A lithium battery pack equalization control circuit

Abstract

This invention discloses a lithium battery pack equalization control circuit, including a DC / DC circuit group, a control circuit group, a cell group, a sampling circuit, and an MCU. Each DC / DC module in the DC / DC circuit group is connected to the positive and negative terminals of a corresponding individual cell in the cell group, outputting a constant voltage to the cell. Each current-limiting control branch in the current-limiting control circuit group is connected between the corresponding DC / DC module and the positive terminal of the corresponding cell, limiting the charging current of the DC / DC module to the corresponding cell. Each acquisition terminal of the sampling circuit is connected between each current-limiting control branch and the positive terminal of the corresponding cell, acquiring the voltage of each cell. The MCU is connected to the sampling circuit and each current-limiting control branch. The sampling circuit outputs the acquired voltage signal of each cell to the MCU. The MCU determines whether a cell is abnormal based on the voltage signal and controls the on / off state of the current-limiting control branch connected to the cell. This invention can effectively control the charging and discharging of the cell group, maximizing the utilization of the cell group's energy and extending its service life.

Description

Technical Field

[0001] This invention relates to a lithium battery pack equalization control circuit, belonging to the field of lithium battery pack control technology. Background Technology

[0002] Currently, lithium batteries are becoming increasingly widespread, with applications ranging from powering toys to large-scale wind and solar energy storage. Theoretically, the voltage and internal resistance of each cell in a lithium battery pack are screened at the factory, ensuring excellent consistency and no differences. However, in actual use, as the usage time increases, differences arise between cells due to manufacturing processes and materials, leading to reduced energy output and, in severe cases, rendering the battery pack unusable. Various balancing circuits have emerged to address this phenomenon, broadly categorized into two types: active balancing and passive balancing. Active balancing transfers high-charge cells to low-charge cells, while passive balancing allows high-charge cells to discharge themselves until they match the low-charge cells. Active balancing is more complex and costly to implement, while passive balancing is easier to implement but carries a higher risk due to resistor-based discharge. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention provides a lithium battery pack equalization control circuit that can effectively control the charging and discharging of the battery cells, thereby maximizing the utilization of the battery cell energy and extending the battery cell lifespan.

[0004] The technical solution adopted in this invention is as follows:

[0005] A lithium battery pack equalization control circuit includes a DC / DC circuit group, a control circuit group, a cell group, a sampling circuit, and an MCU;

[0006] Each DC / DC module in the DC / DC circuit group is connected to the positive and negative terminals of a corresponding individual cell in the cell group, and is used to output a constant voltage to the cell.

[0007] Each current limiting control branch in the current limiting control circuit group is connected between the corresponding DC / DC module and the corresponding positive terminal of the battery cell, and is used to limit the current of the DC / DC module charging the corresponding battery cell;

[0008] Each acquisition terminal of the sampling circuit is connected between each current limiting control branch and the corresponding positive terminal of the battery cell, and is used to acquire the voltage of each battery cell;

[0009] The MCU is connected to the sampling circuit and each current limiting control branch. The sampling circuit outputs the voltage signal of each battery cell to the MCU. The MCU determines whether the battery cell is abnormal based on the voltage signal and controls the current limiting control branch connected to the battery cell to open or close.

[0010] In a preferred embodiment of the present invention, pin 2 of each DC / DC module in the DC / DC circuit group is connected to the DC+ power supply terminal, pin 4 is connected to the positive terminal of the corresponding battery cell through the corresponding current limiting control branch, pin 3 is connected to the negative terminal of the corresponding battery cell, and pin 1 is connected to the DC- power supply terminal.

[0011] As a preferred embodiment of the present invention, each current limiting control branch in the current limiting control circuit group includes a switching MOSFET, a transistor, a resistor, a resistor, and a current limiting resistor.

[0012] The first switching MOSFET is connected in parallel with the first resistor, and then connected to one end of the current-limiting resistor and the collector of the transistor respectively; the first switching MOSFET is also connected to the corresponding positive terminal of the battery cell.

[0013] The other end of the current-limiting resistor is connected to the corresponding DC / DC module;

[0014] One end of the resistor is connected to the base of the transistor, and the other end is connected to the corresponding signal output terminal on the MCU; the emitter of the transistor is connected to GND.

[0015] In a preferred embodiment of the present invention, the gate of the switching MOS transistor is connected to the collector of the transistor, the source is connected to the current-limiting resistor, and the drain is connected to the corresponding positive terminal of the battery cell.

[0016] As a preferred embodiment of the present invention, the sampling circuit includes a chip U1, the acquisition terminal of the chip U1 is connected between the corresponding current limiting control branch and the corresponding positive terminal of the battery cell; pin 7 of the chip U1 is connected to pin 3 of the MCU, and pin 8 is connected to pin 2 of the MCU for voltage signal transmission.

[0017] As a preferred embodiment of the present invention, a resistor R7 is connected between pin 7 of chip U1 and pin 3 of MCU; and a resistor R9 is connected between pin 8 of chip U1 and pin 2 of MCU.

[0018] As a preferred embodiment of the present invention, the battery cells in the battery cell group are connected in series, the positive terminal of the battery cell group is connected to discharge DC+, the negative terminal of the battery cell group is connected to discharge DC- and GND, and the battery cell group, discharge DC+, and discharge DC- form a discharge circuit. The ends of each current limiting control branch and each acquisition terminal of the sampling circuit are connected to the discharge circuit.

[0019] In a preferred embodiment of the present invention, the sampling circuit further includes switching MOSFETs Q5 and Q6, which are connected to the discharge circuit, and the sources of switching MOSFETs Q5 and Q6 are connected together; the gates of switching MOSFETs Q5 and Q6 are connected to pins 6 and 9 of chip U1, respectively; the drain of switching MOSFET Q5 is connected to the negative terminal of the battery pack and connected to GND; the drain of switching MOSFET Q7 is connected to the discharge DC-.

[0020] The MCU determines whether the battery cell group is abnormal based on the voltage signal transmitted by the sampling circuit, and controls the discharge of the entire battery cell group by controlling the switching MOSFETs Q5 and Q6.

[0021] The beneficial effects of this invention are as follows:

[0022] 1. A constant voltage is output from the DC / DC module in the DC / DC circuit group, and the current-limiting resistors in each branch circuit of the current-limiting control circuit group limit the current of the DC / DC module to charge the corresponding battery cell, so as to achieve a balanced charging capacity of each battery cell in the battery cell group.

[0023] 2. By setting a switching MOSFET in each current limiting control branch and connecting the switching MOSFETs Q5 and Q6 in the sampling circuit to the discharge circuit, the MCU can determine whether the battery pack and individual battery cells are abnormal based on the voltage signal transmitted by the sampling circuit. Then, it controls the on / off state of the corresponding switching MOSFET to control the charging of individual battery cells or controls the on / off state of switching MOSFETs Q5 and Q6 to control the discharge of the entire battery pack.

[0024] 3. Through the coordinated action of various circuits, the charging and discharging of the battery pack can be effectively controlled, thereby maximizing the utilization of the battery pack's energy and extending its service life. Attached Figure Description

[0025] Figure 1 This is the overall architecture of the present invention;

[0026] Figure 2 This is a specific circuit diagram of the present invention. Detailed Implementation

[0027] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0028] like Figure 1-2 As shown: This embodiment is a lithium battery pack equalization control circuit, including a DC / DC circuit group, a control circuit group, a cell group, a sampling circuit and an MCU. The MCU is selected as PIC12F519, or a conventional 8-pin unit can be used.

[0029] In the DC / DC circuit group, each DC / DC module is connected to the positive and negative terminals of the corresponding individual cell in the cell group to output a constant voltage to the cell; among them, the DC / DC module selected is model URB2405YMD-6WR3, or a DC / DC module with isolation function can be selected.

[0030] Each current limiting control branch in the current limiting control circuit group is connected between the corresponding DC / DC module and the corresponding positive terminal of the battery cell, and is used to limit the current of the DC / DC module charging the corresponding battery cell.

[0031] Each acquisition terminal of the sampling circuit is connected between each current-limiting control branch and the corresponding positive terminal of the battery cell to acquire the voltage of each battery cell.

[0032] The MCU is connected to the sampling circuit and each current limiting control branch. The sampling circuit outputs the voltage signal of each battery cell to the MCU. The MCU determines whether the battery cell is abnormal based on the voltage signal and controls the current limiting control branch connected to the battery cell to open or close.

[0033] In the DC / DC circuit group, pin 2 of each DC / DC module is connected to the DC+ power supply terminal, pin 4 is connected to the positive terminal of the corresponding battery cell through the corresponding current limiting control branch, pin 3 is connected to the negative terminal of the corresponding battery cell, and pin 1 is connected to the DC- power supply terminal.

[0034] In the current limiting control circuit group, each current limiting control branch includes a switching MOSFET, a transistor, a resistor, a resistor, and a current limiting resistor. Switching MOSFET and resistor are connected in parallel, and then connected to one end of the current limiting resistor and the collector of the transistor, respectively. Switching MOSFET is also connected to the positive terminal of the corresponding battery cell. The other end of the current limiting resistor is connected to the corresponding DC / DC module. One end of resistor is connected to the base of the transistor, and the other end is connected to the corresponding signal output terminal on the MCU.

[0035] The emitter of the transistor is connected to GND; among them, the gate of the switching MOSFET is connected to the collector of the transistor, the source is connected to the current limiting resistor, and the drain is connected to the positive terminal of the corresponding cell.

[0036] like Figure 2 As shown, the first set of switching MOSFETs includes P1, P2, P3, and P4; the second set of transistors includes Q1, Q2, Q3, and Q4; the third set of resistors includes R2, R5, R10, and R13; the fourth set of resistors includes R3, R6, R11, and R14; and the fifth set of current-limiting switches includes R1, R4, R8, and R12. These components are connected in the above manner to form the following configuration: Figure 2 The current limiting control circuit shown is shown.

[0037] The sampling circuit includes chip U1, model BQ76920, or any FAE sampling chip with the same function. The acquisition terminal of chip U1 is connected between the corresponding current limiting control branch and the positive terminal of the corresponding battery cell. Pin 7 of chip U1 is connected to pin 3 of the MCU, and pin 8 is connected to pin 2 of the MCU for voltage signal transmission. Resistor R7 is connected between pin 7 of chip U1 and pin 3 of the MCU; resistor R9 is connected between pin 8 of chip U1 and pin 2 of the MCU.

[0038] The circuit structure described above can output a constant voltage through the DC / DC module in the DC / DC circuit group, and then limit the charging current of the DC / DC module to the corresponding battery cell through the current limiting resistors in each branch circuit of the current limiting control circuit group, so as to achieve a balanced charging capacity of each battery cell in the battery cell group; then, the voltage signal of each battery cell is collected by the sampling circuit and transmitted to the MCU. The MCU determines whether a single battery cell in the battery cell group is abnormal based on the voltage signal transmitted by the sampling circuit. If a battery cell is abnormal, it controls the corresponding switching MOSFET to turn off and stops charging the abnormal battery cell.

[0039] The cells in the battery pack are connected in series. The positive terminal of the battery pack is connected to the discharge DC+, and the negative terminal of the battery pack is connected to the discharge DC- and GND. The battery pack, the discharge DC+, and the discharge DC- form a discharge circuit. The ends of each current limiting control branch and each acquisition terminal of the sampling circuit are connected to this discharge circuit. This connection structure enables the sampling circuit to acquire the voltage signal of the battery pack and transmit it to the MCU.

[0040] The sampling circuit also includes switching MOSFETs Q5 and Q6, which are connected to the discharge circuit. The sources of switching MOSFETs Q5 and Q6 are connected together. The gates of switching MOSFETs Q5 and Q6 are connected to pins 6 and 9 of chip U1, respectively. The drain of switching MOSFET Q5 is connected to the negative terminal of the battery pack and connected to GND. The drain of switching MOSFET Q7 is connected to the discharge DC-.

[0041] The circuit structure described above can acquire the voltage signal of the battery pack through the sampling circuit and transmit it to the MCU. The MCU determines whether the battery pack is abnormal based on the voltage signal transmitted by the sampling circuit. If the battery pack is abnormal, it controls the switching MOSFETs Q5 and Q6 to disconnect, so that the battery pack stops discharging.

[0042] In summary, the lithium battery pack equalization control circuit provided by this invention can effectively control the charging and discharging of the battery pack through the synergistic effect of various circuits, thereby maximizing the utilization of the battery pack's energy and extending the battery pack's service life.

[0043] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A lithium battery pack equalization control circuit, comprising a DC / DC circuit group, a current limiting control circuit group, a cell group, a sampling circuit, and an MCU, characterized in that: Each DC / DC module in the DC / DC circuit group is connected to the positive and negative terminals of a corresponding individual cell in the cell group, and is used to output a constant voltage to the cell. Each current limiting control branch in the current limiting control circuit group is connected between the corresponding DC / DC module and the corresponding positive terminal of the battery cell, and is used to limit the current of the DC / DC module charging the corresponding battery cell; Each current-limiting control branch includes a switching MOSFET, a transistor, a resistor, a resistor, and a current-limiting resistor; The first switching MOSFET is connected in parallel with the first resistor, and then connected to one end of the current-limiting resistor and the collector of the transistor respectively; the first switching MOSFET is also connected to the corresponding positive terminal of the battery cell. The other end of the current-limiting resistor is connected to the corresponding DC / DC module; One end of the resistor is connected to the base of the transistor, and the other end is connected to the corresponding signal output terminal on the MCU. The emitter of the transistor is connected to GND; Each acquisition terminal of the sampling circuit is connected between each current limiting control branch and the corresponding positive terminal of the battery cell, and is used to acquire the voltage of each battery cell; The MCU is connected to the sampling circuit and each current limiting control branch. The sampling circuit outputs the voltage signal of each battery cell to the MCU. The MCU determines whether the battery cell is abnormal based on the voltage signal and controls the current limiting control branch connected to the battery cell to open or close.

2. The lithium battery pack equalization control circuit according to claim 1, characterized in that, In the DC / DC circuit group, pin 2 of each DC / DC module is connected to the DC+ power supply terminal, pin 4 is connected to the positive terminal of the corresponding battery cell through the corresponding current limiting control branch, pin 3 is connected to the negative terminal of the corresponding battery cell, and pin 1 is connected to the DC- power supply terminal.

3. The lithium battery pack equalization control circuit according to claim 1, characterized in that, The gate of the first switching MOSFET is connected to the collector of the transistor, the source is connected to the current-limiting resistor, and the drain is connected to the positive terminal of the corresponding cell.

4. The lithium battery pack equalization control circuit according to claim 1, characterized in that, The sampling circuit includes a chip U1, the acquisition terminal of which is connected between the corresponding current limiting control branch and the positive terminal of the corresponding battery cell; pin 7 of chip U1 is connected to pin 3 of the MCU, and pin 8 is connected to pin 2 of the MCU for voltage signal transmission.

5. The lithium battery pack equalization control circuit according to claim 4, characterized in that, A resistor R7 is connected between pin 7 of chip U1 and pin 3 of MCU; a resistor R9 is connected between pin 8 of chip U1 and pin 2 of MCU.

6. The lithium battery pack equalization control circuit according to claim 4, characterized in that, The battery cells in the battery cell group are connected in series. The positive terminal of the battery cell group is connected to the discharge DC+, and the negative terminal of the battery cell group is connected to the discharge DC- and GND. The battery cell group, the discharge DC+, and the discharge DC- form a discharge circuit. The end of each current limiting control branch and each acquisition terminal of the sampling circuit are connected to this discharge circuit.

7. A lithium battery pack equalization control circuit according to claim 6, characterized in that, The sampling circuit also includes switching MOSFETs Q5 and Q6, which are connected to the discharge circuit and whose sources are connected together; the gates of switching MOSFETs Q5 and Q6 are connected to pins 6 and 9 of chip U1, respectively; the drain of switching MOSFET Q5 is connected to the negative terminal of the battery pack and connected to GND; the drain of switching MOSFET Q7 is connected to the discharge DC-. The MCU determines whether the battery cell group is abnormal based on the voltage signal transmitted by the sampling circuit, and controls the discharge of the entire battery cell group by controlling the switching MOSFETs Q5 and Q6.

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