JP2013068533A - Battery cell state detection device, battery module, and method for detecting battery cell state - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique for making simple a configuration for detecting a cell temperature and a cell voltage of a battery cell.SOLUTION: A battery cell state detection device 10 comprises series circuits SC1 to SC3, sensors Th1 to Th3, and a temperature detection circuit 30. The series circuits are series circuits in which switches SW1 to SW3 are connected in series to voltage dividing resistors R1 to R3, respectively, and are connected to first lines (L1, L2 and L3) connecting a voltage detection circuit 20 to positive poles of battery cells CL, respectively, and second lines (L0, L1 and L2) connecting the voltage detection circuit to negative poles of the battery cells, respectively, and are connected in parallel to the battery cells CL, respectively. The temperature detection circuit 30, when detecting a cell temperature of the battery cell, turns off switches SW of the respective serial circuits to obtain cell voltages VC, turns on the switch SW of the serial circuit corresponding to the battery cell to be detected to obtain a divided voltage VR by a voltage dividing resistor, and detects the cell temperature of the battery cell on the basis of the cell voltages VC and the divided voltage VR.

Description

  The present invention relates to a battery cell state detection device, a battery module, and a state detection of a battery cell.

  Conventionally, an assembled battery in which a plurality of unit batteries (cells) are connected in series to obtain a predetermined high voltage is widely known. In this type of battery pack, for example, as described in Patent Document 1 below, the voltage and temperature of each cell are usually detected in order to grasp the state of each cell.

JP 2006-236789 A

However, in Patent Document 1, temperature detection in the assembled battery (fuel cell stack) is performed individually using wiring separate from voltage detection. For this reason, there are inconveniences that a large number of wirings are required for detection or the circuit configuration for detection becomes complicated. That is, there is an inconvenience that the detection-related configuration becomes complicated if cell temperature detection of the assembled battery or battery cell is performed separately from cell voltage detection.
The present invention has been completed based on the above situation, and provides a technique for simplifying the configuration relating to the detection of the cell temperature and the cell voltage of the battery cell.

  A battery cell state detection device disclosed in this specification is a battery cell state detection device that detects a state of the battery cell with respect to a battery having at least one battery cell, and a voltage detection circuit that detects a voltage. A first line that connects the voltage detection circuit and the positive electrode of the battery cell, a second line that connects the voltage detection circuit and the negative electrode of the battery cell, and a series circuit of a switch and a voltage dividing resistor. And at least one series circuit connected in parallel to the battery cell and connected to the first line and the second line, and the series circuit on the first line in the vicinity of the battery cell; At least one sensor provided between the connection point with the first line and the positive electrode of the battery cell, and when detecting the temperature of each battery cell, the switch of each series circuit is turned off. The cell voltage of the detection battery cell that detects the temperature is acquired from the voltage detection circuit, the switch of the series circuit corresponding to the detection battery cell is turned on, and a divided voltage that is a voltage drop due to the voltage dividing resistor is obtained. A temperature detection circuit that is obtained from the voltage detection circuit and detects a cell temperature of the detection battery cell based on the cell voltage and the divided voltage.

  According to this configuration, the cell voltage can be measured and the cell temperature can be measured only by detecting the cell voltage and the divided voltage by the voltage detection circuit by the arrangement configuration of the sensor and the series circuit. That is, in the cell temperature measurement, for example, the cell current and the sensor voltage drop can be calculated from the divided voltage, and the sensor resistance value can be calculated from the sensor voltage drop and the cell current. Further, the cell temperature can be detected from the resistance value of the sensor. This eliminates the need for separate wiring and detection circuits for cell voltage measurement and cell temperature measurement. As a result, the configuration of the detection device for cell voltage detection and cell temperature detection can be simplified, thereby reducing the cost of the detection device.

In the battery cell state detection device, the temperature detection circuit calculates a voltage drop of the sensor corresponding to the battery cell and a sensor current flowing in the sensor when detecting the cell temperature, and the voltage The resistance value of the sensor may be calculated from the drop and the sensor current.
In this case, by calculating the resistance value of the sensor, the cell temperature can be detected from the relationship between the resistance value of the sensor and the temperature.

The battery cell state detection device further includes a memory for storing a sensor characteristic table indicating a relationship between the resistance value of the sensor and the cell temperature, and the temperature detection circuit refers to the sensor characteristic table, and The cell temperature may be detected. In this case, the cell temperature can be detected quickly by referring to the sensor characteristic table.
In the battery cell state detection device, the sensor may be a temperature sensor.

  Moreover, you may comprise the battery module provided with at least 1 battery cell and one of the said battery cell state detection apparatuses.

  The battery module disclosed in the present specification includes at least one battery cell, and a battery cell state detection device that detects the state of each battery cell with respect to the battery having the at least one battery cell. In the battery module, the battery cell state detection device includes a voltage detection circuit that detects a voltage, a first line that connects the voltage detection circuit and a positive electrode of each battery cell, the voltage detection circuit, and each battery cell. A series circuit of a second line connecting the negative electrode of the switch, a switch and a voltage dividing resistor, connected to the first line and the second line, and at least connected in parallel to the battery cell On the first line in the vicinity of the battery cell, there is a small amount provided between the connection point of the series circuit and the first line and the positive electrode of the battery cell. When the temperature of each battery cell is detected with one sensor, the cell voltage of the detection battery cell for detecting the temperature by turning off the switch of each series circuit is obtained from the voltage detection circuit, and the detection battery The switch of the series circuit corresponding to the cell is turned on to obtain a divided voltage, which is a voltage drop due to the voltage dividing resistor, from the voltage detection circuit, and based on the cell voltage and the divided voltage, the detection battery cell And a temperature detection circuit for detecting the cell temperature.

  The battery cell state detection method disclosed in the present specification is a battery cell state detection method for detecting the state of the battery cell with respect to a battery having at least one battery cell. A voltage detection circuit for detecting a voltage; a first line connecting the voltage detection circuit and the positive electrode of the battery cell; a second line connecting the voltage detection circuit and the negative electrode of the battery cell; a switch and a voltage divider A series circuit with a resistor, connected to the first line and the second line, and connected in parallel to the battery cell, and on the first line in the vicinity of the battery cell A sensor provided between a connection point between the series circuit and the first line, and a positive electrode of the battery cell, and the battery cell state detection method includes: Electric A cell voltage acquisition step of acquiring a cell voltage of the battery cell by a detection circuit, and a voltage dividing circuit that turns on a switch of the series circuit and acquires a divided voltage that is a voltage drop due to the voltage dividing resistor by the voltage detection circuit Calculating a voltage drop of the sensor and a sensor current flowing in the sensor based on the acquisition step, the cell voltage and the divided voltage, and calculating a resistance value of the sensor from the voltage drop and the sensor current; And a cell temperature detecting step of detecting a cell temperature of the battery cell with reference to a sensor characteristic table indicating a relationship between a resistance value of the sensor and a cell temperature of the battery cell.

  According to the present invention, the series circuit of the switch and the voltage dividing resistor is connected to the first line (line connected to the positive electrode of the battery cell) and the second line (line connected to the negative electrode of the battery cell). And connected in parallel with the battery cell. Further, the sensor is connected between the connection point between the series circuit and the first line and the positive electrode of the battery cell on the first line in the vicinity of the battery cell. With such an arrangement of the series circuit and the sensor, the cell temperature and the cell voltage of the battery cell can be detected simply based on the voltage detection by the voltage detection circuit. Therefore, it is not necessary to provide individual wirings and circuits for detecting the cell temperature of the battery cell, and the configuration relating to the detection of the cell temperature and the cell voltage of the battery cell can be simplified.

1 is a block diagram schematically showing an electrical configuration of a battery module according to an embodiment. Flowchart schematically showing cell state detection processing Explanatory drawing which shows the state of the switch of a cell state detection apparatus Explanatory drawing which shows the state of the switch of a cell state detection apparatus

<Embodiment>
With reference to FIGS. 1-4, the battery module which concerns on one Embodiment of this invention is demonstrated. FIG. 1 is a block diagram schematically showing the electrical configuration of the battery module 1.
The battery module 1 includes an assembled battery Ba as a battery having at least one battery cell, and an assembled battery cell state detection device (hereinafter simply referred to as a “cell state detection device”) 10 as a battery cell state detection device. . The cell state detection device 10 includes a plurality of (three in this embodiment) battery cells (hereinafter simply referred to as “cells”) CL connected to each other in series with respect to the assembled battery Ba. The temperature TC and the cell voltage VC are detected.

  The battery Ba, which is a secondary battery, for example, a lithium battery, corresponds to the battery according to the present invention. In FIG. 1, the battery Ba is shown as an assembled battery in which cells CL <b> 1 to CL <b> 3 that are three unit batteries are connected in series, but the series number of the cells CL of the battery Ba is arbitrary. The battery is not limited to a secondary battery, and may be a fuel cell, for example.

1. Configuration of Cell State Detection Device As shown in FIG. 1, the cell state detection device 10 includes a voltage detection circuit 20, a CPU 30, a memory 40, a ground line L0, voltage detection lines L1 to L3, series circuits SC1 to SC3, and a thermistor. Includes Th1 to Th3.

  The voltage detection circuit 20 includes a number of stages corresponding to the number of series connection stages of the cells CL, that is, three stages of input terminals (corresponding to input sections) A1 to A3, a ground terminal G, and three output terminals B1 to B3. The output terminals B1 to B3 are respectively connected to the A / D conversion ports AD1 to AD3 of the CPU 30 in a one-to-one correspondence relationship.

  The voltage detection circuit 20 detects the voltage differences V1 to V3 from the input voltages E1 to E3 input to the terminals A1 to A3 and G, and outputs the voltage differences V1 to V3 to the CPU 30 through the output terminals B1 to B3. The voltage detection circuit 20 includes, for example, a plurality of differential amplifiers (not shown).

  The voltage detection lines L1 to L3 connect the terminals A1 to A3 of the voltage detection circuit 20 and the positive electrodes of the cells CL1 to CL3 in a one-to-one correspondence relationship. That is, the positive electrode of the first-stage cell CL1 and the first input terminal A1 are connected by the first voltage detection line L1, and the positive electrode of the second-stage cell CL2 and the second input terminal A2 are connected by the second voltage detection line L2. The third-stage cell CL3 and the third input terminal A3 are connected by the third voltage detection line L3. The negative electrode of the first-stage cell CL1 and the ground terminal G are connected by a ground line L0.

  With this configuration, the first input voltage (potential with respect to the ground) E1 (V1) applied to the first input terminal A1 through the first voltage detection line L1 is input to AD1 of the CPU 30 through the output terminal B1. The first input voltage E1 is equal to the first voltage V1 corresponding to the difference between the first input voltage E1 and the ground voltage.

  Further, the second voltage V2 corresponding to the difference between the second input voltage E2 (potential with respect to the ground) applied to the second input terminal A2 through the second voltage detection line L2 and the first input voltage E1 is output. The signal is input to AD2 of the CPU 30 through the terminal B2.

  Further, the third voltage V3 corresponding to the difference between the third input voltage E3 (potential with respect to the ground) applied to the third input terminal A3 through the third voltage detection line L3 and the first input voltage E2 is the output terminal B3. Is output to AD3 of the CPU 30.

  Each series circuit SC1 to SC3 is a series circuit of switches SW1 to SW3 and voltage dividing resistors R1 to R3. The first series circuit SC1 is connected in parallel with the first cell CL1 between the first voltage detection line (first-stage voltage detection line) L1 and the ground GND. The second series circuit SC2 is connected in parallel with the second cell CL2 between the first voltage detection line L1 and the second voltage detection line L2. The third series circuit SC3 is connected in parallel with the third cell CL3 between the second voltage detection line L2 and the third voltage detection line L3. Each switch SW1-SW3 is comprised by semiconductor switches, such as FET, for example.

  Here, the first to third voltages V1 to V3, which are voltage differences, correspond to the cell voltages VC1 to VC2 when the switches SW1 to SW3 of the respective series circuits SC1 to SC3 are off. Further, when any of the switches SW1 to SW3 of the series circuits SC1 to SC3 is turned on, the voltage differences V1 to V3 are voltage drops (divided voltages) VR1 to VR1 caused by the voltage dividing resistors R1 to R3 of the turned on series circuit. It corresponds to VR3.

  Each thermistor (an example of a sensor and a temperature sensor) Th1 to Th3 is connected to each series circuit SC1 to SC3 and each voltage detection line L1 to L3 on each voltage detection line L1 to L3 in the vicinity of each cell CL1 to CL3. It is provided between the points Nd1 to Nd3 and the positive electrodes of the cells CL1 to CL3. The temperature sensor is not limited to the thermistor, and may be any temperature sensor that has a correlation between the detected temperature and the sensor resistance.

  Specifically, the first thermistor Th1 includes a connection point Nd1 between the first series circuit SC1 and the first voltage detection line L1 on the first voltage detection line L1 in the vicinity of the first cell CL1, and the first cell CL1. Between the positive electrode and the positive electrode. The second thermistor Th2 is connected to the connection point Nd2 between the second series circuit SC2 and the second voltage detection line L2 on the second voltage detection line L2 in the vicinity of the second cell CL2, and the positive electrode of the second cell CL2. Between. The third thermistor Th3 is connected to the connection point Nd3 between the third series circuit SC3 and the third voltage detection line L3 on the third voltage detection line L3 in the vicinity of the third cell CL3, and the positive electrode of the third cell CL3. Between.

  The CPU (an example of a temperature detection circuit) 20 includes three A / D conversion ports AD1 to AD3. When detecting the temperatures TC1 to TC3 of the cells CL1 to CL3, the CPU 30 turns off the switch SW of the corresponding series circuit SC and acquires the cell voltage VC of the detection cell CL that detects the temperature TC from the voltage detection circuit 20. To do. Then, the CPU 30 turns on the switch SW of the series circuit SC corresponding to the detection cell CL, and acquires the divided voltage VR, which is a voltage drop due to the voltage dividing resistor R, from the voltage detection circuit 20, and the cell voltage VC and the divided voltage are obtained. The cell temperature TC of the detection cell CL is detected based on the voltage VR.

  Further, the CPU 30 generates switch signals Ssw1 to Ssw3 for individually controlling the on / off of the switches SW1 to SW3, and individually controls the on / off of the switches SW1 to SW3 by the switch signals Ssw1 to Ssw3. In FIG. 1, for convenience, the paths of the switch signals Ssw1 to Ssw3 are indicated by a single broken line.

  In the present embodiment, for the first cell CL1, the first voltage detection line L1 corresponds to the “first line” in the present invention, and the ground line L0 corresponds to the “second line” in the present invention. . For the second cell CL2, the second voltage detection line L2 corresponds to a “first line”, and the first voltage detection line L1 corresponds to a “second line”. For the third cell CL3, the third voltage detection line L3 corresponds to a “first line”, and the second voltage detection line L2 corresponds to a “second line”. The “first line” means a line connecting the voltage detection circuit 20 and the positive electrodes of the cells CL1 to CL3, and the “second line” means a line connecting the voltage detection circuit 20 and the negative electrode of each cell. means. Therefore, each of the voltage detection lines L1 to L3 functions as a “first line” and a “second line”.

2. Cell Temperature Detection Process Next, the cell temperature detection process in the present embodiment will be described with reference to FIGS. FIG. 2 is a flowchart schematically showing each process of the cell temperature detection process, and FIGS. 3 and 4 are explanatory diagrams showing states of the switches SW1 to SW3 in the cell temperature detection process. The cell temperature detection process is executed by the CPU 30 according to a program stored in the memory 40, for example, at predetermined time intervals or at appropriate times according to a processing instruction.

  First, the CPU 30 acquires the first voltage V1, the second voltage V2, and the third voltage V3 from the voltage detection circuit 20 with the switches SW1 to SW3 turned off (step S10). If the acquired voltage values at this time are VM11, VM12, and VM13, respectively, the voltage value VM11 corresponds to the cell voltage VC1 of the first cell CL1, and the voltage value VM12 corresponds to the cell voltage VC2 of the second cell CL2. VM13 corresponds to the cell voltage VC3 of the third cell CL3.

  Next, in order to detect the cell temperature TC1 of the first cell CL1, the CPU 30 turns on only the first switch SW1 (see FIG. 3), and uses the first voltage V1 with the first switch SW1 turned on. 20 (step S12). If the acquired voltage value at this time is VM21, the acquired voltage value VM21 corresponds to the divided voltage VR1 of the first voltage dividing resistor R1. That is, the acquired voltage value VM21 is a value obtained by dividing the first cell voltage VC1 by the resistor Rth1 of the first thermistor Th1 and the first voltage dividing resistor R1. Then, the CPU 30 calculates the resistance Rth1 of the first thermistor by the following equation 1 (step S14).

Rth1 = Thermistor voltage drop Vt1 / Thermistor current It1
= (VM11-VM21) / (VM21 / R1) ... Formula 1
Next, for example, the CPU 30 detects the cell temperature TC1 of the first cell CL1 from the sensor characteristic table indicating the relationship between the resistance Rth1 of the first thermistor stored in the memory 40 and the temperature T (step S16).

  Subsequently, in order to detect the cell temperature TC2 of the second cell CL1, the CPU 30 turns on only the second switch SW2 (see FIG. 4), and detects the second voltage V2 with the second switch SW2 turned on. Obtained from the circuit 20 (step S22). When the acquired voltage value at this time is VM22, the acquired voltage value VM22 corresponds to the divided voltage (voltage drop) VR2 of the second voltage dividing resistor R2. That is, the acquired voltage value VM22 is the second voltage dividing resistance when the second cell voltage VC2 is divided by the resistor Rth1 of the first thermistor Th1, the resistor Rth2 of the second thermistor Th2, and the second voltage dividing resistor R2. The value corresponds to the divided voltage VR2 of R2. And CPU30 calculates resistance Rth2 of a 2nd thermistor by the following Formula 2 (step S24).

Rth2 = Thermistor voltage drop Vt2 / Thermistor current It2
= (VM12- (Rth1 * VM22 / R2 + VM22)) / (VM22 / R2) ...... Formula 2
Then, for example, the CPU 30 detects the cell temperature TC2 of the second cell CL2 from the sensor characteristic table indicating the relationship between the resistance Rth2 of the second thermistor stored in the memory 40 and the temperature T (step S26).

  Subsequently, in order to detect the cell temperature TC3 of the third cell CL3, the CPU 30 turns on only the third switch SW3 and turns on the third voltage with the third switch SW3 turned on, as in the case of the cell temperature TC2. V3 is acquired from the voltage detection circuit 20 (step S32). If the acquired voltage value at this time is VM23, the acquired voltage value VM23 corresponds to the divided voltage (voltage drop) VR3 of the third voltage dividing resistor R3. That is, the acquired voltage value VM23 is the third voltage dividing resistance when the third cell voltage VC3 is divided by the resistor Rth2 of the second thermistor Th2, the resistor Rth3 of the third thermistor Th3, and the third voltage dividing resistor R3. The value corresponds to the divided voltage VR3 of R3. Then, the CPU 30 calculates the resistance Rth3 of the third thermistor by the following equation 3 similar to the equation 2 (step S34).

Rth3 = Thermistor voltage drop Vt3 / Thermistor current It3
= (VM13- (Rth2 * VM23 / R3 + VM23)) / (VM23 / R3) ...... Formula 3
Then, for example, the CPU 30 detects the cell temperature TC3 of the third cell CL3 from the sensor characteristic table indicating the relationship between the resistance Rth3 of the third thermistor stored in the memory 40 and the temperature T (step S36).

3. As described above, in this embodiment, the series circuits SC1 to SC3 of the switches SW1 to SW3 and the voltage dividing resistors R1 to R3 are connected to the first line (L1, L2, L3) and the second line ( L0, L1, L3) and in parallel with the cells CL1 to CL3. Further, the thermistors Th1 to Th3 are connected to the connection points Nd1 to Nd3 between the series circuits SC1 to SC3 and the first line on the first line (L1, L2, L3) in the vicinity of each cell, and the positive electrode of each cell. Between.
In other words, the series circuits SC1 to SC3 are connected in parallel with the cells CL1 to CL3 between the voltage detection line L1 of the first stage and the ground GND and between the voltage detection lines (L1-L2, L2-L3). . The thermistors Th1 to Th3 are connected between the connection points of the series circuits SC1 to SC3 and the voltage detection lines on the voltage detection lines in the vicinity of the cells and the positive electrodes of the cells.
With such an arrangement of the series circuits SC1 to SC3 and the thermistors Th1 to Th3, the detection of the cell temperatures TC1 to TC3 and the cell voltages VC1 to VC3 of the battery cells CL1 to CL3 simply based on the voltage detection by the voltage detection circuit 20 It can be performed. Therefore, it is not necessary to provide individual wirings and circuits for detecting the cell temperature TC and the cell voltage VC of the cell CL, and the configuration relating to the detection of the cell temperature and the cell voltage of the cell CL, that is, the cell state detection is simplified. can do. This leads to cost reduction of the cell state detection device 10.

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

  (1) In the above-described embodiment, the assembled battery is configured by connecting three cells (unit batteries) CL1 to CL3 in series. However, the number of connection stages of the cells is not limited to three but four. There may be stages, five stages or more. Alternatively, the number of cell connection stages may be one, that is, the battery is not limited to an assembled battery.

  (2) In the above embodiment, the example in which the temperature detection circuit is configured by the CPU 30 has been described, but the present invention is not limited thereto. The temperature detection circuit may be constituted by, for example, an ASIC (Application Specific Integrated Circuit). In the above embodiment, the voltage detection circuit 20 and the temperature detection circuit 30 are individually configured. However, the present invention is not limited to this, and the voltage detection circuit may also serve as the temperature detection circuit. For example, the voltage detection circuit and the temperature detection circuit may be configured by one ASIC. At that time, the ASIC may also serve as another control of the battery.

  (3) In the above embodiment, an example is shown in which the sensor characteristic table is referred to when the cell temperature TC is detected from the resistance Rth of the thermistor. However, the present invention is not limited to this. For example, the cell temperature TC may be calculated from an equation indicating the relationship between the thermistor resistance Rth and the temperature T. The sensor (temperature sensor) is not limited to the thermistor. The sensor may be any sensor that has a predetermined correlation between the resistance value of the sensor and the battery cell temperature.

DESCRIPTION OF SYMBOLS 1 ... Battery module 10 ... Cell state detection apparatus 20 ... Voltage detection circuit 30 ... CPU (temperature detection circuit)
L1 to L3 Voltage detection line SC1 to SC3 Series circuit R1 to R3 Voltage dividing resistor SW1 to SW3 Switch Th1 to Th3 Thermistor (temperature sensor)

Claims (7)

A battery cell state detection device for detecting a state of each battery cell with respect to a battery having at least one battery cell,
A voltage detection circuit for detecting the voltage;
A first line connecting the voltage detection circuit and the positive electrode of each battery cell;
A second line connecting the voltage detection circuit and the negative electrode of each battery cell;
A series circuit of a switch and a voltage dividing resistor, connected to the first line and the second line, and at least one series circuit connected in parallel to the battery cell;
On the first line in the vicinity of the battery cell, at least one sensor provided between a connection point of the series circuit and the first line and a positive electrode of the battery cell;
When detecting the temperature of each battery cell, the cell voltage of the detection battery cell for detecting the temperature by turning off the switch of each series circuit is obtained from the voltage detection circuit, and the series circuit corresponding to the detection battery cell A voltage at which a divided voltage that is a voltage drop caused by the voltage dividing resistor is acquired from the voltage detection circuit, and a cell temperature of the detection battery cell is detected based on the cell voltage and the divided voltage A detection circuit;
A battery cell state detection device.   When detecting the cell temperature, the temperature detection circuit calculates a voltage drop of the sensor corresponding to the battery cell and a sensor current flowing through the sensor, and the sensor detection circuit calculates the sensor current from the voltage drop and the sensor current. The battery cell state detection device according to claim 1, wherein the resistance value is calculated. A memory for storing a sensor characteristic table indicating a relationship between the resistance value of the sensor and the cell temperature;
The battery cell state detection device according to claim 2, wherein the temperature detection circuit detects the cell temperature with reference to the sensor characteristic table.   The battery cell state detection device according to any one of claims 1 to 3, wherein the sensor is a temperature sensor. At least one battery cell;
The battery cell state detection device according to any one of claims 1 to 4,
Battery module with At least one battery cell;
A battery module comprising a battery cell state detection device for detecting a state of each battery cell for a battery having at least one battery cell,
The battery cell state detection device includes:
A voltage detection circuit for detecting the voltage;
A first line connecting the voltage detection circuit and the positive electrode of each battery cell;
A second line connecting the voltage detection circuit and the negative electrode of each battery cell;
A series circuit of a switch and a voltage dividing resistor, connected to the first line and the second line, and at least one series circuit connected in parallel to the battery cell;
On the first line in the vicinity of the battery cell, at least one sensor provided between a connection point of the series circuit and the first line and a positive electrode of the battery cell;
When detecting the temperature of each battery cell, the cell voltage of the detection battery cell for detecting the temperature by turning off the switch of each series circuit is obtained from the voltage detection circuit, and the series circuit corresponding to the detection battery cell A voltage at which a divided voltage that is a voltage drop caused by the voltage dividing resistor is acquired from the voltage detection circuit, and a cell temperature of the detection battery cell is detected based on the cell voltage and the divided voltage A battery module including a detection circuit. A battery cell state detection method for detecting a state of the battery cell with respect to a battery having at least one battery cell,
The battery includes a voltage detection circuit that detects a voltage, a first line that connects the voltage detection circuit and a positive electrode of the battery cell, a second line that connects the voltage detection circuit and a negative electrode of the battery cell, and a switch And a voltage dividing resistor connected to the first line and the second line and connected in parallel to the battery cell, and the first circuit in the vicinity of the battery cell. On the line, a sensor provided between a connection point of the series circuit and the first line and a positive electrode of the battery cell, and the battery cell state detection method,
A cell voltage acquisition step of acquiring a cell voltage of the battery cell by the voltage detection circuit by turning off the switch of the series circuit;
A voltage dividing acquisition step of turning on the switch of the series circuit and acquiring a divided voltage that is a voltage drop by the voltage dividing resistor by the voltage detection circuit;
Calculating a voltage drop of the sensor and a sensor current flowing through the sensor based on the cell voltage and the divided voltage, and calculating a resistance value of the sensor from the voltage drop and the sensor current;
A cell temperature detecting step of detecting a cell temperature of the battery cell with reference to a sensor characteristic table showing a relationship between a resistance value of the sensor and a cell temperature of the battery cell;
A battery cell state detection method.

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