Lithium battery three-terminal protection circuit

Abstract

The lithium battery three-terminal protection circuit comprises a three-terminal fuse, a switch unit, an opening and closing control unit, an energy storage capacitor and a single-chip microcomputer which are connected in sequence, the single-chip microcomputer is connected with a battery, the switch unit comprises a first MOS tube, a drain electrode of the first MOS tube is connected with the three-terminal fuse, a grid electrode of the first MOS tube is connected with the opening and closing control unit, and a source electrode of the first MOS tube is connected with a grounding terminal; the single-chip microcomputer is used for sending a PWM control signal to the energy storage capacitor to control the energy storage capacitor to discharge when it is detected that the battery is abnormal, the opening and closing control unit is opened to control the first MOS tube to be conducted, and the first MOS tube is conducted to pull down a voltage signal of the three-terminal fuse so that the three-terminal fuse can be fused. The battery is detected through the single-chip microcomputer, and the energy storage capacitor is controlled to discharge when the battery is detected to be abnormal, so that the opening and closing control unit is opened, the first MOS tube is conducted to pull down a voltage signal of the three-terminal fuse, the three-terminal fuse is fused, the battery state is comprehensively detected, the circuit is cut off in time when the battery is abnormal, and potential safety hazards are eliminated.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of battery protection technology, and in particular to a three-terminal protection circuit for a lithium battery. Background Art

[0002] Lithium-ion battery is a secondary battery (rechargeable battery), which mainly relies on the movement of lithium ions between the positive electrode and the negative electrode to work. During the charge and discharge process, Li+ is embedded and de-embedded between the two electrodes: when charging, Li+ is de-embedded from the positive electrode and embedded into the negative electrode through the electrolyte, and the negative electrode is in a lithium-rich state; when discharging, the opposite is true. Lithium batteries are equipped with protection circuits, but the existing lithium battery protection circuits are directly protected by fuses. Although the operation is simple, it is not flexible enough. It can only be protected when the fuse is blown, and the protection value cannot be manipulated at will. Utility Model Content

[0003] The embodiment of the present application provides a three-terminal protection circuit for a lithium battery to solve the problem that the existing lithium battery protection circuit is not flexible enough and can only provide protection when the fuse is blown, and the protection value cannot be arbitrarily controlled.

[0004] In a first aspect, an embodiment of the present application provides a three-terminal protection circuit for a lithium battery, comprising a three-terminal fuse, a switch unit, an on-off control unit, an energy storage capacitor and a single-chip microcomputer connected in sequence, wherein the single-chip microcomputer is connected to a battery, the switch unit comprises a first MOS tube, the drain of the first MOS tube is connected to the three-terminal fuse, the gate is connected to the on-off control unit, and the source is connected to a ground terminal; the single-chip microcomputer is used to send a PWM control signal to the energy storage capacitor to control the discharge of the energy storage capacitor when an abnormality of the battery is detected, the on-off control unit is turned on to control the first MOS tube to be turned on, and the first MOS tube is turned on to pull down the voltage signal of the three-terminal fuse so that the three-terminal fuse is blown.

[0005] In some embodiments, the switch unit further includes a first diode, an anode of the first diode is connected to the three-terminal fuse, and a cathode of the first diode is connected to the drain of the first MOS tube.

[0006] In some embodiments, the opening and closing control unit includes a first transistor, a first resistor, a second resistor, a third resistor and a fourth resistor, the emitter of the first transistor is connected to the first end of the third resistor, the first end of the fourth resistor and the power supply end, the base is connected to the first end of the second resistor, the collector is connected to the first end of the first resistor and the gate of the first MOS tube, the second end of the first resistor is connected to the ground end, and the second end of the third resistor is connected to the second end of the second resistor and the second end of the fourth resistor.

[0007] In some embodiments, a first filtering unit is further included, the first filtering unit includes a second capacitor, a first end of the second capacitor is connected to the emitter of the first transistor, and a second end of the second capacitor is connected to the second end of the second resistor.

[0008] In some embodiments, a second filtering unit is further included, the second filtering unit includes a first capacitor, a first end of the first capacitor is connected to the gate of the first MOS tube, and a second end of the first capacitor is connected to the source of the first MOS tube and a ground terminal.

[0009] In some embodiments, a first protection unit is further included, the first protection unit includes a fifth resistor, a first end of the fifth resistor is connected to the first end of the energy storage capacitor, and a second end of the fifth resistor is connected to the single chip microcomputer.

[0010] In some embodiments, the first protection unit further includes a second diode, an anode of the second diode is connected to the second end of the second resistor, and a cathode of the second diode is connected to the second end of the energy storage capacitor.

[0011] In some embodiments, the first MOS transistor is an N-type MOS transistor.

[0012] In some embodiments, the first transistor is an N-type transistor.

[0013] In some embodiments, the first diode is an anti-reverse diode.

[0014] The embodiment of the present application detects the battery through a single-chip microcomputer, and controls the energy storage capacitor to discharge when a battery abnormality is detected, so that the switch control unit is opened, and the first MOS tube is turned on to lower the voltage signal of the three-terminal fuse, so that the three-terminal fuse is blown, thereby realizing comprehensive detection of the battery status, timely cutting off the circuit when the battery is abnormal, eliminating safety hazards, reducing the charging and discharging of the battery in abnormal status, and more effectively protecting the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a circuit structure diagram of a lithium battery three-terminal protection circuit provided in an embodiment of the present application. DETAILED DESCRIPTION

[0016] In order to make the purpose, technical scheme and advantages of the present application clearer, the specific embodiments of the present application are further described in detail below in conjunction with the accompanying drawings. It is understood that the specific embodiments described herein are only used to explain the present application, rather than to limit the present application. It should also be noted that, for the convenience of description, only the part related to the present application but not all the contents are shown in the accompanying drawings. Before discussing the exemplary embodiments in more detail, it should be mentioned that some exemplary embodiments are described as processes or methods depicted as flow charts. Although the flow chart describes each operation (or step) as a sequential process, many of the operations therein can be implemented in parallel, concurrently or simultaneously. In addition, the order of each operation can be rearranged. The process can be terminated when its operation is completed, but it can also have additional steps not included in the accompanying drawings. The process can correspond to a method, a function, a procedure, a subroutine, a subprogram, etc.

[0017] The lithium battery three-terminal protection circuit of the embodiment of the present application is provided to avoid the problem that the existing lithium battery protection circuit is not flexible enough and can only provide protection at the fuse melting value, and the protection value cannot be arbitrarily controlled.

[0018] Figure 1 A schematic diagram of the circuit structure of a lithium battery three-terminal protection circuit provided in an embodiment of the present application. Figure 1 The lithium battery three-terminal protection circuit comprises a three-terminal fuse F2, a switch unit, an on-off control unit, an energy storage capacitor C3 and a single-chip microcomputer connected in sequence, wherein the single-chip microcomputer is connected to the battery, the switch unit comprises a first MOS tube QS1, the drain of the first MOS tube QS1 is connected to the three-terminal fuse F2, the gate is connected to the on-off control unit, and the source is connected to the ground terminal; the single-chip microcomputer is used to send a PWM control signal to the energy storage capacitor C3 to control the discharge of the energy storage capacitor C3 when detecting battery abnormality, the on-off control unit is turned on to control the first MOS tube QS1 to be turned on, and the first MOS is turned on to pull down the voltage signal of the three-terminal fuse F2 so that the three-terminal fuse F2 is blown.

[0019] As described above, the embodiment of the present application detects the battery through the single-chip microcomputer, and controls the energy storage capacitor C3 to discharge when a battery abnormality is detected, so that the switch control unit is opened, and the first MOS tube QS1 is turned on to lower the voltage signal of the three-terminal fuse F2, so that the three-terminal fuse F2 is melted, thereby realizing comprehensive detection of the battery status, timely cutting off the circuit when the battery is abnormal, eliminating safety hazards, reducing the charging and discharging of the battery in an abnormal state, and more effectively protecting the battery.

[0020] Among them, the switching unit also includes a first diode D1; the opening and closing control unit includes a first transistor QS2, a first resistor R1, a second resistor R2, a third resistor R3 and a fourth resistor R4; it also includes a first filtering unit, the first filtering unit includes a second capacitor C2; it also includes a second filtering unit, the second filtering unit includes a first capacitor C1; it also includes a first protection unit, the first protection unit includes a fifth resistor R5 and a second diode D2.

[0021] Specifically, the anode of the first diode D1 is connected to the three-terminal fuse F2, and the cathode of the first diode D1 is connected to the drain of the first MOS switch; the emitter of the first transistor QS2 is connected to the first end of the third resistor R3, the first end of the second capacitor C2, the first end of the fourth resistor R4 and the power supply end, the base is connected to the first end of the second resistor R2, the collector is connected to the first end of the first resistor R1, the first end of the first capacitor C1 and the gate of the first MOS transistor QS1, the second end of the first resistor R1 is connected to the second end of the first capacitor C1, the source of the first MOS transistor QS1 and the ground end, the second end of the third resistor R3 is connected to the second end of the second resistor R2, the second end of the second capacitor C2 and the anode of the second diode D2, the second end of the fourth resistor R4 is connected to the cathode of the second diode D2 and the second end of the energy storage capacitor C3; the first end of the fifth resistor R5 is connected to the first end of the energy storage capacitor C3, and the second end of the fifth resistor R5 is connected to the single chip computer.

[0022] As described above, the embodiment of the present application uses a three-terminal fuse F2, two filter capacitors (a first capacitor C1 and a second capacitor C2), a storage capacitor C3, a throttling MOS tube (a first MOS tube QS1), an N-type transistor (a first transistor QS2), two anti-reverse diodes (a first diode D1 and a second diode D2), and 5 voltage-dividing resistors (a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, and a fifth resistor R5), which together form a common collector amplifier circuit to control the switch MOS to open. Open; when an abnormal battery state is detected, the single chip microcomputer gives a control signal, the energy storage capacitor C3 releases the energy, the first transistor QS2 opens, and then controls the first MOS tube QS1 to open, the three-terminal control signal is pulled low, and then the three-terminal fuse F2 is blown, the B+ terminal and the B+F terminal of the three-terminal fuse F2 are short-circuited, and the charging and discharging port is closed. By real-time detection of a certain parameter of the lithium battery, the three terminals are blown to protect the battery. By comprehensive monitoring of over-voltage, under-voltage, charging and discharging over-current, over-temperature and under-temperature, the program changes the protection value, and the application is more flexible.

[0023] It can be understood that a lithium battery three-terminal protection circuit of an embodiment of the present application can be applied to a lithium battery protection circuit, wherein the fifth resistor R5 is a current limiting resistor, C3 is an energy storage capacitor C3, the first resistor R1, the second resistor R2, the third resistor R3, the fourth resistor R4 and the first transistor QS2 form a common emitter amplifier circuit to amplify the input signal, and the first MOS tube QS1 is controlled by the first resistor R1 voltage divider drive, the first diode D1 and the second diode D2 are anti-reverse diodes, the first capacitor C1 and the second capacitor C2 are filter capacitors, and F2 is a three-terminal fuse F2; when the circuit is started, the microcontroller needs to send a PWM waveform (SEC CTRL), at this time, the energy storage capacitor C3 is continuously in the charging and discharging state. When PWM increases to a certain extent, the energy storage capacitor C3 is in the charging state for a longer time, the common-emitter amplifier circuit continues to amplify the signal, and the first MOS tube QS1 is turned on for a longer time. At this time, the three-terminal signal is pulled low, and the three-terminal fuse F2 is damaged for protection; the embodiment of the present application actively detects the charging and discharging overcurrent state, over-voltage state, over-temperature and under-temperature state of the battery and gives timely feedback. When the state is abnormal, the circuit is cut off in time to eliminate safety hazards, thereby more effectively protecting the battery, reducing the charging and discharging of the battery in abnormal state, and reducing the occurrence of safety accidents.

[0024] As a preferred implementation, the first MOS transistor QS1 is an N-type MOS transistor; the first transistor QS2 is an N-type transistor.

[0025] The above are only preferred embodiments of the present application and the technical principles used. The present application is not limited to the specific embodiments described herein, and various obvious changes, readjustments and substitutions that can be made by those skilled in the art will not deviate from the scope of protection of the present application. Therefore, although the present application is described in more detail through the above embodiments, the present application is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present application, and the scope of the present application is determined by the scope of the claims.

Claims

1. A lithium battery three-terminal protection circuit, It is characterized in that The invention comprises a three-terminal fuse, a switch unit, an on-off control unit, an energy storage capacitor and a single-chip microcomputer connected in sequence, wherein the single-chip microcomputer is connected to a battery, the switch unit comprises a first MOS tube, a drain of the first MOS tube is connected to the three-terminal fuse, a gate is connected to the on-off control unit, and a source is connected to a ground terminal; the single-chip microcomputer is used to send a PWM control signal to the energy storage capacitor to control the discharge of the energy storage capacitor when an abnormality of the battery is detected, the on-off control unit is turned on to control the first MOS tube to be turned on, and the first MOS tube is turned on to lower the voltage signal of the three-terminal fuse so that the three-terminal fuse is blown.

2. The lithium battery three-terminal protection circuit according to claim 1, It is characterized in that The switch unit further includes a first diode, an anode of the first diode is connected to the three-terminal fuse, and a cathode of the first diode is connected to the drain of the first MOS tube.

3. The lithium battery three-terminal protection circuit according to claim 1, It is characterized in that The opening and closing control unit includes a first triode, a first resistor, a second resistor, a third resistor and a fourth resistor, the emitter of the first triode is connected to the first end of the third resistor, the first end of the fourth resistor and the power supply end, the base is connected to the first end of the second resistor, the collector is connected to the first end of the first resistor and the gate of the first MOS tube, the second end of the first resistor is connected to the ground end, and the second end of the third resistor is connected to the second end of the second resistor and the second end of the fourth resistor.

4. The lithium battery three-terminal protection circuit according to claim 3, It is characterized in that It also includes a first filtering unit, which includes a second capacitor, a first end of the second capacitor is connected to the emitter of the first transistor, and a second end of the second capacitor is connected to the second end of the second resistor.

5. The lithium battery three-terminal protection circuit according to claim 1, It is characterized in that It also includes a second filtering unit, which includes a first capacitor, a first end of which is connected to the gate of the first MOS tube, and a second end of which is connected to the source of the first MOS tube and a ground terminal.

6. The lithium battery three-terminal protection circuit according to claim 3, It is characterized in that It also includes a first protection unit, which includes a fifth resistor, a first end of the fifth resistor is connected to the first end of the energy storage capacitor, and a second end of the fifth resistor is connected to the single chip microcomputer.

7. The lithium battery three-terminal protection circuit according to claim 6, It is characterized in that The first protection unit further includes a second diode, an anode of the second diode is connected to the second end of the second resistor, and a cathode of the second diode is connected to the second end of the energy storage capacitor.

8. The lithium battery three-terminal protection circuit according to claim 1, It is characterized in that The first MOS tube is an N-type MOS tube.

9. The lithium battery three-terminal protection circuit according to claim 3, It is characterized in that The first transistor is an N-type transistor.

10. The lithium battery three-terminal protection circuit according to claim 2, It is characterized in that The first diode is an anti-reverse diode.

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