JP7695855B2 - Cell balancing device and cell balancing method - Google Patents

Description

The present invention relates to a cell balancing device and a cell balancing method that can reduce the amount of wiring inside the device and is easy to maintain.

Electric vehicles (EVs) and hybrid vehicles (HEVs) use battery packs in which multiple secondary batteries such as lithium-ion batteries are connected, and solar cell systems also use battery packs in which multiple secondary batteries are connected to utilize nighttime power. The multiple cells (single cells) that make up a battery pack generally have variations in state of charge (SOC) due to manufacturing variations and other factors. On the other hand, each cell needs to be used so that the cell voltage (the voltage across the cell) falls within a preset range from a lower limit voltage to an upper limit voltage in order to prevent thermal runaway caused by overcharging or overdischarging. To use each cell in this way, it is necessary to suppress the variation in the state of charge of each cell within a certain range, and 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.

Figure 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, a separate wiring path is provided for each cell and connected to a discharge switch SW. However, such conventional devices, especially in the case of a battery pack with a large number of cells connected (an automotive battery cell has a configuration of about 96 cells), have 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, making cell replacement during maintenance cumbersome, and requiring replacement of wiring due to breakage.

International Publication No. 2014/103008 discloses a battery pack system having a battery module management device with a communication unit that transmits battery information wirelessly, and a management device that manages each battery module by wirelessly communicating with the battery module management device, because a method of connecting a battery controller and a storage battery module with a wire requires a large number of wires and costs for insulation and maintenance. In addition, Japanese Patent Application Laid-Open No. 07-110343 discloses a DC current sensor used in DC leakage breakers and the like, which directly detects magnetic flux changes in the core based on changes in DC current flowing in a detection conductor using a Hall element, and Japanese Patent Application Laid-Open No. 2002-189039 discloses a current sensor that can be attached to a small inverter device, which has a U-shaped iron core that forms a magnetic circuit, a magnetic detection element that detects the amount of magnetic flux in the magnetic circuit, and a sensor housing. JP 2020-193876 A discloses a current sensor that detects the magnetic field generated around the current to be measured flowing in a conductor (bus bar) using a magnetic sensor having a sensitivity axis direction in which the magnetic field detection sensitivity is maximized, and thereby calculates the current value of the current to be measured. However, no cell balance device has been reported to date that solves the wiring problems of a battery pack by measuring battery information such as the current and voltage of each cell of the battery pack using a magnetic sensor.

International Publication No. 2014/103008 Japanese Patent Application Publication No. 07-110343 JP 2002-189039 A JP 2020-193876 A

Therefore, the object of the present invention is to provide a cell balancing device and a cell balancing method that can reduce the amount of wiring within the device and is easy to maintain.

After extensive research, the inventors discovered that by using a current sensor to detect the magnetic field generated by the current flowing through each cell (single cell) of a battery module, it is possible to measure the voltage of each cell without contacting the current sensor without connecting each cell to the current sensor by wiring, and thus completed the present invention. That is, the cell balance device of the present invention includes a battery module including a battery pack formed by connecting multiple secondary batteries, a cell voltage measurement unit that measures the voltage of each cell of the multiple 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 the magnetic field generated by the current flowing through each cell, and the battery module and the current sensor of the cell voltage measurement unit are non-contact.

The assembled battery of the battery module may have multiple secondary batteries connected in series, in parallel, or in a combination of these. In one embodiment, the battery module used in the present invention has multiple secondary batteries connected in series.

In one embodiment, the battery module used in the present invention further includes a cell voltage measurement circuit and a cell balance discharge circuit arranged in parallel with each cell of the multiple secondary batteries. In one embodiment, the battery module used in the present invention includes a circuit changeover switch, and each cell of the battery module is switched by the circuit changeover switch to be connected to the cell voltage measurement circuit, connected to the cell balance discharge circuit, or disconnected from both the cell voltage measurement circuit and the cell balance discharge circuit.

When the battery module includes a cell voltage measurement circuit and a cell balance discharge circuit, the magnetic field generated by the current flowing through each cell is a magnetic field generated by 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.

In one embodiment, the cell balancing device of the present invention has a current sensor arranged in a non-contact manner for each cell of a plurality of secondary batteries in a battery module. In one embodiment, the cell balancing device of the present invention has a battery module composed of a plurality of blocks, and one current sensor is arranged in a non-contact manner for a plurality of cells included in each block.

A cell balancing method of the present invention is a cell balancing method using a cell balancing device including 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, wherein 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 sensors are in a non-contact state, wherein the cell voltage measurement unit measures the current flowing through each cell using the current sensor, thereby measuring the voltage of each cell, and the control unit 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.

In one aspect, a cell balancing method of the present invention is a cell balancing method using a cell balancing device including: 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 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 sensors are in non-contact, and the battery module includes a cell voltage measurement circuit and a cell balancing discharge circuit arranged in parallel to 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, thereby measuring the voltage of each of the cells;
The control unit determines a state of charge of each of the cells based on the measured voltage value of each of the cells,
When the voltage of a cell exceeds a preset upper limit voltage, the cell balance discharge circuit discharges the cell whose voltage has exceeded the upper limit voltage based on a command signal from the control unit ,
In order to adjust the voltage of a cell that has exceeded the upper limit voltage so that it is within a preset voltage range, the current sensor measures the cell balance discharge current flowing through the cell balance discharge circuit as the cell is discharged, thereby measuring the voltage of the cell .

FIG. 1A is a schematic diagram showing a cell balance device according to one embodiment of the present invention, and FIG. 1B is a partially enlarged explanatory diagram showing part A of the cell balance device (1). FIG. 1 is a system block diagram of a cell balancing device according to one embodiment of the present invention. FIG. 1 is a schematic diagram showing a scheme for measuring a cell voltage measurement current or a cell balancing discharge current by a current sensor. FIG. 2 is a schematic explanatory diagram showing a configuration of a cell voltage measurement unit according to one embodiment of the present invention. 1A and 1B are schematic explanatory diagrams showing a current measurement method for a cell balancing device according to one embodiment of the present invention, in which FIG. 1A is a schematic perspective view of a battery pack, and FIG. 1B is a schematic explanatory diagram showing the arrangement of measurement insulated conductors and current sensors of a battery module. FIG. 1 is a schematic explanatory diagram illustrating an example of a conventional cell balance device.

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

The assembled battery of the battery module may have multiple secondary batteries connected in series, in parallel, or a combination of these. For example, multiple secondary batteries may be connected in series to ensure a practical voltage, or multiple secondary batteries may be connected in parallel to ensure the capacity of the storage device. For use as a battery module for vehicles, an assembled battery in which multiple secondary batteries are connected in series is preferred.

In one embodiment, 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, and 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 a 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.

The cell balance device of the present invention uses a current sensor to measure the current flowing through each cell of a battery module. 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.

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 conductor from the magnetic field (magnetic flux) generated by the current flowing through the conductor, and any known current sensor can be used. For example, it may be a sensor that detects the magnetic flux flowing through the conductor, outputs a signal according to the magnetic flux density or magnetic flux change, and thereby detects the current flowing through the conductor. The configuration of the current sensor is also not particularly limited. For example, it may be a sensor configuration disclosed in JP-A-07-110343, JP-A-2002-189039, etc., or a configuration that combines known sensors.

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 a cell voltage measurement current value _I1 from a magnetic field generated by a current flowing through the cell voltage measurement circuit (cell voltage measurement current). The cell voltage value ( _V0 ) at this time can be calculated from _V0 = _I1 x R1 (R1 represents a resistance value included in the cell voltage measurement circuit). The current sensor can also measure a cell balance discharge current value _I1 ' from a magnetic field generated by a current flowing through the cell balance discharge circuit (cell balance discharge current). The cell voltage value ( _V0 ) at this time can be calculated from _V0 = _I1 ' x R2 (R2 represents a resistance value included in the cell balance discharge circuit).

The cell balance device of the present invention estimates the state of charge of each cell based on the voltage value (V ₀ ) of each cell measured by the cell voltage measurement unit. The method of estimating the state of charge is not particularly limited, and any known method can be used. For example, a method using a battery equivalent circuit, a method using a nonlinear Kalman filter, etc. are included. The control unit has a preset range of the allowable state of charge, and an allowable upper limit value (upper limit voltage) and lower limit value (lower limit voltage) of the voltage value (V ₀ ) of each cell are set.

The control unit determines whether the measured voltage value of each cell is acceptable based on a preset tolerance range, and outputs a command signal to adjust the voltage of each cell if it determines that the voltage value exceeds the tolerance range. Based on the command signal from the control unit, cell balancing is performed for cells that are determined to require it. The method for performing cell balancing may be a publicly known method. For example, it may be either a passive method (a method of discharging from an overcharged cell) or an active method (a method of distributing charge from an overcharged cell to an undercharged cell).

The method of outputting the command signal from the control unit may be a wired method or a wireless method. From the viewpoint of reducing the amount of wiring within the cell balance device of the present invention, a wireless method is more preferable. When outputting the command signal via wireless communication, it is preferable to house the battery module, cell voltage measurement unit, etc. in a metal casing, etc., from the viewpoint of preventing interference with communication within the device.

The cell balance device of the present invention may include components that are generally included in cell balance devices in addition to the above configuration. For example, it may include a circuit to protect the cell from overcharging and overdischarging, a sensor to measure the cell temperature, and a system to evaluate battery degradation based on the measured cell temperature and voltage.

The cell balance device of the present invention will be described in more detail with reference to FIG. 1. FIG. 1 shows an in-vehicle cell balance device according to one embodiment of the present invention, and the cell balance 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 secondary battery cells (C ₁ to C _n ) connected in series, and a cell voltage measurement circuit and a cell balance discharge circuit arranged in parallel with each cell. A motor drive current I ₀ flows through the secondary battery cells (C ₁ to C _n ). Part A of FIG. 1 shows circuit switching devices (SW ₁ to SW _n ), and each circuit switching device includes a resistor R1 (for cell voltage measurement) and a resistor R2 (for cell balance discharge) arranged in parallel with the cell, and a circuit changeover switch 103. The circuit including the resistor R1 constitutes the cell voltage measurement circuit, and the circuit including the resistor R2 constitutes the cell balance discharge circuit. The cell voltage measurement circuit and the cell balance discharge circuit can be switched by the circuit changeover switch 103. The changeover switch 103 can also be in a state (neutral) in which it is not connected to either the cell voltage measurement circuit or the cell balance discharge circuit, so that each cell of the battery module is either connected to the cell voltage measurement circuit, connected to the cell balance discharge circuit, or not connected to both the cell voltage measurement circuit and the cell balance discharge circuit.

The cell voltage measurement unit 3 includes a measurement module 21, which includes a current sensor 101. In the example shown in FIG. 1, the control unit wirelessly communicates command signals. 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, which serves as a current measurement point. The battery pack housing 25 has an opening where the measurement insulating conductor 104 is arranged, 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 arranged to face the measurement insulating conductor 104, and the measurement module housing 26 has an opening where the current sensor 101 is arranged.

The cell balance device of the present invention is preferably structured to prevent communication interference when performing wireless communication. The structures of the portion of the housing 25 where the measurement insulated conductor 104 is arranged and the portion of the housing 26 where the current sensor 101 is arranged are not limited to the structure shown in FIG. 1, and may be, for example, structures using a material that does not alienate magnetic fields (e.g., a plastic material). The measurement insulated conductor 104 may be structured so that it is exposed to the outside of the battery pack 2 without providing an opening in the housing 25, or it may be structured so that it is not exposed to the outside of the battery pack 2. The current sensor 101 may be structured so that it is exposed to the outside of the housing 26.

The arrangement of the current sensor 101 and the measurement insulated conductor 104 may be any arrangement that allows appropriate measurement of the current flowing through the measurement insulated conductor 104, and is not limited to an arrangement in which the current sensor 101 faces the measurement insulated conductor 104 as shown in FIG. 1. For example, the current sensor 101 may be arranged to surround the measurement insulated conductor 104 without contacting it.

The current sensor 101 is configured to detect a magnetic field H generated by a cell voltage measurement current _I1 flowing through a cell voltage measurement circuit (including resistor R1), or a magnetic field H generated by a cell balance discharge current _I1 ' flowing through a cell balance discharge circuit (including resistor R2). The battery module 2 and the current sensor 101 of the cell voltage measurement unit 3 are not connected by wiring or the like and are in a non-contact state. The voltage value _V0 of each cell can be calculated by, for example, a CPU of the cell voltage measurement unit 3 from the value of the current _I1 or current _I1 ' measured by the current sensor 101.

When discharging the motor drive current using the cell balance device shown in FIG. 1, the circuit changeover switch 103 is in neutral (not connected to either the cell voltage measurement circuit or the cell balance discharge circuit), and the battery module is connected to an external motor, so that the motor drive current _I0 flows through the assembled battery. When measuring the voltage of each cell to check the state of charge of the cell, the control unit sends a command signal to the circuit changeover device (SW ₁ to SW _n ) of each cell, the circuit changeover switch 103 connects each cell to the cell voltage measurement circuit, and the cell voltage measurement current _I1 flows through the cell voltage measurement circuit. A magnetic field H due to the current _I1 is generated in the measurement insulated conductor 104 of the cell voltage measurement circuit, 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 uses the CPU to calculate the cell voltage value _V0 from the measured current value by _V0 = _I1 ×R1.

The current flowing through the cell voltage measurement circuit and the measurement module can also be controlled by switching in a time-division manner. By passing current through the cell voltage measurement circuit and the measurement module only during measurement, power consumption can be reduced. For example, in the case of a 300-cell battery module, if the measurement time per cell is 2 to 6 milliseconds, for example 4 milliseconds, the time required for one scan of 300 cells is 1.2 seconds (4 milliseconds x 300). If the interval between one scan and the next scan is 10 seconds, the number of measurements per hour is approximately 321 (3600/11.2), and the time required for current to flow through one cell is approximately 1.3 seconds/hour (4 milliseconds x 321). In this way, the power consumption of the cell balance device can be reduced by switching and controlling the cell voltage measurement current and the measurement module in a time-division manner.

The cell voltage value _V0 measured by the current sensor 101 is sent to the control unit, which determines whether the voltage value _V0 of each cell is within a set tolerance range. If the measured cell voltage _V0 exceeds a preset upper limit voltage of the 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 changeover switch 103. The cell is discharged by the cell balance discharge circuit so that the cell voltage is equal to or lower than the upper limit voltage (within a preset voltage range). At this time, the current sensor 101 can detect a magnetic field generated by the cell balance discharge current flowing through the cell balance discharge circuit, and can measure the cell balance discharge current _I1 ' from the magnetic field H and calculate the cell voltage value ( _V0 ) by _V0 = _I1 ' x R2. Therefore, while the cell is being discharged using the cell balance discharge circuit, the voltage of the cell can be monitored by the current sensor 101, and the cell voltage value ( _V0 ) can be adjusted to be equal to or lower than the preset upper limit voltage.

The cell balance device of the present invention, for example, has separate circuits for the motor drive current that passes through all the cells connected in series in a battery module and the measurement current that is controlled independently for each cell, making it possible to measure the cell voltage from the measurement current of each cell even when the motor drive current is flowing while driving. 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 making it possible to measure the cell voltage of each cell while driving and to grasp the charging state of each cell.

2 shows a system block diagram of a cell balance device according to an embodiment of the present invention. The cell balance 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 secondary battery cells (C ₁ to C _n ) connected in series, and a cell voltage measurement circuit and a cell balance discharge circuit arranged in parallel with each cell, and the battery module 12 is connected to an external unit 17 (motor, inverter, etc.). Circuit switching devices (SW ₁ to SW _n ) are incorporated in the cell voltage measurement/cell balance discharge circuit, and each circuit switching device includes a circuit changeover switch 203, and the circuit changeover switch 203 switches each cell between three types: 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 disconnection (N) from both the cell voltage measurement circuit and the cell balance discharge circuit. 2, the circuit changeover switch 203 is an FET switch, but the circuit changeover switch used in the present invention is not limited to this and may be an LSI switch or the like. When the circuit changeover switch 203 connects the cell to the cell voltage measurement circuit (M), a cell voltage measurement current _I1 ( _V0 = _I1 x R1) flows through the cell voltage measurement circuit (M). A measurement insulated 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 insulated conductor 204. The measurement insulated conductor 204 is arranged with respect to the current sensor 201 so that the current value flowing through the cell can be measured.

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 (C ₁ to C _n ) of the secondary battery. The temperature sensor 205 is connected to the cell control unit 15, which issues an alarm or shuts off the cell when the temperature is high, 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 the control unit (battery management unit BMU) 14 and the like, and in the example shown in Fig. 2, isolation 16 is provided in consideration of the protection and safety of control devices that operate at low voltages from the high-voltage current of the serially connected cells.

The cell voltage measurement unit 13 includes a current sensor 201 (manufactured by SIRC Corporation) corresponding to each cell, and current management modules (CM ₁ to CM _n ) connected to each current sensor 201. Each current sensor 201 is disposed opposite a corresponding insulated conductor for measurement 204, and detects a magnetic field H generated in the insulated conductor for measurement 204.

3 shows a schematic diagram of a method for measuring the cell voltage measurement current _I1 (or the cell balance discharge current _I1 ') using the current sensor 201. A is a current line of the cell voltage measurement circuit (or the cell balance discharge circuit) of the battery module 12, B is a 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 expressed by H = _αI1 (or H = _αI1 ') (α is a coefficient). The generated magnetic field H brings about a magnetoresistance effect that changes the electrical resistance of the current sensor 201 (ΔRmr). The electrical resistance change (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 balancing discharge current _I1 '), and the cell voltage measurement current _I1 (or the cell balancing discharge current _I1 ') can be measured from ΔVmr. Therefore, the cell voltage _V0 when checking the charge state of each cell can be calculated from the cell voltage measurement current I1 measured by the current sensor 201 _{by V0} = _I1 × R1, and the cell voltage _V0 during cell balance discharge can be calculated from the cell balance discharge current I1 _' measured by the current sensor 201 by _V0 = I1' × _R2 .

Fig. 4 shows an example of the configuration of the cell voltage measurement unit 13 (current sensor 201 and current management modules CM ₁ to CM _n ) of the cell balance device shown in Fig. 2. The cell voltage measurement unit 13 has a current sensor 201, an instrumentation amplifier 211, an A/D converter 212, a data processing unit 213, and a power supply controller 214, and 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 V ₀ by the data processing unit 213. Data on the measured cell voltage of each cell is sent to the control unit 14 (including a CPU).

The control unit 14 determines whether the cell voltage of each cell falls within a preset cell voltage tolerance range, 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. If the cell voltage _V0 exceeds a preset upper limit voltage, the control unit 14 outputs a command signal to the battery module 12 to adjust the cell voltage, and connects the cell to a cell balance discharge circuit via the circuit changeover switch 203. The cell balance discharge circuit discharges the cell until the cell voltage falls within the preset tolerance range.

When discharging a driving current from the battery module 12 to the motor, the circuit changeover switch 203 is disconnected (N) by a command signal from the control unit 14 (no current flows in the cell voltage measurement/cell balance discharge circuit), and a driving current _I0 flows through the cells connected in series in the battery module 12.

Figure 5 shows a cell balance device according to another embodiment of the present invention. The battery pack 22 shown in Figure 5 (a) includes a battery pack in which multiple secondary batteries are connected, and a cell voltage measurement/cell balance discharge circuit is connected to both terminals of each cell of the secondary batteries. The measurement insulating conductors 304 of the cell voltage measurement/cell balance discharge circuit of each cell are arranged on the side of the battery pack 22 in a state in which the current can be measured by a current sensor. As shown in Figure 5 (a), the measurement insulating conductors 304 are arranged in three rows, namely, the measurement insulating conductors 304-1, the measurement insulating conductors 304-2, and the measurement insulating conductors 304-3. The measurement insulating conductors 304 are composed of multiple blocks, and each block includes one measurement insulating conductor for each row of the measurement insulating conductors 304-1, the measurement insulating conductors 304-2, and the measurement insulating conductors 304-3. One current sensor 301 is arranged for each block.

5B shows the arrangement of the measurement insulating conductor 304 and the current sensor 301 in each block. As shown in FIG. 5B, the current sensor 301 is arranged facing the measurement insulating conductor 304-1, the measurement insulating conductor 304-2, and the measurement insulating conductor 304-3. At this time, the distance between the current sensor 301 and the measurement insulating conductor 304-1 and the current sensor 301 and the measurement insulating conductor 304-3 is L ₁ , and the distance between the current sensor 301 and the measurement insulating conductor 304-2 is L _2. When measuring the value of the current flowing through the measurement insulating conductor 304, the measurement insulating conductor 304-1, the measurement insulating conductor 304-2, and the measurement insulating conductor 304-3 are measured sequentially by the current sensor 301, and the current value of the current flowing through each measurement insulating conductor 304 is measured by correcting the distance in consideration of the distance (L ₁ , L ₂ ) between the current sensor 301 and each measurement insulating conductor 304 and the magnetic field attenuation due to the distance.

The cell balancing device of the present invention includes multiple secondary battery cells 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 cell as shown in Figures 1 and 2, but may be configured, for example, in which one current sensor is arranged for multiple secondary battery cells as shown in Figure 5.

The cell balance device of the present invention can measure cell voltage without contacting the battery module and the current sensor. Therefore, there is no need to connect the battery module and the current sensor with wires, and it is possible to significantly reduce the amount of wiring inside the device. In addition, by using a simple circuit configuration in which cell voltage measurement and cell balance discharge are switched by a changeover switch, it is possible to further reduce the amount of wiring inside the device. Furthermore, it is possible to reduce power consumption by switching and controlling the cell voltage measurement current and the measurement module in a time-division manner. According to the cell balance device of the present invention, it is possible to reduce the amount of wiring, reduce the weight of the device, and reduce manufacturing costs. In addition, since the amount of wiring is small, cell replacement can be performed efficiently, and since the amount of wiring is small, there is less disconnection and it is possible to prevent poor insulation and leakage.

1, 11: Cell balance device 2, 12, 22, 32: Battery module (battery pack)
3, 13: Cell voltage measurement section 14: Control section 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 insulated conductor 205: Temperature sensor 211: Instrumentation amplifier 212: A/D converter 213: Data processing unit 214: Power supply controller C ₁ to C _n : Cells of secondary battery SW ₁ to SW _n : Circuit changeover device CM ₁ to CM _n : Current management module

Claims (7)

A battery module including a battery pack formed by connecting a plurality of secondary batteries;
a cell voltage measurement unit that measures a voltage of each cell of the plurality of secondary batteries;
a control unit that outputs a command signal for adjusting the voltage of each of the cells based on the voltage value of each of the cells 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 of the cells;
The cell balancing device, wherein the battery module and the current sensor of the cell voltage measuring unit are in a non-contact state. The cell balance device according to claim 1, wherein the battery module includes a battery pack formed by connecting multiple secondary batteries in series. The cell balance device according to claim 1 or 2, wherein the battery module further includes a cell voltage measurement circuit and a cell balance discharge circuit arranged in parallel with each cell of the plurality of secondary batteries. The cell balancing device according to claim 3, wherein the battery module includes a circuit changeover switch, and each cell of the battery module is switched by the circuit changeover switch to be connected to the cell voltage measurement circuit, connected to the cell balance discharge circuit, or disconnected from both the cell voltage measurement circuit and the cell balance discharge circuit. The cell balance 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 balance discharge current flowing through the cell balance discharge circuit. A cell balancing method using a cell balancing device including: a battery module including an assembled battery formed by connecting a plurality of secondary batteries; a cell voltage measurement unit that measures a voltage of each cell of the plurality of secondary batteries; and a control unit that outputs a command signal for adjusting a voltage of each cell based on a voltage value of each cell measured by the cell voltage measurement unit, wherein 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 sensors are in non-contact ,
the cell voltage measurement unit measures a current flowing through each of the cells using the current sensor, thereby measuring a voltage of each of the cells;
A cell balancing method in which the control unit determines a state of charge of each of the cells based on the voltage value of each of the cells measured by the cell voltage measurement unit, and outputs a command signal to adjust the voltage of each of the cells based on the determination. a cell balancing method using a cell balancing device including: a battery module including an assembled battery formed by connecting a plurality of secondary batteries; a cell voltage measurement unit that measures a voltage of each cell of the plurality of secondary batteries; and a control unit that outputs a command signal for adjusting a voltage of each cell based on a voltage value of each cell 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 sensors being non-contact with each other, the battery module including a cell voltage measurement circuit and a cell balance discharge circuit arranged in parallel to 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, thereby measuring the voltage of each of the cells;
The control unit determines a state of charge of each of the cells based on the measured voltage value of each of the cells,
When the voltage of a cell exceeds a preset upper limit voltage, the cell balance discharge circuit discharges the cell whose voltage has exceeded 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 that has exceeded the upper limit voltage to be within a preset voltage range, the current sensor measures the cell balancing discharge current flowing through the cell balancing discharge circuit while discharging the cell, thereby measuring the voltage of the cell.

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