Protection circuit for lithium battery pack

Abstract

The utility model provides a protection circuit for a lithium battery pack, which comprises a battery pack, a battery management chip IC (integrated circuit), an MOS (metal oxide semiconductor) tube, a three-end self-recovery fuse, a fusing control circuit and a protection detection unit, the positive electrode of the battery pack is connected with the battery management chip IC, and the battery management chip IC is in control connection with the grid electrode of the MOS tube. The protection detection unit is arranged corresponding to the MOS tube and is used for detecting safety information of the MOS tube; the fusing control circuit is connected with the three-end self-recovery fuse according to the detection information of the protection detection unit; the positive electrode of the battery pack is connected with the source electrode of the MOS tube through a three-end self-recovery fuse. According to the utility model, the protection detection unit is additionally arranged in the protection main loop of the battery pack and is used for detecting the safety information of the MOS tube and protecting the MOS tube according to the detection result, so that the protection reliability of the battery pack can be improved, the application scheme is simple, and the battery pack protection circuit has the advantages of simple structure, high reliability, safety and convenience.

Description

Technical Field

[0001] The utility model relates to the field of lithium battery packs, in particular to a protection circuit for lithium battery packs. Background Art

[0002] Lithium batteries are widely used in many products, but due to their very active chemical properties and the need for safety protection, charging and discharging protection circuits are generally added in reality. Currently, the lithium battery pack protection board uses an IC (chip) + MOS tube circuit to protect the battery pack from charging and discharging.

[0003] Although the primary protection of the protection board is considered reliable, in reality, there is a certain rate of short-circuit failure of key components in the charge and discharge protection circuit, especially in ultra-high temperature conditions. Failure of key components in the protection circuit will cause varying degrees of damage to the battery pack. The amount of lithium batteries used in lithium battery packs is very large. If lithium batteries burn or even explode, it will bring serious consequences. Therefore, ensuring the safety of lithium batteries is an urgent matter. Summary of the invention

[0004] In order to solve the problems existing in the background technology, the utility model proposes a protection circuit for a lithium battery pack.

[0005] A protection circuit for a lithium battery pack comprises a battery pack, a battery management chip IC and a MOS tube, wherein the positive electrode of the battery pack is connected to the battery management chip IC, and the battery management chip IC controls the gate electrode connected to the MOS tube, and further comprises a three-terminal self-recovery fuse, a fuse control circuit and a protection detection unit, wherein the protection detection unit is arranged corresponding to the MOS tube and is used to detect safety information of the MOS tube, and the fuse control circuit controls the connection of the three-terminal self-recovery fuse according to the detection information of the protection detection unit; the positive electrode of the battery pack is connected to the source electrode of the MOS tube through the three-terminal self-recovery fuse.

[0006] Based on the above, the protection detection unit includes a PTC thermistor, the safety information is the temperature information of the MOS tube, and the PTC thermistor is connected to the fuse control circuit.

[0007] Based on the above, the protection detection unit includes a voltage stabilizing diode Z1, a PTC thermistor and a MOS tube Q4, one end of the voltage stabilizing diode Z1 is connected to the output end of the three-terminal self-recovery fuse, the other end of the voltage stabilizing diode Z1 is respectively connected to one end of the PTC thermistor and the source of the MOS tube Q4, the other end of the PTC thermistor and the gate of the MOS tube Q4 are respectively grounded through a resistor R3, the capacitor C2 is connected in parallel to both ends of the PTC thermistor, the drain of the MOS tube Q4 is connected to one end of the resistor R2, the other end of the resistor R2 is respectively grounded through the resistor R4 and the capacitor C3, and the other end of the resistor R2 is also connected to the fuse control circuit through a diode D1.

[0008] Based on the above, the fuse control circuit includes a MOS tube Q3, the drain of the MOS tube Q3 is controlled to be connected to a three-terminal self-recovery fuse, the source of the MOS tube Q3 is connected to the gate of the MOS tube Q3 through a resistor R1 and a capacitor C1 respectively, and the gate of the MOS tube Q3 is connected to a protection detection unit.

[0009] Based on the above, the battery management chip IC is connected to the gate of the MOS tube Q3 through the diode D2.

[0010] Based on the above, the MOS tube includes a MOS tube Q1 and a MOS tube Q2, the battery management chip IC controls the gates connected to the MOS tube Q1 and the MOS tube Q2, the source of the MOS tube Q1 is connected to the output end of the three-terminal self-recovery insurance, the drain of the MOS tube Q1 is connected to the drain of the MOS tube Q2, and the source of the MOS tube Q2 is used to connect to the electrical equipment.

[0011] The utility model has substantial characteristics and progress compared with the prior art. Specifically, the utility model adds a protection detection unit in the protection main circuit of the battery pack to detect the safety information of the MOS tube and protects the MOS tube according to the detection result. This not only improves the protection reliability of the battery pack, but also has a simple application scheme and has the advantages of simple structure, high reliability, safety and convenience. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a schematic diagram of the principle structure of the utility model.

[0013] Figure 2 The utility model is a circuit structure diagram of a protection detection unit and a fuse control circuit. DETAILED DESCRIPTION

[0014] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0015] like Figure 1 As shown, a protection circuit for a lithium battery pack includes a battery pack, a battery management chip IC and a MOS tube. The positive electrode of the battery pack is connected to the battery management chip IC, and the battery management chip IC controls the gate of the MOS tube. It also includes a three-terminal self-recovery fuse, a fuse control circuit and a protection detection unit. The protection detection unit is set corresponding to the MOS tube and is used to detect safety information of the MOS tube. The fuse control circuit controls the connection of the three-terminal self-recovery fuse according to the detection information of the protection detection unit; the positive electrode of the battery pack is connected to the source of the MOS tube through the three-terminal self-recovery fuse.

[0016] When in use, the protection detection unit is used to detect the change of the safety information of the MOS tube in the main circuit. When the change of the safety information of the MOS tube exceeds the preset value, the fuse control circuit (i.e. Figure 1 The Fuse control circuit in the battery management chip (B) actively controls the three-terminal self-recovery fuse to work and disconnects the three-terminal fuse of the main circuit according to the detection information, so that the main circuit MOS tube is protected to avoid the failure of the main circuit MOS tube or the protection failure of the battery management chip IC, which causes the MOS tube to be unable to be controlled.

[0017] Specifically, Figure 2 As shown, the protection detection unit includes a voltage stabilizing diode Z1, a PTC thermistor and a MOS tube Q4, and the fuse control circuit includes a MOS tube Q3. The PTC thermistor is set close to the MOS tube Q1 and the MOS tube Q2. When the battery is working normally, the resistance of the PTC thermistor is a stable 10KΩ, and the resistance of the resistor R3 is 1MΩ. The battery BAT voltage passes through the voltage stabilizing diode Z1 to prevent overvoltage from causing damage to components such as Q4. Under normal conditions, the voltage drop across the PTC thermistor is close to 0V. At this time, the MOS tube Q4 is turned off, and no driving signal BFUS1 is transmitted to the MOS tube Q3 of the fuse control circuit. The MOS tube Q3 is in a closed state, and the three-terminal self-recovery fuse Fuse is in a normal working state.

[0018] When the IC of the battery protection board fails or MOS tube 1 or MOS tube 2 fails, MOS tube Q1 and MOS tube Q2 are not fully turned on, and the DS end (drain, source) of MOS tube Q1 and MOS tube Q2 has Ω or 10Ω impedance. If the battery is charged and discharged with unlimited current or charged and discharged in an ultra-high temperature environment, the temperature of MOS tube Q1 and MOS tube Q2 will be very high after working for a period of time. At this time, the resistance of the PTC thermistor will also increase with the temperature of MOS tube Q1 or Q2. When the temperature increases, when it reaches about 105℃, the voltage U1 divided by the PTC thermistor and the resistor R3 turns on the PMOS tube Q4. After the turned-on U1 divides the voltage on the resistors R2 and R4, it turns on the MOS tube Q3 through the diode D1. At this time, the driving end of the three-terminal self-recovery fuse is at a low level, the three-terminal fuse is closed, the main circuit of the battery has no current, and the temperature of the MOS tube drops. In this way, there will be no risk of thermal explosion of the device and combustion or even explosion of the battery due to the continuous heating of the MOS tube Q1 or MOS tube Q2.

[0019] In reality, the MOS tube includes MOS tube Q1 and MOS tube Q2. The battery management chip IC controls the gates connected to MOS tube Q1 and MOS tube Q2. The source of MOS tube Q1 is connected to the output end of the three-terminal resettable fuse. The drain of MOS tube Q1 is connected to the drain of MOS tube Q2. The source of MOS tube Q2 is used to connect to the electrical equipment. The battery management chip IC and MOS tube Q1 and MOS tube Q2 serve as double protection for the battery pack. The PTC thermistor serves as the third protection for the battery pack. The multiple protections for the battery pack greatly improve the safety and reliability.

[0020] It is obvious to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be regarded as exemplary and non-restrictive from any point of view, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention. Any reference numeral in a claim should not be regarded as limiting the claim to which it relates.

Claims

1. A protection circuit for a lithium battery pack, comprising a battery pack, a battery management chip IC and a MOS tube, wherein the positive electrode of the battery pack is connected to the battery management chip IC, and the battery management chip IC controls the gate electrode connected to the MOS tube, characterized in that: It also includes a three-terminal self-recovery fuse, a fuse control circuit and a protection detection unit. The protection detection unit is set corresponding to the MOS tube and is used to detect the safety information of the MOS tube. The fuse control circuit controls the connection of the three-terminal self-recovery fuse according to the detection information of the protection detection unit; the positive electrode of the battery pack is connected to the source electrode of the MOS tube through the three-terminal self-recovery fuse.

2. The protection circuit for a lithium battery pack according to claim 1, characterized in that: The protection detection unit includes a PTC thermistor, the safety information is the temperature information of the MOS tube, and the PTC thermistor is connected to the fuse control circuit.

3. The protection circuit for a lithium battery pack according to claim 1, characterized in that: The protection detection unit includes a voltage stabilizing diode Z1, a PTC thermistor and a MOS tube Q4. One end of the voltage stabilizing diode Z1 is connected to the output end of the three-terminal self-recovery fuse. The other end of the voltage stabilizing diode Z1 is respectively connected to one end of the PTC thermistor and the source of the MOS tube Q4. The other end of the PTC thermistor and the gate of the MOS tube Q4 are respectively grounded through a resistor R3. The capacitor C2 is connected in parallel to both ends of the PTC thermistor. The drain of the MOS tube Q4 is connected to one end of the resistor R2. The other end of the resistor R2 is respectively grounded through the resistor R4 and the capacitor C3. The other end of the resistor R2 is also connected to the fuse control circuit through a diode D1.

4. The protection circuit for a lithium battery pack according to claim 1, characterized in that: The fuse control circuit includes a MOS tube Q3, the drain of the MOS tube Q3 is controlled to be connected to a three-terminal self-recovery fuse, the source of the MOS tube Q3 is connected to the gate of the MOS tube Q3 through a resistor R1 and a capacitor C1, and the gate of the MOS tube Q3 is connected to a protection detection unit.

5. The protection circuit for a lithium battery pack according to claim 4, characterized in that: The battery management chip IC is connected to the gate of the MOS tube Q3 through the diode D2.

6. The protection circuit for a lithium battery pack according to claim 1, characterized in that: The MOS tube includes a MOS tube Q1 and a MOS tube Q2. The battery management chip IC controls the gates connected to the MOS tube Q1 and the MOS tube Q2. The source of the MOS tube Q1 is connected to the output end of the three-terminal self-recovery fuse. The drain of the MOS tube Q1 is connected to the drain of the MOS tube Q2. The source of the MOS tube Q2 is used to connect to the electrical equipment.

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