JP5316343B2 - Battery monitoring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a battery monitoring device capable of shortening a time period required for troubleshooting in failure diagnosis performed by varying a threshold across several levels and comparing each of thresholds with a voltage of a battery cell. <P>SOLUTION: The battery monitoring device includes: a monitoring circuit 30 inputting cell voltages at both ends of a battery cell 10 for each of a plurality of battery cells 10, comparing each of the cell voltages with each of thresholds, and outputting each of comparison results; and a microcomputer 50 sequentially varying the thresholds of the monitoring circuit 30 across several levels from a minimum threshold to a maximum threshold for each of a plurality of battery cells 10 to be compared with the cell voltage and performing failure diagnosis for detecting the glitch of the monitoring circuit 30 based on the comparison result. The microcomputer 50 sequentially performs failure diagnosis for each of the plurality of battery cells 10, and in the failure diagnosis, varies the threshold sequentially from an optional threshold value between the minimum threshold and the maximum threshold. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a battery monitoring device.

  Conventionally, for example, Patent Literature 1 proposes a battery control device having a failure diagnosis function for detecting that a threshold value for battery overcharge detection or overdischarge detection has spontaneously changed. In Patent Document 1, a configuration is proposed in which the voltage of a battery is detected and the voltage is compared with a threshold value.

  Specifically, a switch that switches the threshold value by one step from the original value of the threshold value is provided. Then, the battery control device switches the switch at the time of failure diagnosis to relatively change the threshold value by one level, and when the magnitude relationship between the threshold value and the battery voltage is not reversed even though the threshold value is forcibly changed, It is determined that the spontaneous change is large. In this way, a failure of the battery control device can be detected.

JP 2003-92840 A

  However, in the above conventional technique, when the threshold value is relatively changed by one step by the switch, for example, when a malfunction occurs in the switch or the like, the magnitude relationship between the voltage of the battery and the threshold value is changed even though the threshold value is forcibly changed. May reverse. As described above, conventionally, there is a problem in that the reliability of the determination of the spontaneous change of the threshold is low because the threshold is only relatively changed by one step by the switch.

  In view of this, it is conceivable that a plurality of switches are provided in order to detect a spontaneous change in the threshold value more reliably, and the threshold value is switched in a plurality of stages by sequentially switching each switch. However, there is a problem that a plurality of switches must be switched in order at the time of failure diagnosis, and the time required for failure diagnosis becomes long.

  In view of the above points, the present invention provides a battery monitoring device capable of reducing the time taken for failure diagnosis when performing failure diagnosis by switching the threshold value to a plurality of stages and comparing each threshold value with the cell voltage of the battery cell. The purpose is to do.

In order to achieve the above object, according to the first aspect of the present invention, there is provided a battery monitoring device for monitoring the state of a plurality of battery cells connected in series,
Monitoring means for inputting the cell voltage at both ends of the battery cell for each of the plurality of battery cells, comparing the cell voltage with the threshold value, and outputting the comparison result, respectively;
While determining the state of each of the plurality of battery cells based on the comparison result of the monitoring means, the threshold value of the monitoring means is switched in order from the minimum threshold value to the maximum threshold value for each of the plurality of battery cells and compared with the cell voltage. Determination means for performing failure diagnosis for detecting an abnormality of the monitoring means based on the comparison result,
The determination means is configured to perform failure diagnosis in order for each of the plurality of battery cells, and the threshold value is switched in order from an arbitrary threshold value between the minimum threshold value and the maximum threshold value at the time of the failure diagnosis. To do.

  According to this, since the determination means switches the threshold value in a stepwise manner in a part of the entire range from the minimum threshold value to the maximum threshold value at the time of failure diagnosis, the threshold value is switched in the entire range from the minimum threshold value to the maximum threshold value. It is possible to shorten the threshold switching time. Furthermore, it is possible to reduce the total time required for failure diagnosis performed in order for a plurality of battery cells.

  The invention according to claim 2 is characterized in that the determination means switches the threshold value in order so that the threshold value increases.

  In this way, by sequentially switching the threshold value so as to increase, it is only necessary to switch the threshold value from an arbitrary threshold value to the maximum threshold value. Accordingly, it is possible to reduce the time required for failure diagnosis.

  The invention according to claim 3 is characterized in that the determination means switches the threshold value in order so that the threshold value becomes smaller.

  In this way, by switching in order so that the threshold value becomes smaller, it is only necessary to switch the threshold value from an arbitrary threshold value to the minimum threshold value. Accordingly, it is possible to reduce the time required for failure diagnosis.

The invention according to claim 4 comprises block voltage detection means for detecting block voltages at both ends of a plurality of battery cells connected in series and outputting them to the determination means,
The judging means estimates the comparison result of the monitoring means from the block voltage at the time of failure diagnosis, sets a range for switching the threshold based on the estimated result, and switches the threshold in order within the range. .

  According to this, since the comparison result of the monitoring means can be estimated from the block voltage, the range for switching the threshold can be set narrower. Therefore, the threshold switching time can be shortened, and as a result, the time required for failure diagnosis can be shortened.

  The invention according to claim 5 is characterized in that, when the threshold value is sequentially switched, the determination unit omits switching of the threshold value after the determination when the presence / absence of abnormality of the monitoring unit is determined.

  According to this, since the threshold value switching is not performed after the presence / absence of the abnormality of the monitoring means is determined, the time required for the threshold value switching can be further shortened. Accordingly, it is possible to reduce the time required for failure diagnosis.

As in the invention described in claim 6, the monitoring means has a plurality of resistors and a plurality of switches for dividing the cell voltage of the battery cell,
The determination means can be configured to relatively change the threshold value in a plurality of stages by switching the ON state or OFF state of the plurality of switches and dividing the voltage of the battery cell by the plurality of resistors.

1 is an overall configuration diagram of a battery monitoring system including a battery monitoring device according to a first embodiment of the present invention. It is the figure which showed the circuit structure with respect to one battery cell in a monitoring circuit. 6 is an input / output timing chart of the first comparator and the second comparator when there is no threshold characteristic deviation as an abnormality of the monitoring circuit. It is a timing chart of the input / output of the first comparator and the second comparator when there is a threshold characteristic deviation as an abnormality of the monitoring circuit. In the monitoring circuit which concerns on 2nd Embodiment of this invention, it is the figure which showed the circuit structure with respect to one battery cell. In another embodiment, it is a figure for demonstrating that a failure diagnosis is complete | finished when the presence or absence of abnormality of the monitoring circuit is decided.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, the same or equivalent parts are denoted by the same reference numerals in the drawings.

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an overall configuration diagram of a battery monitoring system including a battery monitoring apparatus according to the present embodiment. As shown in FIG. 1, the battery monitoring system includes a battery cell 10 and a battery monitoring device 20.

  The battery cell 10 is a voltage source capable of generating a constant voltage, and is a so-called single cell. The battery cell 10 is used, for example, as a power source for driving a load or a power source for an electronic device. For example, a rechargeable secondary battery is employed as the battery cell 10. In the present embodiment, a lithium ion secondary battery is used as the battery cell 10.

  In addition, a plurality of battery cells 10 are connected in series to form a block 11. The block 11 is a unit for dividing the plurality of battery cells 10 into a predetermined number. In the present embodiment, six battery cells 10 are connected in series to form a block 11. That is, the block 11 is obtained by modularizing a plurality of battery cells 10. In FIG. 1, only one block 11 is shown, but actually, a plurality of blocks 11 are set, and a plurality of blocks 11 are combined in series to form one assembled battery.

  The battery monitoring device 20 has an overcharge / discharge detection function for monitoring overcharge and overdischarge as the state of the battery cell 10, and a failure diagnosis function for diagnosing a deviation in the threshold characteristic of these overcharge / discharge detections. It is. These overcharge and overdischarge states are abnormal in the battery cell 10.

  The overcharge / discharge detection function is a function of monitoring the voltage of the battery cell 10 by comparing the voltage of the battery cell 10 with a threshold value. When the battery cell 10 is a secondary battery, the battery monitoring device 20 monitors whether the voltage of the battery cell 10 is between a threshold value for detecting overcharge and a threshold value for detecting overdischarge.

  The failure diagnosis function is a function for detecting that the threshold for detecting overcharge / discharge has changed for some reason (for example, a circuit failure or the like). In other words, the failure diagnosis function uses the failure detection threshold for diagnosing whether there is an abnormality in the threshold for overcharge / discharge detection, and detects abnormalities (failures, disturbances, etc.) of each part that realizes the overcharge / discharge detection function. It is a function to detect.

  Such a battery monitoring device 20 includes a monitoring circuit 30, a block voltage detecting unit 40, and a microcomputer 50 (hereinafter referred to as a microcomputer 50).

  The monitoring circuit 30 is a circuit configured to input the cell voltages at both ends of the battery cell 10 for each battery cell 10, compare the cell voltage with a threshold value, and output the comparison result. This monitoring circuit 30 is provided for each block 11. For example, an IC is used as the monitoring circuit 30.

  FIG. 2 is a diagram showing a circuit configuration for one battery cell 10 in the monitoring circuit 30. The monitoring circuit 30 includes a first monitoring circuit 60 and a second monitoring circuit 70, and the first monitoring circuit 60 and the second monitoring circuit 70 constitute a dual circuit. That is, the first monitoring circuit 60 and the second monitoring circuit 70 have the same circuit configuration.

  The first monitoring circuit 60 compares the threshold value with the cell voltage of the battery cell 10 and outputs the comparison result. The first monitoring circuit 61, the first band gap unit 62, the first comparator 63, A transistor 64 is provided.

  The first switching unit 61 generates a threshold voltage corresponding to the threshold from the cell voltage of the battery cell 10. For this reason, the 1st switching part 61 is between the 1st wiring 31 electrically connected to the positive voltage of the battery cell 10, and the 2nd wiring 32 electrically connected to the negative voltage of the battery cell 10. It is connected.

  Such a first switching unit 61 includes a plurality of resistors 65 and a plurality of switches 66 in order to generate a threshold voltage that is a threshold value. The plurality of resistors 65 are connected in series between the first wiring 31 and the second wiring 32 and are used to divide the cell voltage of the battery cell 10.

  The switch 66 is a path switching circuit configured by, for example, a resistance element or a transistor. Each switch 66 is connected to a connection point of each resistor 65, and each switch 66 is connected in parallel. A connection point where the switches 66 are connected in parallel is connected to a non-inverting input terminal (+ terminal) of the first comparator 63.

  In the present embodiment, eleven resistors 65 are connected in series, and ten switches 66 are connected to the connection points of the resistors 65, respectively. The resistor 65 located closest to the second wiring 32 among the resistors 65 is a variable resistor for performing overcharge detection. On the other hand, the resistor 65 located closest to the first wiring 31 among the resistors 65 is a resistor for performing overdischarge detection.

  When any one of the switches 66 is turned on, the cell voltage of the battery cell 10 is divided by the resistors 65, and the divided voltage is used as a threshold voltage for the non-inverting input terminal of the first comparator 63. Is input. Therefore, when the switch 66 closest to the first wiring 31 among the switches 66 is turned on, there is one resistance 65 connected to the first wiring 31 and ten resistances 65 connected to the second wiring 32. The partial pressure is input to the first comparator 63 as an overdischarge detection threshold, that is, a threshold voltage. Each switch 66 is on / off controlled by the microcomputer 50.

  As described above, when each switch 66 is switched, the partial voltage of the battery cell 10 corresponding to any one of the overcharge detection threshold, the first threshold to the eighth threshold, and the overdischarge detection threshold is set as the threshold voltage. 1 is output from the first switching unit 61 to the first comparator 63.

  These overcharge detection threshold values, the first threshold value to the eighth threshold value, and the overdischarge detection threshold value are set within the voltage range of the battery cell 10. When a lithium ion battery is used as the battery cell 10, the overcharge detection threshold is set to 4.25V, for example, and the overdischarge detection threshold is set to 1.75V, for example. Therefore, the first threshold value to the eighth threshold value between the overcharge detection threshold value and the overdischarge detection threshold value are set in the operating voltage range of the battery cell 10, and are set, for example, between 1.75V and 4.25V, respectively. .

  In addition, each of the first to eighth threshold values is used by the microcomputer 50 for failure diagnosis in which an abnormality of the monitoring circuit 30 such as a threshold characteristic deviation is detected. Each of the first to eighth threshold values is a constant value and is set so as to relatively change in order in a plurality of stages. For example, if the constant value is 0.1 V, each threshold value is set so that the difference between the first threshold value and the second threshold value is 0.1 V, and the difference between the second threshold value and the third threshold value is 0.1 V. ing. In other words, the resistance value of each resistor 65 is determined such that each threshold value changes stepwise with a constant value. In this embodiment, at the time of failure diagnosis, switching is performed in stages from the largest first threshold value (maximum threshold value) to the smallest eighth threshold value (minimum threshold value).

  Thus, the first threshold value to the eighth threshold value are switched stepwise within the voltage range used in the battery cell 10. By setting each threshold in this way, it is not necessary to switch the threshold stepwise for the entire range from the minimum value of the voltage of the battery cell 10 to the maximum value (for example, 0 V to 5 V). Further, since the threshold value is divided more finely than when the threshold value is switched only in one step, the accuracy of abnormality detection of the monitoring circuit 30 is improved.

  The first band gap unit 62 is a voltage source that generates a constant first reference voltage. The first band gap portion 62 is connected between the inverting input terminal (− terminal) of the first comparator 63 and the second wiring 32.

  The first comparator 63 receives the threshold voltage from the first switching unit 61 and the first reference voltage from the first band gap unit 62, and outputs these comparison results to the microcomputer 50 as the first output from the output terminal. This is a comparison circuit. As such a first comparator 63, a comparator can be used.

  As described above, the first reference voltage is input to the inverting input terminal of the first comparator 63, and the threshold voltage is input to the non-inverting input terminal. Therefore, when the threshold voltage is higher than the first reference voltage, the first output becomes a high level signal, and when the threshold voltage is lower than the first reference voltage, the first output becomes a low level signal.

  The transistor 64 is dark current blocking means for preventing dark current from flowing through each resistor 65 that connects the first wiring 31 and the second wiring 32 when the battery cell 10 is not used. Thereby, when the battery cell 10 is not used, the battery cell 10 can be prevented from being consumed by the dark current. The transistor 64 is controlled by the microcomputer 50.

  The second monitoring circuit 70 constitutes a dual circuit together with the first monitoring circuit 60. The circuit configuration of the second monitoring circuit 70 is the same as the circuit configuration of the first monitoring circuit 60. That is, the second monitoring circuit 70 compares the threshold value with the voltage of the battery cell 10 and outputs the comparison result. The second switching unit 71, the second band gap unit 72, the second comparator 73, And a transistor 74.

  Similar to the first switching unit 61, the second switching unit 71 generates a threshold voltage corresponding to the threshold value from the cell voltage of the battery cell 10, and is connected between the first wiring 31 and the second wiring 32. Has been. The second switching unit 71 has the same configuration as the first switching unit 61, and includes a plurality of resistors 75 and a plurality of switches 76.

  The connection form of the plurality of resistors 75 and the plurality of switches 76 is the same as the connection form of the resistors 65 and the switches 66 described above. A connection point where the switches 76 are connected in parallel is connected to a non-inverting input terminal (+ terminal) of the second comparator 73. The configuration of the switch 76 is the same as that of the switch 66 of the first switching unit 61.

  Further, the overcharge detection threshold, the first to eighth thresholds, and the overdischarge detection threshold in the second switching unit 71 are set to the same values as the thresholds of the first switching unit 61. When each switch 76 is switched, the divided voltage corresponding to any one of the overcharge detection threshold value, the first threshold value to the eighth threshold value, and the overdischarge detection threshold value is set as the threshold voltage from the second switching unit 71. 2 is output to the comparator 73.

  The second band gap portion 72 is a voltage source that generates a constant second reference voltage, like the first band gap portion 62. The second reference voltage generated by the second band gap unit 72 is a voltage having the same value as the first reference voltage generated by the first band gap unit 62. The second band gap portion 72 is connected between the inverting input terminal (− terminal) of the second comparator 73 and the second wiring 32.

  The second comparator 73 receives the threshold voltage from the second switching unit 71 and the second reference voltage from the second band gap unit 72, and outputs the comparison result as a second output from the output terminal. is there. As such a second comparator 73, a comparator is used similarly to the first comparator 63.

  The second reference voltage is input from the second band gap unit 72 to the inverting input terminal of the second comparator 73, and the threshold voltage is input from the second switching unit 71 to the non-inverting input terminal. When the threshold voltage is larger than the second reference voltage, the second output becomes a high level signal, and when the threshold voltage is smaller than the second reference voltage, the second output becomes a low level signal.

  Similar to the transistor 64 of the first monitoring circuit 60, the transistor 74 is dark current interrupting means for interrupting dark current flowing through each resistor 65 when the battery cell 10 is not used. The transistor 74 is controlled by the microcomputer 50.

  As described above, the first monitoring circuit 60 and the second monitoring circuit 70 have the same configuration. Note that the configurations of the first monitoring circuit 60 and the second monitoring circuit 70 shown in FIG. 2 are configurations for one battery cell 10. Therefore, actually, each monitoring circuit 60 and 70 shown in FIG. 2 is provided in each monitoring circuit 30 for each battery cell 10.

  The block voltage detection unit 40 shown in FIG. 1 detects a voltage across the block 11, that is, a block voltage in which six battery cells 10 are connected in series. For this reason, the block voltage detection part 40 is connected to the positive electrode side of the battery cell 10 located on the highest voltage side in the block 11 and the negative electrode side of the battery located on the lowest voltage side. The block voltage detected by the block voltage detector 40 is output to the microcomputer 50.

  The microcomputer 50 has a monitoring function for determining the state of each of the plurality of battery cells 10 based on the comparison result of the monitoring circuit 30, and the threshold value of the monitoring circuit 30 for each of the plurality of battery cells 10 in a plurality of stages from the minimum threshold value to the maximum threshold value It is provided with a failure diagnosis function for switching in order and comparing with the cell voltage and detecting an abnormality of the monitoring circuit 30 based on the comparison result. Such a microcomputer 50 includes a CPU, a ROM, an EEPROM, a RAM, and the like (not shown), and monitors the state of the battery cell 10 and diagnoses a failure of the monitoring circuit 30 according to a program stored in the ROM.

  When the microcomputer 50 performs monitoring of the state of the battery cell 10 or failure diagnosis of the monitoring circuit 30, the on / off of each switch 66 of the first switching unit 61 in the first monitoring circuit 60 and the second in the second monitoring circuit 70. The switches 76 of the switching unit 71 are switched on / off. Thereby, the threshold voltage output from the first switching unit 61 and the second switching unit 71 is switched. In other words, the microcomputer 50 switches the on / off states of the switches 66 and 76 and divides the voltage of the battery cell 10 by the resistors 65 and 75, respectively, thereby relatively changing the threshold value in a plurality of stages.

  In monitoring the battery cell 10, the microcomputer 50 outputs the threshold voltage corresponding to the overcharge detection threshold or the overdischarge detection threshold so that each of the first switching unit 61 and the second switching unit 71 outputs the threshold voltage. The switch 66 and the switch 76 are switched for the first switching unit 61 and the second switching unit 71, respectively. Then, overdischarge or overcharge of the battery cell 10 is monitored by the first output and the second output input from the first monitoring circuit 60 and the second monitoring circuit 70.

  On the other hand, at the time of fault diagnosis, the microcomputer 50 switches on / off of the switches 66 and 76 to thereby change the threshold from the first threshold that is the minimum threshold to the first monitoring circuit 60 and the second monitoring circuit 70. The cell voltage is compared with the cell voltage by sequentially switching to a plurality of stages up to the eighth threshold which is the maximum threshold. When the comparison result (first output) of the first monitoring circuit 60 is different from the comparison result (second output) of the second monitoring circuit 70, it is detected that an abnormality has occurred in the monitoring circuit 30. “An abnormality has occurred in the monitoring circuit 30” means that a failure has occurred in a component of the first monitoring circuit 60 or the second monitoring circuit 70.

  The above is the overall configuration of the battery monitoring device 20 according to the present embodiment and the battery monitoring system including the battery monitoring device 20. As described above, a plurality of blocks 11 are actually connected in series, and a plurality of monitoring circuits 30 are connected to each block 11. Each monitoring circuit 30 is electrically connected to a common microcomputer 50. In FIG. 1, one block 11 and one monitoring circuit 30 are shown.

  Next, the monitoring operation of the battery monitoring device 20, that is, the operation of overcharge / discharge detection will be described. The monitoring operation and overcharge / discharge detection operation in the battery monitoring device 20 are, for example, when the battery monitoring device 20 is turned on or off, or when the battery monitoring device 20 receives an external command. To begin.

  The overcharge / discharge detection function of the battery monitoring device 20 includes an overcharge detection mode and an overdischarge detection mode. First, overcharge detection will be described. In the battery monitoring device 20, when the overcharge detection mode is started, the microcomputer 50 corresponds to the overcharge detection threshold value from the first switching unit 61 of the first monitoring circuit 60 and the second switching unit 71 of the second monitoring circuit 70. The switches 66 and 76 are switched so that the threshold voltage is output.

  The comparators 63 and 73 compare the magnitude relationship between the threshold voltage corresponding to the overcharge detection threshold and the first and second reference voltages, and the results are input from the comparators 63 and 73 to the microcomputer 50, respectively. The In the microcomputer 50, whether or not the voltage of the battery cell 10 is overcharged is detected based on whether the outputs of the comparators 63 and 73 are at a high level or a low level.

  On the other hand, in the battery monitoring device 20, when the overdischarge detection mode is started, the switches 66 and 76 are switched so that the microcomputer 50 outputs a threshold voltage corresponding to the overdischarge detection threshold from the switching units 61 and 71. It is done. Then, the comparators 63 and 73 compare the threshold voltage corresponding to the overdischarge detection threshold with the first and second reference voltages, and the results are input from the comparators 63 and 73 to the microcomputer 50, respectively. In the microcomputer 50, whether or not the voltage of the battery cell 10 is overdischarged is determined based on whether the output of each of the comparators 63 and 73 is high level or low level.

  In the above, overcharge / discharge detection is performed based on the outputs of the monitoring circuits 60 and 70, but overdischarge detection is performed based only on the output of one of the monitoring circuits 60 and 70. It may be broken.

  Next, the failure diagnosis operation of the battery monitoring device 20 will be described with reference to FIGS. 3 and 4. FIG. 3 is an input / output timing chart of the first comparator 63 and the second comparator 73 when there is no threshold characteristic deviation as an abnormality of the monitoring circuit 30. FIG. 4 is an input / output timing chart of the first comparator 63 and the second comparator 73 when there is a threshold characteristic deviation as an abnormality of the monitoring circuit 30.

  In the battery monitoring device 20, when the failure diagnosis mode is started, the microcomputer 50 inputs a block voltage from the block voltage detection unit 40. Then, the microcomputer 50 estimates each comparison result of the first monitoring circuit 60 and the second monitoring circuit 70 from the block voltage.

  Here, “estimate” means that the cell voltage of one battery cell 10 is obtained from the block voltage, and this cell voltage is input to each of the monitoring circuits 60, 70, and the first threshold value is set by each switching unit 61, 71. When the threshold value is switched from the threshold value to the eighth threshold value, it is estimated at which switching stage of the threshold value the outputs of the monitoring circuits 60 and 70 are inverted.

  And the microcomputer 50 sets the range which switches a threshold value on the basis of the estimation result using a block voltage, and switches a threshold value in order within the said range. For example, assuming that the outputs of the monitoring circuits 60 and 70 are inverted at the switching stage between the fifth threshold value and the sixth threshold value, the microcomputer 50 sets the cell voltage to the reference timing as the switching timing between the fifth threshold value and the sixth threshold value. Estimate the estimation range. This estimation range is a partial range of the entire switching range from the first threshold that is the minimum threshold to the eighth threshold that is the maximum threshold, for example, the range from the third threshold to the eighth threshold. In other words, a part of the entire switching range from the first threshold value to the eighth threshold value is set so as to include the estimated “reference”.

  In the following, the outputs of the monitoring circuits 60 and 70 are inverted at the switching stage between the fifth threshold value and the sixth threshold value, and the estimated range is the range from the third threshold value to the eighth threshold value.

  In the present embodiment, the microcomputer 50 switches the threshold values in order so that the threshold value increases. Therefore, the threshold switching start point is the third threshold, and the threshold switching end point is the eighth threshold.

  Then, the microcomputer 50 switches the switches 66 and 76 of the first switching unit 61 of the first monitoring circuit 60 and the second switching unit 71 of the second monitoring circuit 70, and starts the estimation range from the switching units 61 and 71. A threshold voltage corresponding to the third threshold value that is a point is output.

  Thereby, each switch 66 of the 1st switching part 61 is switched, the cell voltage of the battery cell 10 is divided, and the threshold voltage equivalent to a 3rd threshold value is output from the 1st switching part 61. Similarly, each switch 76 of the second switching unit 71 is switched to divide the cell voltage of the battery cell 10, and a threshold voltage corresponding to the third threshold is output from the second switching unit 71.

  The first comparator 63 compares the first reference voltage input from the first band gap unit 62 with the threshold voltage corresponding to the third threshold value input from the first switching unit 61, and the comparison result is obtained. The first output is output to the microcomputer 50. Similarly, the second comparator 73 compares the second reference voltage input from the second band gap unit 72 with the threshold voltage corresponding to the third threshold value input from the second switching unit 71, and the comparison result. Is output to the microcomputer 50 as the second output.

  In this case, when the threshold voltage is higher than the first and second reference voltages, the first output and the second output are high level signals, respectively, and when the threshold voltage is lower than the first and second reference voltages, the first output and Each of the second outputs is a low level signal.

  In the microcomputer 50, the first output input from the first monitoring circuit 60 is compared with the second output input from the second monitoring circuit 70.

  Thereafter, similarly to the above, the microcomputer 50 switches the threshold values of the monitoring circuits 60 and 70 from the fourth threshold value to the eighth threshold value. In other words, it can be said that the first switching unit 61 and the second switching unit 71 relatively change the first reference voltage and the second reference voltage in a plurality of stages, respectively. For each threshold, the first output of the first monitoring circuit 60 and the second output of the second monitoring circuit 70 are input to the microcomputer 50 and compared.

  The microcomputer 50 performs the failure diagnosis as described above in order for each of the plurality of battery cells 10, and the threshold value for each of the plurality of battery cells 10 is changed from the first threshold value which is the minimum threshold value to the eighth threshold value which is the maximum threshold value. Switching is performed in order from an arbitrary threshold value up to the threshold value, that is, the third threshold value.

  According to this, the microcomputer 50 uses a partial range (the third threshold value to the eighth threshold value) in the entire switching range from the first threshold value which is the minimum threshold value to the eighth threshold value which is the maximum threshold value when performing failure diagnosis. Will only switch in stages. Therefore, the switching time of the threshold is shortened compared to switching the threshold over the entire range from the minimum threshold to the maximum threshold. If this time shortening process is realized in each of the plurality of battery cells 10, the total time required for failure diagnosis of the plurality of battery cells 10 is significantly reduced.

  As described above, the failure diagnosis mode in which the thresholds of the first switching unit 61 and the second switching unit 71 are switched in stages within the estimated range is executed, and the threshold characteristics of the first monitoring circuit 60 and the second monitoring circuit 70 are obtained. When there is no failure such as a shift, the input / output of each switching unit 61, 71 is shown in FIG.

  In the upper and lower timing charts shown in FIG. 3, the vertical axis of the upper timing chart represents the voltage at the inverting input terminal (−terminal voltage) and the voltage at the non-inverting input terminal of the first comparator 63 or the second comparator 73 (− + Terminal voltage). In addition, the vertical axis of the lower timing chart indicates each output voltage of the first output of the first comparator 63 or the second output of the second comparator 73. The horizontal axis of the upper and lower timing charts indicates the switching stage of each threshold value from the first threshold value to the eighth threshold value.

  As described above, the configurations of the first switching unit 61 and the second switching unit 71 are exactly the same, and the first and second references generated by the first band gap unit 62 and the second band gap unit 72 are the same. The voltage is exactly the same voltage. Therefore, when there is no failure such as a threshold characteristic deviation in the first monitoring circuit 60 and the second monitoring circuit 70, the threshold voltage and the first reference voltage input to the first comparator 63 have the waveforms shown in FIG. This waveform is the same as the threshold voltage and the second reference voltage input to the second comparator 73.

  When the microcomputer 50 switches the output of the first switching unit 61 and the second switching unit 71 step by step so that the threshold value increases in order from the third threshold value, for example, from the third threshold value to the fifth threshold value. Until the threshold voltage corresponding to each of these threshold values is larger than the first and second reference voltages, the first output of the first comparator 63 and the second output of the second comparator 73 are the same high level. Output voltage. That is, the comparison results of the first comparator 63 and the second comparator 73 are the same high level output voltage.

  Then, the magnitude relationship between the threshold voltage corresponding to the sixth threshold and the first and second reference voltages is inverted at the switching stage of the sixth threshold and the threshold voltage is smaller than the first and second reference voltages. Then, the first output of the first comparator 63 and the second output of the second comparator 73 have the same low level output voltage. That is, the switching timing from the fifth threshold value to the sixth threshold value becomes the inversion timing of the outputs of the comparators 63 and 73, and the comparison results of the comparators 63 and 73 have the same low level output voltage.

  In this way, when there is no failure such as a threshold characteristic deviation in the first monitoring circuit 60 and the second monitoring circuit 70, the input and output of the first comparator 63 and the second comparator 73 are completely as shown in FIG. The same result. Therefore, the microcomputer 50 determines that the comparison results of the first monitoring circuit 60 and the second monitoring circuit 70 from the third threshold value to the eighth threshold value are the same, and the first monitoring circuit 60 and the second monitoring circuit are determined by this determination. It is detected that there is no abnormality in 70.

  On the other hand, when the first monitoring circuit 60 and the second monitoring circuit 70 have a failure such as a threshold characteristic shift, the inputs and outputs of the switching units 61 and 71 are not the same. A failure such as a deviation in threshold characteristics occurs due to, for example, a characteristic change in the first band gap part 62 or the second band gap part 72, a change in resistance value of each of the resistors 65 and 75, and the like.

  Here, for example, a case where a threshold characteristic deviation occurs in the first monitoring circuit 60 and a threshold characteristic deviation does not occur in the second monitoring circuit 70 will be described as an example. Further, it is assumed that the threshold characteristic deviation in the first monitoring circuit 60 is a characteristic deviation in which the output of the first switching unit 61 is largely shifted by a certain value. That is, as shown in FIG. 4, the voltage (+ terminal voltage) of the non-inverting input terminal of the first comparator 63 in the first monitoring circuit 60 is a constant value than the voltage of the non-inverting input terminal of the second comparator 73. Only getting bigger. The relationship between the vertical axis and the horizontal axis of the upper and lower timing charts in FIG. 4 is the same as that shown in FIG.

  Then, when the microcomputer 50 switches the threshold values step by step so that the threshold value increases in order from the third threshold value, the first switching unit 61 and the second switching unit 71 have no threshold characteristic deviation. In the second monitoring circuit 70, for example, from the third threshold value to the fifth threshold value, if the threshold voltage corresponding to each of these threshold values is larger than the second reference voltage, the first comparator 63 of the first comparator 63 is similar to the above. One output and the second output of the second comparator 73 have the same high level output voltage. That is, from the third threshold value to the fifth threshold value, the comparison results of the first comparator 63 and the second comparator 73 are the same high level output voltage.

  However, when the microcomputer 50 switches the outputs of the first switching unit 61 and the second switching unit 71 to the sixth threshold value, the second monitoring circuit 70 having no threshold characteristic deviation has a magnitude difference between the threshold voltage and the second reference voltage. While the relationship is reversed, in the first monitoring circuit 60 having the threshold characteristic deviation, the magnitude relationship between the threshold voltage and the first reference voltage is not reversed. Therefore, the second output of the second comparator 73 is a low level output voltage, and the first output of the first comparator 63 is maintained at a high level output voltage. That is, the switching timing from the fifth threshold value to the sixth threshold value becomes the output inversion timing in the second monitoring circuit 70.

  Subsequently, when the microcomputer 50 switches the outputs of the switching units 61 and 71 to the seventh threshold value, the second output of the second comparator 73 is maintained at the low output voltage, and the first comparator 63 is maintained. The first output is maintained at a high level output voltage. That is, the comparison results of the first comparator 63 and the second comparator 73 are different between the sixth threshold value and the seventh threshold value.

  Thereafter, when the microcomputer 50 switches the outputs of the switching units 61 and 71 to the eighth threshold value, the magnitude relationship between the threshold voltage and the first reference voltage is reversed in the first monitoring circuit 60 having a threshold characteristic deviation. . Therefore, the first output of the first comparator 63 is maintained at a low level output voltage. The second output of the second comparator 73 is maintained at the low level output voltage from when the second comparator 73 is switched to the sixth threshold value. That is, the switching timing from the seventh threshold value to the eighth threshold value becomes the output inversion timing in the first monitoring circuit 60.

  In this manner, when there is a failure such as a threshold characteristic deviation in the first monitoring circuit 60, the input and output of the first comparator 63 and the second comparator 73 are the sixth threshold value and the seventh threshold value as shown in FIG. Therefore, the comparison results of the comparators 63 and 73 are different. Therefore, the microcomputer 50 determines that the comparison results of the first monitoring circuit 60 and the second monitoring circuit 70 from the third threshold value to the eighth threshold value are different, and this determination causes the first monitoring circuit 60 and the second monitoring circuit 70 to be different. Detect that something is wrong. That is, the microcomputer 50 detects the threshold characteristic deviation based on the difference in inversion timing between the first output and the second output. In this way, a fault such as a threshold characteristic deviation is detected.

  As described above, in the present embodiment, when the failure diagnosis of the monitoring circuit 30 is performed, the threshold for performing the failure diagnosis is not switched in the entire switching range (the first threshold value to the eighth threshold value), but the entire switching is performed. It is characterized in that only a part of the range is switched in stages.

  According to this, since the range in which the threshold value is switched in one battery cell 10 is narrower than the threshold value is switched in the entire switching range, it is possible to shorten the time for failure diagnosis per one of the plurality of battery cells 10. As described above, since the time for failure diagnosis per one of the plurality of battery cells 10 is shortened, the total time for failure diagnosis performed in order for the plurality of battery cells 10 can be shortened.

  In the present embodiment, since the threshold values are switched in order so as to increase, it is only necessary to switch the threshold values until the threshold value reaches the maximum threshold value.

  Further, in the present embodiment, the block voltage detection unit 40 detects the block voltage so that the microcomputer 50 switches in order from an arbitrary threshold value, for example, the third threshold value, and the monitoring circuit 30 It is characterized by estimating the comparison result. Thereby, since the range which switches a threshold value can be estimated, the range which switches a threshold value can be set more narrowly. Therefore, the threshold switching time can be shortened, and as a result, the time required for failure diagnosis can be shortened.

  As for the correspondence between the description of the present embodiment and the description of the claims, the monitoring circuit 30 corresponds to the “monitoring means” in the claims, and the microcomputer 50 corresponds to the “determination means” in the claims. Corresponding to The block voltage detector 40 corresponds to “block voltage detector” in the claims.

(Second Embodiment)
In the present embodiment, only different parts from the first embodiment will be described. In the first embodiment, the monitoring circuit 30 is provided with two monitoring circuits 60 and 70 to form a dual circuit, and the outputs of the monitoring circuits 60 and 70 are compared with each other to compare the threshold characteristics of the monitoring circuit 30. A fault such as a shift was detected. The present embodiment is characterized in that the cell voltage of the battery cell 10 is monitored by one monitoring circuit 60.

  FIG. 5 is a diagram showing a circuit configuration for one battery cell 10 in the monitoring circuit 30 according to the present embodiment. As shown in this figure, the monitoring circuit 30 includes the first switching unit 61, the first band gap unit 62, the first comparator 63, and the transistor 64 of the first monitoring circuit 60 shown in the first embodiment. It is prepared for. These connection relationships are the same as those shown in FIG.

  In FIG. 5, the configuration of the monitoring circuit 30 for one battery cell 10 is shown. However, as described above, the circuit shown in FIG. 5 is actually configured for each battery cell 10. . Moreover, the whole structure of the battery monitoring apparatus 20 is the same as the structure shown by FIG.

  In the configuration of the monitoring circuit 30 as described above, when the overcharge detection mode is started, the microcomputer 50 corresponds to the overcharge detection threshold value from the first switching unit 61 of the monitoring circuit 30 corresponding to the battery cell 10 to be monitored. The switch 66 is switched so that the threshold voltage to be output is output. Then, the first comparator 63 compares the magnitude relationship between the threshold voltage corresponding to the overcharge detection threshold and the reference voltage, and the result is input from the monitoring circuit 30 to the microcomputer 50 as a first output. The microcomputer 50 determines whether or not the cell voltage of the battery cell 10 is overcharged depending on whether the first output is high level or low level.

  On the other hand, when the overdischarge detection mode is started, the microcomputer 50 outputs a threshold voltage corresponding to the overdischarge detection threshold from the first switching unit 61 of the monitoring circuit 30 corresponding to the battery cell 10 to be monitored. Switch 66 is switched. Then, the first comparator 63 compares the magnitude relationship between the threshold voltage corresponding to the overdischarge detection threshold and the reference voltage, and the result is input from the monitoring circuit 30 to the microcomputer 50 as the first output. The microcomputer 50 determines whether or not the cell voltage of the battery cell 10 is overdischarged depending on whether the first output is at a high level or a low level.

  As described above, the microcomputer 50 monitors the states of the plurality of battery cells 10 based on the comparison result of the monitoring circuit 30.

  Subsequently, the operation of failure diagnosis of the battery monitoring device 20 will be described. In the battery monitoring device 20, when the failure diagnosis mode is started, the microcomputer 50 receives the block voltage from the block voltage detection unit 40 and obtains the cell voltage from the block voltage, as in the first embodiment. The comparison result of the monitoring circuit 30 is estimated from the voltage. And the microcomputer 50 sets the range which switches a threshold value on the basis of the said estimation result.

  For example, as in the first embodiment, assuming that the outputs of the monitoring circuits 60 and 70 are inverted in the switching stage between the fifth threshold value and the sixth threshold value, the threshold switching range is from the first threshold value, which is the minimum threshold value, to the maximum value. It is set to a range from the third threshold value to the eighth threshold value among all switching ranges up to the eighth threshold value which is the threshold value.

  The microcomputer 50 switches the switch 66 of the first switching unit 61 corresponding to the circuit for one battery cell 10 in the monitoring circuit 30 step by step from the third threshold value to the eighth threshold value. As a result, the first comparator 63 compares the threshold voltage corresponding to each threshold with the first reference voltage, and each result is input from the monitoring circuit 30 to the microcomputer 50. Thereby, the microcomputer 50 obtains a comparison result indicating which threshold value among the third threshold value to the eighth threshold value determines the magnitude relationship with the first reference voltage from each result.

  Thereafter, the microcomputer 50 compares the estimation result estimated based on the block voltage with the comparison result obtained from the monitoring circuit 30. The microcomputer 50 determines that there is no abnormality in the monitoring circuit 30 if the results match, and determines that an abnormality has occurred in the monitoring circuit 30 if they do not match. In this way, the microcomputer 50 performs a failure diagnosis of the monitoring circuit 30.

  Then, the microcomputer 50 sequentially performs failure diagnosis of the monitoring circuit 30 for the plurality of battery cells 10 connected to the monitoring circuit 30.

  As described above, even if the configuration of the monitoring circuit 30 is configured by a single comparison circuit, the battery can be set by setting the range in which the threshold is switched to a partial range of the entire threshold switching range. The time for fault diagnosis per cell 10 can be shortened. Accordingly, it is possible to reduce the total time required for failure diagnosis performed in order for the plurality of battery cells 10.

(Other embodiments)
In each said embodiment, although the battery monitoring apparatus 20 detected the overcharge / discharge of the secondary battery as the battery cell 10, the battery monitoring apparatus 20 may monitor the voltage of a primary battery as the battery cell 10. FIG. When the battery monitoring device 20 monitors the voltage of the primary battery, the voltage to be detected corresponds to the monitoring threshold value. Moreover, it is not necessary to monitor both overcharge and discharge, and it is only necessary to monitor either overcharge or overdischarge.

  Furthermore, in each said embodiment, although the lithium ion secondary battery was demonstrated to the example as the battery cell 10, you may employ | adopt another secondary battery. Moreover, this secondary battery can be applied to a vehicle-mounted battery mounted on an electric vehicle such as a hybrid vehicle. Such an in-vehicle battery is configured by combining a plurality of battery cells 10 that are packaged, so that the number of battery cells 10 is very large. Therefore, the time taken for the failure diagnosis of the in-vehicle battery can be significantly shortened by performing the failure diagnosis with the battery monitoring device 20 described above.

  In each of the above embodiments, each switching unit 61, 71 is configured to switch the threshold for performing failure diagnosis such as threshold characteristic deviation into eight stages from the first threshold to the eighth threshold. The number of stages is an example.

  In each of the above embodiments, the overdischarge detection threshold value is larger than the first threshold value, and the overcharge detection threshold value is smaller than the eighth threshold value. However, the values of these detection threshold values are examples. For example, the overdischarge detection threshold value may be a value between the second threshold value and the third threshold value, and the overcharge detection threshold value may be a value between the sixth threshold value and the seventh threshold value.

  In each of the above embodiments, the cell voltage of the battery cell 10 is estimated based on the block voltage detected by the block voltage detection unit 40, and the threshold value is sequentially determined from an arbitrary threshold value between the minimum threshold value and the maximum threshold value based on the estimation result. However, the method for determining an arbitrary threshold value is not limited to this, and another method may be used. For example, you may determine arbitrary threshold values using the estimated value estimated based on an empirical rule. For this reason, the battery monitoring device 20 may not include the block voltage detection unit 40.

  In each of the above embodiments, the threshold values are switched in order so as to increase. However, the threshold values may be switched in order so that the threshold value decreases. Thereby, it is possible to simply switch the threshold until the threshold reaches the minimum threshold. Accordingly, it is possible to reduce the time required for failure diagnosis.

  In each of the above embodiments, even when the microcomputer 50 detects a failure when the threshold is switched in a part of the entire threshold switching range during the failure diagnosis, the switching of the threshold is continued. That is, the threshold value is switched even after a failure is detected. Therefore, in order to further shorten the time for failure diagnosis, when the microcomputer 50 sequentially switches the threshold values, if the presence or absence of a failure is determined, the threshold value may not be switched after the determination. In other words, the microcomputer 50 omits switching of the threshold value after the determination and performs a failure diagnosis related to the next battery cell 10.

  FIG. 6 shows how the threshold value switching is forcibly terminated in this way. As described above, the output of the monitoring circuit 30 is inverted at the switching stage between the fifth threshold value and the sixth threshold value, and the estimated range is the range from the third threshold value to the eighth threshold value.

  FIGS. 6A and 6B are input / output timing charts of the first comparator 63 and the second comparator 73 when there is no threshold characteristic deviation as an abnormality of the monitoring circuit 30. FIG.

  As shown in FIG. 6A, when the threshold value is switched from the third threshold value so that the third threshold value becomes larger, the outputs of the monitoring circuits 60 and 70 are inverted at the stage of the sixth threshold value. At this stage, the threshold value is not switched, and the failure diagnosis ends. Further, as shown in FIG. 6B, when the threshold value is switched from the eighth threshold value so that the eighth threshold value becomes smaller, the outputs of the monitoring circuits 60 and 70 are inverted at the fifth threshold value stage. Therefore, the threshold value is not switched at this stage, and the failure diagnosis ends.

  According to this, in each of the above-described embodiments, the six steps from the third threshold value to the eighth threshold value are switched. However, when the failure diagnosis is completed at the stage where the inversion of the output is detected, in the case of FIG. 4 steps from the first threshold to the sixth threshold, and in the case of FIG. 6B, only four steps from the eighth threshold to the fifth threshold are required.

  6C and 6D are input / output timing charts of the first comparator 63 and the second comparator 73 when there is a threshold characteristic deviation as an abnormality of the monitoring circuit 30. FIG.

  As shown in FIG. 6C, when the threshold value is switched from the third threshold value so that the third threshold value becomes larger, the output of the second monitoring circuit 70 is inverted at the stage of the sixth threshold value. Since the output of the first monitoring circuit 60 is inverted at the threshold level, the failure diagnosis ends at the eighth threshold level. Further, as shown in FIG. 6D, when the threshold value is switched from the eighth threshold value so that the eighth threshold value becomes smaller, the output of the first monitoring circuit 60 is inverted at the seventh threshold value stage, Since the output of the second monitoring circuit 70 is inverted at the stage of the fifth threshold value, the threshold value is not switched at this stage, and the fault diagnosis ends.

  According to this, in the case of FIG. 6C, since the output of the first monitoring circuit 60 is inverted at the stage of the eighth threshold, it is necessary to switch in six stages from the third threshold to the eighth threshold. In the case of (d), four steps from the eighth threshold value to the fifth threshold value are sufficient.

  As described above, since the threshold value is not switched after the presence / absence of the abnormality in the monitoring circuit 30 is determined, the time required for the threshold value switching can be further shortened. Therefore, the total time required for failure diagnosis can be shortened. In this case, the threshold switching stage can be further reduced depending on whether the threshold value is increased or decreased so that the time can be further reduced.

10 battery cell 30 monitoring circuit (monitoring means)
40 Block voltage detection unit (block voltage detection means)
50 Microcomputer (determination means)
65, 75 Resistance 66, 76 Switch

Claims (6)

A battery monitoring device for monitoring the state of a plurality of battery cells connected in series,
Monitoring means for inputting the cell voltage at both ends of the battery cell for each of the plurality of battery cells, comparing the cell voltage with a threshold value, and outputting the comparison result;
While determining the state of each of the plurality of battery cells based on the comparison result of the monitoring means, the threshold value of the monitoring means for each of the plurality of battery cells is sequentially switched in a plurality of stages from a minimum threshold value to a maximum threshold value. A determination means for performing a failure diagnosis for detecting an abnormality of the monitoring means based on a comparison result with the cell voltage,
The determination means performs failure diagnosis in order for each of the plurality of battery cells, and the threshold is set in order from an arbitrary threshold value between the minimum threshold value and the maximum threshold value in the failure diagnosis. A battery monitoring device characterized by switching.   The battery monitoring apparatus according to claim 1, wherein the determination unit sequentially switches the threshold values so that the threshold value increases.   The battery monitoring apparatus according to claim 1, wherein the determination unit sequentially switches the threshold values so that the threshold value becomes smaller. Block voltage detection means for detecting a block voltage at both ends of the plurality of battery cells connected in series and outputting to the determination means;
The determination unit estimates a comparison result of the monitoring unit from the block voltage at the time of the failure diagnosis, sets a range for switching the threshold based on the estimation result, and sequentially sets the threshold within the range. The battery monitoring device according to claim 1, wherein the battery monitoring device is switched.   5. The determination unit according to claim 1, wherein, when the threshold values are sequentially switched, if the presence or absence of abnormality of the monitoring unit is determined, the switching of the threshold value after the determination is omitted. The battery monitoring apparatus as described in any one. The monitoring means has a plurality of resistors and a plurality of switches for dividing the cell voltage of the battery cell,
The determination unit is configured to relatively change the threshold value in a plurality of stages by switching an ON state or an OFF state of the plurality of switches and dividing the voltage of the battery cell by the plurality of resistors. The battery monitoring device according to any one of 1 to 5.

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