Lithium battery protection circuit

Abstract

The utility model discloses a lithium battery protection circuit is connected with the fast discharge module to charge MOS pipe, the fast discharge module includes triode Q4, diode D3 and resistance R2, the emitter of triode Q4 connects the gate of each charge MOS pipe, the base connects the charge control CHC pin of protection chip U1, the collector connects negative pole charging terminal P, the base still passes through resistance R2 negative pole charging terminal P, adds diode D3 between the emitter and the base, forms the potential difference between the base and the emitter, guarantees triode Q4 normal conduction. The utility model discloses a triode Q4, diode D3 and resistance R2 constitute the fast discharge circuit, effectively solved the gate charge accumulation problem of parallel MOS pipe under high pressure condition, avoids the breakdown damage of device. Diode D3 ensures that triode Q4 is stable conduction, and accelerates MOS pipe gate charge discharge.

Description

Technical Field

[0001] This utility model relates to the field of lithium-ion battery technology, and in particular to a lithium battery protection circuit. Background Technology

[0002] Lithium-ion batteries, as the mainstream rechargeable battery technology, have been widely used in consumer electronics, electric vehicles, and energy storage systems due to their advantages such as high energy density, long cycle life, and excellent temperature adaptability. However, significant safety hazards and technical challenges still exist in practical applications of lithium batteries.

[0003] Traditional MOSFET protection schemes suffer from response delays in high-voltage, high-current scenarios, potentially causing battery damage before protection actions are activated. Furthermore, the gate charge accumulation effect in parallel MOSFET architectures can lead to device breakdown. These technical shortcomings pose significant challenges to existing lithium-ion battery protection circuits in emerging applications such as fast-charging electric vehicles and high-rate drone batteries, necessitating innovative circuit designs to address key technical issues related to response speed, device reliability, and system integration. Utility Model Content

[0004] The purpose of this invention is to provide a lithium battery protection circuit that adds a fast discharge circuit to protect the MOS.

[0005] The technical solution of this utility model is: A lithium battery protection circuit is provided, wherein the lithium battery consists of N cells connected in series. The positive and negative terminals B+ and B- of the lithium battery are connected to the positive and negative charging terminals P+ and P- for charging, respectively. A three-terminal fuse F1 is connected in series on the positive charging line, and a charge / discharge MOSFET group is connected in series on the negative charging line. The lithium battery protection circuit includes protection chips U1 and U2. Protection chip U1 collects the voltage of each cell of the lithium battery and connects to control the on / off state of the charge / discharge MOSFET group, thereby controlling the charging and discharging of the lithium battery. Protection chip U1 collects the voltage of each cell of the lithium battery and connects to control the on / off state of the three-terminal fuse F1.

[0006] Preferably, the charge / discharge MOS transistor group includes multiple charging MOS transistors connected in parallel and multiple discharging MOS transistors connected in parallel.

[0007] Preferably, the charging MOSFET is also connected to a fast discharge module, which includes a transistor Q4, a diode D3, and a resistor R2. The emitter of the transistor Q4 is connected to the gate of each charging MOSFET, the base is connected to the charging control CHC pin of the protection chip U1, the collector is connected to the negative charging terminal P-, and the base is also connected to the negative charging terminal P- through the resistor R2. A diode D3 is added between the emitter and the base to form a potential difference between the base and the emitter, ensuring that the transistor Q4 can conduct normally.

[0008] Preferably, the anode of the diode D3 is connected to the base of the transistor Q4, and the cathode is connected to the emitter of the transistor Q4.

[0009] Preferably, the protection chips U1 and U2 are HTL6024AAA and HTL6215, respectively.

[0010] Preferably, the protection chips U1 and U2 are both powered by the positive terminal of a lithium battery.

[0011] The advantages of this utility model are: 1. This utility model employs a combination of protection chips U1 and U2 to achieve high-precision sampling of cell voltage and utilizes a hierarchical protection mechanism: U1 monitors the voltage of each cell in real time and dynamically controls the switching of the three-terminal fuse F1 and the MOSFET group to prevent overcharging / over-discharging. U2 provides redundant protection, triggering a backup protection path when U1 fails.

[0012] 2. This utility model designs a fast discharge module: A fast discharge circuit composed of transistor Q4, diode D3, and resistor R2 effectively solves the problem of gate charge accumulation in parallel MOSFETs under high voltage conditions, preventing device breakdown and damage. Diode D3 ensures stable conduction of transistor Q4, accelerating the discharge of gate charge from the MOSFET. Attached Figure Description

[0013] The present invention will be further described below with reference to the accompanying drawings and embodiments: Figure 1 This is a schematic diagram of the lithium battery protection circuit of this utility model; Figure 2 The schematic diagram of the fast discharge module designed for this utility model is shown. Detailed Implementation

[0014] like Figure 1 As shown, the lithium battery protection circuit of this utility model comprises N cells connected in series. The positive and negative terminals B+ and B- of the lithium battery are connected to the positive and negative charging terminals P+ and P- for charging, respectively. A three-terminal fuse F1 is connected in series on the positive charging line, and a charge / discharge MOSFET is connected in series on the negative charging line. The lithium battery protection circuit includes protection chips U1 and U2. Protection chip U1 collects the voltage of each cell of the lithium battery and connects to control the on / off state of the charge / discharge MOSFET group, thereby controlling the charging and discharging of the lithium battery. Protection chip U1 collects the voltage of each cell of the lithium battery and connects to control the on / off state of the three-terminal fuse F1.

[0015] The charge / discharge MOSFET group includes multiple charging MOSFETs (Q1-Q3) connected in parallel and multiple discharging MOSFETs (Q5-Q7) connected in parallel. The gates of each MOSFET are connected in parallel with a 10Ω resistor and then connected to the control signal.

[0016] The protection chips U1 and U2 are HTL6024AAA and HTL6215, respectively.

[0017] The protection chips U1 and U2 are both powered by the positive terminal of a lithium battery.

[0018] like Figure 2 As shown, the charging MOSFET is also connected to a fast discharge module. The fast discharge module includes a transistor Q4, a diode D3, and a resistor R2. The emitter of transistor Q4 is connected to the gate of each charging MOSFET, the base is connected to the charging control CHC pin of the protection chip U1, and the collector is connected to the negative charging terminal P-. The base is also connected to the negative charging terminal P- through resistor R2. A diode D3 is added between the emitter and base to create a potential difference between them, ensuring that transistor Q4 can conduct normally. The anode of diode D3 is connected to the base of transistor Q4, and the cathode is connected to the emitter of transistor Q4.

[0019] During normal charging, after the charger is connected to the P+ and P- terminals, U1 continuously monitors the voltage of each cell. When the voltage of all cells is <4.15V, the CO pin outputs a high level, turning on Q1-Q3.

[0020] When any cell voltage is overcharged, the CHC pin of U1 outputs a low level → Q4 turns on, and the gate charge of Q1-Q3 is quickly discharged to P- through Q4. The CO pin outputs a low level simultaneously, providing double protection to turn off the MOSFET. When overcharging continues, U1 triggers the F1 fuse to blow.

[0021] When the load is short-circuited, U1 detects a sudden current change within 100μs and simultaneously turns off the CO / DO pin output, while Q4 turns on to achieve rapid release of the gate charge of the MOS transistor.

[0022] The above embodiments are only for illustrating the technical concept and features of this utility model, and are intended to enable those skilled in the art to understand the content of this utility model and implement it accordingly. They should not be construed as limiting the scope of protection of this utility model. All modifications made in accordance with the spirit and essence of the main technical solution of this utility model should be included within the scope of protection of this utility model.

Claims

1. A lithium battery protection circuit, characterized in that, The lithium battery consists of N cells connected in series. The positive and negative terminals B+ and B- of the lithium battery are connected to the positive and negative charging terminals P+ and P- for charging, respectively. A three-terminal fuse F1 is connected in series on the positive charging line, and a charge / discharge MOSFET group is connected in series on the negative charging line. The lithium battery protection circuit includes protection chips U1 and U2. Protection chip U1 collects the voltage of each cell of the lithium battery and connects to control the on / off state of the charge / discharge MOSFET group, thereby controlling the charging and discharging of the lithium battery. Protection chip U1 collects the voltage of each cell of the lithium battery and connects to control the on / off state of the three-terminal fuse F1.

2. The lithium battery protection circuit according to claim 1, characterized in that, The charge / discharge MOSFET group includes multiple charging MOSFETs connected in parallel and multiple discharging MOSFETs connected in parallel.

3. The lithium battery protection circuit according to claim 2, characterized in that, The charging MOSFET is also connected to a fast discharge module, which includes a transistor Q4, a diode D3, and a resistor R2. The emitter of transistor Q4 is connected to the gate of each charging MOSFET, the base is connected to the charging control CHC pin of the protection chip U1, the collector is connected to the negative charging terminal P-, and the base is also connected to the negative charging terminal P- through resistor R2. A diode D3 is added between the emitter and the base to form a potential difference between the base and the emitter, ensuring that transistor Q4 can conduct normally.

4. The lithium battery protection circuit according to claim 3, characterized in that, The anode of diode D3 is connected to the base of transistor Q4, and the cathode is connected to the emitter of transistor Q4.

5. The lithium battery protection circuit according to claim 1, characterized in that, The protection chips U1 and U2 are HTL6024AAA and HTL6215, respectively.

6. The lithium battery protection circuit according to claim 1, characterized in that, The protection chips U1 and U2 are both powered by the positive terminal of a lithium battery.

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