KR-20260062841-A - CELL BALANCING CIRCUIT AND BATTERY DEVICE

KR20260062841AKR 20260062841 AKR20260062841 AKR 20260062841AKR-20260062841-A

Abstract

Provides a cell balance circuit capable of continuously performing cell balance operations for each battery cell connected in series. A cell balance circuit (100) that controls the cell balance between a battery cell (11) that generates a cell voltage (V1) and a battery cell (12) connected in series with the battery cell (11) that generates a cell voltage (V2), has a voltage divider circuit (103) that outputs a voltage divider voltage (Vd1) based on the average voltage of the battery cell (11) and the battery cell (12), a differential voltage-current converter (101) that discharges a cell balance current (Ib1) generated according to the voltage difference obtained by subtracting the cell voltage (V2) from the voltage divider voltage (Vd1) from the battery cell (11), and a differential voltage-current converter (102) that discharges a cell balance current (Ib2) generated according to the voltage difference obtained by reversing the voltage.

Inventors

미야모토 야스히로

Assignees

에이블릭 가부시키가이샤

Dates

Publication Date: 20260507
Application Date: 20251017
Priority Date: 20241029

Claims (9)

A cell balance circuit that controls the cell balance between a first battery cell that generates a first cell voltage and a second battery cell connected in series with the first battery cell that generates a second cell voltage, A first voltage divider circuit that outputs a first voltage divider voltage as the average voltage of the first battery cell and the second battery cell, and A first differential voltage-current converter that discharges a first cell balance current generated according to the voltage difference obtained by subtracting the second cell voltage from the first divided voltage, and A second differential voltage-current converter that discharges a second cell balance current generated according to the above voltage difference with reversed positive and negative values from the second battery cell, A cell balance circuit characterized by having
In claim 1, The cell balance circuit wherein the first differential voltage-current converter and the second differential voltage-current converter do not discharge the first cell balance current and the second cell balance current in a predetermined range including a voltage difference of 0.
In claim 1, The first differential voltage-current converter and the second differential voltage-current converter are a cell balance circuit in which the cell balance current becomes constant in a range where the absolute value of the voltage difference is greater than a predetermined value.
In claim 1, A current monitoring circuit connected to both ends of a current sense resistor connected in series with the main current path, which monitors the current flowing through the current sense resistor to determine whether the first battery cell and the second battery cell are in a discharge, charging, or open state, and A switching element that turns on and off by a signal output from the above current monitoring circuit, short-circuits to prevent the above voltage difference from occurring when turned on, and does not short-circuit to prevent the above voltage difference from occurring when turned off. With more, The above current monitoring circuit turns on the switching element when it is determined to be in the discharge phase, and turns off the switching element when it is determined to be in the charging phase or the open phase, forming a cell balance circuit.
In claim 1, A first current mirror circuit that discharges from the first battery cell by using the current according to the supply current from the first differential voltage-current converter as the first cell balance current, and A second current mirror circuit that discharges from the second battery cell by using the current according to the supply current from the second differential voltage-current converter as the second cell balance current, Cell balance circuit with more.
In claim 5, A first balance detection unit that detects the operating state of the first current mirror circuit by comparing the first cell voltage and the input voltage of the first current mirror circuit, and A second balance detection unit that detects the operating state of the second current mirror circuit by comparing the second cell voltage and the input voltage of the second current mirror circuit, and A diagnostic circuit that outputs an error signal externally when it diagnoses that either the first current mirror circuit or the second current mirror circuit is abnormal based on the detection result of the first balance detection unit and the detection result of the second balance detection unit. Cell balance circuit with more.
In claim 6, The device further has an external signal input terminal to which an off signal is input to stop the discharge of the first cell balance current and the second cell balance current, When the off signal is input to the external signal input terminal, The first balance detection unit and the second balance detection unit detect that the cell balance current is being discharged, and The above diagnostic circuit is a cell balance circuit that outputs the above error signal externally.
In claim 1, In the case where a third battery cell generating a third cell voltage is connected in series to the negative side of the second battery cell, A second voltage divider circuit that outputs a second voltage divider voltage as the average voltage of the second battery cell and the third battery cell, and A third differential voltage-current converter that discharges a third cell balance current generated according to the voltage difference obtained by subtracting the third cell voltage from the second divided voltage from the second cell, and A fourth differential voltage-current converter that discharges the fourth cell balance current generated according to the above voltage difference with reversed positive and negative values from the third battery cell, With more, A cell balance circuit in which the second cell balance current and the third cell balance current are added in the second battery cell.
A first battery cell that generates a first cell voltage, and A second battery cell connected in series with the first battery cell to generate a second cell voltage, and A cell balance circuit as described in any one of claims 1 to 8, A battery device characterized by having at least

Description

Cell Balancing Circuit and Battery Device The present invention relates to a cell balance circuit and a battery device. There is a battery group in which multiple rechargeable secondary battery cells are connected in series. The voltage of each cell in the battery group is not identical due to factors such as manufacturing variations or variations in the cell's self-leakage current. Additionally, the voltage of each cell may vary depending on the ambient temperature. Furthermore, as this battery group undergoes repeated charging and discharging cycles, degradation progresses, causing the State of Health (SOH) to differ for each cell, resulting in differences in the cell voltage of each cell. As degradation progresses, the cell voltage increases during charging but decreases during discharging. If the cell voltages of each battery cell differ significantly, and a charge/discharge control circuit is connected to each battery cell, the battery cell with the higher cell voltage will quickly become overcharged and stop charging when charged, and the battery cell with the lower cell voltage will quickly become overdischarged and stop discharging when discharged. Therefore, there is a concern that efficient charging and discharging will not be possible. Various proposals have been made to adjust the balance of the cell voltages of each battery cell in such a battery. For example, a battery control device is proposed that measures the cell voltage of each battery cell using an ADC (Analog to Digital Converter) and performs calculations in a signal processing circuit such as an MPU (Micro Processing Unit) to equalize the cell voltage of each battery cell (see Patent Document 1). In addition, a voltage regulating device for a battery is proposed that uses a comparator to selectively discharge battery cells with a voltage higher than the average voltage of the battery, thereby ultimately making the cell voltages of all battery cells equal (see Patent Document 2). In addition, a voltage balance correction circuit is proposed in which a negative feedback loop is formed by a comparator to make the potential difference between the average voltage of two adjacent battery cells and the intermediate voltage of two battery cells zero, and the battery cell with the higher cell voltage is discharged when a voltage difference occurs (see Patent Document 3). [Fig. 1] Fig. 1 is a circuit diagram illustrating a battery device (during discharge) using a cell balance circuit in a first embodiment of the present invention. [Fig. 2] Fig. 2 is a graph illustrating the cell balance current-voltage difference characteristics of a differential voltage-current converter in the first embodiment of the present invention. [Fig. 3] Fig. 3 is a graph illustrating the cell balance current-voltage difference characteristics of a differential voltage-current converter in the first embodiment of the present invention. [Fig. 4] Fig. 4 is a graph illustrating the cell balance current-voltage difference characteristics of a differential voltage-current converter in the first embodiment of the present invention. [Fig. 5] Fig. 5 is a circuit diagram illustrating a battery device (when charging) using a cell balance circuit in the first embodiment of the present invention. [Fig. 6] Fig. 6 is a circuit diagram illustrating a battery device (when open) using a cell balance circuit in the first embodiment of the present invention. [Fig. 7] Fig. 7 is a circuit diagram illustrating a battery device (during discharge) using a cell balance circuit in a second embodiment of the present invention. [Fig. 8] Fig. 8 is a circuit diagram illustrating a battery device (when charging) using a cell balance circuit in a second embodiment of the present invention. [Fig. 9] Fig. 9 is a circuit diagram illustrating a battery device (when open) using a cell balance circuit in a second embodiment of the present invention. [Fig. 10] Fig. 10 is a circuit diagram illustrating a battery device (during discharge) using a cell balance circuit in a third embodiment of the present invention. [Fig. 11] Fig. 11 is a circuit diagram illustrating a battery device (when charging) using a cell balance circuit in a third embodiment of the present invention. [Fig. 12] Fig. 12 is a circuit diagram illustrating a battery device (when open) using a cell balance circuit in a third embodiment of the present invention. [Fig. 13] Fig. 13 is a circuit diagram illustrating a battery device (during discharge) using a cell balance circuit in the fourth embodiment of the present invention. [Fig. 14] Fig. 14 is a circuit diagram illustrating a battery device (when charging) using a cell balance circuit in the fifth embodiment of the present invention. [Fig. 15] Fig. 15 is a schematic diagram illustrating an example of a battery device using multiple cell balance circuits of Fig. 14. [Fig. 16] Fig. 16 is a schematic diagram illustrating another example of a battery device using multiple cell balance circui