Cell Balancing Device and Cell Balancing Method

Abstract

To provide a cell balancing apparatus and a cell balancing method capable of reducing wiring amount in the apparatus and facilitating maintenance.SOLUTION: A cell balancing apparatus 11 comprises: a battery module 12 including a battery pack formed by connecting a plurality of secondary batteries; a cell voltage measuring unit 13 for measuring a voltage of each cell C1 to Cn of the plurality of secondary batteries; and a control unit 14 that outputs a command signal for adjusting the voltage of each cell on the basis of the voltage value of each cell measured in the cell voltage measuring unit. The voltage measuring unit includes one or more current sensors 201 that detect a magnetic field generated by a current flowing through each cell. The battery module and the current sensors of the cell voltage measuring unit are non-contact.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a cell balancing device and a cell balancing method that can reduce the amount of wiring in a device and are easy to maintain.

Background Art

[0002] In electric vehicles (EVs), hybrid electric vehicles (HEVs), etc., a battery pack in which a plurality of secondary batteries such as lithium-ion batteries are connected is used. Also, in a solar power generation system, a battery pack in which a plurality of secondary batteries are connected for nighttime power utilization is used. A plurality of cells (single cells) constituting the battery pack generally have variations in the state of charge (SOC) due to manufacturing variations and the like. On the other hand, each cell needs to be used so that the cell voltage (voltage across both ends of the cell) falls within a range from a preset lower limit voltage to an upper limit voltage in order to prevent thermal runaway due to overcharging or over-discharging. In order to use each cell in such a manner, it is necessary to suppress variations in the state of charge of each cell within a certain range. It is necessary to estimate the state of charge of each cell by measuring the terminal voltage, current, etc. of each cell and perform cell balancing.

[0003] Fig. 6 shows an example of a conventional cell balancing device. In this device, both terminals of each cell are connected to a voltage measurement module 31 by wiring, and in order to perform cell balancing, each cell is provided with a separate path of wiring and connected to a discharge switch SW. However, in such a conventional device, particularly in the case of a battery pack in which a large number of cells are connected (a configuration of about 96 cells in an in-vehicle battery cell), problems such as an increase in the weight of the cell balancing device due to the wiring connecting each cell to the voltage measurement module and the like, complication of cell replacement in maintenance, and the need for wiring replacement due to disconnection have occurred.

[0004] In International Publication No. 2014 / 103008, in a method of wired connection between a battery controller and a storage battery module, since a large number of wirings are costly for insulation and maintenance, a storage battery module side management device having a communication unit for wirelessly transmitting battery information, and a management device for mutually wirelessly communicating with the storage battery module side management device to manage each storage battery module are disclosed. Further, Japanese Patent Application Laid-Open No. 07-110343 discloses a DC current sensor for use in a DC leakage breaker or the like that directly detects a change in magnetic flux in a core based on a change in DC current flowing through a detection conductor by a Hall element, and Japanese Patent Application Laid-Open No. 2002-189039 discloses a current sensor attachable to a small inverter device, having a U-shaped core forming a magnetic circuit, a magnetic detection element for detecting the amount of magnetic flux in the magnetic circuit, and a sensor housing. Japanese Patent Application Laid-Open No. 2020-193876 discloses a current sensor that detects a magnetic field generated around a measured current flowing in a conductor (bus bar) with a magnetic force sensor having a sensitivity axis direction in which the detection sensitivity of the magnetic field is maximized, and thereby calculates the current value of the measured current. However, a cell balancing device that solves the wiring problem of a battery pack by measuring battery information such as the current and voltage of each cell of the battery pack with a magnetic force sensor has not been reported so far.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0006] Accordingly, an object of the present invention is to provide a cell balancing device and a cell balancing method capable of reducing the amount of wiring in the device and facilitating maintenance.

Means for Solving the Problems

[0007] As a result of intensive studies, the inventors of the present invention have found that by detecting the magnetic field generated by the current flowing through each cell (single cell) of the battery module using a current sensor, the voltage of each cell can be measured in non-contact with the current sensor without connecting each cell to the current sensor by wiring, and thus the present invention has been completed. That is, the cell balancing device of the present invention includes a battery module including an assembled battery formed by connecting a plurality of secondary batteries, a cell voltage measurement unit that measures the voltage of each cell of the plurality of secondary batteries, and a control unit that outputs a command signal for adjusting the voltage of each cell based on the voltage value of each cell measured by the cell voltage measurement unit. The voltage measurement unit includes one or more current sensors configured to detect a magnetic field generated by the current flowing through each cell, and the current sensors of the battery module and the cell voltage measurement unit are non-contact.

[0008] The assembled battery of the battery module may have a plurality of secondary batteries connected in series, parallel, or a combination thereof. In one embodiment, the battery module used in the present invention has a plurality of secondary batteries connected in series.

[0009] In one embodiment, the battery module used in the present invention further includes a cell voltage measurement circuit and a cell balancing discharge circuit arranged in parallel with each cell of the plurality of secondary batteries. In one embodiment, the battery module used in the present invention includes a circuit switching switch, and each cell of the battery module can be switched by the circuit switching switch to be connected to the cell voltage measurement circuit, connected to the cell balancing discharge circuit, or disconnected from both the cell voltage measurement circuit and the cell balancing discharge circuit.

[0010] When the battery module includes a cell voltage measurement circuit and a cell balancing discharge circuit, the magnetic field generated by the current flowing through each cell is the magnetic field generated by the cell voltage measurement current flowing through the cell voltage measurement circuit or the cell balancing discharge current flowing through the cell balancing discharge circuit.

[0011] In one form, in the cell balancing device of the present invention, current sensors are arranged non - contactingly for each cell of a plurality of secondary batteries of a battery module. In one form, in the cell balancing device of the present invention, the battery module is composed of a plurality of blocks, and one current sensor is arranged non - contactingly for a plurality of cells included in each block.

[0012] The cell balancing method of the present invention includes a battery module including a battery pack formed by connecting a plurality of secondary batteries, and each cell of the plurality of secondary batteries Measure the voltage a cell voltage measurement unit, Output a command signal for adjusting the voltage of each cell based on the voltage value of each cell measured by the cell voltage measurement unit and a control unit, The voltage measurement unit includes one or more current sensors configured to detect a magnetic field generated by a current flowing through each cell wherein the battery module and the current sensor is is non - contact A cell balancing method using a cell balancing device, the cell voltage measurement unit is , measures the current flowing through each cell by the current sensor, thereby measuring the voltage of each cell, and the control unit is , determines the state of charge of each cell based on the voltage value of each cell measured by the cell voltage measurement unit, and outputs a command signal for adjusting the voltage of each cell based on the determination.

[0013] In one aspect, the cell balancing method of the present invention A battery module including a battery pack formed by connecting a plurality of secondary batteries, a cell voltage measurement unit that measures the voltage of each cell of the plurality of secondary batteries, and a control unit that outputs a command signal for adjusting the voltage of each cell based on the voltage value of each cell measured by the cell voltage measurement unit, the voltage measurement unit includes one or more current sensors configured to detect a magnetic field generated by a current flowing through each cell, and the battery module and the current sensor are non-contact wherein the battery module includes a cell voltage measurement circuit and a cell balancing discharge circuit arranged in parallel with each cell of the plurality of secondary batteries A cell balancing method using a cell balancing device, the current sensor measures the cell voltage measurement current from the magnetic field generated by the cell voltage measurement current flowing through the cell voltage measurement circuit, thereby measuring the voltage of each cell, The control unit determines the state of charge of each cell based on the measured voltage value of each cell, When the voltage of the cell exceeds a preset upper limit voltage is , The cell balancing discharge circuit discharge the cell that has exceeded the upper limit voltage based on a command signal from the control unit 、 and In order to adjust the voltage of the cell exceeding the upper limit voltage to be within a preset voltage range while discharging the cell, measure the cell balance discharge current flowing through the current sensor and the cell balance discharge circuit, thereby measuring the voltage of the cell is such.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0015] The cell balance device of the present invention includes a battery module including a battery pack formed by connecting a plurality of secondary batteries, a cell voltage measurement unit that measures the voltage of each cell of the plurality of secondary batteries, and a control unit that outputs a command signal for adjusting the voltage of each cell based on the voltage value of each cell measured by the cell voltage measurement unit.

[0016] ​ The assembled battery of the battery module may have a plurality of secondary batteries connected in series, in parallel, or in a combination thereof. For example, a plurality of secondary batteries may be connected in series to ensure a practical voltage, or a plurality of secondary batteries may be connected in parallel to ensure the storage device capacity. For an in-vehicle battery module, an assembled battery with a plurality of secondary batteries connected in series is preferred.

[0017] In one form, the battery module includes a cell voltage measurement circuit for measuring the voltage of each cell, and a cell balance discharge circuit for discharging a cell whose cell voltage exceeds the upper limit of the allowable range. The cell voltage measurement circuit and the cell balance discharge circuit are preferably arranged in parallel with each cell of the secondary battery. The cell voltage measurement circuit and the cell balance discharge circuit corresponding to each cell include the corresponding cell within each circuit. A cell voltage measurement current flows through the cell voltage measurement circuit, and a cell balance discharge current flows through the cell balance discharge circuit.

[0018] The cell balance device of the present invention measures the current flowing through each cell of the battery module using a current sensor. The current sensor is configured to detect a magnetic field generated by the current flowing through each cell, and measures the current value flowing through each cell from the detected magnetic field. When the battery module includes a cell voltage measurement circuit and a cell balance discharge circuit, the current flowing through each cell is the cell voltage measurement current flowing through the cell voltage measurement circuit or the cell balance discharge current flowing through the cell balance discharge circuit.

[0019] The current sensor used in the present invention is not particularly limited as long as it is a sensor that detects the current flowing through a wire from the magnetic field (magnetic flux) generated by the current flowing through the wire, and a known current sensor can be used. For example, it may be a sensor that detects the magnetic flux flowing through a wire, outputs a signal according to the magnetic flux density or the change in magnetic flux, and thereby detects the current flowing through the wire. The configuration of the current sensor is not particularly limited either. For example, it may be the configuration of the sensors disclosed in JP-A-07-110343, JP-A-2002-189039, etc., or a configuration combining known sensors.

[0020] The current sensor used in the present invention is, for example, a sensor configured to detect a magnetic field generated by a current flowing through a cell voltage measurement circuit or a cell balance discharge circuit of a cell balance device. The current sensor can measure the cell voltage measurement current value I1 from the magnetic field generated by the current (cell voltage measurement current) flowing through the cell voltage measurement circuit. The voltage value (V0) of the cell at this time can be obtained from V0 = I1 × R1 (where R1 represents the resistance value included in the cell voltage measurement circuit). Also, the current sensor can measure the cell balance discharge current value I1' from the magnetic field generated by the current (cell balance discharge current) flowing through the cell balance discharge circuit. The voltage value (V0) of the cell at this time can be obtained from V0 = I1' × R2 (where R2 represents the resistance value included in the cell balance discharge circuit).

[0021] The cell balance device of the present invention estimates the charge state of each cell based on the voltage value (V0) of each cell measured by the cell voltage measurement unit. The method for estimating the charge state is not particularly limited, and a known method can be used. For example, a method using a battery equivalent circuit, a method using an extended Kalman filter, etc. can be mentioned. In the control unit, a range of allowable charge states is preset, and an upper limit value (upper limit voltage) and a lower limit value (lower limit voltage) of the allowable voltage value (V0) of each cell are set.

[0022] The control unit determines whether the measured voltage value of each cell is allowable based on a preset allowable range, and when it is determined that the voltage value exceeds the allowable range, it outputs a command signal for adjusting the voltage of each cell. Based on the command signal from the control unit, cell balance is performed on the cells determined to be necessary. The method for performing cell balance may be a known method. For example, it may be either a passive method (a method of discharging from a cell with an excessive charge state) or an active method (a method of distributing charges from a cell with an excessive charge state to a cell with a deficient charge state).

[0023] The method of outputting a command signal from the control unit may be a wired method or a wireless communication method. From the perspective of reducing the amount of wiring within the device, a wireless communication method is more preferable for the cell balancing device of the present invention. When outputting a command signal by wireless communication, it is preferable to house the battery module, the cell voltage measurement unit, etc. in a metal housing or the like from the perspective of preventing interference in the communication within the device.

[0024] In addition to the above configuration, the cell balancing device of the present invention can generally include configurations included in a cell balancing device. For example, it may be provided with a circuit for protecting the cell from overcharging and overdischarging, a sensor for measuring the temperature of the cell, a system for evaluating the deterioration of the battery based on the measured temperature and voltage of the cell, etc.

[0025] The cell balancing device of the present invention will be described in more detail with reference to FIG. 1. FIG. 1 shows an in-vehicle cell balancing device according to one embodiment of the present invention. The cell balancing device 1 includes a battery module (battery pack) 2, a cell voltage measurement unit 3, and a control unit (not shown). The battery pack 2 includes cells (C1 to C n ) of secondary batteries connected in series, a cell voltage measurement circuit and a cell balancing discharge circuit arranged in parallel with each cell. A motor drive current I0 flows through the cells (C1 to C n ) of the secondary battery. Portion A in FIG. 1 shows circuit switching devices (SW1 to SW n ). Each circuit switching device includes a resistor R1 (for cell voltage measurement) and a resistor R2 (for cell balancing discharge) arranged in parallel with the cell, and a circuit switching switch 103. The circuit including the resistor R1 constitutes a cell voltage measurement circuit, and the circuit including the resistor R2 constitutes a cell balancing discharge circuit. The cell voltage measurement circuit and the cell balancing discharge circuit can be switched by the circuit switching switch 103. Also, the switching switch 103 can be in a state (neutral) where it is not connected to either the cell voltage measurement circuit or the cell balancing discharge circuit. Therefore, each cell of the battery module is in a state of being connected to the cell voltage measurement circuit, connected to the cell balancing discharge circuit, or not connected to both the cell voltage measurement circuit and the cell balancing discharge circuit.

[0026] The cell voltage measurement unit 3 includes a measurement module 21, and the measurement module 21 includes a current sensor 101. In the example shown in FIG. 1, the control unit communicates a command signal wirelessly. To prevent interference due to wireless communication, the battery pack 2 is housed in a battery pack housing 25, and the cell voltage measurement unit 3 is housed in a measurement module housing 26. The cell voltage measurement circuit includes a measurement insulating conductor 104, and the measurement insulating conductor 104 serves as a current measurement point. The battery pack housing 25 has an opening at the portion where the measurement insulating conductor 104 is disposed, and the measurement insulating conductor 104 is exposed to the outside of the battery pack 2. The current sensor 101 of the measurement module 21 is disposed so as to face the measurement insulating conductor 104, and the measurement module housing 26 has an opening at the portion where the current sensor 101 is disposed.

[0027] The cell balancing device of the present invention preferably has a structure that can prevent communication interference when performing wireless communication. The structures of the portion of the housing 25 where the measurement insulating conductor 104 is disposed and the portion of the housing 26 where the current sensor 101 is disposed are not limited to the structure shown in FIG. 1, and for example, a structure using a material that does not exclude magnetic fields (for example, a plastic material) may be used. The measurement insulating conductor 104 may have a structure that is exposed to the outside of the battery pack 2 without providing an opening in the housing 25, or may have a structure that is not exposed to the outside of the battery pack 2. The current sensor 101 may have a structure that is exposed to the outside of the housing 26.

[0028] The arrangement of the current sensor 101 and the measurement insulating conductor 104 may be any arrangement that can appropriately measure the current flowing through the measurement insulating conductor 104, and is not limited to the arrangement in which the current sensor 101 faces the measurement insulating conductor 104 as shown in FIG. 1. For example, an arrangement in which the current sensor 101 surrounds the measurement insulating conductor 104 non - contactingly may be used.

[0029] The current sensor 101 is configured to be able to detect the magnetic field H generated by the cell voltage measurement current I1 flowing through the cell voltage measurement circuit (including resistor R1) or the magnetic field H generated by the cell balance discharge current I1' flowing through the cell balance discharge circuit (including resistor R2). The current sensor 101 of the battery module 2 and the cell voltage measurement unit 3 is not connected by wiring or the like and is non-contact. The voltage value V0 of each cell can be calculated by, for example, the CPU of the cell voltage measurement unit 3 from the value of the current I1 or the current I1' measured by the current sensor 101.

[0030] When discharging the motor drive current using the cell balance device shown in FIG. 1, the circuit switching switch 103 is in the neutral state (not connected to either the cell voltage measurement circuit or the cell balance discharge circuit). By connecting the battery module to an external motor, the motor drive current I0 flows through the battery pack. When measuring the voltage of each cell to check the charge state of the cell, a command signal is sent from the control unit to the circuit switching device (SW1 to SW n ) of each cell, and each cell is connected to the cell voltage measurement circuit by the circuit switching switch 103, and the cell voltage measurement current I1 is passed through the cell voltage measurement circuit. A magnetic field H is generated in the measurement insulation conductor 104 of the cell voltage measurement circuit by the current I1, and the current sensor 101 of the measurement module 21 detects this magnetic field H and measures the cell voltage measurement current value I1 from the magnetic field H. The cell voltage measurement unit 3 calculates the voltage value V0 of the cell by the CPU from the measured current value as V0 = I1 × R1.

[0031] The current flowing through the cell voltage measurement circuit and the measurement module can also be controlled by switching them in a time division manner. By energizing only during measurement for the cell voltage measurement circuit and the measurement module, the power consumption can be suppressed. For example, in the case of a 300-cell battery module, if the measurement time per cell is set to 2 to 6 milliseconds, for example, 4 milliseconds, the scan time for 300 cells is 1.2 seconds (4 milliseconds × 300). Also, if the interval between one scan and the next scan is 10 seconds, the number of measurements per hour is approximately 321 times (3600 / 11.2), and the energization time per cell is approximately 1.3 seconds / hour (4 milliseconds × 321). In this way, by controlling the cell voltage measurement current and the measurement module by switching them in a time division manner, the power consumption of the cell balancing device can be suppressed.

[0032] The cell voltage value V0 measured by the current sensor 101 is sent to the control unit, and the control unit determines whether the voltage value V0 of each cell is within the set allowable range. When the measured cell voltage V0 exceeds the upper limit voltage of the preset cell voltage, the control unit outputs a command signal for the cell, and the cell exceeding the upper limit voltage is connected to the cell balance discharge circuit by the circuit switching switch 103. The cell balance discharge circuit discharges the cell so that the voltage of the cell becomes below the upper limit voltage (within the preset voltage range). At this time, the current sensor 101 can detect the magnetic field generated by the cell balance discharge current flowing through the cell balance discharge circuit, measure the cell balance discharge current I1' from the magnetic field H, and calculate the voltage value (V0) of the cell by V0 = I1' × R2. Therefore, while discharging the cell using the cell balance discharge circuit, the voltage of the cell can be monitored by the current sensor 101, and thus the cell voltage value (V0) can be adjusted to be below the preset upper limit voltage.

[0033] The cell balancing device of the present invention, for example, has a separate circuit for the motor drive current passing through all cells connected in series in a battery module and the measurement current independently controlled for each cell, so that the cell voltage can be measured by the measurement current of each cell even when the motor drive current is flowing during running. Each cell of the battery module appropriately selects and passes a measurement current (cell voltage measurement current and cell balance discharge current) for each cell in parallel with the motor drive current connected in series, thereby measuring the cell voltage of each cell during running and grasping the charge state of each cell.

[0034] FIG. 2 shows a system block diagram of a cell balancing device according to an embodiment of the present invention. The cell balancing device 11 includes a battery module 12, a cell voltage measurement unit 13, and a control unit (battery management unit BMU) 14. The battery module 12 includes cells (C1 to C n ) of secondary batteries connected in series and a cell voltage measurement circuit and a cell balance discharge circuit arranged in parallel with each cell. The battery module 12 is connected to an external unit 17 (such as a motor and an inverter). The cell voltage measurement / cell balance discharge circuit incorporates circuit switching devices (SW1 to SW n ), and each circuit switching device includes a circuit switching switch 203. By the circuit switching switch 203, each cell can be switched to three states: connection to a cell voltage measurement circuit (M) including a resistor R1, connection to a cell balance discharge circuit (B) including a resistor R2, and non-connection (N) to both the cell voltage measurement circuit and the cell balance discharge circuit. In the example shown in FIG. 2, the circuit switching switch 203 is an FET switch, but the circuit switching switch used in the present invention is not limited to this and may be an LSI switch or the like. When the cell is connected to the cell voltage measurement circuit (M) by the circuit switching switch 203, a cell voltage measurement current I1 (V0 = I1 × R1) flows through the cell voltage measurement circuit (M). A measurement insulation conductor 204 is provided in the cell voltage measurement / cell balance discharge circuit, and a magnetic field based on the cell voltage measurement current I1 is generated in the measurement insulation conductor 204. The measurement insulation conductor 204 is arranged with respect to the current sensor 201 so as to be able to measure the current value flowing through the cell.

[0035] The battery module 12 includes a temperature sensor 205 that measures the temperature of each cell. The temperature sensor 205 measures the temperature of the cells (C1 to C n ). The temperature sensor 205 is connected to the cell control unit 15, and the cell control unit 15 issues an alarm when the temperature is high and shuts off the cell based on the temperature data of each cell sent from the temperature sensor 205. The cell control unit 15 transmits and receives signals to and from a control unit (battery management unit BMU) 14 and the like. In the example shown in FIG. 2, an isolation 16 is provided in consideration of protecting and ensuring the safety of control devices that operate at a low voltage from the current of the high voltage of the serially connected cells.

[0036] The cell voltage measurement unit 13 includes current sensors 201 (manufactured by SIRC Co., Ltd.) corresponding to each cell, and current management modules (CM1 to CM n ) connected to each current sensor 201. Each current sensor 201 is arranged to face each measurement insulating conductor 204 and detects a magnetic field H generated in the measurement insulating conductor 204.

[0037] A method for measuring the cell voltage measurement current I1 (or the cell balance discharge current I1') using the current sensor 201 is schematically shown in FIG. 3. A is the current line of the cell voltage measurement circuit (or the cell balance discharge circuit) of the battery module 12, B is the current line passing through the current sensor 201 of the cell voltage measurement unit 13, and the current line B is connected to the instrumentation amplifier 211. In the current line A, a magnetic field H is generated by the cell voltage measurement current I1 (or the cell balance discharge current I1'). The magnetic field H is represented by H = αI1 (or H = αI1') (α represents a coefficient). The generated magnetic field H brings about a magnetoresistive effect that changes the electrical resistance of the current sensor 201 (ΔRmr). The change in electrical resistance (ΔRmr) is represented by ΔRmr = βH (β represents a coefficient) = αβI1 (or αβI1'), and the voltage change (ΔVmr) detected by the current sensor 201 is represented by ΔVmr = ΔRmr × I2 (I2 represents the current flowing through the current sensor 201) = αβI1 × I2 (or αβI1' × I2). Here, when the current I2 flowing through the current sensor 201 is fixed, the voltage change (ΔVmr) detected by the current sensor 201 is proportional to the cell voltage measurement current I1 (or the cell balance discharge current I1'), and the cell voltage measurement current I1 (or the cell balance discharge current I1') can be measured from ΔVmr. Therefore, the cell voltage V0 when examining the charge state of each cell can be obtained from V0 = I1 × R1 from the cell voltage measurement current I1 measured by the current sensor 201, and the cell voltage V0 during cell balance discharge can be obtained from V0 = I1' × R2 from the cell balance discharge current I1' measured by the current sensor 201.

[0038] The cell voltage measurement unit 13 (current sensor 201 and current management modules CM1 to CM) of the cell balance device shown in FIG. 2 n) The configuration example of () is shown in FIG. 4. The cell voltage measurement unit 13 includes a current sensor 201, an instrumentation amplifier 211, an A / D converter 212, a data processing unit 213, and a power supply controller 214. The signal detected by the current sensor 201 is amplified by the instrumentation amplifier 211, converted into an electrical signal by the A / D converter 212, and then converted into a cell voltage V0 by the data processing unit 213. The data of the cell voltage of each measured cell is transmitted to the control unit 14 (including a CPU).

[0039] In the control unit 14, based on the cell voltage V0 of each cell measured by the cell voltage measurement unit 13 and the temperature information of each cell sent from the cell control unit 15, it is determined whether the cell voltage of each cell falls within the allowable range of the preset cell voltage. When the cell voltage V0 exceeds the preset upper limit voltage, the control unit 14 outputs a command signal for adjusting the cell voltage to the battery module 12, and connects the cell to the cell balance discharge circuit by the circuit switching switch 203. The cell balance discharge circuit discharges until the cell voltage falls within the set allowable range.

[0040] When discharging the drive current from the battery module 12 to the motor, the circuit switching switch 203 is set to non-connected (N) by a command signal from the control unit 14 (the cell voltage measurement / cell balance discharge circuit has no current), and a drive current I0 flows through the cells connected in series to the battery module 12.

[0041] Fig. 5 shows a cell balancing device according to another embodiment of the present invention. The battery pack 22 shown in Fig. 5(a) includes a battery pack in which a plurality of secondary batteries are connected. A cell voltage measurement / cell balancing discharge circuit is connected to both terminals of each cell of the secondary battery. The measurement insulation conductor 304 of the cell voltage measurement / cell balancing discharge circuit of each cell is arranged on the side surface of the battery pack 22 in a state where the current can be measured by a current sensor. As shown in Fig. 5(a), the measurement insulation conductor 304 is arranged in three rows of a measurement insulation conductor 304-1, a measurement insulation conductor 304-2, and a measurement insulation conductor 304-3. Further, the measurement insulation conductor 304 is composed of a plurality of blocks, and each block includes one measurement insulation conductor of each row of the measurement insulation conductor 304-1, the measurement insulation conductor 304-2, and the measurement insulation conductor 304-3. One current sensor 301 is arranged for each block.

[0042] Fig. 5(b) shows the arrangement of the measurement insulation conductor 304 and the current sensor 301 in each block. As shown in Fig. 5(b), the current sensor 301 is arranged opposite to the measurement insulation conductor 304-1, the measurement insulation conductor 304-2, and the measurement insulation conductor 304-3. At this time, the distance between the current sensor 301 and the measurement insulation conductor 304-1 and the distance between the current sensor 301 and the measurement insulation conductor 304-3 are L1, and the distance between the current sensor 301 and the measurement insulation conductor 304-2 is L2. When measuring the current value flowing through the measurement insulation conductor 304, the current sensor 301 sequentially measures the measurement insulation conductor 304-1, the measurement insulation conductor 304-2, and the measurement insulation conductor 304-3, and considering the distance (L1, L2) between the current sensor 301 and each measurement insulation conductor 304 and the magnetic field attenuation amount thereby, the distance is corrected to measure the current value of the current flowing through each measurement insulation conductor 304.

[0043] The cell balancing device of the present invention includes cells of a plurality of secondary batteries and one or more current sensors. The cell balancing device of the present invention is not limited to a configuration in which a current sensor is arranged for each of the cells as shown in Figs. 1 and 2. For example, a configuration in which one current sensor is arranged for cells of a plurality of secondary batteries as shown in Fig. 5 may also be used.

[0044] The cell balance device of the present invention can measure the cell voltage in a non-contact state between the battery module and the current sensor. Therefore, there is no need to connect the battery module and the current sensor with wiring, and it is possible to significantly reduce the amount of wiring in the device. Further, by adopting a simple circuit configuration in which the cell voltage measurement and the cell balance discharge are switched by a changeover switch, it is possible to further reduce the amount of wiring in the device. Furthermore, by controlling the cell voltage measurement current and the measurement module by switching them in a time-division manner, it is also possible to suppress the power consumption. According to the cell balance device of the present invention, the amount of wiring can be reduced, the weight of the device can be reduced, and the manufacturing cost can be reduced. In addition, since the amount of wiring is small, cell replacement can be efficiently performed, and since the amount of wiring is small, there are few disconnections, and insulation failure, leakage, etc. can be prevented.

Explanation of Signs

[0045] 1, 11... Cell balance device 2, 12, 22, 32... Battery module (battery pack) 3, 13... Cell voltage measurement unit 14... Control unit 15... Cell control unit 17... External unit 21, 31... Measurement module 25... Battery pack housing 26... Measurement module housing 101, 201, 301... Current sensor 103, 203... Circuit changeover switch 104, 204, 304... Measurement insulating conductor 205... Temperature sensor 211... Instrumentation amplifier 212... A / D converter 213... Data processing unit 214... Power controller C1~C n ... Cells of secondary battery SW1~SW n ... Circuit changeover device CM1~CMn ···Current management module

Claims

1. A battery module including an assembled battery formed by connecting a plurality of secondary batteries, a cell voltage measurement unit configured to measure the voltage of each cell of the plurality of secondary batteries, a control unit configured to output a command signal for adjusting the voltage of each cell based on the voltage value of each cell measured by the cell voltage measurement unit, and the voltage measurement unit includes one or more current sensors configured to detect a magnetic field generated by a current flowing through each cell, a cell balancing device, wherein the battery module and the current sensor of the cell voltage measurement unit are non-contact.

2. The cell balancing device according to claim 1, wherein the battery module includes an assembled battery formed by connecting a plurality of secondary batteries in series.

3. The cell balancing device according to claim 1 or 2, wherein the battery module further includes a cell voltage measurement circuit and a cell balancing discharge circuit disposed in parallel with each cell of the plurality of secondary batteries.

4. The cell balancing device according to claim 3, wherein the battery module includes a circuit switching switch, and each cell of the battery module is switched by the circuit switching switch to be connected to the cell voltage measurement circuit, connected to the cell balancing discharge circuit, or disconnected from both the cell voltage measurement circuit and the cell balancing discharge circuit.

5. The cell balancing device according to claim 3 or 4, wherein the magnetic field generated by the current flowing through each cell is a magnetic field generated by a cell voltage measurement current flowing through the cell voltage measurement circuit or a cell balancing discharge current flowing through the cell balancing discharge circuit.

6. A cell balancing method using a cell balance device including a battery module including a plurality of secondary batteries connected together, a cell voltage measurement unit that measures the voltage of each cell of the plurality of secondary batteries, and a control unit that outputs a command signal for adjusting the voltage of each cell based on the voltage values of the respective cells measured by the cell voltage measurement unit, the voltage measurement unit including one or more current sensors configured to detect a magnetic field generated by a current flowing through each cell, the battery module and the current sensor being non-contact, the cell voltage measurement unit measures the current flowing through each cell by the current sensor, and thereby measures the voltage of each cell, the control unit determines the state of charge of each cell based on the voltage values of the respective cells measured by the cell voltage measurement unit, and outputs a command signal for adjusting the voltage of each cell based on the determination.

7. A cell balancing method using a cell balance device including a battery module including a plurality of secondary batteries connected together, a cell voltage measurement unit that measures the voltage of each cell of the plurality of secondary batteries, and a control unit that outputs a command signal for adjusting the voltage of each cell based on the voltage values of the respective cells measured by the cell voltage measurement unit, the voltage measurement unit including one or more current sensors configured to detect a magnetic field generated by a current flowing through each cell, the battery module and the current sensor being non-contact, and the battery module including a cell voltage measurement circuit and a cell balance discharge circuit arranged in parallel with each cell of the plurality of secondary batteries, the current sensor measures the cell voltage measurement current from a magnetic field generated by the cell voltage measurement current flowing through the cell voltage measurement circuit, and thereby measures the voltage of each cell, the control unit determines the state of charge of each cell based on the measured voltage values of the respective cells, when the voltage of a cell exceeds a preset upper limit voltage, the cell balance discharge circuit discharges the cell exceeding the upper limit voltage based on a command signal from the control unit, A cell balancing method in which, in order to adjust the voltage of a cell exceeding the upper limit voltage to be within a preset voltage range, as the cell discharges, the current sensor measures the cell balance discharge current flowing through the cell balance discharge circuit, thereby measuring the voltage of the cell.

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