JP2016152693A - Abnormality determination device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an abnormality determination device capable of determining the abnormality of a balancer circuit appropriately, at a relatively low cost.SOLUTION: An abnormality determination device is constituted of a first temperature change detector 36 for detecting the temperature of a balancer resistor 35 provided on a unit board 20, a second temperature change detector 37 for detecting the reference temperature in the unit board 20, and an abnormality determination unit 38 for determining that there is an abnormality in a balancer circuit 33, when the temperature difference between a detection temperature detected by the first temperature change detector 36 and the reference temperature detected by the second temperature change detector 37, while the balancer circuit 33 is off, falls within a predetermined range.SELECTED DRAWING: Figure 4

Description

  The present invention relates to an abnormality determination device that determines an abnormality of a balancer circuit provided in a battery module including a plurality of battery cells.

  In general, a battery mounted on an electric vehicle that travels by a driving force of a motor such as an electric vehicle or a hybrid vehicle is connected to a plurality of battery cells such as lithium ion secondary batteries in series. It is comprised so that the voltage required in order to drive | work can be obtained. The battery is mounted on each electric vehicle as a battery module housed in a housing case together with a battery monitoring unit for monitoring the state of charge and discharge of each battery cell.

  By the way, in a battery constituted by a plurality of battery cells as described above, there is a possibility that each battery cell cannot be appropriately charged due to variations in voltage of each battery cell. That is, when the voltage variation of each battery cell becomes large, it becomes impossible to fully charge a battery cell having a low voltage. Due to this, the substantial charge capacity of the battery may be reduced.

  In order to solve such a problem, some battery monitoring units include a balancer circuit that discharges battery cells. By performing discharge of each battery cell as necessary by such a balancer circuit, variations in voltage of each battery cell can be suppressed (see, for example, Patent Documents 1 and 2).

JP 2012-191679 A JP 2013-223378 A

  However, in the case where the balancer circuit is provided, there is a possibility that the battery cell corresponding to the balancer circuit will continue to be discharged if the balancer circuit switch is stuck (ON failure) in the ON state.

  If the battery cells continue to be discharged, the voltage variation between the battery cells increases, and the amount of charge as a battery may be significantly reduced. For this reason, when the balancer circuit has an ON failure, it is desired to determine the occurrence of the failure early and notify the passenger.

  Further, for example, by monitoring a change in the current value flowing through the balancer circuit, it is possible to appropriately determine an abnormality in the balancer circuit such as an ON failure. However, in order to provide a current sensor for monitoring the current value of the balancer circuit, for example, it is necessary to greatly change the layout of the circuit board, and since the current flowing through the balancer circuit is very small, a highly accurate current sensor Need to be employed, and the cost may increase significantly.

  The present invention has been made in view of such circumstances, and an object thereof is to provide an abnormality determination device that can appropriately determine abnormality of a balancer circuit at a relatively low cost.

  A first aspect of the present invention for solving the above problem is provided in a battery module comprising a plurality of battery cells and a unit board provided with a balancer circuit including a balancer resistor corresponding to each battery cell, and the balancer An abnormality determination device for determining an abnormality of a circuit, the first temperature change detection unit for detecting the temperature of the balancer resistance provided on the unit substrate, and the second temperature change for detecting a reference temperature in the unit substrate. A detection unit, a switch control unit for controlling on / off of the switch of the balancer circuit, and a detected temperature detected by the first temperature detection unit in a state where switch-on operation permission information is not transmitted from the switch control unit; And the reference temperature detected by the second temperature detection unit is within a predetermined range, the balancer circuit is abnormal. In the abnormality determination apparatus characterized by having an abnormality determination unit that determines that that, a.

  According to a second aspect of the present invention, in the abnormality determination device according to the first aspect, the first temperature detection unit is provided in a first wiring region including the balancer resistor formed on the unit substrate. The abnormality determination apparatus is characterized by the above.

  According to a third aspect of the present invention, in the abnormality determination device according to the second aspect, the second temperature detection unit is provided in a second wiring region substantially separated from the first wiring region. It is in the abnormality determination apparatus characterized by having.

  According to a fourth aspect of the present invention, in the abnormality determination device according to any one of the first to third aspects, the unit substrate is provided with a plurality of cell temperature detection units for detecting the temperature of the battery cell. In the abnormality determination device, the first temperature detection unit and the second temperature detection unit are configured by any one of the cell temperature detection units.

  A fifth aspect of the present invention is the abnormality determination device according to any one of the first to fourth aspects, wherein the abnormality determination unit stops transmission of the switch-on operation permission information from the switch control unit. The abnormality determination device is characterized in that even when a temperature difference between the detected temperature and the reference temperature is maintained, the balancer circuit is determined to be abnormal.

  According to the present invention, it is possible to realize an abnormality determination device that can accurately determine abnormality of the balancer circuit. Furthermore, since the abnormality of the balancer circuit is determined based on the temperature of the balancer resistance, it is not necessary to use a highly accurate current sensor or the like, and the abnormality determination device can be realized at a relatively low cost. Furthermore, for example, since an existing configuration such as a cell temperature detection unit that detects the temperature of the battery cell is used as the temperature of the balancer resistance or the like, an increase in cost can be further suppressed.

It is a figure which shows schematic structure of an example of an electric vehicle. It is a perspective view which shows schematic structure of a battery module. It is a schematic diagram for demonstrating the abnormality determination apparatus which concerns on this invention. It is a schematic diagram explaining the schematic structure of an example of a unit board | substrate. It is a graph explaining the relationship between the operation of the balancer circuit, the temperature of the balancer resistance, and the reference temperature. It is a flowchart which shows an example of the abnormality determination control which concerns on this invention.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

  First, an example of an electric vehicle equipped with an abnormality determination device will be briefly described. As shown in FIG. 1, the electric vehicle 1 according to the present embodiment is an electric vehicle (EV), and includes a battery module 10 including a battery 11 for traveling that is a secondary battery, and power supply from the battery 11. A traveling motor 2, which is an electric motor that operates, is mounted. The travel motor 2 is connected to, for example, a front wheel 4 that is a drive wheel via an automatic transmission 3, and the electric vehicle 1 travels by the driving force of the travel motor 2.

  As shown in FIG. 2, the battery 11 included in the battery module 10 is configured by a plurality (four in this embodiment) of battery cell units 13 including a plurality (three in the present embodiment) of battery cells 12. . The battery cells 12 constituting the battery cell unit 13 are connected in series by a bus bar or the like although not shown.

  The plurality of battery cell units 13 are housed in a housing case 14, and the housing case 14 is closed by a lid member 15. The housing case 14 includes a plurality of battery cell units 13 and a plurality of CMUs (Cell Monitor Units) 30 for monitoring the state of each battery cell unit 13, for example, the voltage of each battery cell 12. A unit substrate 20 is accommodated.

  In the present embodiment, the unit substrate 20 is formed with a size that covers the plurality of battery cell units 13 accommodated in the accommodation case 14. In addition, a plurality of temperature sensors (cell temperature detection units) 17 (17A to 17F) such as thermistors are arranged on the unit substrate 20 with a predetermined interval. Each of these temperature sensors 17 is provided to detect the temperature of each of the plurality of battery cell units 13, and is disposed, for example, on a bus bar (not shown) that connects the battery cell units 13.

  As shown in FIG. 3, the CMU 30 includes a voltage monitoring IC 31 and a microcomputer 32. The voltage monitoring IC 31 is connected to the upstream side and the downstream side of each battery cell 12, and detects the voltage value of each battery cell 12. The microcomputer 32 is connected to a BMU (Battery Management Unit) 40, and each battery cell 12 includes, for example, the voltage value of the battery cell 12 detected by the voltage monitoring IC 31 and the temperature of the battery cell 12 detected by the temperature sensor 17. The information regarding the state of is transmitted to the BMU 40. The CMU 30 is provided corresponding to each battery cell unit 13, and the BMU 40 performs integrated control of the battery 11 based on the information of the CMU 30.

  Further, the CMU 30 includes a balancer circuit 33 for suppressing the voltage variation of each battery cell 12 constituting the battery cell unit 13. The balancer circuit 33 includes a switch (switching element) 34 and a balancer resistor 35 in parallel with each battery cell 12. Therefore, electronic components such as a balancer resistor 35 constituting the balancer circuit 33 are arranged on the unit substrate 20 as will be described later.

  The on / off operation of the balancer circuit 33 is controlled by the microcomputer 32 of the CMU 30. When the voltage in each battery cell 12 varies, the microcomputer 32 turns on the balancer circuit 33 corresponding to the battery cell 12 having a high voltage, that is, turns on the switch 34 to discharge the battery cell 12.

  Thereby, equalization of the voltage of each battery cell 12 can be aimed at, and the fall of the substantial charge capacity of the battery 11 can be suppressed. While the battery 11 is repeatedly charging and discharging, the voltage of each battery cell 12 is likely to vary due to, for example, a difference in temperature state or deterioration state of each battery cell 12. When the voltage variation of each battery cell 12 becomes large, it becomes impossible to fully charge the battery cell 12 with a low voltage. For this reason, the substantial charge capacity of the battery 11 will fall. However, such a decrease in the charge capacity of the battery 11 can be suppressed by appropriately discharging the battery cell 12 having a high voltage by the balancer circuit 33.

  In this embodiment, the BMU (switch control unit) 40 determines whether or not the balancer circuit 33 can be turned on / off (the switch 34 is actuated) based on information transmitted from the CMU 30. The BMU 40 transmits information such as switch-on operation permission information of the balancer circuit 33 and target cell voltage to the CMU 30 as necessary, and the microcomputer 32 controls the on / off operation of the balancer circuit 33 based on the information. The CMU 30 may be regarded as a switch control unit and may have the function of the BMU 40.

  Incidentally, the CMU 30 also serves as an abnormality determination device that acquires the detection result of the temperature sensor 17 for detecting the temperature of each battery cell 12 as described above, and determines whether there is an abnormality in the battery cell 12 based on the detection result. Function. For example, when the detected value by any of the temperature sensors 17 rapidly increases beyond a predetermined value, it is determined that an abnormality such as an internal short circuit has occurred in any of the battery cells 12. And based on this determination result, a passenger | crew is alert | reported by lighting a warning lamp, for example.

  Further, the CMU 30 functions not only as an abnormality of the battery cell 12 but also as an abnormality determination device that determines whether there is an abnormality in the balancer circuit 33 provided corresponding to each battery cell 12. In the present invention, as will be described below, based on the temperature difference between the temperature of the balancer resistor 35 provided on the unit substrate 20 and the reference temperature in the unit substrate 20, whether or not there is an abnormality in the balancer circuit 33, specifically The presence or absence of an ON failure of the switch 34 is determined.

  Further, as shown in FIG. 3, the CMU 30 as the abnormality determination device includes a first temperature detection unit 36 that detects the temperature of the balancer resistor 35 formed on the unit substrate 20 and a first temperature that detects the reference temperature in the unit substrate 20. 2 temperature detectors 37, and an abnormality determination unit 38 that determines whether or not the balancer circuit 33 is abnormal based on detection results of the first temperature detector 36 and the second temperature detector 37. . Specifically, the abnormality determination unit 38 is in a state where the switch-on operation permission information is not transmitted from the BMU (switch control) 40, that is, in a state where the balancer circuit 33 should be turned off, by the first temperature detection unit 36. When the temperature difference between the detected temperature detected and the reference temperature detected by the second temperature detector 37 is within a predetermined range, it is determined that the balancer circuit 33 is abnormal.

  Here, the first temperature detection unit 36 detects the temperature of the balancer resistor 35, but may be any device that can detect the presence or absence of a temperature change of the balancer resistor 35. Therefore, the detection target for the first temperature detection unit 36 to detect the temperature is not particularly limited, and may naturally be the balancer resistor 35 itself, the battery cell 12, the unit substrate 20, or the like. The position where the first temperature detection unit 36 is provided is not particularly limited as long as the detection value changes as the temperature of the balancer resistor 35 changes, and may be a position slightly away from the balancer resistor 35.

  Further, the second temperature detection unit 37 detects the temperature of the detection target as a reference temperature so that the temperature change of the balancer resistor 35 is not substantially affected. More specifically, the detection target by the second temperature detection unit 37 is the same type as the detection target of the first temperature detection unit 36. However, the second temperature detection unit 37 detects the temperature of the detection target in a state where it is not substantially affected by the temperature change of the balancer resistor 35 even when the temperature change of the balancer resistor 35 occurs.

  For example, in the present embodiment, the second temperature detection unit 37 detects an average value of temperatures to be detected at a plurality of locations as a reference temperature. As shown in FIG. 4, on the unit substrate 20, there are a first wiring region 21 and a second wiring region 22 in which wiring patterns made of a conductor are densely formed, and these first wirings Between the region 21 and the second wiring region 22, there is a third wiring region 23 with a small wiring pattern. The balancer resistor 35 constituting the balancer circuit 33 is provided in the first wiring region 21.

  Further, as described above, the plurality of temperature sensors 17A to 17F for detecting the temperature of the battery cell 12 are arranged on the unit substrate 20 with predetermined intervals. Two of the temperature sensors 17A and 17B are arranged in the first wiring region 21 in which the balancer resistor 35 is formed. That is, the temperature sensors 17A and 17B are arranged in the first wiring region 21 that is easily affected by the temperature change of the balancer resistor 35. For this reason, for example, when the temperature of the balancer resistor 35 rises due to heat generation, the heat is easily transmitted to the temperature sensors 17A and 17B via the wiring pattern of the first wiring region 21, and the detection values by the temperature sensors 17A and 17B are the balancer. It changes appropriately according to the temperature change of the resistor 35. Therefore, in this embodiment, the temperature of the balancer resistor 35 (temperature change) is detected by these temperature sensors 17A and 17B. That is, in the present embodiment, these temperature sensors 17A and 17B function as the first temperature detection unit 36 that detects the temperature (temperature change) of the balancer resistor 35, and the detection target is the battery cell 12.

  The remaining temperature sensors 17C to 17F are arranged in the second wiring region 22 where the balancer resistor 35 is not formed. For this reason, for example, even when the temperature of the balancer resistor 35 rises due to heat generation, the third wiring region exists between the first wiring region 21 and the second wiring region 22. Is not easily transmitted to the temperature sensors 17C to 17F. Therefore, in the temperature sensors 17C to 17F, the change in the detection value due to the temperature change of the balancer resistor 35 is extremely small. Therefore, in this embodiment, the average value of the detected temperatures detected by the temperature sensors 17C to 17F is used as the reference temperature. That is, in the present embodiment, these temperature sensors 17C to 17F function as the second temperature detection unit 37 that detects the reference temperature in the unit substrate 20, and the detection target is the battery as in the first temperature detection unit 36. Cell 12.

  FIG. 5 is a graph for explaining the relationship between the operating state of the balancer circuit 33 and the detected temperature detected by the first temperature detector 36 and the reference temperature detected by the second temperature detector 37. More specifically, this graph shows a change in the detected temperature Te1a detected by the temperature sensor 17A and a change in the detected temperature Te1b detected by the temperature sensor 17B when the normal balancer circuit 33 is turned on and off, and the temperature sensor. An example of a change in the reference temperature Te2 that is an average value of the detected temperatures detected by 17C to 17F is shown.

  As shown in FIG. 5, when the balancer circuit 33 is in an off state (before time t1), the detected temperatures Te1a and Te1b and the reference temperature Te2 basically match each other. When the balancer circuit 33 is turned on at time t1, power is supplied to the balancer resistor 35, and the temperature of the balancer resistor 35 rises. At this time, the temperature rise of the balancer resistor 35 is about several degrees C. at maximum, but the detected temperatures Te1a, Te1b of the temperature sensors 17A, 17B also increase about several degrees C. accordingly. Thereafter, the detected temperatures Te1a and Te1b maintain the increased temperature while the balancer circuit 33 is on, and drop to the vicinity of the reference temperature Te2 when the balancer circuit 33 is turned off at time t2.

  Thus, if the balancer circuit 33 is normal, the temperature difference between the detected temperature Te1a and the reference temperature Te2 (Te1a-Te2) or the temperature between the detected temperature Te1b and the reference temperature Te2 only when the balancer circuit 33 is on. A difference (Te1b−Te2) is generated. Therefore, in a state where the balancer circuit 33 should be off, that is, in a state where the BMU 40 has not transmitted the switch-on operation permission information of the balancer circuit 33, the temperature difference (Te1a-Te2) between the detected temperatures Te1a, Te1b and the reference temperature Te2 , Te1b-Te2) has occurred, the abnormality determination unit 38 can determine that an abnormality of the balancer circuit 33, for example, an ON failure of the switch 34 has occurred.

  For example, in the state where the balancer circuit 33 should be off, the abnormality determination unit 38 may detect a temperature difference between the detected temperature Te1a and the reference temperature Te2 (Te1a−Te2) or a temperature difference between the detected temperature Te1b and the reference temperature Te2 (Te1b− When Te2) is a predetermined temperature range set in advance (for example, a range between the first temperature Ta1 and the second temperature Ta2), it is determined that there is an abnormality in the balancer circuit 33.

  For example, even when an abnormality occurs in the battery cell 12 such as an internal short circuit, the detected temperatures Te1a and Te1b rise and the temperature difference (Te1a−Te2, Te1b−Te2) may occur. However, the rise in the detected temperatures Te1a and Te1b due to the abnormality of the battery cell 12 is much larger than that at the time of the abnormality of the balancer circuit 33, and the temperature difference greatly exceeds the temperature range (Ta1 to Ta2). In other words, when the temperature range (Ta1 to Ta2) is set, the temperature difference (Te1a-Te2, Te1b-Te2) when the balancer circuit 33 is on is included in the temperature range. Therefore, the abnormality determination unit 38 can accurately determine the abnormality of the balancer circuit 33.

  FIG. 6 is a flowchart showing an example of the abnormality determination control of the balancer circuit according to this embodiment.

  As shown in FIG. 6, the abnormality determination unit 38 first detects the detected temperature (Te1a, Te1b) detected by the first temperature detection unit 36 and the reference temperature (second temperature detection unit 37) detected in step S1. Te2) is acquired. Next, in step S2, the operating state of the balancer circuit 33 is determined. That is, it is determined whether or not the switch-on operation permission information of the balancer circuit 33 is transmitted from the BMU 40 to the CMU 30. Here, when the balancer circuit 33 is operating (step S2: No), the process ends without determining the abnormality of the balancer circuit 33.

  On the other hand, when the balancer circuit 33 is not operating (step S2: Yes), the process proceeds to step S3, and whether or not the temperature difference (Te1a-Te2, Te1b-Te2) is within a predetermined range (Ta1 to Ta2). Determine whether. If the temperature difference is within the predetermined range (Ta1 to Ta2) (step S3: Yes), the abnormality determination unit 38 determines that there is an abnormality in the balancer circuit 33 (step S4). Thereafter, the passenger is notified by turning on a warning light based on the determination that there is an abnormality. If the temperature difference is outside the predetermined range (step S3: No), the process ends without determining that the balancer circuit 33 is abnormal. For example, when the temperature difference is larger than a predetermined range, there is a possibility that the battery cell 12 is abnormal, but it can be determined that the balancer circuit 33 is not abnormal. Therefore, the process is terminated without determining that the balancer circuit 33 is abnormal.

  As described above, in the present embodiment, the abnormality determination unit 38 detects the detected temperature and the second temperature detected by the first temperature detection unit 36 (temperature sensors 17A and 17B) in a state where the balancer circuit 33 should be off. When the temperature difference from the reference temperature detected by the detection unit 37 (temperature sensors 17C to 17F) is within a predetermined range, it is determined that the balancer circuit 33 is abnormal. Thereby, the abnormality of the balancer circuit 33 can be determined appropriately. Further, since the temperature sensor 17 that detects the temperature of the battery cell 12 is used as the first temperature detection unit 36 and the second temperature detection unit 37, the abnormality determination device that determines whether there is an abnormality in the balancer circuit 33 is compared. Can be realized at low cost.

  Although one embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment.

  In the above-described embodiment, the abnormality determination unit 38 determines that the balancer circuit 33 is in a state where the balancer circuit 33 should be off and the temperature difference between the detected temperature and the reference temperature is within a predetermined temperature range set in advance. Although it is determined that there are 33 abnormalities, the determination method is not limited to this.

  For example, if the balancer circuit 33 is normal, the detected temperatures Te1a and Te1b and the reference temperature Te2 substantially coincide with each other in a state where the balancer circuit 33 should be off. Accordingly, although the balancer circuit 33 is switched from on to off at time t2 in FIG. 5, that is, transmission of switch-on operation permission information from the BMU (switch control unit) 40 is stopped. Even when the temperature difference (Te1a-Te2, Te1b-Te2) between the detected temperatures Te1a, Te1b and the reference temperature Te2 is maintained without decreasing, the abnormality determination unit 38 causes an abnormality in the balancer circuit 33. Can be determined.

  In the above-described embodiment, the average value of the temperature detected by the temperature sensors 17C to 17F is set as the reference temperature. For example, the temperature detected by any one of the temperature sensors 17C to 17F located sufficiently away from the balancer resistor 35 is used. May be used as a reference temperature.

  In the above-described embodiment, the temperature sensor 17 for detecting the temperature of the battery cell 12 is used as the first temperature detection unit 36 and the second temperature detection unit 37. You may make it provide the temperature sensor as the detection part 36 and the 2nd temperature detection part 37 separately.

DESCRIPTION OF SYMBOLS 1 Electric vehicle 2 Driving motor 3 Automatic transmission 4 Front wheel 10 Battery module 11 Battery 12 Battery cell 13 Battery cell unit 14 Housing case 15 Cover member 17 Temperature sensor (cell temperature detection part)
20 unit substrate 21 first wiring area 22 second wiring area 23 third wiring area 30 CMU
32 Microcomputer 33 Balancer circuit 34 Switch (switch element)
35 Balancer resistance 36 1st temperature detection part 37 2nd temperature detection part 38 Abnormality determination part 40 BMU

Claims (5)

An abnormality determination device provided in a battery module including a plurality of battery cells and a unit substrate provided with a balancer circuit including a balancer resistor corresponding to each battery cell, and determining an abnormality of the balancer circuit,
A first temperature change detection unit for detecting a temperature of the balancer resistor provided on the unit substrate;
A second temperature change detection unit for detecting a reference temperature in the unit substrate;
A switch control unit for controlling on / off of the switch of the balancer circuit;
The temperature difference between the detected temperature detected by the first temperature detector and the reference temperature detected by the second temperature detector in a state where the switch-on operation permission information is not transmitted from the switch controller. And an abnormality determination unit that determines that the balancer circuit is abnormal when the value is within a predetermined range. In the abnormality determination device according to claim 1,
The abnormality determination device, wherein the first temperature detection unit is provided in a first wiring region including the balancer resistor formed on the unit substrate. In the abnormality determination device according to claim 2,
The abnormality determination device, wherein the second temperature detection unit is provided in a second wiring region substantially separated from the first wiring region. In the abnormality determination device according to any one of claims 1 to 3,
The unit substrate is provided with a plurality of cell temperature detection units for detecting the temperature of the battery cell, and the first temperature detection unit and the second temperature detection unit are any of the cell temperature detection units. An abnormality determination device characterized by comprising The abnormality determination device according to any one of claims 1 to 4, wherein
The abnormality determination unit is also provided in the balancer circuit when the temperature difference between the detected temperature and the reference temperature is maintained when transmission of the switch-on operation permission information from the switch control unit is stopped. An abnormality determination device characterized by determining that there is an abnormality.