JP2013050312A - Assembled battery monitoring device and battery pack - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an assembled battery monitoring device which allows for more accurate determination of the presence or absence of disconnection in a detection line by suppressing variation in voltage among cells without opening and closing control of a switch device, compared with a configuration in which resistances connected in parallel to the respective neighboring cells have an identical value of resistance.SOLUTION: In an assembled battery monitoring device 3, resistances R1 in a first group which are connected in parallel to the respective neighboring cells C have different values of resistance from each other. And resistances R2 in a second group which are connected in parallel to the respective neighboring cells have different values of resistance from each other. In addition, a plurality of the cells each have an identical combined resistance of the resistance in the first group and the resistance in the second group which are connected in parallel to the respective cells.

Description

  The invention disclosed in this specification relates to a technique for determining the presence or absence of disconnection of a detection line for individually detecting the voltage of each unit cell constituting the assembled battery.

  2. Description of the Related Art Conventionally, there is an assembled battery monitoring device that determines the presence or absence of disconnection of a detection line for individually detecting the voltage of each cell constituting the assembled battery (see Patent Document 1). In this assembled battery monitoring device, a switch device and a resistor having the same resistance value are connected in parallel between the terminals of each cell, and a microprocessor that controls opening and closing of each switch device is provided. The microprocessor controls the switch device connected in parallel to one of the two adjacent cells to be closed and the switch device connected in parallel to the other cell to be opened, Based on the voltage across the resistor connected in parallel to the cell, it is determined whether or not the detection line for detecting the voltage of the one cell is disconnected.

JP 2009-288034 A

  However, in the conventional assembled battery monitoring device, in order to determine whether or not the detection line is disconnected, opening / closing control of each switch device is necessary. For this reason, for example, the processing load for determining the presence / absence of disconnection is increased by the amount of opening / closing control of the switch device, or the device having no switch device cannot determine the presence / absence of disconnection of the detection line. Occurs.

  Here, in the conventional assembled battery monitoring device, if it is determined whether or not there is a disconnection with both switch devices connected in parallel to adjacent cells being closed, Accuracy will be reduced. That is, in the above-described conventional assembled battery management device, the resistance values of two resistors connected in parallel to adjacent cells are the same, so that the detection line of each cell is different depending on whether the detection line is disconnected or disconnected. The difference between the voltages at both ends becomes very small. As a result, for example, there is a possibility that it may be erroneously determined that the terminal is not disconnected although it is disconnected.

  Therefore, if the resistance values of the two resistors connected in parallel to each of the adjacent cells are different from each other, the erroneous determination can be suppressed. However, in this configuration, the resistance values of the resistors connected in parallel for each cell are different from each other, resulting in voltage variation between the cells.

  In the present specification, the resistance value of the resistors connected in parallel to each of the adjacent cells is the same while suppressing the voltage variation between the cells without requiring the switching control of the switching device or the switching device itself. In comparison, a technique capable of accurately determining whether or not a detection line is disconnected is disclosed.

  An assembled battery monitoring device disclosed in the present specification is an assembled battery monitoring device that monitors an assembled battery in which a plurality of cells are connected in series, and is connected in parallel to each of the plurality of cells via a detection line. A plurality of first group resistors, wherein a plurality of first group resistors having different resistance values between the first group resistors connected in parallel to each of adjacent cells, and a detection line connected to each of the plurality of cells. A plurality of second group resistors connected in parallel to each other, each of the second group resistors connected in parallel to each of adjacent cells having a resistance value different from each other, and a control unit. The plurality of cells have the same combined resistance of the first group resistor and the second group resistor connected in parallel to each cell, and the control unit includes the plurality of first groups. A first voltage detection process for detecting a voltage for each cell based on each voltage across the anti-cell, and whether or not the detection line is disconnected based on a detected value of the voltage for each cell in the first voltage detection process. Disconnection determination processing to be determined.

In the present invention, the plurality of first group resistors are connected in parallel to each of the plurality of cells via the detection line, and the resistance values of the first group resistors connected in parallel to each of the adjacent cells are different from each other. Therefore, compared to the case where the resistance values of the first group resistors are the same, the resistance value varies greatly between the case where the detection line is not disconnected and the case where the detection line is disconnected. be able to.
In addition, the plurality of second group resistors are connected in parallel to each of the plurality of cells via the detection line, and the resistance values of the second group resistors connected in parallel to each of the adjacent cells are different from each other. Further, in any of the plurality of cells, the combined resistance of the first group resistor and the second group resistor connected in parallel to each cell is the same. Therefore, voltage variation between cells due to the resistors connected in parallel can be suppressed as compared with the configuration without the second group resistor.
As described above, according to the present invention, without requiring switching control of the switching device or the switching device itself, the resistance of the resistors connected in parallel to each of the adjacent cells can be suppressed while suppressing the voltage variation between the cells. Compared to the configuration having the same resistance value, it is possible to accurately determine whether or not the detection line is disconnected.

  In the assembled battery monitoring apparatus, in addition to the first voltage detection process, the control unit detects a voltage for each cell based on voltages at both ends of the plurality of second group resistors. In the disconnection determination process, it may be determined that there is a disconnection when the difference between the detected values in the first voltage detection process and the second voltage detection process is greater than or equal to a reference value.

  According to the present invention, the presence / absence of disconnection is determined based on the voltage across the two resistors per cell. For this reason, compared with the structure which determines the presence or absence of a disconnection based only on the both-ends voltage of one resistance per cell, the precision of the presence or absence of a disconnection can be improved.

  In the assembled battery monitoring apparatus, the first group resistance and the second group resistance are both three or more, and the resistance value is the same for each skip.

  According to the present invention, the first group resistor and the second group resistor have the same resistance value every time they are skipped. Therefore, the combined resistance of the first group resistor and the second group resistor connected in parallel to each cell can be made the same for adjacent cells with a relatively simple circuit configuration.

  In addition, the battery pack includes an assembled battery in which a plurality of cells are connected in series, and any one of the above assembled battery monitoring devices.

  According to the present invention, the resistance value of the resistors connected in parallel to each of adjacent cells is the same while suppressing the voltage variation between the cells without requiring switching control of the switching device or the switching device itself. Compared to the above, it is possible to accurately determine whether or not the detection line is disconnected.

Electrical configuration diagram of a battery pack according to an embodiment Flow chart showing the first control process Flow chart showing second control process

  A battery pack 1 according to an embodiment will be described with reference to FIGS. 1 to 3. The battery pack 1 is mounted on a rechargeable device such as an electric vehicle.

(Battery pack configuration)
As shown in FIG. 1, the battery pack 1 includes an assembled battery 2 and an assembled battery monitoring device 3.

1. The assembled battery The assembled battery 2 has a configuration in which a plurality of cells C, in other words, a plurality of single cells are connected in series. In the present embodiment, the cell C is a rechargeable secondary battery such as a lithium ion battery, but may be a battery other than the secondary battery. Hereinafter, the assembled battery 2 will be described as having four cells C <b> 1 to C <b> 4, but any configuration having two or more cells C may be used.

2. The assembled battery monitoring device 3 is electrically connected to the assembled battery 2 and performs monitoring based on the voltage between terminals of each cell C. The assembled battery 2 and the assembled battery monitoring device 3 are preferably detachably connected via a connector (not shown). Hereinafter, the voltage between terminals of each cell C may be referred to as a cell voltage. The assembled battery monitoring device 3 includes four first group resistors R1 belonging to the first group, four second group resistors R2 belonging to the second group, and the control unit 4.

  The four first group resistors R1 are connected in parallel to the individual cells C via the detection lines L, and the voltage VR1 across each first group resistor R1 is connected in parallel to the first group resistor R1. A value proportional to the cell voltage of the cell C is shown. Specifically, the first group resistor R11 is connected in parallel to the cell C1 via detection lines L11 and L12, and the first group resistor R12 is connected in parallel to the cell C2 via detection lines L12 and L13. The first group resistor R13 is connected in parallel to the cell C3 via detection lines L13 and L14, and the first group resistor R14 is connected in parallel to the cell C4 via detection lines L14 and L15. .

  Of the four first group resistors R1, the first group resistors R1 connected to the adjacent cells C have different resistance values. Further, in the present embodiment, the resistance values of the four first group resistors R1 are substantially the same for each jump. Specifically, the two first group resistors R11, R13 have substantially the same resistance value, for example, 2 kΩ, and the two first group resistors R12, R14 have substantially the same resistance value, for example, 1 kΩ. In addition, examples of combinations of both resistance values include 1 MΩ and 700 kΩ, 1 MΩ and infinite Ω, and the like.

  The four second group resistors R2 are connected in parallel to the individual cells C via the detection lines L, and the voltage VR2 across each second group resistor R2 is connected in parallel to the second group resistor R2. A value proportional to the cell voltage of the cell C is shown. Specifically, the second group resistor R21 is connected in parallel to the cell C1 via the detection lines L21 and L22, and the second group resistor R22 is connected in parallel to the cell C2 via the detection lines L22 and L23. The second group resistor R23 is connected in parallel to the cell C3 via the detection lines L23 and L24, and the second group resistor R24 is connected in parallel to the cell C4 via the detection lines L24 and L25. .

  Of the four second group resistors R2, the second group resistors R2 connected to each of the adjacent cells C have different resistance values. Furthermore, in the present embodiment, the resistance values of the four second group resistors R2 are substantially the same for each jump. Specifically, the two second group resistors R21 and R23 have substantially the same resistance value, for example, 1 kΩ, and the two second group resistors R22 and R24 have substantially the same resistance value, for example, 2 kΩ. In addition, examples of combinations of both resistance values include 700 kΩ and 1 MΩ, infinite Ω and 1 MΩ, and the like.

  With the above configuration, for all the cells C, the combined resistance values of the first group resistor R1 and the second group resistor R2 connected in parallel to each cell C are substantially the same.

  The control unit 4 includes a first battery monitoring unit 5 and a second battery monitoring unit 6, and the first battery monitoring unit 5 and the second battery monitoring unit 6 monitor the assembled battery 2. Thereby, even if any one of the 1st battery monitoring unit 5 and the 2nd battery monitoring unit 6 fails, monitoring of the assembled battery 2 can be continued.

  The first battery management unit 5 individually reads the voltage VR1 across the first group resistor R1 via an A / D converter (not shown), and executes the monitoring process for the assembled battery 2 based on the voltage across the both ends VR1. Specifically, the first battery monitoring unit 5 includes a first CPU 5A, a first memory 5B, and a first communication unit 5C. The first memory 5B stores a program for executing monitoring processing, disconnection detection processing described later, and the like. The first memory 5B is a non-volatile memory such as a flash memory, for example. The first communication unit 5C is an interface that performs data communication with the second battery monitoring unit 6 by a wireless method or a wired method.

  The second battery management unit 6 individually reads the voltage VR2 across the second group resistor R2 via an A / D converter (not shown), and executes the monitoring process for the assembled battery 2 based on the voltage across the voltage VR2. Specifically, the second battery monitoring unit 6 includes a second CPU 6A, a second memory 6B, and a second communication unit 6C. The second memory 6B stores a program for executing monitoring processing and the like. The second memory 6B is a non-volatile memory such as a flash memory, for example. The second communication unit 6 </ b> C is an interface that performs data communication with the first communication unit 5 </ b> C of the first battery monitoring unit 5.

(Control contents of the control unit)
For example, when the battery pack monitoring device 3 is powered on, the control unit 4 periodically executes a first voltage detection process, a second voltage detection process, a disconnection determination process, and the like at a predetermined cycle.

1. Control Process of First Battery Management Unit The first battery monitoring unit 5 performs a first voltage detection process, a disconnection determination process, a monitoring process, and the like. Specifically, the first CPU 5A reads the program from the first memory 5B and executes the first control process shown in FIG.

  The first CPU 5A first executes a first voltage detection process (S1). In the first voltage detection process, the first CPU 5A reads each voltage VR1 of the first group resistor R1, detects the cell voltage of each cell C based on the voltage VR1, and identifies the identification information of each cell C. First information indicating a correspondence relationship with the detected value of the cell voltage of the cell is stored in the first memory 5B.

  When the first CPU 5A receives the second information obtained by the second voltage detection process described later from the second battery monitoring unit 6 after executing the first voltage detection process, the first CPU 5A stores the second information in the first memory 5B. Then, the detected value comparison process is performed (S3). In the detection value comparison process, the first CPU 5A refers to the first information and the second information, and for each cell, the detection value of the cell voltage in the first voltage detection process and the cell voltage in the second voltage detection process. And the detected value is compared to determine whether the difference between the detected values is larger than the reference value (S4). If the first CPU 5A determines that the difference between the detected values is less than or equal to the reference value for all cells (S4: NO), the first CPU 5A executes the monitoring process assuming that none of the detection lines L is disconnected (S5). .

  In this monitoring process, the first CPU 5A refers to the first information, for example, and executes a known monitoring process based on the cell voltage (S5). For example, for each cell, the first CPU 5A measures the impedance or performs deterioration diagnosis based on a cell voltage and a detected current value of a current sensor (not shown) that detects a current flowing in the assembled battery 2. The first CPU 5A ends the control process after executing the management process.

  If the first CPU 5A determines that the difference between the detected values is larger than the reference value for at least one cell (S4: YES), the first CPU 5A executes a disconnection error process assuming that any one of the detection lines L is disconnected. (S6). For example, when the first CPU 5A determines that the difference between the detection values for the cell C2 is larger than the reference value, the first CPU 5A can recognize that at least one of the detection lines L12, L13, L22, and L23 is disconnected. For example, the detection line L connected to either the first group resistor R1 or the second group resistor R2 based on the magnitude comparison between the detection value of the first voltage detection process and the detection value of the second voltage detection process. It is also possible to grasp whether the cable is disconnected. For example, for the cell C2, when the detection value of the first voltage detection process is smaller than the detection value of the second voltage detection process, one of the detection lines L12 and L13 connected to the first group resistor R12 is disconnected. I can understand what happened.

  As the disconnection error processing, the first CPU 5A transmits, for example, information on the disconnection to an external device such as a display device, a sound generation device, and a host control device via the first notification unit 5C.

2. Control Process of Second Battery Management Unit The second battery monitoring unit 6 executes a second voltage detection process, a monitoring process, and the like. More specifically, the second CPU 6A reads the program from the second memory 6B and executes the second control process shown in FIG. First, the second CPU 6A executes a second voltage detection process (S11). In the second voltage detection process, the second CPU 6A reads each voltage VR2 of the second group resistor R2, detects the cell voltage of each cell C based on the voltage VR2, and identifies the identification information of each cell C. Second information indicating a correspondence relationship with the detected value of the cell voltage of the cell is stored in the second memory 6B.

  Next, the second CPU 6A transmits the second information to the first battery monitoring unit 5 (S12), and waits until the determination result in S4 is transmitted from the first battery monitoring unit 5. When the determination result indicates that there is no disconnection (S13: NO), the second CPU 6A executes a monitoring process similar to the above S5 independently of the first battery monitoring unit 5 (S14). The control process ends. On the other hand, when the determination result indicates that there is a disconnection (S13: YES), the second CPU 6A ends the second control process without executing the monitoring process.

(Effect of this embodiment)
For example, consider a comparative configuration in which the first group resistor R11 and the first group resistor R12 have the same resistance value as the configuration of FIG. In this comparative configuration, when the detection line L12 is disconnected, the potential between the resistors R11 and R12 fluctuates around the intermediate potential between the detection line L11 and the detection line L13. The voltage VR1 between both ends of the group resistor R11 and the first group resistor R12 does not change much. In addition, since the current flowing in the closed loop including the cell C1 and the first group resistor R11 and the current flowing in the closed loop including the cell C2 and the first group resistor R12 are substantially the same and cancel each other, each first group resistor Only a very small current flows through R1, and in order to detect the voltage across the first group resistor R1, it is necessary to use a low-resistance circuit line such as a gold-plated wire, which may increase the cost.

  On the other hand, in this embodiment, the resistance values of the first group resistors R1 connected in parallel to the adjacent cells are different from each other. Therefore, as compared with the comparative configuration, the resistance value varies greatly between the case where the detection line L is not disconnected and the case where the detection line L is disconnected. Therefore, it is possible to accurately determine the presence or absence of the disconnection. In addition, since a current that is not larger than that of the comparison configuration flows through each first group resistor R1, a low resistance circuit line such as a gold-plated wire is used to detect the voltage across the first group resistor R1. There is no need, and high costs can be suppressed.

  Moreover, in addition to the first group resistor R1, the second group resistor R2 is connected in parallel to each cell C, and each cell C is connected to the first group resistor R1 connected in parallel to the cell C. The combined resistance with the second group resistor R2 is the same. Accordingly, it is possible to suppress impedance variation and voltage variation between the cells C due to the resistors connected in parallel as compared with the configuration without the second group resistance. Further, the assembled battery monitoring device 3 can determine whether or not the detection line L is disconnected without requiring opening / closing control of the switch device as in the conventional configuration.

  Further, the presence / absence of disconnection is determined based on the voltages VR1 and VR2 across the two resistors R1 and R2 per cell C. For this reason, compared with the structure which determines the presence or absence of a disconnection based on only the voltage across one resistor per cell C, the accuracy of the determination of the presence or absence of a disconnection can be improved.

  Furthermore, the resistance values of the first group resistor R1 and the second group resistor R2 are the same for each jump. Therefore, the combined resistance of the first group resistor R1 and the second group resistor R2 connected in parallel to each cell C can be made the same for adjacent cells C with a relatively simple circuit configuration.

<Other embodiments>
The present invention is not limited to the embodiments described with reference to the above description and the drawings, and for example, the following various aspects are also included in the technical scope of the present invention.

(1) In the above-described embodiment, the first group resistor R1 and the second group resistor R2 are connected in parallel to a common cell through separate detection lines L over the entire length. However, the present invention is not limited to this, and the first group resistor R1 and the second group resistor R2 are connected in parallel to a common cell via, for example, a detection line L in which a part near the cell is shared. However, if it is the said embodiment, it can be judged more accurately which detection line was disconnected.

(2) In the embodiment described above, the resistance values of the group resistors R1 and R2 are substantially the same for each jump. However, the resistance value of each resistor may be different. In short, if at least the resistance values of the same group resistors connected to the adjacent cells C are different from each other, the resistance values of the resistors connected in parallel to the adjacent cells are compared with the same configuration. It is possible to accurately determine whether or not there is a disconnection.

(3) In the said embodiment, the control part 4 which has the 1st battery monitoring unit 5 and the 2nd battery monitoring unit 6 was mentioned as an example as an example of a control part. However, the control unit is not limited to this, and may be configured not to include any one of the first battery monitoring unit 5 and the second battery monitoring unit 6 in the circuit configuration of FIG. For example, a configuration in which the second battery monitoring unit 6 is removed while leaving the second group resistor R2 in the configuration of FIG. Even in such a configuration, since the combined resistance of the resistors connected in parallel to each cell is substantially the same, voltage variation between the cells can be suppressed.

(4) In the above embodiment, the control unit 4 is configured to perform the detection value comparison process after detecting the cell voltage based on the both-ends voltage VR1 of all the first group resistors R1. However, every time the control unit 4 detects the cell voltage based on the voltage VR1 across the first group resistor R1 for a predetermined number, for example, one, the control unit 4 and the second group connected in parallel with the first group resistor R1. A configuration in which the detected value comparison process is performed for the group resistor R2 may be employed.

(5) In the above embodiment, the control unit 4 determines whether or not the detection line L is disconnected by the detection value comparison process. However, for example, when at least one of the first battery monitoring unit 5 and the second battery monitoring unit 6 has a detection value of each cell voltage that is outside a predetermined range, more specifically, when it is below a predetermined threshold value. Alternatively, it may be determined that the detection line L is disconnected.

(6) In the said embodiment, the control part 4 performed the detected value comparison process in the 1st battery monitoring unit 5. FIG. However, the detection value comparison process may be executed by the second battery monitoring unit 6 or another unit (not shown) in the control unit 4.

(7) In the said embodiment, the assembled battery monitoring apparatus 3 which does not have a switch apparatus like the conventional structure was mentioned as an example as an example of an assembled battery monitoring apparatus. However, the assembled battery monitoring device may have a switch device. As an example of this configuration, a configuration including a balancer circuit for equalizing the cell voltage of each cell can be given. The balancer circuit has a configuration in which switching elements are connected in series to the resistors R1 and R2, respectively, with respect to the configuration of FIG. The control unit 4 is configured to turn on the switch element corresponding to the cell C having a cell voltage higher than that of the other cell C and reduce the cell voltage of the cell having a higher cell voltage due to the voltage drop of the resistor R at the time of charge / discharge. It is. In the case of this configuration, the operation of the balancer circuit is stopped, and whether or not the detection line L is disconnected is determined with all the switch elements turned on.

(8) In the above embodiment, as a specific configuration of the control unit 4, a configuration including the first CPU 5 </ b> A, the second CPU 6 </ b> A, and the like has been described as an example. However, the control unit includes a configuration including one or three or more CPUs, a configuration including hardware circuits such as ASIC (Application Specific Integrated Circuit) and FPGA (Field Programmable Gate Array), and both hardware circuits and CPUs. The structure provided may be sufficient. In short, the control unit only needs to be configured to execute at least the first voltage detection process and the disconnection determination process.

  1: battery pack 2: assembled battery 3: assembled battery monitoring device 4: control unit C: cell L: detection line R1: first group resistance R2: second group resistance VR1, VR2: voltage across both ends

Claims (4)

An assembled battery monitoring device for monitoring an assembled battery in which a plurality of cells are connected in series,
A plurality of first group resistors connected in parallel to each of the plurality of cells via a detection line, wherein a plurality of first group resistors connected in parallel to each of adjacent cells have different resistance values. 1 group resistance,
A plurality of second group resistors connected in parallel to each of the plurality of cells via a detection line, wherein a plurality of second group resistors connected in parallel to each of adjacent cells have different resistance values. Two group resistors,
A control unit,
Each of the plurality of cells has the same combined resistance of the first group resistor and the second group resistor connected in parallel to each cell,
The controller is
A first voltage detection process for detecting a voltage for each cell based on a voltage across each of the plurality of first group resistors;
An assembled battery monitoring device that executes a disconnection determination process for determining whether or not the detection line is disconnected based on a detection value of the voltage for each cell in the first voltage detection process. The assembled battery monitoring device according to claim 1,
The controller is
In addition to the first voltage detection process, a second voltage detection process for detecting a voltage for each cell based on the voltage across each of the plurality of second group resistors is performed.
In the disconnection determination process, the assembled battery monitoring device determines that there is a disconnection when a difference between detection values in the first voltage detection process and the second voltage detection process is greater than or equal to a reference value. The assembled battery monitoring device according to claim 1 or 2,
The first group resistor and the second group resistor are both three or more, and the resistance value is the same for each jump. An assembled battery in which a plurality of cells are connected in series;
A battery pack comprising: the assembled battery monitoring device according to any one of claims 1 to 3.

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