JP2005114401A - Device and method for determining abnormality of battery pack - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device for determining abnormality which does not make such an erroneous determination that a new battery being exchanged for one of two or more batteries making up a battery pack is an abnormal battery. <P>SOLUTION: An MPU 23 of a battery controller 10 detects charging and discharging hysteresis values, i.e., amounts of charging and discharging of modules M1-M20 making up the battery pack 1, and sets a threshold value used for determining the abnormality, on the basis of the detected charging and discharging hysteresis values. The threshold value is compared with the difference voltage Vd between the maximum voltage and the minimum voltage from among voltage values of the modules M1-M20 detected by voltage sensors 20a-20t, thereby determining whether or not the modules M1-M20 are in abnormal states. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an apparatus and a method for determining whether or not an abnormality has occurred in a plurality of batteries constituting an assembled battery.

  In order to detect abnormal cells among assembled batteries composed of multiple cells, the difference between the average voltage of each cell and each cell voltage is calculated, and the calculated voltage difference is equal to or greater than a predetermined threshold value. An apparatus that determines a cell as an abnormal cell is known (see Patent Document 1).

JP 2002-334726 A

  However, in the conventional apparatus, when a cell determined to be abnormal is replaced with a new cell, the internal resistance of the cell that is continuously used is different from the internal resistance of the new cell. There is a possibility that the difference between the voltage of the new cell and the voltage exceeds a predetermined threshold value, and the new cell is erroneously determined as an abnormal cell.

  An assembled battery abnormality determination device according to the present invention is configured to determine the presence or absence of an abnormal battery based on a voltage difference between a maximum voltage and a minimum voltage of a plurality of batteries constituting the assembled battery and an abnormality determination threshold value. The abnormality determination threshold value is set based on the usage frequency of each battery.

  The battery pack abnormality determination device according to the present invention sets an abnormality determination threshold for determining battery abnormality based on the use frequency of a plurality of batteries constituting the battery pack. It is possible to prevent the replaced new battery from being erroneously determined as an abnormal battery.

  FIG. 1 is a diagram showing a configuration of an embodiment in which an assembled battery abnormality determination device according to the present invention is applied to a hybrid electric vehicle. In FIG. 1, the strong electric line is indicated by a thick solid line, the weak electric line is indicated by a thin solid line, and the control signal line is indicated by a dotted line. This hybrid electric vehicle includes an engine 1 and a motor generator 4 (hereinafter simply referred to as a motor 4) as a vehicle driving source. That is, the driving force of both or either of the engine 1 and the motor 4 is transmitted to the drive wheels 17a and 17b via the speed reducer 6.

  Generally, an electric motor (motor) is a power running operation by converting electric power into driving force, but can be regenerated by reversely converting driving force into electric power with the same structure. In addition, the generator (generator) converts the driving force into electric power for power generation operation (equivalent to regenerative operation), but it can be converted to electric power for driving operation with the same structure. It is. That is, the electric motor (motor) and the generator (generator) basically have the same structure, and both can be driven (power running) and generated (regenerated). Therefore, in this specification, a rotating electrical machine having both the function of an electric motor (motor) that converts electrical energy (electric power) into rotational energy (driving force) and the function of a generator (generator) that converts rotational energy into electrical energy. Is called a motor generator or simply a motor.

  The motor generator 3 (hereinafter simply referred to as the motor 3) is connected to the engine 2 and is used to start the engine 2 and is also driven by the engine 2 to generate electric power. The engine 2 is connected to the speed reducer 6 and the motor 4 via the power split mechanism 30. That is, the driving force of the engine 2 is transmitted to the drive wheels 17 a and 17 b and the motor 4 by the power split mechanism 30. As described above, the motor 4 is used as a vehicle drive source, and generates power by performing a regenerative operation when the vehicle is decelerated. Motor 3 and motor 4 are three-phase AC motors.

  The inverter 5 converts the DC power stored in the assembled battery 1 (high-power battery) into three-phase AC power and supplies it to the motor 4 to drive (power running) the motor 4. Further, the inverter 5 converts the three-phase AC power generated by the regenerative operation of the motor 3 or the motor 4 into DC power. The converted DC power is used for charging the assembled battery 1, and is stepped down by the DC / DC converter 7 and used for charging the 12V battery 8.

  The DC power stored in the 12V battery 8 is used to drive an auxiliary machine (not shown) and is boosted by the DC / DC converter 7 in accordance with the SOC of the assembled battery 1 to Also used when charging.

  The vehicle controller 9 controls the traveling of the vehicle by controlling the engine 2, the battery controller 10, and the motor controller 11. When the battery controller 9 detects a module indicating abnormality among a plurality of modules (unit batteries) constituting the assembled battery, the vehicle controller 9 turns on the warning lamp 16 to cause an abnormality in the passenger. Is notified. The vehicle controller 9, the battery controller 10, and the motor controller 11 are connected by an in-vehicle communication line 15, and exchange various information.

  The motor controller 11 controls the inverter 5 in order to control the operation modes of the motor 3 and the motor 4, that is, the power running operation mode and the regenerative operation mode. The battery controller 10 controls charging / discharging of the assembled battery 1 and detects a module in which an abnormality has occurred from among a plurality of modules constituting the assembled battery 1. A detailed configuration of the battery controller 10 and a method for detecting a module abnormality will be described later.

  The current sensor 12 detects a discharge current flowing from the assembled battery 1 to the inverter 5 and a charging current flowing from the inverter 5 to the assembled battery 1 and outputs the detected current to the battery controller 10. The temperature sensor 13 is provided on the surface of the assembled battery 1, detects the temperature of the assembled battery 1, and outputs it to the battery controller 10. In addition, a temperature difference shall not arise in the assembled battery 1, and the temperature of each module which comprises the assembled battery 1 shall be equal. The cooling fan 14 is provided in the vicinity of the assembled battery 1, and cools the assembled battery 1 based on a command from the battery controller 10.

  FIG. 2 is a diagram illustrating a detailed configuration of the assembled battery 1 and the battery controller 10. The assembled battery 1 is configured by connecting 20 modules M1 to M20 in series. Each of the modules M1 to M20 is configured by connecting 12 cells in series. For example, the module M1 includes cells s1 to s12. The cells s1 to s240 constituting each of the modules M1 to M20 are, for example, nickel hydrogen batteries having a rated capacity of 6.5 (Ah) and a rated voltage of 1.2 (V).

  The battery controller 10 includes voltage sensors 20 a to 20 t, a multiplexer (MPX) 21, an A / D converter 22, a microprocessor 23 (hereinafter referred to as MPU 23), and a memory 24. The voltage sensors 20 a to 20 t are provided for each of the modules M 1 to M 20, detect the voltages of the corresponding modules M 1 to M 20, and output them to the multiplexer 21. The multiplexer 21 sequentially outputs the voltage values detected by the voltage sensors 20 a to 20 t to the A / D converter 22.

  The A / D converter 22 converts the voltage value, which is analog data input from the multiplexer 21, into a digital value and outputs the digital value to the MPU 23. The MPU 23 calculates a difference Vd between the maximum voltage and the minimum voltage among the module voltages detected by the voltage sensors 20a to 20t, and compares the calculated voltage difference Vd with the abnormality determination threshold value Vdmx. Modules with large voltage variations, that is, abnormal modules are detected.

  Further, the MPU 23 changes the abnormality determination threshold value Vdmx based on the use frequency (charge / discharge history) of each module M1 to M20, that is, the integrated value of the charge / discharge amount. A method for changing the abnormality determination threshold value Vdmx will be described with reference to a flowchart shown in FIG. The memory 24 stores a charge / discharge history of each of the modules M1 to M20, a table indicating a relationship between the temperature of the assembled battery 1 and the initial value Vdmx0 of the abnormality determination threshold value Vdmx, and the like.

  FIG. 3 is a flowchart showing an embodiment of an abnormal module detection program executed by the MPU 23. The process starting from step S10 is started when, for example, a module determined to be abnormal is replaced with a new module at a repair shop.

  In step S10, the charge / discharge history Asx of the replaced module is reset (Asx = 0). The replaced module is specified by connecting a jig (not shown) to the MPU 23 and specifying it using the jig. The MPU 23 resets the charge / discharge history Asx of the replaced module among the charge / discharge histories of the modules M1 to M20 stored in the memory 24. When the charge / discharge history Asx of the replaced module is reset, the process proceeds to step S20.

  In step S20, the charge / discharge current I of the assembled battery 1 detected by the current sensor 12 is acquired, and the temperature of the assembled battery 1 detected by the temperature sensor 13 is acquired. The voltages V1 to V20 of the modules M1 to M20 detected by the voltage sensors 20a to 20t and input to the MPU 23 via the multiplexer 21 and the A / D converter 22 are acquired.

  In step S30 following step S20, the internal resistances r1 to r20 of the modules M1 to M20 are determined based on the charge / discharge current of the assembled battery 1 detected in step S20 and the voltages V1 to V20 of the modules M1 to M20. calculate.

  FIG. 4 is a diagram for explaining a method of calculating the internal resistances r1 to r20 of the modules M1 to M20. The MPU 23 performs a linear regression calculation based on a plurality of data obtained by combining the module voltage detected by the voltage sensors 20a to 20t and the current detected by the current sensor 12, and generates a regression line as shown in FIG. Ask. The slope of the regression line obtained is the internal resistance. The internal resistance increases as charging / discharging is repeated. When the internal resistances r1 to r20 of all the modules M1 to M20 are calculated and stored in the memory 24, the process proceeds to step S40.

  In order to calculate the regression line, a predetermined number of the latest data is used among the data obtained by combining the charge / discharge current and the voltage. These data are stored in the memory 24, and when one new data is acquired in step S20, one old data is deleted.

In step S40, based on the charging / discharging current I of the assembled battery 1 detected in step S20, the charging / discharging history Asec of each module M1 to M20 is calculated by the following equation (1). However, the charging / discharging current I shall be measured every 1/10 second. This charge / discharge history Asec means the amount of charge and discharge that each module M1 to M20 has performed so far, that is, an integrated value of the charge / discharge amount, and its unit is [Ah].
Asec = I / 10 + Asec (1)

Further, the charge / discharge history Asx of the replaced module is calculated based on the following equation (2).
Asx = I / 10 + Asx (2)
When the charge / discharge histories Asec and Asx of all the modules M1 to M20 including the replaced module are calculated, the process proceeds to step S50.

In step S50, in order to confirm that the assembled battery 1 is in a state close to no load, a predetermined time T1 (seconds) in a state where the charge / discharge current I detected in step S20 satisfies the relationship of the following equation (3). It is determined whether it has continued.
-0.5 <I <0.5 (3)

  If it is determined in step S50 that the state satisfying the relationship of expression (3) does not continue for the predetermined time T1, the process returns to step S20, and again, the charge / discharge current I of the assembled battery 1, the temperature of the assembled battery, and the module voltages V1 to V1. V20 is measured. On the other hand, if it is determined that the state satisfying the relationship of Expression (3) has continued for the predetermined time T1, the process proceeds to step S60.

  In step S60, the difference Vd between the maximum voltage and the minimum voltage among the voltages V1 to V20 of the modules M1 to M20 acquired in step S20 is calculated. This voltage difference Vd means the maximum value among the voltage variations of the modules M1 to M20. When the voltage difference Vd is calculated, the process proceeds to step S70.

In step S70, the variable K used for calculating the abnormality determination threshold value Vdmx in step S80 described later is calculated based on the following equation (4). However, r_max is an internal resistance indicating the maximum value among the internal resistances r1 to r20 of the modules M1 to M20 calculated in step S30. Also, r_min is an internal resistance indicating the minimum value, and immediately after the module is replaced, it is the internal resistance of the replaced module. A is a constant.
K = A × (r_max−r_min) (4)

When the variable K is calculated, the process proceeds to step S80. In step S80, the abnormality determination threshold value Vdmx is calculated by the following equation (5).
Vdmx = K × (Asmx−Asx) × Vdmx0 (5)
However, Asmx shows the maximum value among the charging / discharging log | history Asec of each module M1-M20 calculated by step S40. Vdmx0 is an initial value of the abnormality determination threshold value Vdmx, and is calculated based on the temperature of the assembled battery 1 detected in step S20 and a table stored in the memory 24. A table stored in the memory 24 is shown in FIG.

  As shown in Expression (5), the abnormality determination threshold value Vdmx is a difference between Asmx indicating the maximum value among the charge / discharge histories Asec of the modules M1 to M20 and the charge / discharge history Asx of the replaced module. Calculated based on As a result, the larger the difference in charge / discharge history between the replaced new module and the non-replaced module, the larger the abnormality determination threshold value Vdmx is set. Therefore, the new module is erroneously determined as an abnormal module. Can be prevented.

  In principle, the difference between Asmx and Asx does not change even if charging and discharging are repeated unless a new module is replaced. However, when charging / discharging of each module M1-M20 is repeatedly performed, the difference between the internal resistance of the replaced new module and the internal resistance of the module not replaced is reduced.

  In other words, since the internal resistance of the module does not increase any more when the value becomes large to some extent, the difference in internal resistance between the replaced module and the module not replaced is large immediately after the module replacement. However, it becomes smaller as charging / discharging is repeatedly performed. Therefore, in order to reliably detect an abnormal module having a large voltage variation, it is necessary to decrease the abnormality determination threshold value Vdmx as the difference in internal resistance decreases.

  As described above, even if the module is repeatedly charged and discharged, the value of (Asmx−Asx) does not change in principle. Therefore, the variable K is calculated based on the difference in the internal resistance of the module (calculated in step S70). Is used to correct the abnormality determination threshold value Vdmx. Thus, the abnormality determination threshold value Vdmx is set to be smaller as the module usage frequency is higher.

  When the abnormality determination threshold value Vdmx is calculated in step S80, the process proceeds to step S90. In step S90, it is determined whether or not the state in which the voltage difference Vd calculated in step S60 is greater than the abnormality determination threshold value Vdmx calculated in step S90 continues for a predetermined time T2 (seconds) or longer. If it is determined that the state of Vd> Vdmx has not continued for the predetermined time T2 or more, it is determined that there is no abnormal module, the process returns to step S20, and the processes after step S20 are performed again. On the other hand, if it is determined that the state of Vd> Vdmx has continued for the predetermined time T2 or more, it is determined that there is an abnormal module, and the process proceeds to step S100. Note that it is determined whether or not it has continued for a predetermined time T2 or more in order to avoid instantaneous voltage fluctuations and noise.

  In step S100, an abnormality flag indicating that an abnormal module exists is set in the memory 24, and the process proceeds to step S110. This abnormality flag is used, for example, when determining the type of abnormality that has occurred in the vehicle at a repair shop. In step S110, the input / output limit of the assembled battery 1 is set to 0 kW. Thereby, charging and discharging of the assembled battery 1 are prohibited. When the input / output limit of the assembled battery 1 is set to 0 kW and a signal notifying that is transmitted to the vehicle controller 9, the process proceeds to step S120.

  In step S120, the vehicle controller 9 turns on the warning lamp 16 to notify the occupant of the occurrence of an abnormality. When the warning lamp 16 is turned on, the process of the flowchart shown in FIG. 3 ends. Thereafter, for example, an operation of replacing an abnormal module with a new module is performed at a repair shop.

  As described above, the battery pack abnormality determination device according to the embodiment determines the module abnormality based on the voltage difference between the maximum voltage and the minimum voltage of the modules constituting the battery pack and the abnormality determination threshold value. An apparatus for determination, wherein an abnormality determination threshold value is set based on the use frequency (integrated value of charge / discharge amount) of each module. Thereby, it can prevent that the new module replaced | exchanged among several modules is misjudged as an abnormal module.

  According to the battery pack abnormality determination device according to the embodiment, the abnormality determination threshold is set to be smaller as the integrated value of the charge / discharge amount is larger, that is, as the frequency of use of the module is higher. Can be detected. That is, it is possible to accurately determine the presence or absence of an abnormal module by setting the abnormality determination threshold based on the integrated value of the charge / discharge amount of each module and the internal resistance of each module.

  Further, according to the assembled battery abnormality determination device in one embodiment, when a state where the voltage difference between the maximum voltage and the minimum voltage of the module is larger than the abnormality determination threshold value continues for a predetermined time, it is determined that an abnormal module exists. Therefore, it can be prevented that a module having no abnormality is erroneously determined to be abnormal due to an instantaneous voltage fluctuation or noise.

  The present invention is not limited to the embodiment described above. For example, in the above-described embodiment, the case where the abnormality of the modules M1 to M20 configured by a plurality of cells is determined has been described. However, the presence or absence of the abnormality may be determined in units of cells s1 to s240. In this case, in Expression (5) for calculating the abnormality determination threshold, Asmx indicates the maximum value among the charge / discharge histories of the cells s1 to s240, and Asx is the charge / discharge history of the replaced cell. Further, in order to calculate the variable K by the equation (4), the internal resistance of each of the cells s1 to s240 may be calculated.

  In step S10 of the flowchart shown in FIG. 3, the replaced module is specified by specifying it using a jig (not shown). However, the internal resistances of the modules M1 to M20 may be calculated, and among the calculated internal resistances, the module having the smallest internal resistance may be determined as the replaced module.

  The assembled battery 1 has been described as being mounted on a hybrid electric vehicle. However, the assembled battery 1 may be mounted on an electric vehicle or may be an assembled battery used for other purposes than a vehicle. Further, the present invention is not limited by the number of cells and modules constituting the assembled battery 1 or the type of cells.

  The variable K used to calculate the abnormality determination threshold value Vdmx is calculated based on the difference between the maximum internal resistance and the minimum internal resistance of the module, but the difference between the maximum value and the minimum value of the full charge capacity of the module. It may be calculated on the basis of the deterioration rate of the module.

  In the above-described embodiment, when a difference Vd between the maximum voltage and the minimum voltage among the voltages of the modules M1 to M20 is greater than the abnormality determination threshold value Vdmx for a predetermined time T2 or longer, an abnormal module is present. Determination was made (step S90 in the flowchart of FIG. 3). The predetermined time T2 may be a variable based on the module temperature, and may be set to a smaller value as the module temperature is lower.

  The correspondence between the constituent elements of the claims and the constituent elements of the embodiment is as follows. That is, the voltage sensors 20a to 0t constitute voltage detection means, the MPU 23 constitutes voltage difference calculation means, threshold value setting means and determination means, and the current sensor 12 and MPU 23 constitute usage frequency detection means. In addition, unless the characteristic function of this invention is impaired, each component is not limited to the said structure.

The figure which shows the structure of one Embodiment which applied the abnormality determination apparatus of the assembled battery by this invention to the hybrid electric vehicle. The figure which shows the detailed structure of an assembled battery and a battery controller A flowchart showing an embodiment of an abnormality module detection program The figure for explaining the method of calculating the internal resistance of each module A table showing the relationship between the module temperature and the initial value Vdmx0 of the abnormality determination threshold value Vdmx

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Battery assembly 2 ... Engine 3 ... Motor generator 4 ... Motor generator 5 ... Inverter 6 ... Reduction gear 7 ... DC / DC converter 8 ... 12V battery 9 ... Vehicle controller 10 ... Battery controller 11 ... Motor controller 12 ... Current sensor 13 ... Temperature sensor 14 ... cooling fan 15 ... communication line 16 ... warning lights 17a, 17b ... wheels 20a-20t ... voltage sensor 21 ... multiplexer 22 ... A / D converter 23 ... microprocessor 24 ... memory 30 ... power split mechanism M1-M20 ... Modules s1 to s240 ... cell

Claims (8)

In an abnormality determination device for an assembled battery composed of a plurality of batteries,
Voltage detecting means for detecting the voltages of the plurality of batteries,
Voltage difference calculating means for calculating a voltage difference between the maximum voltage and the minimum voltage based on the plurality of voltages detected by the voltage detecting means;
Usage frequency detection means for detecting the usage frequency of each of the plurality of batteries;
An abnormality determination threshold value setting means for setting a threshold value for performing abnormality determination (hereinafter referred to as an abnormality determination threshold value) based on the usage frequency detected by the usage frequency detection means;
Whether an abnormality has occurred in the battery constituting the assembled battery based on the abnormality determination threshold set by the abnormality determination threshold setting means and the voltage difference calculated by the voltage difference calculation means An abnormality determination device for an assembled battery, comprising: determination means for determining whether or not. In the assembled battery abnormality determination device according to claim 1,
The assembled battery abnormality determination device, wherein the usage frequency detection means detects the usage frequency of the plurality of batteries by respectively calculating integrated values of charge / discharge amounts of the plurality of batteries. In the assembled battery abnormality determination device according to claim 1 or 2,
An internal resistance calculating means for calculating internal resistances of the plurality of batteries;
The abnormality determination threshold value setting means sets the abnormality determination threshold value based on the use frequency detected by the use frequency detection means and the internal resistance calculated by the internal resistance calculation means. A battery pack abnormality determination device as a feature. In the assembled battery abnormality determination device according to any one of claims 1 to 3,
The abnormality determination device for an assembled battery, wherein the abnormality determination threshold value setting unit sets the abnormality determination threshold value to a smaller value as the use frequency detected by the use frequency detection unit is higher. In the assembled battery abnormality determination device according to any one of claims 1 to 4,
The determination means determines that there is a battery in which an abnormality has occurred when the voltage difference calculated by the voltage difference calculation means is greater than the abnormality determination threshold set by the abnormality determination threshold setting means. An abnormality determination device for an assembled battery, characterized in that: In the assembled battery abnormality determination device according to claim 5,
The determination means has the abnormality when the voltage difference calculated by the voltage difference calculation means is larger than the abnormality determination threshold set by the abnormality determination threshold setting means for a predetermined time. An apparatus for determining an abnormality of an assembled battery, characterized in that a battery is present. In the assembled battery abnormality determination device according to any one of claims 1 to 6,
The assembled battery abnormality determination device, wherein the plurality of batteries constituting the assembled battery is a cell or a module composed of a plurality of cells. In an abnormality determination method for an assembled battery composed of a plurality of batteries,
Detecting the voltage of each of the plurality of batteries,
Based on the plurality of detected voltages, a voltage difference between the maximum voltage and the minimum voltage is calculated,
Detecting the usage frequency of each of the plurality of batteries,
Based on the detected use frequency, set an abnormality determination threshold for performing abnormality determination,
An assembled battery abnormality determination method, comprising: determining whether an abnormality has occurred in a battery constituting the assembled battery based on the abnormality determination threshold value and the voltage difference.

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