CN-121984166-A - Cell equalization circuit and storage battery device

Abstract

A cell balancing circuit capable of always performing cell balancing operation for each battery cell connected in series, and a storage battery device. A cell balancing circuit (100) controls cell balancing between a battery cell (11) generating a cell voltage (V1) and a battery cell (12) connected in series with the battery cell (11) and generating a cell voltage (V2), the cell balancing circuit comprising a voltage dividing circuit (103) outputting a divided voltage (Vd 1) which is an average voltage of the battery cells (11, 12), a differential voltage-current converter (101) discharging the cell balancing current (Ib 1) from the battery cell (11), the current (Ib 1) being generated by subtracting a voltage difference of the cell voltage (V2) from the divided voltage, and a differential voltage-current converter (102) discharging the cell balancing current (Ib 2) from the battery cell (12) and the current (Ib 2) being generated by a voltage difference of positive and negative directions.

Inventors

• YASUHIRO MIYAMOTO

Assignees

• 艾普凌科株式会社

Dates

Publication Date

20260505

Application Date

20251013

Priority Date

20241029

Claims (9)

1. 1. A cell balancing circuit for controlling cell balancing of a first battery cell generating a first cell voltage and a second battery cell connected in series with the first battery cell and generating a second cell voltage, the cell balancing circuit characterized by: a first voltage dividing circuit that outputs a first divided voltage that is an average voltage of the first battery cell and the second battery cell; a first differential voltage-to-current converter discharging a first cell balance current from the first battery cell, the first cell balance current being generated based on a voltage difference obtained by subtracting the second cell voltage from the first divided voltage, and And a second differential voltage-to-current converter discharging a second cell balance current from the second battery cell, the second cell balance current being generated according to the voltage difference after reversing positive and negative directions.
2. 2. The cell balancing circuit of claim 1, wherein the first and second differential voltage-to-current converters do not discharge the first and second cell balancing currents at a specified range where the voltage difference includes 0.
3. 3. The cell balancing circuit according to claim 1, wherein the first differential voltage-to-current converter and the second differential voltage-to-current converter make the cell balancing current constant when an absolute value of the voltage difference is in a range larger than a prescribed value.
4. 4. The cell balancing circuit of claim 1, further comprising: A current monitoring circuit connected to both ends of a current sensing resistor connected in series to a main current path, for monitoring a current value flowing through the current sensing resistor and determining which of discharge time, charge time and open circuit time the first battery cell and the second battery cell are, and A switching element which is turned on/off in accordance with a signal outputted from the current monitoring circuit, short-circuited when turned on so that the voltage difference is not generated, not short-circuited when turned off so that the voltage difference is generated, The current monitoring circuit turns on the switching element when the discharge is determined, and turns off the switching element when the charge is determined or the open circuit is determined.
5. 5. The cell balancing circuit of claim 1, further comprising: A first current mirror circuit for discharging a current corresponding to a supply current from the first differential voltage-to-current converter from the first battery cell as the first cell balance current, and And a second current mirror circuit that discharges a current corresponding to a supply current from the second differential voltage-to-current converter from the second battery cell as the second cell balance current.
6. 6. The cell balancing circuit of claim 5, further comprising: A first balance detection unit that compares the first cell voltage with an input voltage of the first current mirror circuit to detect an operation state of the first current mirror circuit; a second balance detection unit for comparing the second cell voltage with the input voltage of the second current mirror circuit to detect the operation state of the second current mirror circuit, and And a diagnostic circuit configured to output an error signal to the outside when it is diagnosed that either one of the first current mirror circuit and the second current mirror circuit is abnormal based on a detection result of the first equalization detecting unit and a detection result of the second equalization detecting unit.
7. 7. The cell balancing circuit according to claim 6, further comprising an external signal input terminal for inputting an off signal for stopping discharge of the first cell balancing current and the second cell balancing current, In the case where the off signal is input to the external signal input terminal, The first balance detection part and the second balance detection part detect that the battery cell balance current is discharging, The diagnostic circuit outputs the error signal to the outside.
8. 8. The cell balancing circuit according to claim 1, wherein in case that a third battery cell generating a third cell voltage is connected in series on a negative side of the second battery cell, further comprising: a second voltage dividing circuit that outputs a second divided voltage that is an average voltage of the second battery cell and the third battery cell; A third differential voltage-to-current converter discharging a third cell balancing current from the second battery cell, the third cell balancing current being generated based on a voltage difference obtained by subtracting the third cell voltage from the second differential voltage, and A fourth differential voltage-to-current converter discharging a fourth cell balancing current from the third battery cell, the fourth cell balancing current being generated according to the voltage difference after reversing the positive and negative directions, And adding the second cell equalization current and the third cell equalization current in the second battery cell.
9. 9. A storage battery device characterized by at least comprising: A first battery cell generating a first cell voltage; a second battery cell connected in series with the first battery cell and generating a second cell voltage, and Cell balancing circuit according to any of claims 1 to 8.

Description

Cell equalization circuit and storage battery device Technical Field The invention relates to a battery cell equalization circuit and a storage battery device. Background There is a battery pack in which battery cells of a plurality of chargeable and dischargeable secondary batteries are connected in series. The cell voltages of the plurality of battery cells in the assembled battery are different due to, for example, manufacturing variations of the battery cells, self-leakage current variations of the battery cells, and the like. In addition, the cell voltages may vary depending on the ambient temperature. Further, when the deterioration is advanced during the repetition of the charge and discharge of the battery pack, a State of Health (SOH) becomes different for each battery cell, and the cell voltage of each battery cell is deviated. As degradation progresses, the cell voltage of the battery cell becomes higher when charged, but becomes lower when discharged. If the cell voltages of the battery cells are greatly different, when the battery cells are connected with the charge/discharge control circuit, the battery cell with the high cell voltage immediately reaches overcharge to stop charging when charging, and the battery cell with the low cell voltage immediately reaches overdischarge to stop discharging when discharging. Therefore, efficient charge and discharge may not be performed. In order to adjust the equalization of the cell voltages of the battery cells in such a battery pack, various proposals have been made. For example, there is proposed a battery pack control device in which cell voltages of battery cells are measured by analog-to-digital converters (Analog to Digital Converter, ADC) and calculated by a signal processing circuit such as a microprocessor (Micro Processing Unit, MPU) to equalize the cell voltages of the battery cells (see patent document 1). Further, a voltage adjustment device for a battery cell has been proposed, in which battery cells having a higher average voltage than the battery cell are selectively discharged using a comparator, and finally, the cell voltages of all the battery cells are equalized (see patent document 2). Further, a voltage balance correction circuit has been proposed in which a negative feedback loop is formed by a comparator so that a potential difference between an average voltage of two adjacent battery cells and an intermediate voltage of the two battery cells is zero, and when a voltage difference is generated, a battery cell having a high cell voltage is discharged (see patent document 3). [ Prior Art literature ] [ Patent literature ] [ Patent document 1] International publication No. 2015/029283 [ Patent document 2] Japanese patent laid-open No. 2000-83327 Patent document 3 japanese patent laid-open publication No. 2010-63264 Disclosure of Invention [ Problem to be solved by the invention ] In one aspect of the present invention, it is an object of the present invention to provide a cell balancing circuit that can perform a cell balancing operation on each battery cell connected in series by current control. [ Means of solving the problems ] The cell balancing circuit according to an embodiment of the present invention is, A cell balancing circuit for controlling cell balancing of a first battery cell generating a first cell voltage and a second battery cell connected in series with the first battery cell and generating a second cell voltage, comprising: a first voltage dividing circuit that outputs a first divided voltage that is an average voltage of the first battery cell and the second battery cell; a first differential voltage-to-current converter discharging a first cell balance current from the first battery cell, the first cell balance current being generated based on a voltage difference obtained by subtracting the second cell voltage from the first divided voltage, and And a second differential voltage-to-current converter discharging a second cell balance current from the second battery cell, the second cell balance current being generated according to the voltage difference after reversing positive and negative directions. [ Effect of the invention ] In one aspect of the present invention, a cell balancing circuit is provided that performs cell balancing operations on battery cells connected in series by current control. Drawings Fig. 1 is a circuit diagram showing a battery device (at the time of discharge) using a cell balancing circuit according to a first embodiment of the present invention. Fig. 2 is a graph showing a cell balance current-voltage difference characteristic of the differential voltage-current converter according to the first embodiment of the present invention. Fig. 3 is a graph showing a cell balance current-voltage difference characteristic of the differential voltage-current converter according to the first embodiment of the present invention. Fig. 4 is a graph showing a cell balance current-voltage differen