JP2009276169A - Condition detector for electric storage device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To surely detect the condition of an electric storage device such as a battery pack. <P>SOLUTION: For each block of a battery pack 100, timing at which a predetermined voltage is reached is detected by comparators 140-1 to 140-n. A determination section 160 detects a current at the timing the predetermined voltage is reached and calculates a representative current value for each block. A deviation of the representative current value for each block is compared to a threshold value, and when the deviation is large, it is determined that an abnormality such as a short circuit is occurring. When the voltage of the battery pack 100 does not reach a predetermined one, the control of the battery pack 100 is changed to make it easier for the predetermined voltage to be reached. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a state detection device for a power storage device, and more particularly to detection of an abnormal state or SOC.

  Conventionally, one or a plurality of batteries are connected in series to form a block, and an assembled battery configured by connecting a plurality of blocks in series is mounted on a hybrid vehicle or an electric vehicle to form an assembled battery. Devices have been developed that detect abnormalities by measuring the voltage and current of each block. As a basic method for detecting an abnormality, voltage and current are measured for each block, and an internal resistance (IR) is calculated by a least square method. Then, an abnormality is detected based on the increase or deviation of IR.

Patent Document 1 listed below discloses a technique for detecting an abnormal temperature rise of a battery by calculating IR of each block based on the block voltage and current and comparing the IR with a predetermined threshold value. . FIG. 25 shows the configuration of the assembled battery control device disclosed in this prior art. The assembled battery control device is mounted on a hybrid vehicle. The assembled battery control device controls input / output of the assembled battery 10. The assembled battery 10 includes a plurality of blocks 10A connected in series. Each of the plurality of blocks 10A includes a plurality of single cells 10B connected in series. The battery pack control apparatus includes a battery power input / output unit 1 that controls power input / output of the battery pack 10, a voltage detection unit 2 that detects each block voltage of the plurality of blocks 10 </ b> A, and a battery current of the battery pack 10. Based on the current detection unit 3 to detect, the abnormal temperature rise detection unit 4 for detecting the abnormal temperature rise of the unit cell 10B based on the block voltage and the battery current, and the detection result of the abnormal temperature rise by the abnormal temperature rise detection unit 4 A vehicle control unit 5 that controls the battery power input / output unit 1 and a battery temperature detection unit 6 that detects the battery temperature of the assembled battery 10 are provided. The abnormal temperature rise detection unit 4 sets the threshold based on the internal resistance calculation unit 4A that calculates the internal resistance of each of the plurality of blocks 10A based on the block voltage and the battery current, and the battery temperature of the assembled battery 10 Threshold value setting unit 4B, a variance calculation unit 4C for calculating the average value and variance σ ² of each block voltage of the plurality of blocks 10A, and the block voltage, average value and variance σ of each of the plurality of blocks 10A ² , a dispersion abnormal temperature rise detection unit 4D that detects an abnormal temperature rise of the unit cell 10B based on ^2, and a remaining capacity abnormal rise that detects an abnormal temperature rise of the unit cell 10B based on the remaining capacity of each of the plurality of blocks 10A. And a temperature detector 4E. Battery power input / output unit 1 includes an inverter 1A and a motor generator 1B of a hybrid vehicle. Motor generator 1 </ b> B drives a shaft (not shown) and wheels connected thereto via transmission 11. The engine control unit 13 controls the engine 12 based on the output of the vehicle control unit 5. The vehicle control unit 5 is connected to the accelerator pedal 7, the brake pedal 8, the shift lever 9, and the battery remaining capacity detection unit 14. The vehicle control unit 5 controls the battery power input / output unit 1 based on the detection result of the abnormal temperature increase by the abnormal temperature increase detection 4.

  In Patent Document 2, the voltage of each of a plurality of batteries of the assembled battery is measured at a predetermined timing, the current flowing through the assembled battery is measured at the same timing, and the maximum of each voltage obtained by the measurement is measured. A technique is disclosed in which a deviation between a value and a minimum value is calculated and an abnormality of the assembled battery is detected based on a pair value of a current and a deviation.

JP 2001-196102 A JP 2005-195604 A

  However, in the configuration in which the block voltage and current are measured for each block, there is a problem in that the A / D conversion of the block voltage is required and the cost is increased. Further, since IR is calculated by the least square method based on the block voltage and current, there is a problem in that the processing time increases due to an increase in the amount of calculation and the load on the processing program increases. Further, if the calculation speed is increased in such a state, there is a problem that heat generation occurs and hinders downsizing of the detection apparatus.

  Accordingly, the applicant of the present application has proposed a technique for sampling a current value at a timing when the voltage of a power storage device such as an assembled battery becomes a predetermined voltage, and detecting abnormality or SOC of the power storage device based on the current value at the predetermined timing. . However, since this technology assumes that the voltage of the power storage device reaches a predetermined voltage, there is a problem that abnormality detection or SOC detection cannot be performed if the voltage of the power storage device does not reach the predetermined voltage.

  It is an object of the present invention to reliably detect a current value in a device that detects a state of a power storage device based on a current value at a timing when the voltage of the power storage device becomes a predetermined voltage. There is to detect.

  The present invention is an apparatus for detecting a state of a power storage device, wherein a measuring unit that measures a current value at a timing when a voltage of the power storage device becomes equal to a predetermined voltage, and a state of the power storage device based on the measured current value And a control means for changing control of the power storage device when the time during which the voltage of the power storage device does not reach the predetermined voltage continuously reaches a predetermined time.

In one embodiment of the present invention, the power storage device is composed of a plurality of blocks connected in series, the block is composed of one or a plurality of capacitors, and the detection means is configured to apply a block voltage for each block. The abnormality of the power storage device is detected based on the deviation of the current value at the timing when becomes equal to the predetermined voltage.
In another embodiment of the present invention, the detection means is based on a first current value at a timing when the voltage of the power storage device becomes equal to a first predetermined voltage and a second current value at a timing when the voltage becomes equal to a second predetermined voltage. The state of charge of the power storage device is detected.

  According to the present invention, in the device that detects the state of the power storage device based on the current value at the timing when the voltage of the power storage device becomes the predetermined voltage, the control of the power storage device is changed when the voltage does not reach the predetermined voltage. Since the predetermined voltage is easily reached by changing the voltage, the current value can be reliably detected.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<First prerequisite technology>
First, a technology for detecting a state of a power storage device based on a current value at a timing when the voltage of the power storage device becomes a predetermined voltage, which is a prerequisite technology of the present embodiment, will be described.

  FIG. 1 shows the configuration of an assembled battery abnormality detection device that is a prerequisite technology. The abnormality detection device is mounted on the hybrid vehicle similarly to the assembled battery control device shown in FIG. 25, and detects abnormality of the assembled battery. FIG. 1 does not show the battery power input / output unit 1, the vehicle control unit 5, the engine control unit 13 and the like in FIG. 25, but these are the same as those in FIG.

  In FIG. 1, an assembled battery 100 as a power storage device includes a plurality of blocks B1 to Bn, and the blocks B1 to Bn are connected in series. Each block is configured by connecting one or more single cells in series. Each battery is, for example, a nickel metal hydride battery or a lithium ion battery.

  The voltage sensors 120-1 to 120-n detect the block voltages VB1 to VBn of the blocks B1 to Bn constituting the assembled battery 100, respectively. The detected block voltages VB1 to VBn are supplied to the comparators 140-1 to 140-n, respectively.

  The comparators 140-1 to 140-n compare the input block voltages VB1 to VBn with a predetermined voltage, respectively, and determine whether or not each of the block voltages VB1 to VBn has reached the predetermined voltage. When the block voltages VB1 to VBn match the predetermined voltage, each of the comparators 140-1 to 140-n supplies a match signal to the determination unit 160. The predetermined voltage for determination in each of the comparators 140-1 to 140-n has the same value. Therefore, if the block voltages VB1 to VBn are almost equal values, coincidence signals are output from the comparators 140-1 to 140-n at substantially the same timing. On the other hand, when the block voltages VB1 to VBn are not equal, each comparator 140-1 to 140-n outputs a coincidence signal at a timing corresponding to the value of the block voltage. The coincidence signal output from each of the comparators 140-1 to 140n functions as a sampling signal that defines the timing for sampling the battery pack current.

  The current sensor 180 detects the current IB of the assembled battery 100. The detected current IB is supplied to the determination unit 160.

  The determination unit 160 samples the current IB supplied from the current sensor 180 at the timing of the coincidence signal supplied from each of the comparators 140-1 to 140-n and stores it in the memory. Therefore, in the memory, the current group at the timing when the block voltage VB1 of the block B1 reaches the predetermined voltage, the current group at the timing when the block voltage VB2 of the block B2 reaches the predetermined voltage, ..., the block voltage VBn of the block Bn Each current group at the timing when the predetermined voltage is reached is stored. The determination unit 160 performs a statistical process on the sampling current group stored in the memory for each block to obtain a representative current value of the block. For example, an average value is used as statistical processing, an average value of the sampling current group is calculated for the block B1 to obtain the representative current value I1 of the block B1, and an average value of the sampling current group is calculated for the block B2 to represent the representative current value of the block B2. I2 is calculated, and the average value of the sampling current group is calculated for the block Bn to obtain the representative current value In of the block Bn. The determination unit 160 determines whether or not an abnormality has occurred in the assembled battery 100 based on the degree of variation based on the representative current values I1 to In calculated for each block as described above. Output the result.

  In the prior art, the combination data of the block voltage and the block current is detected, and the presence or absence of abnormality is determined by calculating the IR of each block by the least square method or regression analysis, but in this embodiment, the representative for each block is determined. It should be noted that the presence or absence of abnormality is determined based on the current values I1 to In.

  The determination unit 160 may be configured by a microcomputer, and may be configured by an IC including the comparators 140-1 to 140-n.

  FIG. 2 shows an abnormality determination process flowchart. First, a threshold voltage Vth, which is a predetermined voltage to be compared with the block voltages VB1 to VBn by each of the comparators 140-1 to 140-n, is set (S101). The threshold voltage Vth can be set by any method. However, in order to enable a large amount of current sampling in a short time, the assembled battery 100 is set to a predetermined value within the voltage fluctuation range when the battery 100 repeats charging and discharging as the vehicle travels. It is preferable to set. The threshold voltage Vth may be set as an absolute value, or may be set based on a ratio of the assembled battery 100 to the reference SOC (charged state). The threshold voltage Vth as a predetermined voltage may be supplied to the comparators 140-1 to 140-n in advance, and the contents of the registers are configured so as to be registered in the registers and supplied to the comparators 140-1 to 140-n. The threshold voltage Vth may be appropriately adjusted by rewriting.

  After setting the threshold voltage Vth (S101), each of the comparators 140-1 to 140-n compares the block voltages VB1 to VBn with the threshold voltage Vth, respectively, and the block voltages VB1 to VBn are set to the threshold voltage Vth. The current value at the time of reaching is acquired (S102). The acquired current is sequentially stored in the memory for each block. Then, a representative value of current is calculated for each block (S103). The number of samples of current to be acquired is arbitrary and may be fixed to a predetermined value. Alternatively, the sampling time may be fixed. When the sampling time is fixed, the number of samples may be different for each block. The number of samples is at least two and can be several tens of samples. The representative value for each block is generally an average value as described above, but an intermediate value, a maximum value, or a minimum value can also be adopted. However, it is desirable to calculate the representative value according to the same standard for all blocks.

  After calculating the representative current value for each block, it is determined whether there is an abnormality according to the degree of variation in the representative current value for each block (S104). The determination result is supplied to the vehicle control unit as in the conventional case, and the vehicle control unit controls the power input / output unit of the assembled battery 100 or notifies the vehicle occupant of the abnormality of the assembled battery.

The processing in FIG. 2 is realized by sequentially executing the abnormality diagnosis program stored in the ROM by the microcomputer that configures the determination unit 160 or includes the determination unit 160 and the comparators 140-1 to 140-n. it can. The current value for each block acquired in S102 is sequentially stored in the work memory of the microcomputer. In S103, the microcomputer processor reads a plurality of current values for each block stored in the memory, performs predetermined statistical processing, for example, average value calculation processing, and calculates a representative current value for each block. The calculated representative current value is stored again in the work memory. In S104, the microcomputer processor reads the representative current value for each block stored in the work memory and calculates the deviation. There are several methods for calculating the deviation. For example, the minimum value and the maximum value of the representative current values are extracted and the difference is calculated, or the variance σ ² is calculated. An average of the representative current values may be calculated, and a maximum difference value from the average value may be calculated. Then, the calculated deviation is compared with the threshold value stored in the working memory, and it is determined that an abnormality has occurred in the block having a representative current value exceeding the threshold value, and determined externally via the input / output interface. Output the result. As a determination result, in addition to the presence / absence of an abnormality, information specifying a block in which an abnormality has occurred may be output.

  In FIG. 3, the current sampling timing about arbitrary blocks Bi which comprise the assembled battery 100 is shown. FIG. 3A shows a change over time of the block voltage detected by the voltage sensor 120-i. The horizontal axis is time (s), and the vertical axis is voltage value (V). By repeating charge and discharge, the block voltage also changes from about 6V to about 10V. The figure also shows the set threshold voltage Vth. In the figure, the threshold voltage Vth is set to about 7V. In the figure, the block voltage and the threshold voltage Vth coincide with each other at a timing indicated by a black circle.

  FIG. 3B shows a signal waveform as a result of comparison between the block voltage and the threshold voltage Vth by the comparator 140-i. The comparators 140-1 to 140-n compare the block voltage with the threshold voltage, and output a high level voltage signal if the block voltage ≧ the threshold voltage Vth, and a low level voltage signal if the block voltage <the threshold voltage. Then, a rectangular signal as shown in FIG. The rising timing and falling timing of the rectangular signal indicate that the block voltage and the threshold voltage Vth are equal. Therefore, when a rectangular signal as shown in FIG. 3B is input, the determination unit 160 samples the current IB at a timing synchronized with the rising timing and the falling timing, thereby making the block voltage a threshold voltage. The current at the timing when Vth is reached can be acquired.

  FIG. 3C shows the time change of the current detected by the current sensor 180. By repeatedly charging and discharging, the current also changes to the positive side and the negative side (when the positive side is charged, the negative side indicates discharging). The determination unit 160 samples the current IB at the rising and falling timings of the rectangular signal from the comparator 140-i, and acquires I1 to I8. The acquired current values are sequentially stored in the memory, and representative values of these current values I1 to I8 are calculated. The representative current value in the block Bi is referred to as IBi.

  FIG. 4 is a diagram in which representative current values calculated for each block are plotted with the block voltage on the vertical axis and the current on the horizontal axis. The current-voltage characteristic is conventionally used to calculate the IR of each block, but in this embodiment, each representative value is plotted as a current value at a threshold voltage Vth which is a specific voltage. Please note that. In the figure, the representative current value IB1 of the block B1, the representative current value IB2 of the block B2, the representative current value IB3 of the block B3, and the representative current value IBi of the block Bi are illustrated. Since the slope of the current-voltage characteristic is IR and each block has a specific IR, a straight line (or curve) passing through the representative current value plotted for each block can be assumed. In the figure, a straight line passing through each plotted representative current value is shown. Conventionally, a plurality of (current, voltage) are detected and plotted, and these are subjected to regression analysis to calculate a straight line 50, and the slope of the straight line 50 is calculated as IR. A straight line passing through is assumed. The slope of the assumed straight line indicates IR, but a straight line is assumed assuming that it has a predetermined slope. Then, the presence / absence of abnormality is determined according to the assumed variation of the straight line group, essentially the variation of the representative current value of each block.

Examples of the abnormal mode of the assembled battery 100 include the following.
(1) Self-short circuit (short)
(2) Minute short circuit (increase in self-discharge and internal discharge)
(3) IR rise (due to lifetime and airtight leakage)
(4) Capacity drop (5) Temperature rise

Among these, in the self-short circuit of (1), since the electrode plates inside the single cells (single cells) in the block are in contact with each other and are short-circuited, the OCV (Open Circuit Voltage) is also lowered. In the current-voltage characteristic, the intercept corresponding to OCV, which is the voltage value when the current is 0, becomes small. In FIG. 4, the straight line group 150 and the straight line 200 have the same inclination, but the intercept of the straight line group 150 and the intercept of the straight line 200 are greatly different. This is due to the large variation between the representative current values IB1, IB2, and IB3 and the representative current value IBi. In this case, it is determined that there is a high possibility that a self-short circuit has occurred in the block Bi of the representative current value IBi, and it is determined as abnormal. Specifically, the variation (deviation) is compared with a predetermined value, and if the variation is not more than the predetermined value, it is determined to be normal, and if it exceeds the predetermined value, it is determined to be abnormal. The degree of variation of each representative current value can be evaluated by an arbitrary evaluation formula. For example, the degree of variation may be evaluated by comparing the variance σ ² with a predetermined value, and the maximum and minimum values of the representative current value may be evaluated. The degree of variation may be evaluated by comparing the difference with a predetermined value.

  In addition, in the micro short circuit (2), the metal inside the battery is deposited to form a conductive path between the positive and negative electrodes, and self-discharge and internal discharge increase. FIG. 5 shows current-voltage characteristics in the case of a minute short circuit. Since the voltage drops during discharge, the voltage drops like a straight line 300 with respect to the normal straight line group 150. Also in this case, it is determined that there is a high possibility that a minute short circuit has occurred in the block Bi of the representative current value IBi because the variation of the representative current values IB1, IB2, IB3 and the representative current value IBi is large. To do.

  In addition, when the IR rises in (3), the slope of the current-voltage characteristic increases. FIG. 6 shows current-voltage characteristics in the case of IR rise. The inclination increases like a straight line 400 with respect to the normal straight line group 150. Also in this case, it is because the variation of the representative current values IB1, IB2, and IB3 and the representative current value IBi is large, and there is a possibility that the IR increases due to the lifetime or airtight leakage in the block Bi of the representative current value IBi. It is determined as abnormal as high.

  Further, the capacity decrease in (4) is caused by repeated charge and discharge, and as in the case of the micro short circuit in (2), as shown in FIG. Show properties. Also in this case, it is possible to grasp that the variation of the representative current value IBi with respect to the representative current values IB1, IB2, and IB3 is large, and it is abnormal that there is a high possibility that the capacity Bi is reduced in the block Bi of the representative current value IBi. Is determined.

  In addition, the temperature rise in (5) occurs as a result of the IR rise in (3), and the inclination increases like a straight line 400 with respect to the normal straight line group 150 as shown in FIG. Also in this case, it is possible to grasp that the variation of the representative current value IBi with respect to the representative current values IB1, IB2, and IB3 is large, and it is abnormal that the temperature rise is likely to occur in the block Bi of the representative current value IBi. Is determined.

  As described above, any of the abnormal modes (1) to (5) can be evaluated based on the variation (deviation) of the representative current values IB1 to IBn of each block, and the variation of the representative current values IB1 to IBn. Is within the predetermined range, no abnormality has occurred, and if the variation of the representative current values B1 to Bn exceeds the predetermined range, the block with the representative current value exceeding the range is (1). It can be determined that any one of the abnormalities (5) to (5) has occurred. In the present embodiment, normal / abnormality is not determined by comparing the representative current value itself of each block with the threshold value as a target, but normal / abnormal is determined by the variation of the representative current value. The reason is that the electrochemical reaction of each block of the assembled battery is easily affected by temperature, and the block may change from the initial state due to the so-called memory effect, but it is difficult to fully predict this change. This is because it is difficult to set an appropriate threshold for abnormality determination.

  In this technique, it is possible to easily and quickly determine that any of the abnormalities (1) to (5) has occurred depending on the degree of variation in the representative current values B1 to Bn of each block. Although it is possible to determine which block among the blocks B1 to Bn constituting 100 is abnormal, it is not possible to specify which abnormal mode is occurring. Therefore, after determining that any abnormality has occurred, it is possible to specify which abnormality has occurred using another parameter.

  Further, although a battery is used as the power storage device, it can also be applied to a capacitor as a power storage device. Among the abnormal modes (1) to (5) above, the capacity reduction of (4) may occur as the abnormal mode of the capacitor, but similarly, the variation (deviation) in the representative current value of each block constituting the capacitor is large. Is compared with a predetermined range, and when the variation is large and exceeds the predetermined range, it can be determined that an abnormality has occurred.

  In the present embodiment, the timing at which a certain voltage is reached as a current at a predetermined timing for each block is used. However, two or more threshold voltages are provided and the current at the timing at which the first threshold voltage is reached for each block. The abnormality may be comprehensively detected by using the variation between the blocks and the variation between the currents at the timing when the second threshold voltage is reached for each block. That is, when both the fluctuation of current between blocks at the timing of reaching the first threshold voltage for each block and the fluctuation of current between blocks at the timing of reaching the second threshold voltage for each block exceed the threshold value Is determined to be abnormal. Alternatively, at least one of the current-to-block variation at the timing of reaching the first threshold voltage for each block and the current-to-block variation at the timing of reaching the second threshold voltage for each block has a threshold value. If it exceeds, it is determined as abnormal. The setting method of the first threshold voltage and the second threshold voltage is arbitrary, but the first threshold voltage may be set as the discharge-side threshold value, and the second threshold voltage may be set as the charge-side threshold value.

  Hereinafter, an example in which an abnormality is detected by providing two threshold voltages will be described. When one threshold voltage is set and an abnormality is detected, it is not possible to specify which abnormal mode (1) to (5) is occurring, but by providing two threshold voltages, which abnormality It is possible to specify whether a mode has occurred.

  Specifically, the threshold voltage on the charging side is set in addition to the threshold voltage on the discharging side. The threshold voltage on the discharge side is Vth1, and the threshold voltage on the charge side is Vth2. Then, the current when the threshold voltages Vth1 and Vth2 are reached is detected, and the degree of variation is evaluated on the discharge side and the charge side, respectively. As the variation, the maximum value ΔI of the variation between the representative currents of each block and the variation ΔIdif = ΣIBj / n−IBi from the inter-block average value of the block Bi where the variation is maximum are used. The variations with respect to the threshold voltage Vth1 on the discharge side are ΔI1 and ΔIdif1, respectively, and the variations with respect to the threshold voltage Vth2 on the charge side are ΔI2 and ΔIdif2, respectively. On each of the discharge side and the charge side, ΔI and ΔIdif are compared with threshold values to identify the presence / absence of abnormality and the mode of abnormality.

  FIG. 7 shows the current-voltage characteristics in the case of the short circuit (1). Although it is almost the same as FIG. 4, the difference from FIG. 4 is that the threshold voltage Vth2 is set on the charging side (positive side of the current), and the current is detected for each block. Paying attention to the discharge side, if the absolute value of the difference between IBi and IB3 is the maximum among IB1 to IBn, ΔI1 is | IB3−IBi |. If it exceeds, it can be detected as abnormal. The same applies to the charging side, and ΔI2 = | IB3−IBi |. This is compared with the threshold value, and when it exceeds the threshold value, it can be determined as abnormal. On the other hand, paying attention to ΔIdif, from the definition, it is negative when the representative current value of the abnormal block Bi is larger than the average current value of all blocks, and positive when it is smaller. In FIG. 7, on the discharge side, the representative current value IBi of the abnormal block is located on the positive side with respect to the other normal block groups, and therefore ΔIdif1 is negative. Similarly, ΔIdif2 is negative on the charging side.

  FIG. 8 shows current-voltage characteristics at the time of overdischarge in the case of (2) micro short circuit and (4) capacity reduction. Although it is almost the same as FIG. 5, the difference from FIG. 5 is that a threshold voltage Vth2 is set on the charging side, and a current is detected for each block. Focusing on the discharge side, ΔI1 exceeds the threshold value and an abnormality of the block Bi is detected, but ΔI2 is within the threshold value. ΔIdif1 is negative as in FIG. 7, but ΔIdif2 is within the normal range because ΔI2 is within the threshold value.

<Second prerequisite technology>
Next, the second prerequisite technology of this embodiment will be described.

  Although the overall configuration is the same as in FIG. 1, the comparators 140-1 to 140-n compare the input block voltages VB1 to VBn with the first and second predetermined voltages, respectively, and block voltages VB1 to VBn. Determines whether the first and second predetermined voltages have been reached. When the block voltages VB1 to VBn match the first and second predetermined voltages, the comparators 140-1 to 140-n supply matching signals to the determination unit 160, respectively. The predetermined voltage for determination in each of the comparators 140-1 to 140-n has the same value. Therefore, if the block voltages VB1 to VBn are almost equal values, coincidence signals are output from the comparators 140-1 to 140-n at substantially the same timing. The coincidence signal output from each of the comparators 140-1 to 140n functions as a sampling signal that defines the timing for sampling the battery pack current.

  The current sensor 180 detects the current IB of the assembled battery 100. The detected current IB is supplied to the determination unit 160.

  The determination unit 160 samples the current IB supplied from the current sensor 180 at the timing of the coincidence signal supplied from each of the comparators 140-1 to 140-n and stores it in the memory. Therefore, in the memory, the current group at the timing when the block voltage VB1 of the block B1 reaches the first predetermined voltage, the current group at the timing when the block voltage VB1 reaches the second predetermined voltage, and the block voltage VB2 of the block B2 has reached the first predetermined voltage. Current group at timing and current group at timing when second predetermined voltage is reached,..., Current group when block voltage VBn of block Bn reaches first predetermined voltage, current at timing when second predetermined voltage is reached Each group is stored. The determination unit 160 performs statistical processing on the sampling current group stored in the memory for each block, and calculates a representative current value at a timing when the first predetermined voltage is reached and a representative current value at a timing when the second predetermined voltage is reached. The statistical process is, for example, an average value calculation process. Further, the determination unit 160 calculates the open circuit voltage Vocv for each block based on the representative current value calculated as described above, and further calculates the SOC based on Vocv.

  In the prior art, the combination data of the block voltage and the block current is detected, and the open circuit voltage Vocv is calculated by the least square method or regression analysis. In this embodiment, the current value at the timing when the block voltage reaches the predetermined voltage is calculated. Note that Vocv is calculated based on this.

  The determination unit 160 may be configured by a microcomputer, and may be configured by an IC including the comparators 140-1 to 140-n.

  FIG. 9 shows a flowchart of the SOC calculation process. First, two threshold voltages Vth1 and Vth2 (where Vth1 <Vth2), which are predetermined voltages to be compared with the block voltages VB1 to VBn by the respective comparators 140-1 to 140-n, are set (S201). The threshold voltages Vth1 and Vth2 can be set by any method. However, in order to enable a large amount of current sampling in a short time, the battery pack 100 is predetermined within a voltage fluctuation range when charging and discharging are repeated as the vehicle travels. It is preferable to set the value. The threshold voltages Vth1 and Vth2 may be set to Vth1 = 7.5V, Vth2 = 8.5V, for example. The threshold voltages Vth1 and Vth2 may be supplied to the comparators 140-1 to 140-n in advance, and the contents of the registers are rewritten so that they are registered in the registers and supplied to the comparators 140-1 to 140-n. The threshold voltages Vth1 and Vth2 may be appropriately adjusted.

After setting two threshold voltages Vth1 and Vth2, each of the comparators 140-1 to 140-n compares the block voltages VB1 to VBn with the threshold voltages Vth1 and Vth2, respectively. The current value at the time when the voltages Vth1 and Vth2 are reached is acquired (S202). The acquired current is sequentially stored in the memory for each block. Then, the representative current value at the timing when the threshold voltage Vth1 is reached and the representative current value at the timing when the threshold voltage Vth2 is reached are calculated for each block, and is released based on these representative current values and the threshold voltages Vth1 and Vth2. The end voltage Vocv is calculated (S203). Specifically, between the block voltage VB and the block current IB, the internal resistance of the battery is R,
VB = IB · R + Vocv
Therefore, when the current value I1 at the timing when the block voltage VB reaches the threshold voltage Vth1 and the current value at the timing when the block voltage VB reaches the threshold voltage Vth2 are I2,
Vth1 = I1 · R + Vocv
Vth2 = I2 · R + Vocv
Because
Vocv = (I 2 · Vth 2 −I 1 · Vth 1) / (I 2 −I 1) (1)
Thus, Vocv can be calculated.

  After calculating Vocv, the SOC corresponding to the calculated Vocv is calculated using a map that prescribes the relationship between Vocv and SOC determined in advance (S204). The SOC of each block is calculated by the same process.

  The processing in FIG. 9 is realized by sequentially executing the SOC calculation program stored in the ROM by the microcomputer that configures the determination unit 160 or includes the determination unit 160 and the comparators 140-1 to 140-n. it can. The current value for each block acquired in S202 is sequentially stored in the work memory of the microcomputer. In S203, the microcomputer processor reads out a plurality of current values for each block stored in the memory, performs predetermined statistical processing, for example, average value calculation processing, and calculates representative current values. The calculated representative current value is stored again in the work memory. And the open end voltage Vocv is calculated using (1) Formula. In S204, the processor of the microcomputer reads Vocv stored in the work memory, and searches for an SOC corresponding to Vocv by referring to a map stored in advance in the memory.

  FIG. 10 shows current-voltage characteristics in which the horizontal axis represents the block current and the vertical axis represents the block voltage. Current groups at timing when the block voltage reaches the threshold voltages Vth1 and Vth2 are denoted by IBm and IBn, respectively.

  FIG. 11 is a diagram plotted as the representative current I1 of the current group IBm and the representative current I2 of the current group IBn in FIG. A straight line connecting (I1, Vth1) and (I2, Vth2) represents VB = IB · R + Vovv, and the intercept of this straight line corresponds to Vocv.

  FIG. 12 shows an example of a map that defines the relationship between SOC and Vocv. The relationship between SOC and Vocv is temperature dependent, and is a map at a battery temperature of 25 ° C. This map is prepared for each temperature, and the SOC corresponding to Vocv can be calculated.

<Process of this embodiment>
As described above, the abnormality of the assembled battery 100 can be detected or the SOC can be detected based on the current value at the timing when the voltage of the assembled battery 100 matches the predetermined voltage. Unless the voltage reaches a predetermined voltage, the abnormality of the assembled battery 100 and the SOC cannot be detected. The cause that the voltage of the assembled battery 100 does not reach the predetermined voltage includes the case where the voltage fluctuation of the assembled battery 100 is very small and the malfunction of the voltage sensor and the comparator. Therefore, in the present embodiment, the time interval at which the voltage of the assembled battery 100 does not reach the predetermined voltage is measured, and when the time interval at which the voltage does not reach the predetermined voltage exceeds the threshold time, the control of the assembled battery 100 is changed. The voltage of the assembled battery 100 is allowed to reach a predetermined voltage positively or forcibly.

  FIG. 13 shows a process flowchart for each second of the determination unit 160 in the present embodiment. When the ignition of the vehicle is turned on, the parameters i, j, and k are reset to 0, respectively. The parameters i and j are timer count values that are incremented every second, and the parameter k is a parameter that becomes 0 when the battery pack 100 is normally controlled and becomes 1 when the control is changed. In FIG. 13, first, it is determined whether or not the parameter k is 0 (S301). When the parameter k is 0, normal processing is executed (S302), and when the parameter k is 1, abnormality determination processing is executed (S303). The normal process and the abnormality determination process will be described later. Then, the battery allowable input / output calculation is executed (S304).

  FIG. 14 shows a detailed flowchart of the normal process (S302) in FIG. First, it is determined whether or not the voltage of the assembled battery 100 matches the threshold voltage (whether or not it is synchronized) (S401). If not synchronized, the parameter i is incremented by 1 (S402). Then, it is determined whether or not the parameter i exceeds a predetermined threshold value i1, that is, whether or not the non-synchronized duration exceeds the threshold time i1 (S403), and if i exceeds i1, the parameter is determined. k is changed from 0 to 1 (S404). On the other hand, when the voltage of the assembled battery 100 matches the threshold voltage (when synchronized), the parameter i is reset to 0 (S405). If i does not exceed i1, the parameter k is kept at 0.

  FIG. 15 is a detailed flowchart of the abnormality determination process (S303) in FIG. This is processing when the time not synchronized exceeds the threshold time i1. First, it is determined whether or not the voltage of the assembled battery 100 matches the threshold voltage (whether or not it is synchronized) (S501). If it is not synchronized, the parameter j is incremented by 1 (S502). Then, it is determined whether or not the parameter j exceeds a predetermined threshold value j1, that is, whether or not the threshold time j1 is further exceeded after the parameter k is set to 1 (S503). If j exceeds j1, it is determined that there is an abnormality (S504). Thereafter, the parameters i, j, and k are reset to 0 (S505). Even if the parameter k is 1, when the voltage of the assembled battery 100 matches the threshold voltage (when synchronized), the parameters i, j, and k are immediately reset to 0 (S505).

  FIG. 16 shows a detailed flowchart of the battery allowable input / output process (S304) of FIG. This is a process of increasing the input / output power by relaxing the allowable input / output power of the battery pack 100. First, the vehicle control unit 5 acquires the average temperature TBave, SOC, and accelerator opening of the battery pack 100 (S601). Next, control values PBin (TB), PBout (TB), BSOCin, BSOCout, and coefficient ACC are acquired using a map stored in advance in the memory (S602). Here, PBin (TB) and PBout (TB) are power input limit values and output limit values determined by the average battery temperature, BSOCin and BSOCout are coefficients determined by SOC, and ACC is a coefficient determined by accelerator opening.

  Examples of these control values are shown in FIG. 17, FIG. 18, FIG. 19, and FIG. FIG. 17 shows the relationship between the average temperature TBave of the battery pack 100 and PBin (TB) and PBout (TB). PBin (TB) is a characteristic that increases as the temperature increases from TB1 lower than 0 ° C., becomes constant over time, and further decreases to zero at TB2. PBout (TB) also exhibits the same characteristics as PBin (TB) (however, the sign is reversed). 18 and 19 show the relationship between the SOC, BSOCin, and BSOCout. BSOCin decreases from 1 and becomes 0 at SOC1. Also, when the SOC increases from a certain value SOC2, BSOCout increases and eventually becomes 1. FIG. 20 shows the relationship between the accelerator opening and the ACC. The ACC differs between k = 0 and k = 1. When k = 1, the ACC is set larger than when k = 0, and eventually becomes 1.

Returning to FIG. 16 again, after obtaining various control values using the maps shown in FIGS. 17 to 20, the basic input limit value PBin and the basic output limit value PBout of the assembled battery 100 are calculated (S603). Specifically, using PBin (TB), PBout (TB), BSOCin, BSOCout,
PBin = PBin (TB) × BSOCin
PBout = PBout (TB) × BSOCout
Calculated by

Then, using the calculated basic input limit value PBin and the basic output limit value PBout, the input limit value Pin and the output limit value Pout of the assembled battery 100 are calculated as follows (S604).
Pin = PBin × ACC
Pout = PBout × ACC

  As can be seen from the above equation, when k = 1, ACC is set larger for the same accelerator opening than when k = 0, so that both the input limit value Pin and the output limit value Pout are k = In the case of 1, it becomes large. This means that the input / output restriction of the assembled battery 100 is relaxed, and the voltage of the assembled battery 100 is likely to fluctuate. As a result, the voltage of the assembled battery 100 easily matches (synchronizes) with the threshold voltage.

  FIG. 21 shows a detailed flowchart of the battery allowable input / output process (S304) of FIG. This is a process for changing the SOC of the battery pack 100. Note that the SOC variation includes an aspect in which the range of motion of the SOC is changed and an aspect in which the control center of the SOC is changed. It is desirable to determine the movable range of the SOC so as to satisfy the life of the assembled battery 100 and to ensure reliability. First, the vehicle control unit 5 acquires the average temperature TBave and SOC of the assembled battery 100 (S701). Next, control values PBin (TB), PBout (TB), BSOCin, and BSOCout are acquired using a map stored in advance in the memory (S702).

  22, FIG. 23, and FIG. 24 show the relationship between SOC, BSOCin, and BSOCout. FIG. 22 shows k = 0, that is, BSOCin and BSOCout in a normal state. With respect to BSOCin, it becomes 0 when the SOC becomes larger than a certain value SOC1, and with respect to BSOCout, it becomes larger than 0 when the SOC is 2 or more, and eventually becomes 1. 23 and 24 show BSOCin and BSOCout in the case of k = 1, FIG. 23 is a map for the first 300 seconds, and FIG. 24 is a map for the subsequent 300 seconds. When an abnormality is determined in S504, the timer counter n is incremented every second. FIG. 23 is used when 0 <n ≦ 300, and FIG. 24 is used when 300 <n ≦ 600. n is reset together with i, j, and k in S505. The values of BSOCin and BSOCout vary by switching the map according to the elapsed time. As described above, the range of movement of the SOC can be controlled by controlling the values of BSOCin and BSOCout so as to fluctuate with time and controlling the distribution of the SOC movement range to swing up and down. In FIG. 22, the current of the assembled battery 100 is limited on the charge and discharge sides by the values of BSOCin and BSOCout. The time transition of the SOC is more often limited to the range of SOC1 on the BSOCin graph and SOC2 on the BSOCout graph. In FIG. 23, the current of the assembled battery 100 is controlled to be limited on the charge and discharge sides by the values of BSOCin and BSOCout. The time transition of the SOC is more often limited to the range of SOC3 on the BSOCin graph and SOC4 on the BSOCout graph. In FIG. 24, the current of the assembled battery 100 is controlled to be limited on the charge and discharge sides by the values of BSOCin and BSOCout. The time transition of the SOC is more often limited to the range of SOC5 on the BSOCin graph and SOC6 on the BSOCout graph. In this way, by changing the values of BSOCin and BSOCout to FIG. 22, FIG. 23 and FIG. 24, the time transition of the SOC is SOC1 or lower, SOC2 or higher, SOC3 or lower, SOC4 or higher, and SOC5. In the following, it is possible to swing up and down the SOC region to a region of SOC6 or higher. As a result, normally, the performance of the assembled battery 100 is ensured, and only when an abnormality is detected, the SOC movable range is expanded or swung up and down the SOC. Deterioration such as gas generation during overdischarge or overcharge can be minimized.

  Further, in the hybrid vehicle, when the SOC of the battery pack 100 is lowered, the discharge allowable value is reduced, and as a result, the SOC is induced higher. Further, in a situation where the SOC is high, the SOC is guided to the lower side by reducing the charge allowable value. In addition, the battery ECU outputs an SOC value, and the vehicle control ECU performs control such that the charge / discharge balance is adjusted with this value as the target of the control center point of the SOC, for example, near SOC = 60%. Thus, the charging / discharging characteristics of the assembled battery 100 can be exhibited without excess and deficiency, and the power performance and fuel efficiency performance as a hybrid vehicle can be exhibited. The control center point is approximately (SOC1 + SOC2) / 2 for the values of BSOCin and BSOCout in FIG. 22, and is approximately (SOC3 + SOC4) / 2 for the values of BSOCin and BSOCout in FIG. The value of BSOCout is approximately (SOC5 + SOC6) / 2. Thus, the control center point of BSOCin and BSOCout can be changed, and the control center point can be swung up and down in the SOC region. As a result, normally, the performance of the assembled battery 100 is ensured, and only when an abnormality is detected, the influence on the fuel consumption and the like can be minimized by expanding the SOC movable range or swinging up and down the SOC. 23 and 24, the movement range of BSOCin and BSOCout, that is, SOC3-SOC4 or SOC5-SOC6 is set to a narrower range than SOC1-SOC2, so that the change rate of SOC, that is, the control center that is changed by BSOCin and BSOCout. It is also possible to increase the convergence speed of the SOC to the point.

Returning to FIG. 21 again, the input limit value Pin and the output limit value Pout of the assembled battery 100 are calculated as follows using the acquired control values (S703).
Pin = PBin (TB) × BSOCin
Pout = PBout (TB) × BSOCout

  As can be seen from the above equation, since BSOCin and BSOCout vary with time, Pin and Pout also vary with time, which makes it easy for the voltage of the assembled battery 100 to match (synchronize) with the threshold voltage.

  As described above, the two cases of changing the power allowable input / output value have been described, but the voltage of the assembled battery 100 may be changed forcibly by other methods. An arbitrary technique for dynamically changing the power ratio and changing the voltage of the assembled battery 100 during traveling with the power of the engine and the motor can be used.

1 is an overall configuration diagram of an abnormality detection apparatus according to an embodiment. It is a process flowchart of the 1st base technology. It is a timing chart which shows electric current sampling timing. It is a graph which shows the current-voltage characteristic at the time of a short circuit. It is a graph which shows the current-voltage characteristic at the time of a micro short circuit. It is a graph figure at the time of IR rise. It is a graph which shows the current-voltage characteristic at the time of a short circuit. It is a graph which shows the current-voltage characteristic at the time of a micro short circuit. It is a processing flowchart of the 2nd base technology. It is explanatory drawing which shows the sampled current group. It is a graph which shows Vocv. It is a graph which shows the correspondence of Vocv and SOC. It is a processing flowchart of an embodiment. It is a flowchart at the time of normal processing. It is a flowchart at the time of abnormality determination. It is a battery allowable input / output calculation process flowchart. It is map explanatory drawing of embodiment. It is map explanatory drawing of embodiment. It is map explanatory drawing of embodiment. It is map explanatory drawing of embodiment. It is another battery allowable input / output calculation process flowchart. It is map explanatory drawing of other embodiment. It is map explanatory drawing of other embodiment. It is map explanatory drawing of other embodiment. It is a whole block diagram of the conventional apparatus.

Explanation of symbols

  100 assembled battery, 120-1 to 120-n voltage sensor, 140-1 to 140-n comparator, 160 determination unit.

Claims (10)

A device for detecting a state of a power storage device,
Measuring means for measuring a current value at a timing when the voltage of the power storage device becomes equal to a predetermined voltage;
Detecting means for detecting the state of the power storage device based on the measured current value;
An apparatus for detecting a state of a power storage device, comprising: a control unit configured to change control of the power storage device when a time during which the voltage of the power storage device does not reach the predetermined voltage continuously reaches a predetermined time. The apparatus of claim 1.
The power storage device includes a plurality of blocks connected in series, and the block includes one or a plurality of power storage units,
The state detection device for a power storage device, wherein the detection means detects an abnormality of the power storage device based on a deviation of a current value at a timing at which the block voltage becomes equal to a predetermined voltage for each block. The apparatus of claim 1.
The detection means detects a state of charge of the power storage device based on a first current value at a timing when the voltage of the power storage device becomes equal to the first predetermined voltage and a second current value at a timing when the voltage becomes equal to the second predetermined voltage. An apparatus for detecting a state of a power storage device. In the apparatus in any one of Claims 1-3,
The state detection device for a power storage device, wherein the control means changes an input / output power allowable value of the power storage device. The apparatus of claim 4.
The power storage device state detection device is characterized in that the control means changes so as to relax an input / output power allowable value of the power storage device. In the apparatus in any one of Claims 1-3,
The state detection device for a power storage device, wherein the control means changes the SOC of the power storage device. The apparatus of claim 6.
The state detection device for a power storage device, wherein the control means increases or decreases the SOC of the power storage device. The apparatus of claim 6.
The state detection device for a power storage device, wherein the control means changes a control range of the SOC of the power storage device. The apparatus of claim 6.
The power storage device state detection device, wherein the control means changes a control center point of the SOC of the power storage device. The apparatus of claim 8.
The state detection device for a power storage device, wherein the control means changes the SOC control range of the power storage device so as to be narrowed sequentially.

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