution flag is ON (S4).
When the control unit 7 determines that the previous value normal substitution flag is OFF (S4: NO), the current current stored in the storage unit 6 is set as the previous current and stored in the storage unit 6. The current voltage is set as the previous voltage, and the previous value normal substitution flag is turned ON (S5).

If the control unit 7 determines that the previous value normal substitution flag is ON (S4: YES), the control unit 7 determines whether or not the current current does not match the previous current (S6).
When determining that the current current matches the previous current (S6: NO), the control unit 7 stores the internal resistance of the battery 2 as zero in the storage unit 6 (S7).

  If the control unit 7 determines that the current current does not match the previous current (S6: YES), the control unit 7 estimates the internal resistance of the battery 2 and stores it in the storage unit 6 (S8), and proceeds to S5. . For example, the control unit 7 obtains 5 [A] as a current difference value between the current (15 [A]) shown in FIG. 4 and the current (10 [A]) shown in FIG. 0.05 [V] is obtained as a voltage difference value between (3.95 [V]) and the previous voltage (3.90 [V]), and the voltage difference value (0.05 [V]) is obtained as a current difference value. 10 [mΩ], which is a value divided by (5 [A]), is estimated as the internal resistance of the battery 2. At this time, the control unit 7 turns on the previous value normal substitution flag as shown in FIG.

  Next, in FIG. 3, the control unit 7 increments the measurement counter by 1 (S9), and when the internal resistance stored in the storage unit 6 is equal to or greater than the abnormal threshold (S10: YES), the abnormal counter is incremented by 1. Count up (S11).

  Next, when the internal resistance memorize | stored in the memory | storage part 6 is more than a serious abnormality threshold value (S12: YES), the control part 7 counts up a serious abnormality counter by 1 (S13). Note that the abnormality threshold (for example, 10 [mΩ]) <the serious abnormality threshold (for example, 20 [mΩ]). Further, for example, the abnormal threshold value is a value corresponding to the internal resistance of the battery 2 when the battery 2 has deteriorated over time, and the serious abnormal threshold value is an electrical inside the battery 2 by a CID (Current Interrupt Device) inside the battery 2. A value corresponding to the internal resistance of the battery 2 when the cutting is performed.

  Next, when the control unit 7 determines that the measurement counter is not equal to or greater than the abnormality determination permitted number (S14: NO), the operation shown in the flowcharts of FIGS. 2 and 3 is terminated, and the next time of FIGS. The operation shown in the flowchart is executed.

  Further, after determining that the measurement counter is equal to or greater than the number of times of abnormality determination allowed (S14: YES), the control unit 7 turns on the abnormality flag (S16: YES) when the abnormality counter is equal to or greater than the number of times of abnormality determination (S15: YES). ) When the abnormality counter is not equal to or more than the number of abnormality determination (S15: NO), the abnormality flag is turned OFF (S17). For example, when the abnormality determination permission count is 30 and the abnormality determination count is 10, the control unit 7 determines that if the measurement counter is 30 and the abnormality counter is 10 or more, as shown in FIG. Turn on the flag.

  Next, when the critical abnormality counter is equal to or greater than the number of critical abnormality determinations (S18: YES), the control unit 7 turns on the critical abnormality flag (S19), and when the critical abnormality counter is not equal to or greater than the number of critical abnormality determinations (S18: NO), the serious abnormality flag is turned OFF (S20). For example, when the abnormality determination permission count is 30 and the serious abnormality determination count is 3, as shown in FIG. 4, when the measurement counter becomes 30 and the serious abnormality counter is 3 or more, the control unit 7 Set the serious abnormality flag to ON.

  Then, the control unit 7 clears the measurement counter, the abnormality counter, the serious abnormality counter, and the internal resistance stored in the storage unit 6 (S21), and ends the operations shown in the flowcharts of FIGS. Then, the next operation shown in the flowcharts of FIGS. 2 and 3 is executed. In addition, when the flowchart of FIG.2 and FIG.3 of this time is complete | finished, the control part 7 will carry out driving | running | working of a vehicle to the effect that the battery 2 is abnormal when the abnormality flag memorize | stored in the memory | storage part 6 is ON. You may notify to the high-order control part not shown to control, or may display that the battery 2 is abnormal on a display part not shown. In addition, when the flowchart of FIGS. 2 and 3 is finished, the control unit 7 indicates that the battery 2 is seriously abnormal when the serious abnormality flag stored in the storage unit 6 is ON. You may notify to the high-order control part not shown which controls driving | running | working, or you may display that the battery 2 is serious abnormality on a display part not shown.

  In the battery abnormality determination device of the embodiment, since the internal resistance of the battery 2 is estimated from the difference in the current of the battery 2 detected twice and the difference in the voltage of the battery 2 detected twice, a large number of currents and Compared to the case where the internal resistance is estimated from the voltage, the storage area of the storage unit for storing the current and voltage can be reduced, and an increase in cost can be suppressed.

  In the battery abnormality determination device according to the embodiment, when the internal resistance equal to or higher than the abnormality threshold is equal to or greater than the number of abnormality determinations, the battery 2 is determined to be abnormal, and the internal resistance equal to or greater than the abnormality threshold is equal to or greater than the number of serious abnormality determinations. Since it is determined that the battery 2 is seriously abnormal, the reliability of the internal resistance abnormality determination can be improved, and deterioration of the abnormality determination accuracy of the battery 2 can be suppressed.

  In the above embodiment, the abnormal threshold value and the serious abnormal threshold value are fixed values. However, the abnormal threshold value and the serious abnormal threshold value may be varied. For example, as shown in FIG. 5A, the internal resistance of the battery 2 increases as the SOC of the battery 2 decreases. In consideration of this, the control unit 7 may increase the abnormality threshold or the serious abnormality threshold as the SOC of the battery 2 is lower. As a result, the abnormality threshold and the serious abnormality threshold can be increased as the SOC of the battery 2 decreases, so that the abnormality threshold and the serious abnormality threshold can be set to a more accurate value. Can be performed with higher accuracy. For example, as shown in FIG. 5B, the internal resistance of the battery 2 increases as the temperature of the battery 2 decreases. In consideration of this, the control unit 7 may increase the abnormality threshold or the serious abnormality threshold as the temperature acquired from the temperature detection unit 5 is lower. As a result, the abnormality threshold value and the serious abnormality threshold value can be increased as the temperature of the battery 2 decreases, so that the abnormality threshold value and the serious abnormality threshold value can be set to more accurate values. Can be performed with higher accuracy.

  Further, in the above embodiment, every time the measurement counter becomes equal to or greater than the number of times of abnormality determination, determination processing whether or not the abnormality counter is equal to or greater than the number of times of abnormality determination and whether or not the serious abnormality counter is equal to or greater than the number of times of serious abnormality determination. However, every time the internal resistance is estimated, it is determined whether the internal resistance is greater than or equal to an abnormal threshold, whether the internal resistance is greater than or equal to a serious abnormal threshold, and A process for determining whether or not the abnormality counter is greater than or equal to the number of times of abnormality determination or a process for determining whether or not the significant abnormality counter is greater than or equal to the number of times of serious abnormality determination is performed. May be.

  Moreover, in the said embodiment, although the temperature detection part 5 was contained in the battery abnormality determination apparatus, the temperature detection part 5 does not need to be. In this case, the condition “the temperature detected by the temperature detection unit 5 is within the predetermined temperature range” is excluded from the resistance calculation permission conditions in step S2.

DESCRIPTION OF SYMBOLS 1 Load 2 Battery 3 Current detection part 4 Voltage detection part 5 Temperature detection part 6 Memory | storage part 7 Control part

Claims (5)

A current detector for detecting the current flowing through the battery;
A voltage detector for detecting the voltage of the battery;
The internal resistance of the battery is estimated from the difference between the current detected twice by the current detection unit and the difference between the voltages detected twice by the voltage detection unit, and the internal resistance equal to or higher than the abnormality threshold is greater than the number of abnormal determinations. A control unit that determines that the battery is abnormal;
A battery abnormality determination device comprising: The battery abnormality determination device according to claim 1,
The control unit determines that the battery is critically abnormal when an internal resistance greater than or equal to a critical abnormality threshold greater than the abnormality threshold is equal to or greater than the number of critical abnormality determinations. The battery abnormality determination device according to claim 1 or 2,
The control unit does not estimate the internal resistance according to the output of the battery or the output or torque of a load at the power supply destination of the battery at the time of detection of the current voltage and current. . The battery abnormality determination device according to any one of claims 1 to 3,
The battery abnormality determination device, wherein the control unit increases the abnormality threshold as the ratio of the current charge capacity to the full charge capacity of the battery is lower. The battery abnormality determination device according to any one of claims 1 to 4,
A temperature detection unit for detecting the temperature of the battery;
The battery abnormality determination device, wherein the control unit increases the abnormality threshold as the temperature detected by the temperature detection unit is lower.

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