Charging overvoltage protection circuit of battery management system and battery management system

Abstract

The utility model discloses a charging overvoltage protection circuit of a battery management system and the battery management system. The charging overvoltage protection circuit comprises a power supply module, a battery management system switch loop and a charging overvoltage protection module. The battery management system switch loop comprises an input end and an output end, and the battery management system switch loop turns off the power supply input of the power supply module according to the control of the battery management system; the output end of the switch loop of the battery management system is used as an output positive electrode P + and an output negative electrode P-of the charging overvoltage protection circuit of the battery management system; the input end of the charging overvoltage protection module is connected with an output positive electrode P + and an output negative electrode P-, the charging overvoltage protection module outputs an overhigh voltage signal to the battery management system switch loop when the voltage of the input end exceeds a preset voltage value, and the battery management system switch loop keeps being disconnected according to the received overhigh voltage signal. And charging overvoltage of the power module is avoided.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of battery management systems, and particularly relates to a charging overvoltage protection circuit of a battery management system and the battery management system. BACKGROUND

[0002] In current lithium battery applications, there is basically no operation of monitoring and collecting the voltages of the total positive end and the total negative end of a battery pack. The main reason is that the BMS (Battery Management System) generally takes the B-end of the battery as the ground end GND of the entire system. When the MOS of the main loop is turned off, the total negative end P- of the battery pack is in a floating state relative to the entire system. When it is necessary to measure some voltages related to the total negative end P- of the battery pack, there is no common ground, which leads to the inability to measure or collect the voltages of the total positive end and the total negative end of the battery pack. However, more and more applications need to monitor the voltages of the total positive end P+ and the total negative end P- of the battery pack to prevent some problems caused by excessively high external access voltage and to maintain the safe use of the entire system.

[0003] For example, in a 12V battery system, if the user accesses a charging voltage of 24V, which is much higher than the standard charging voltage of 14.4V. At this time, if the voltages of the total positive end P+ and the total negative end P- of the battery pack cannot be monitored, the possible problems are: 1. The excessively high charging voltage may cause the charging current to be too large when the charging is started, leading to system protection and even damage to the battery system; 2. If the battery has a heating module, when heating is needed, the voltage at this time has exceeded the rated voltage of the heating film, and when a higher voltage is supplied to the heating film, the power of the heating film may be too high, leading to burning of the heating film and even causing thermal runaway of the battery. Therefore, it is necessary to monitor the voltages of the total positive end P+ and the total negative end P- of the battery pack. CONTENT OF THE UTILITY MODEL

[0004] In order to overcome the deficiencies of the prior art, the application provides a charging overvoltage protection circuit of a battery management system and a battery management system, which can monitor and charge overvoltage protection for the voltages of the total positive end P+ and the total negative end P- of the battery pack.

[0005] The utility model provides a kind of charging overvoltage protection circuit of battery management system, including power module, battery management system switch loop and charging overvoltage protection module;

[0006] The power module provides power supply for the entire charging overvoltage protection circuit of the battery management system, the power module receives external power supply to charge, and the negative electrode of the power module serves as the ground end of the charging overvoltage protection circuit of the battery management system.

[0007] The battery management system switch circuit includes an input end and an output end, the input end of the battery management system switch circuit is connected to the power module, and the battery management system switch circuit turns off the power input of the power module according to the control of the battery management system; the output end of the battery management system switch circuit serves as an output positive electrode P+ and an output negative electrode P- of the charge overvoltage protection circuit of the battery management system.

[0008] The charge overvoltage protection module includes an input end and an output end, the input end of the charge overvoltage protection module is connected to the output positive electrode P+ and the output negative electrode P-, the output positive electrode P+ and the output negative electrode P- serve as a positive electrode and a negative electrode of a charging voltage respectively, the output end of the charge overvoltage protection module is connected to the output end of the battery management system switch circuit, and the charge overvoltage protection module outputs a voltage overhigh signal to the battery management system switch circuit when the voltage of the input end exceeds a preset voltage value, so that the battery management system switch circuit keeps the switch circuit disconnected according to the received voltage overhigh signal, thereby avoiding the charging overvoltage of the power module.

[0009] Further, the power module includes a rechargeable battery pack.

[0010] Further, the battery management system switch circuit includes a battery management system, a seventh resistor R7 and a switch unit.

[0011] One end of the seventh resistor R7 is connected to the negative electrode of the power module, the other end of the seventh resistor R7 is connected to the switch unit, the other end of the switch unit is connected to the charge overvoltage protection module, and the positive electrode of the power module is connected to the charge overvoltage protection module.

[0012] The battery management system is connected to the positive electrode and the negative electrode of the battery module to collect the voltage of the power module, the battery management system is connected to both ends of the seventh resistor R7 to collect the current of the seventh resistor R7, and the battery management system is connected to the switch unit.

[0013] Further, the switch unit includes a fifth switch tube Q5, a sixth switch tube Q6 and a TVS diode TVS1.

[0014] The gate of the fifth switch tube Q5 is connected to the battery management system, one end of the TVS diode TVS1 is connected to the source of the fifth switch tube Q5, and the drain of the fifth switch tube Q5 is connected to the drain of the sixth switch tube Q6; the gate of the sixth switch tube Q6 is connected to the battery management system, the other end of the TVS diode TVS1 is connected to the source of the sixth switch tube Q6; and the source of the fifth switch tube Q5 is connected to one end of the seventh resistor R7, and the source of the sixth switch tube Q6 is connected to the charge overvoltage protection module.

[0015] Furthermore, the fifth switch tube Q5 and the sixth switch tube Q6 are both NMOS tubes.

[0016] Furthermore, the charging overvoltage protection module includes a first voltage protection unit, a second voltage protection unit and a third voltage protection unit;

[0017] The input end of the first voltage protection unit is connected to the output positive electrode P+ and the output negative electrode P-, and the first voltage protection unit is turned on when the charging voltage between the output positive electrode P+ and the output negative electrode P- exceeds a preset voltage value; the output end of the first voltage protection unit is connected to the input end of the second voltage protection unit, and the second voltage protection unit is turned on according to the turn-on voltage of the first voltage protection unit; the output end of the second voltage protection unit is connected to the input end of the third voltage protection unit, and the third voltage protection unit is turned on according to the turn-on voltage of the second voltage protection unit, and the output end of the third voltage protection unit is connected to the battery management system switch circuit and outputs an overvoltage signal to the battery management system switch circuit.

[0018] Furthermore, the first voltage protection unit includes a second resistor R2, a sixth resistor R6, a first voltage stabilizing diode ZD1 and a second diode D2;

[0019] One end of the second resistor R2 is connected to the output positive electrode P+ and connected to the positive electrode of the charging voltage, the other end of the second resistor R2 is connected to the negative electrode of the first voltage regulator diode ZD1, the positive electrode of the first voltage regulator diode ZD1 is connected to one end of the sixth resistor R6, the other end of the sixth resistor R6 is connected to the positive electrode of the second diode D2, and the negative electrode of the second diode D2 is connected to the output negative electrode P- and the negative electrode of the power module; the output negative electrode P- is connected to the negative electrode of the charging voltage.

[0020] Furthermore, the second voltage protection unit includes a first resistor R1, a fourth resistor R4 and a second switch tube Q2; the second switch tube Q2 is an NPN transistor;

[0021] One end of the first resistor R1 is connected to the output positive electrode P+, ​​the other end of the first resistor R1 is connected to the fourth resistor R4, the other end of the fourth resistor R4 is connected to the collector of the second switch tube Q2, the base of the second switch tube Q2 is connected to the anode of the first voltage regulator diode ZD1, and the emitter of the second switch tube Q2 is connected to the anode of the second diode D2.

[0022] Furthermore, the third voltage protection unit includes a first switch tube Q1, a fifth resistor R5, a first photocoupler OP1 and a first diode D1; the first switch tube Q1 is a PMOS tube;

[0023] The gate of the first switching tube Q1 is connected between the first resistor R1 and the fourth resistor R4, the source of the first switching tube Q1 is connected to the output positive electrode P+, ​​the drain of the first switching tube Q1 is connected to one end of the fifth resistor R5, the other end of the fifth resistor R5 is connected to pin 1 of the light source of the first photocoupler OP1, pin 2 of the light source of the first photocoupler OP1 is connected to the anode of the second diode D2, pin 3 of the light receiver of the first photocoupler OP1 is grounded, pin 4 of the light receiver of the first photocoupler OP1 is connected to the cathode of the first diode D1, and the anode of the first diode D1 is connected to the battery management system switch circuit.

[0024] The present application also provides a battery management system, which includes the charging overvoltage protection circuit and the battery heating module of the battery management system described in the present application;

[0025] The battery heating module includes a third resistor R3, a third switch tube Q3, and a fourth switch tube Q4. The third resistor R3 is a heating resistor. The third switch tube Q3 and the fourth switch tube Q4 are both NMOS tubes.

[0026] One end of the third resistor R3 is connected to the output positive electrode P+ of the charging overvoltage protection circuit of the battery management system, the other end of the third resistor R3 is connected to the source of the third switch tube Q3, the gate of the third switch tube Q3 is connected to the battery management system of the charging overvoltage protection circuit of the battery management system, the drain of the third switch tube Q3 is connected to the drain of the fourth switch tube Q4, the gate of the fourth switch tube Q4 is connected to the battery management system, and the source of the fourth switch tube Q4 is connected to the output negative electrode P- of the charging overvoltage protection circuit of the battery management system.

[0027] The beneficial effects of the present invention are as follows: This application provides a charging overvoltage protection circuit for a battery management system and a battery management system. The charging overvoltage protection circuit detects the charging voltage value at the input end through a charging overvoltage protection module. If the charging voltage at the output end exceeds a preset value, an overvoltage signal is output to the battery management system and the switch circuit of the battery management system is disconnected to prevent battery overvoltage. In addition, the charging overvoltage protection circuit has a simple structure and is relatively low in cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The following detailed description of the specific embodiments of the present application in conjunction with the accompanying drawings will make the technical solutions and other beneficial effects of the present application apparent.

[0029] Figure 1 This is a schematic diagram of the structure of the charging overvoltage protection circuit of the battery management system provided in this embodiment.

[0030] Figure 2 This is a schematic diagram of the first voltage protection unit circuit provided in this embodiment.

[0031] Figure 3 This is a schematic diagram of the second voltage protection unit circuit provided in this embodiment.

[0032] Figure 4 This is a schematic diagram of the third voltage protection unit circuit provided in this embodiment. DETAILED DESCRIPTION

[0033] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the embodiments described are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative efforts are within the scope of protection of this application.

[0034] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the said features. In the description of the present application, "multiple" means two or more, unless otherwise clearly and specifically defined.

[0035] The disclosure below provides many different embodiments or examples for realizing different structures of the present application. In order to simplify the disclosure of the present application, the components and settings of specific examples are described below. Of course, they are merely examples and are not intended to limit the present application. In addition, the present application may repeat reference numbers and / or reference letters in different examples, and such repetition is for the purpose of simplicity and clarity, and does not itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the present application provides examples of various specific processes and materials, but those of ordinary skill in the art will appreciate the application of other processes and / or the use of other materials.

[0036] The present invention will now be further described with reference to the accompanying drawings and specific implementation methods.

[0037] like Figure 1 , which is a schematic structural diagram of a charging overvoltage protection circuit of a battery management system provided in this embodiment. The charging overvoltage protection circuit includes: a power module, a battery management system switch circuit, and a charging overvoltage protection module.

[0038] The power module provides power to the entire battery management system's overvoltage protection circuit. The power module receives external power for charging, and the negative electrode of the power module serves as the ground terminal for the battery management system's overvoltage protection circuit. The power module includes a rechargeable battery pack. The battery pack may include multiple battery packs, with the negative electrodes of the battery packs serving as ground terminals.

[0039] The battery management system switch circuit includes an input end and an output end. The input end of the battery management system switch circuit is connected to the power module, and the battery management system switch circuit cuts off the power input of the power module according to the control of the battery management system; the output end of the battery management system switch circuit serves as the output positive electrode P+ and the output negative electrode P- of the charging overvoltage protection circuit of the battery management system.

[0040] The charging overvoltage protection module includes an input end and an output end. The input end of the charging overvoltage protection module is connected to the output positive electrode P+ and the output negative electrode P-. The output positive electrode P+ and the output negative electrode P- serve as the positive electrode and negative electrode of the charging voltage, respectively. The output end of the charging overvoltage protection module is connected to the output end of the battery management system switch circuit. When the voltage of the input end exceeds a preset voltage value, the charging overvoltage protection module outputs an overvoltage signal to the battery management system switch circuit. The battery management system switch circuit keeps the switch circuit disconnected according to the received overvoltage signal to prevent the power module from overcharging.

[0041] Specifically, if Figure 1As shown, the battery management system switch circuit includes a battery management system BMS, a seventh resistor R7, and a switch unit. One end of the seventh resistor R7 is connected to the negative pole of the power module, the other end of the seventh resistor R7 is connected to the switch unit, and the other end of the switch unit is connected to the charging overvoltage protection module; the positive pole of the power module is connected to the charging overvoltage protection module; the battery management system is connected to the positive pole and the negative pole of the battery module, and the voltage of the power module is collected; the battery management system is connected to both ends of the seventh resistor R7, and the current of the seventh resistor R7 is collected; and the battery management system is connected to the switch unit.

[0042] The switch unit includes a fifth switch tube Q5, a sixth switch tube Q6, and a TVS diode TVS1. The gate of the fifth switch tube Q5 is connected to the battery management system, the source of the fifth switch tube Q5 is connected to one end of the TVS diode TVS1, and the drain of the fifth switch tube Q5 is connected to the drain of the sixth switch tube Q6; the gate of the sixth switch tube Q6 is connected to the battery management system, and the source of the sixth switch tube Q6 is connected to the other end of the TVS diode TVS1; the source of the fifth switch tube Q5 is connected to one end of the seventh resistor R7, and the source of the sixth switch tube Q6 is connected to the charging overvoltage protection module.

[0043] In this embodiment, the fifth switch tube Q5 and the sixth switch tube Q6 are both NMOS tubes.

[0044] As shown, Figure 1 The charging overvoltage protection module includes a first voltage protection unit, a second voltage protection unit, and a third voltage protection unit; the input end of the first voltage protection unit is connected to the output positive pole P+ and the output negative pole P-, and the first voltage protection unit is turned on when the charging voltage between the output positive pole P+ and the output negative pole P- exceeds the preset voltage value; the output end of the first voltage protection unit is connected to the input end of the second voltage protection unit, and the second voltage protection unit is turned on according to the turn-on voltage of the first voltage protection unit; the output end of the second voltage protection unit is connected to the input end of the third voltage protection unit, and the third voltage protection unit is turned on according to the turn-on voltage of the second voltage protection unit, and the output end of the third voltage protection unit is connected to the battery management system switch circuit and outputs a voltage too high signal to the battery management system switch circuit.

[0045] Specifically, the first voltage protection unit includes a second resistor R2, a sixth resistor R6, a first voltage zener diode ZD1 and a second diode D2; one end of the second resistor R2 is connected to the output positive electrode P+ and connected to the positive electrode of the charging voltage, the other end of the second resistor R2 is connected to the negative electrode of the first voltage zener diode ZD1, the positive electrode of the first voltage zener diode ZD1 is connected to one end of the sixth resistor R6, the other end of the sixth resistor R6 is connected to the positive electrode of the second diode D2, and the negative electrode of the second diode D2 is connected to the output negative electrode P- and the negative electrode of the power module; the output negative electrode P- is connected to the negative electrode of the charging voltage.

[0046] The second voltage protection unit includes a first resistor R1, a fourth resistor R4 and a second switch tube Q2; wherein the second switch tube Q2 is an NPN-type transistor; one end of the first resistor R1 is connected to the output positive electrode P+, ​​the other end of the first resistor R1 is connected to the fourth resistor R4, the other end of the fourth resistor R4 is connected to the collector of the second switch tube Q2, the base of the second switch tube Q2 is connected to the anode of the first voltage regulator diode ZD1, and the emitter of the second switch tube Q2 is connected to the anode of the second diode D2.

[0047] The third voltage protection unit includes a first switching tube Q1, a fifth resistor R5, a first photocoupler OP1 and a first diode D1; the first switching tube Q1 is a PMOS tube; the gate of the first switching tube Q1 is connected between the first resistor R1 and the fourth resistor R4, the source of the first switching tube Q1 is connected to the output positive electrode P+, ​​the drain of the first switching tube Q1 is connected to one end of the fifth resistor R5, the other end of the fifth resistor R5 is connected to pin 1 of the light source of the first photocoupler OP1, pin 2 of the light source of the first photocoupler OP1 is connected to the anode of the second diode D2, pin 3 of the light receiver of the first photocoupler OP1 is grounded, pin 4 of the light receiver of the first photocoupler OP1 is connected to the cathode of the first diode D1, and the anode of the first diode D1 is connected to the battery management system switch circuit.

[0048] In this embodiment, the breakdown voltage of the first voltage zener diode ZD1 and the forward voltage drop of the second diode D2 in the first voltage protection unit can be set according to the overvoltage reference value of the power module, that is, the breakdown voltage of the first voltage zener diode ZD1 and the forward voltage drop of the second diode D2 are less than the minimum overvoltage value of the power module.

[0049] In particular, the charging overvoltage protection circuit of the battery management system described in this embodiment further includes a battery heating module, and the battery heating module is connected to the charging overvoltage protection module.

[0050] like Figure 1 As shown, the battery heating module includes a third resistor R3, a third switch tube Q3, and a fourth switch tube Q4. The third resistor R3 is a heating resistor, and the third and fourth switches Q3 and Q4 are both NMOS transistors. One end of the third resistor R3 is connected to the positive output electrode P+ of the battery management system's overvoltage protection circuit. The other end of the third resistor R3 is connected to the source of the third switch tube Q3. The gate of the third switch tube Q3 is connected to the battery management system's overvoltage protection circuit. The drain of the third switch tube Q3 is connected to the drain of the fourth switch tube Q4. The gate of the fourth switch tube Q4 is connected to the battery management system. The source of the fourth switch tube Q4 is connected to the negative output electrode P- of the battery management system's overvoltage protection circuit.

[0051] The working principle of the charging overvoltage protection circuit of the battery management system provided in this embodiment is as follows:

[0052] like Figure 2 As shown in FIG, when the switch unit in the battery management system switch circuit is closed, if the external charging voltage Vin is connected at this time, when the external charging voltage Vin is too high, and the charging voltage Vin is greater than the sum of the breakdown voltage Vzd1 of the first voltage stabilizing diode ZD1 and the forward voltage drop Vd2 of the second diode D2, that is, Vin>Vzd1+Vd2, the first voltage stabilizing diode ZD1 will be turned on, forming the following Figure 2 In the circuit shown, the first voltage protection unit is turned on, and at this time the sixth resistor R6 will obtain a certain divided voltage.

[0053] like Figure 3 As shown, when the voltage on the sixth resistor R6 reaches the turn-on voltage of the second switch tube Q2 in the second voltage protection unit, the second switch tube Q2 is turned on, thereby turning on the second voltage protection unit. At this time, the collector and emitter loops of the second switch tube Q2 are also turned on, forming the following Figure 3 The circuit shown.

[0054] like Figure 4 As shown, after the second voltage protection unit is turned on, when the divided voltage on the first resistor reaches the turn-on voltage of the first switch tube Q1 in the third voltage protection unit, the first switch tube Q1 is turned on, and the source and drain circuits of the first switch tube Q1 are turned on, thereby turning on pins 1 and 2 of the light source of the first optocoupler OP1, forming the following Figure 4 The circuit shown.

[0055] When the first switch Q1 is turned on, the light source of the first photocoupler OP1 is turned on and emits light, and the light receiver of the first photocoupler OP1 is also turned on after receiving light. At this time, the external MCU signal can be pulled down to ground by the first photocoupler OP1 through the first diode D1. At this point, the battery management system BMS can successfully receive the signal indicating that the external charging voltage is too high. At the same time, the first diode D1 can synchronously and directly control the heating MOS tube signal of the battery heating module through electrical connection.

[0056] At this point, the battery management system (BMS) can detect signals indicating an external charging voltage is too high. When the external charging voltage Vin is too high, the BMS controls the battery management system switch circuit to keep the MOS in the switch unit in the off state, preventing overcharging of the power module. Simultaneously, the BMS can also control the third and fourth switching transistors Q3 and Q4 in the battery heating module to remain off, avoiding a series of dangers caused by overpowering the heating resistor.

[0057] This embodiment further provides a battery management system, which includes the charging overvoltage protection circuit of the battery management system of this embodiment and a battery heating module. The battery heating module includes a third resistor R3, a third switch tube Q3, and a fourth switch tube Q4. The third resistor R3 is a heating resistor, and the third switch tube Q3 and the fourth switch tube Q4 are both NMOS tubes.

[0058] One end of the third resistor R3 is connected to the output positive electrode P+ of the charging overvoltage protection circuit of the battery management system, the other end of the third resistor R3 is connected to the source of the third switch tube Q3, the gate of the third switch tube Q3 is connected to the battery management system of the charging overvoltage protection circuit of the battery management system, the drain of the third switch tube Q3 is connected to the drain of the fourth switch tube Q4, the gate of the fourth switch tube Q4 is connected to the battery management system, and the source of the fourth switch tube Q4 is connected to the output negative electrode P- of the charging overvoltage protection circuit of the battery management system.

[0059] This application provides a charging overvoltage protection circuit for a battery management system and a battery management system. The charging overvoltage protection circuit uses a charging overvoltage protection module to detect the charging voltage value at the input end. If the charging voltage at the output end exceeds a preset value, an overvoltage signal is output to the battery management system and the battery management system's switch circuit is disconnected to prevent battery overvoltage. Furthermore, the charging overvoltage protection circuit has a simple structure and is relatively low in cost.

[0060] Although the preferred embodiments of the present application have been described, those skilled in the art who once know the basic creative concept can make other changes and modifications to the embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present application. Finally, it should be noted that in this paper, relationship terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between the entities or operations. Moreover, the terms "include", "contain" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or terminal device including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or terminal device. Without more limitations, the element defined by the statement "including a" does not exclude the presence of other identical elements in the process, method, article or terminal device including the element.

[0061] The charging overvoltage protection circuit and the battery management system provided by the embodiments of the present application are described in detail above, and the principles and implementation manners of the present application are described by applying specific examples in this paper. The above description of the embodiments is only used to help understand the technical solutions of the present application and the core idea thereof; those skilled in the art should understand that the technical solutions recorded in the foregoing embodiments can still be modified, or some technical features thereof can be replaced by equivalents; and such modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A charging overvoltage protection circuit for a battery management system, characterized in that: Including power module, battery management system switch circuit and charging overvoltage protection module; The power module provides power to the charging overvoltage protection circuit of the entire battery management system. The power module receives external power for charging, and the negative electrode of the power module serves as the ground terminal of the charging overvoltage protection circuit of the battery management system. The battery management system switch circuit includes an input end and an output end. The input end of the battery management system switch circuit is connected to the power module. The battery management system switch circuit cuts off the power input of the power module according to the control of the battery management system. The output end of the battery management system switch circuit serves as the output positive electrode P+ and the output negative electrode P- of the charging overvoltage protection circuit of the battery management system. The charging overvoltage protection module includes an input end and an output end. The input end of the charging overvoltage protection module is connected to the output positive electrode P+ and the output negative electrode P-. The output positive electrode P+ and the output negative electrode P- serve as the positive electrode and negative electrode of the charging voltage, respectively. The output end of the charging overvoltage protection module is connected to the output end of the battery management system switch circuit. When the voltage of the input end exceeds a preset voltage value, the charging overvoltage protection module outputs an overvoltage signal to the battery management system switch circuit. The battery management system switch circuit keeps the switch circuit disconnected according to the received overvoltage signal to prevent the power module from overcharging.

2. The charging overvoltage protection circuit of the battery management system according to claim 1, characterized in that: The power module includes a rechargeable battery pack.

3. The charging overvoltage protection circuit of the battery management system according to claim 1, characterized in that: The battery management system switch circuit includes a battery management system, a seventh resistor R7 and a switch unit; One end of the seventh resistor R7 is connected to the negative electrode of the power module, the other end of the seventh resistor R7 is connected to the switch unit, and the other end of the switch unit is connected to the charging overvoltage protection module; the positive electrode of the power module is connected to the charging overvoltage protection module; The battery management system is connected to the positive and negative poles of the battery module to collect voltage from the power module; the battery management system is connected to both ends of the seventh resistor R7 to collect current from the seventh resistor R7; and the battery management system is connected to the switch unit.

4. The charging overvoltage protection circuit of the battery management system according to claim 3, characterized in that: The switch unit includes a fifth switch tube Q5, a sixth switch tube Q6 and a TVS diode TVS1; The gate of the fifth switch tube Q5 is connected to the battery management system, the source of the fifth switch tube Q5 is connected to one end of the TVS diode TVS1, and the drain of the fifth switch tube Q5 is connected to the drain of the sixth switch tube Q6; the gate of the sixth switch tube Q6 is connected to the battery management system, and the source of the sixth switch tube Q6 is connected to the other end of the TVS diode TVS1; the source of the fifth switch tube Q5 is connected to one end of the seventh resistor R7, and the source of the sixth switch tube Q6 is connected to the charging overvoltage protection module.

5. The charging overvoltage protection circuit of the battery management system according to claim 4, characterized in that: The fifth switch tube Q5 and the sixth switch tube Q6 are both NMOS tubes.

6. The charging overvoltage protection circuit of the battery management system according to claim 1, characterized in that: The charging overvoltage protection module includes a first voltage protection unit, a second voltage protection unit and a third voltage protection unit; The input end of the first voltage protection unit is connected to the output positive electrode P+ and the output negative electrode P-, and the first voltage protection unit is turned on when the charging voltage between the output positive electrode P+ and the output negative electrode P- exceeds a preset voltage value; The output end of the first voltage protection unit is connected to the input end of the second voltage protection unit, and the second voltage protection unit is turned on according to the turn-on voltage of the first voltage protection unit; The output end of the second voltage protection unit is connected to the input end of the third voltage protection unit, and the third voltage protection unit is turned on according to the turn-on voltage of the second voltage protection unit. The output end of the third voltage protection unit is connected to the battery management system switch circuit and outputs an overvoltage signal to the battery management system switch circuit.

7. The charging overvoltage protection circuit of the battery management system according to claim 6, characterized in that: The first voltage protection unit includes a second resistor R2, a sixth resistor R6, a first voltage stabilizing diode ZD1 and a second diode D2; One end of the second resistor R2 is connected to the output positive electrode P+ and connected to the positive electrode of the charging voltage, the other end of the second resistor R2 is connected to the negative electrode of the first voltage regulator diode ZD1, the positive electrode of the first voltage regulator diode ZD1 is connected to one end of the sixth resistor R6, the other end of the sixth resistor R6 is connected to the positive electrode of the second diode D2, and the negative electrode of the second diode D2 is connected to the output negative electrode P- and the negative electrode of the power module; the output negative electrode P- is connected to the negative electrode of the charging voltage.

8. The charging overvoltage protection circuit of the battery management system according to claim 7, characterized in that: The second voltage protection unit includes a first resistor R1, a fourth resistor R4 and a second switch tube Q2; the second switch tube Q2 is an NPN transistor; One end of the first resistor R1 is connected to the output positive electrode P+, ​​the other end of the first resistor R1 is connected to the fourth resistor R4, the other end of the fourth resistor R4 is connected to the collector of the second switch tube Q2, the base of the second switch tube Q2 is connected to the anode of the first voltage regulator diode ZD1, and the emitter of the second switch tube Q2 is connected to the anode of the second diode D2.

9. The charging overvoltage protection circuit of the battery management system according to claim 8, characterized in that: The third voltage protection unit includes a first switch tube Q1, a fifth resistor R5, a first photocoupler OP1 and a first diode D1; the first switch tube Q1 is a PMOS tube; The gate of the first switching tube Q1 is connected between the first resistor R1 and the fourth resistor R4, the source of the first switching tube Q1 is connected to the output positive electrode P+, ​​the drain of the first switching tube Q1 is connected to one end of the fifth resistor R5, the other end of the fifth resistor R5 is connected to pin 1 of the light source of the first photocoupler OP1, pin 2 of the light source of the first photocoupler OP1 is connected to the anode of the second diode D2, pin 3 of the light receiver of the first photocoupler OP1 is grounded, pin 4 of the light receiver of the first photocoupler OP1 is connected to the cathode of the first diode D1, and the anode of the first diode D1 is connected to the battery management system switch circuit.

10. A battery management system, characterized in that: The battery management system comprises a charging overvoltage protection circuit and a battery heating module of the battery management system according to any one of claims 1 to 9; The battery heating module includes a third resistor R3, a third switch tube Q3, and a fourth switch tube Q4. The third resistor R3 is a heating resistor. The third switch tube Q3 and the fourth switch tube Q4 are both NMOS tubes. One end of the third resistor R3 is connected to the output positive electrode P+ of the charging overvoltage protection circuit of the battery management system, the other end of the third resistor R3 is connected to the source of the third switch tube Q3, the gate of the third switch tube Q3 is connected to the battery management system of the charging overvoltage protection circuit of the battery management system, the drain of the third switch tube Q3 is connected to the drain of the fourth switch tube Q4, the gate of the fourth switch tube Q4 is connected to the battery management system, and the source of the fourth switch tube Q4 is connected to the output negative electrode P- of the charging overvoltage protection circuit of the battery management system.

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