Battery pack protection circuit and vehicle

Abstract

The utility model provides a battery pack protection circuit and a vehicle, the circuit is applied to the field of vehicles, the circuit comprises a positive contactor and a negative contactor which are in an off state when an insulation resistance value is smaller than a preset resistance value, one end of the positive contactor is connected with a positive electrode of a battery module, and one end of the negative contactor is connected with a negative electrode of the battery module; the protection circuit is used for carrying out current limiting control on a high-voltage loop of the battery pack when the insulation resistance value is smaller than a preset resistance value and the positive contactor and / or the negative contactor are / is adhered, the first end of the protection circuit is connected with the other end of the positive contactor, the second end is connected with the other end of the negative contactor, and the third end is connected with the positive output end of the battery pack; the fourth end is connected with the cathode output end of the battery pack. According to the method, when the BMS detects the insulation resistance fault and the high-voltage contactor is not disconnected, the loop resistance can be increased by using another circuit, so that the risk of electric shock caused by the fault of the high-voltage contactor is reduced, and the safety of users in a vehicle is improved.

Description

Technical Field

[0001] The present application relates to the field of vehicles, and more specifically, to a protection circuit for a battery pack and a vehicle in the field of vehicles. Background Art

[0002] With the development of electric vehicles and other new energy vehicles, the safety of power batteries used in vehicles has become an important research field. Among them, high-voltage contactors play an important energy transmission task in vehicles, and are used to control the on and off of current in the high-voltage system. However, due to potential safety hazards during their operation, the safety of high-voltage contactors is the primary concern.

[0003] In the related art, the current power battery pack detects the insulation resistance value by the BMS (Battery Management System). When the detected resistance value is too low, the BMS controls the high-voltage contactor to disconnect to achieve insulation protection.

[0004] However, in the case of extreme conditions of the high-voltage contactor, the high-voltage contactor may malfunction such as adhesion. At this time, when the detected resistance value is too low, only the BMS controls the disconnection of the high-voltage contactor, which may result in the inability to disconnect the high-voltage contactor, thereby increasing the risk of electric shock and safety hazards for vehicle users, which urgently needs to be solved. Summary of the Utility Model

[0005] The present application provides a protection circuit for a battery pack and a vehicle. When the BMS detects an insulation resistance value failure and the high-voltage contactor is not disconnected, this method can use another circuit to increase the loop resistance, thereby reducing the risk of electric shock caused by high-voltage contactor failure and increasing the safety of vehicle users.

[0006] In a first aspect, a protection circuit for a battery pack is provided. The circuit includes: a positive contactor, one end of the positive contactor is connected to the positive electrode of the battery module, and is used to be in a disconnected state when the insulation resistance value is less than a preset resistance value; a negative contactor, one end of the negative contactor is connected to the negative electrode of the battery module, and is used to be in a disconnected state when the insulation resistance value is less than the preset resistance value; a protection circuit, the first end of the protection circuit is connected to the other end of the positive contactor, the second end of the protection circuit is connected to the other end of the negative contactor, the third end of the protection circuit is connected to the positive output terminal of the battery pack, and the fourth end of the protection circuit is connected to the negative output terminal of the battery pack, and is used to perform current limiting control on the high-voltage loop of the battery pack when the insulation resistance value is less than the preset resistance value and the positive contactor and / or the negative contactor is / are adhered.

[0007] Through the above technical solution, an insulation redundancy circuit is added between the positive contactor, the negative contactor, and the battery pack output interface, so that when the insulation resistance value is less than the preset resistance value, the positive contactor and the negative contactor are in the off state, and when both the positive contactor and the negative contactor are stuck, current limiting control is performed on the high-voltage circuit of the battery pack, thereby improving the safety of users in the vehicle.

[0008] Combined with the first aspect, in some possible implementation manners, the protection circuit includes a first insulation redundancy circuit and a second insulation redundancy circuit. Wherein, one end of the first insulation redundancy circuit is connected to the output end of the positive contactor, and the other end of the first insulation redundancy circuit is connected to the positive output interface of the battery pack; one end of the second insulation redundancy circuit is connected to the output end of the negative contactor, and the other end of the second insulation redundancy circuit is connected to the negative output interface of the battery pack.

[0009] Through the above technical solution, by setting the positive and negative poles of the insulation redundancy circuit, a more comprehensive and reliable protection mechanism can be provided to ensure that there are corresponding measures to guarantee the safety of the personnel in the vehicle when a failure occurs on either side.

[0010] Combined with the first aspect and the above implementation manners, in some possible implementation manners, there is an insulation judgment circuit which is connected to the battery management system and is used to generate a first electrical signal when the insulation resistance value is less than a preset resistance value; a contactor judgment circuit which is respectively connected to the insulation judgment circuit and the battery management system and is used to generate the first electrical signal when the current contactor is not disconnected and generate a second electrical signal when the current contactor is disconnected, wherein the levels of the first electrical signal and the second electrical signal are opposite; a delay control circuit which is connected to the contactor judgment circuit. When the contactor judgment circuit generates the first electrical signal, the delay control circuit generates the first level signal, and when the contactor judgment circuit generates the second electrical signal, the delay control circuit generates the second level signal; a high-voltage circuit protection circuit which includes a redundant protection switch, a protection resistor and a first switch. One end of the redundant protection switch is connected to the output end of the contactor, the other end of the redundant protection switch is connected to the battery pack output interface, one end of the protection resistor is connected to one end of the redundant protection switch, the other end of the protection resistor is connected to one end of the first switch, the other end of the first switch is connected to the other end of the redundant protection switch, and the control end of the high-voltage circuit protection circuit is connected to the insulation judgment circuit. When the delay control circuit generates the second level signal, the first switch is in the off state and the redundant protection switch is in the on state, and the battery pack supplies power to the load. When the delay control circuit generates the first level signal, the first switch is in the on state and the redundant protection switch is in the off state, and the protection resistor of the protection circuit of the battery pack is used to perform current limiting control on the high-voltage circuit of the battery pack.

[0011] Through the above technical solution, when the BMS detects an insulation resistance value fault and the high-voltage contactor is not disconnected, another circuit can be used to increase the loop resistance, thereby reducing the electric shock risk caused by the high-voltage contactor fault and increasing the safety of the vehicle occupants.

[0012] Combined with the first aspect and the above implementation manners, in some possible implementation manners, the insulation judgment circuit includes: a first AND gate, a first input end of the first AND gate is connected to a first output end of the battery management system, and an output end of the first AND gate is connected to the contactor judgment circuit; a first voltage reducing component, a first end of the first voltage reducing component is connected to a power access node, and a second end of the first voltage reducing component is connected to a grounding node; a first capacitor, one end of the first capacitor is connected to the first end of the first voltage reducing component, and the other end of the first capacitor is connected to the grounding node; a second capacitor, one end of the second capacitor is connected to a third end of the first voltage reducing component, and the other end of the second capacitor is connected to the grounding node; a first resistor, one end of the first resistor is connected to a fourth output end of the battery management system; a second resistor, one end of the second resistor is connected to the other end of the first resistor, and the other end of the second resistor is connected to the grounding node; a first comparator, a non-inverting input end of the first comparator is connected to a second output end of the battery management system, an inverting input end of the first comparator is connected to a connection node between the first resistor and the second resistor, a power input end of the first comparator is connected to the third end of the first voltage reducing component, a grounding end of the first comparator is connected to the grounding node, and an output end of the first comparator is connected to a second input end of the first AND gate.

[0013] Through the above technical solution, the accurate detection and judgment of the insulation resistance value of the high-voltage circuit by the insulation judgment circuit realizes the effective management and maintenance of the vehicle safety, thereby improving the safety of the vehicle under extreme conditions as a whole.

[0014] Combined with the first aspect and the above implementation manners, in some possible implementation manners, the contactor judgment circuit includes: a second AND gate, the first input terminal of the second AND gate is connected to the output terminal of the first AND gate; a second voltage reducing component, the first end of the second voltage reducing component is connected to the power access node, the second end of the second voltage reducing component is connected to the grounding node; a third capacitor, one end of the third capacitor is connected to the first end of the second voltage reducing component, the other end of the third capacitor is connected to the grounding node; a fourth capacitor, one end of the fourth capacitor is connected to the third end of the second voltage reducing component, the other end of the fourth capacitor is connected to the grounding node; a third resistor, one end of the third resistor is connected to the power access node; a fourth resistor, one end of the fourth resistor is connected to the other end of the third resistor, the other end of the fourth resistor is connected to the grounding node; a second comparator, the non-inverting input terminal of the second comparator is connected to the third output terminal of the battery management system, the inverting input terminal of the second comparator is connected to the connection node between the third resistor and the fourth resistor, the power input terminal of the second comparator is connected to the third end of the second voltage reducing component, the grounding terminal of the second comparator is connected to the grounding node, and the output terminal of the second comparator is connected to the second input terminal of the second AND gate.

[0015] Through the above technical solution, by detecting whether the high-voltage contactor has been successfully disconnected according to the instruction of the BMS, the situation that the high-voltage circuit cannot be cut off due to contactor adhesion can be avoided, thereby improving the safety of users in the vehicle.

[0016] Combined with the first aspect and the above implementation manners, in some possible implementation manners, the delay control circuit includes: a fifth to an eighth resistor, an amplifier, a fifth capacitor, a sixth capacitor and a first diode, wherein one end of the fifth resistor is connected to the output terminal of the second AND gate, the other end of the fifth resistor is connected to one end of the fifth capacitor; the other end of the fifth capacitor is connected to the negative input terminal of the amplifier; one end of the sixth capacitor is connected to the negative input terminal of the amplifier, the other end of the sixth capacitor is connected to the grounding node; one end of the sixth resistor is connected to one end of the sixth capacitor; the anode of the first diode is connected to one end of the sixth resistor, the cathode of the first diode is connected to the other end of the sixth resistor; one end of the seventh resistor is connected to the grounding node, the other end of the seventh resistor is connected to the eighth resistor; the other end of the eighth resistor is connected to the other end of the sixth resistor; the positive input terminal of the amplifier is connected to the connection node between the seventh resistor and the eighth resistor, the first end of the amplifier is connected to the output terminal of the second AND gate, the second end of the amplifier is connected to the grounding node, and the output terminal of the amplifier is connected to the high-voltage circuit protection circuit.

[0017] Through the above technical solution, by controlling the charging process of the capacitor in the circuit, the access of the protection resistor in the high-voltage circuit is made more stable, preventing sudden changes from impacting the system and improving the overall reliability of the system.

[0018] Combined with the first aspect and the above implementation manners, in some possible implementation manners, the high-voltage circuit protection circuit further includes: a third AND gate, the first input terminal of the third AND gate is connected to the first output terminal of the battery management system, and the second input terminal of the third AND gate is connected to the output terminal of the amplifier; a NOT gate, the input terminal of the NOT gate is connected to the output terminal of the third AND gate; a first triode, the base of the first triode is connected to the output terminal of the second AND gate, the collector of the first triode is connected to the control terminal of the first switch, and the emitter of the first triode is connected to the power supply access node; a second triode, the base of the second triode is connected to the output terminal of the NOT gate, the collector of the second triode is connected to the control terminal of the redundant protection switch, and the emitter of the second triode is connected to the power supply access node.

[0019] Through the above technical solution, when the high-voltage contactor fails to disconnect normally, the high-voltage circuit protection circuit can increase the resistance of the circuit by connecting a high-value resistor, thereby reducing the current and effectively reducing the risk of electric shock to the personnel in the vehicle.

[0020] Combined with the first aspect and the above implementation manners, in some possible implementation manners, both the first triode and the second triode are PNP type triodes.

[0021] Through the above technical solution, by using PNP type triodes, the flexibility of circuit design can be increased, the power supply adaptability is strong, and better compatibility can be provided at the same time.

[0022] Combined with the first aspect and the above implementation manners, in some possible implementation manners, the protection circuit of the above battery pack further includes: a power supply component, the power supply component is connected to the power input node and is used to supply power to the high-voltage circuit protection circuit, the insulation judgment circuit, the contactor judgment circuit, and the delay control circuit.

[0023] Through the above technical solution, the power supply component provides the required voltage and current for each part in the circuit to ensure that the circuit can obtain a stable and reliable power supply, thereby supporting the smooth realization of various functions of the circuit.

[0024] In a second aspect, a vehicle is provided, including the protection circuit of the battery pack according to any one of the above embodiments. Description of the Drawings

[0025] Figure 1 It is a schematic diagram of the high voltage inside the vehicle in the related art;

[0026] Figure 2 Schematic diagram of high voltage inside a battery pack in related technologies;

[0027] Figure 3 Overall design schematic diagram of the protection circuit of the battery pack provided by an embodiment of the present application;

[0028] Figure 4 Overall connection schematic diagram of the insulation redundancy circuit of an embodiment of the present application;

[0029] Figure 5 Design schematic diagram of the insulation redundancy circuit of a battery pack of an embodiment of the present application. Detailed implementation manners

[0030] Hereinafter, the technical solutions in the present application will be clearly and thoroughly described in conjunction with the accompanying drawings. Among them, in the description of the embodiments of the present application, unless otherwise specified, " / " means "or". For example, A / B may mean A or B. The "and / or" in the text is only a description of the association relationship of the associated objects, indicating that there can be three relationships. For example, A and / or B may mean: A exists alone, A and B exist simultaneously, and B exists alone. In addition, in the description of the embodiments of the present application, "a plurality" means two or more than two.

[0031] Hereinafter, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as implying or suggesting relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features.

[0032] With the popularization of new energy vehicles, the safety of vehicle battery systems has become particularly important and has become an important research field of vehicle safety. In particular, the safety of high-voltage contactors is involved because high-voltage contactors undertake important energy transmission tasks in vehicles and are used to control the on / off of current in high-voltage systems. However, there are also potential safety hazards during vehicle operation. Therefore, relevant circuit designs for the safety of high-voltage contactors are very necessary.

[0033] However, as Figure 1 and Figure 2 shown, Figure 1 and Figure 2 are circuit design schemes of related technologies, Figure 1 is a schematic diagram of high voltage inside a vehicle in related technologies. In current vehicles, the high voltage of the battery pack is connected to high-voltage devices, and there are insulation protection measures between the battery pack, high-voltage devices, and users. Under normal conditions, users inside the vehicle will not be triggered. However, when the vehicle usage years increase and the aging degree of high-voltage devices increases, the risk of electric shock to users inside the vehicle also rises; Figure 2It is a schematic diagram of the internal high voltage of a battery pack in the related art. When the vehicle is running, the BMS will constantly detect the insulation resistance values from the positive and negative poles of the battery to the ground. When it detects that the resistance value is too low and there is a risk of electric shock, it will control the main positive and main negative contactors to disconnect, thereby cutting off the output from the battery module to the interface to protect the safety of users. However, if the high-voltage contactor fails to disconnect in time due to a fault, for example, when the high-voltage contactor sticks in extreme cases and cannot disconnect, the risk of electric shock will increase, which will increase the life safety of users in the vehicle.

[0034] Therefore, based on the above existing problems, in the embodiments of the present application, an insulation redundancy circuit is directly added between the high-voltage contactor and the output interface of the battery pack. As Figure 3 shown, when the high-voltage contactor sticks and the BMS determines that the insulation resistance value is too low, this circuit will be triggered, so that the resistance in the circuit increases and the current decreases, thereby improving the safety of vehicle users.

[0035] Specifically, before introducing the embodiments of the present application, first introduce each device involved in the insulation redundancy circuit in the protection circuit of the battery pack designed in the embodiments of the present application. As Figure 4 shown, taking a single insulation redundancy circuit as an example, where "V+" is the battery voltage, which is the power supply voltage for this circuit, generally 12V; the AH8027 step-down chip 1 provides a 12V to 5V voltage for B1, and the AH8027 step-down chip 2 provides a 12V to 5V voltage for B2 and the IC device respectively. Among them, B1 and B2 are comparators. When the voltage input at the "+" end is higher than the voltage at the "-" end, the output voltage is the voltage input at the upper end, otherwise the output is 0V. B1 is responsible for comparing the current insulation resistance value with the preset resistance value, and B2 is responsible for comparing the voltage of the contactor power supply circuit with the preset voltage. The IC is an operational amplifier, which is used to form a circuit with a delay control function; R1-1, R1-2, R2-1, R2-2, R3-3, and R3-4 are all voltage-dividing resistors, which are used for voltage division in the circuit; R4 is a high-voltage circuit protection resistor with a relatively large resistance value, which is used to be connected to the high-voltage circuit to significantly increase the circuit resistance; a total of 3 AND gate chips, namely AND gate chip 1, AND gate chip 2, AND gate chip 3 and 1 NOT gate chip, are used for logical judgment; K1 and K2 are triodes, which are used to control the closing and opening of K3 and K4; K3 and K4 are switches, which are used to control the closing and opening of the high-voltage circuit protection resistor connected to the high-voltage circuit; R3-1 and R3-2 are resistors, C3-1 and C3-2 are capacitors, and M1 is a diode, which are all used for the delay control function circuit. When the voltage enters, the capacitor starts to charge, and the voltage between the capacitor and the resistor will gradually increase, playing a role of delay. The purpose is to connect the high-voltage circuit protection resistor R4 first and then disconnect K4 during the switching process to ensure that a path is formed after the high-voltage circuit protection resistor is connected.

[0036] Figure 3 This is a schematic diagram of the overall connection of a protection circuit for a battery pack provided by an embodiment of the present application.

[0037] Exemplarily, as Figure 3 shown, the protection circuit 10 of the battery pack includes: a positive contactor 100, a negative contactor 200, and a protection circuit 300.

[0038] Among them, one end of the positive contactor 100 is connected to the positive electrode of the battery module and is used to be in an open state when the insulation resistance value is less than a preset resistance value; one end of the negative contactor 200 is connected to the negative electrode of the battery module and is used to be in an open state when the insulation resistance value is less than a preset resistance value; the first end of the protection circuit 300 is connected to the other end of the positive contactor 100, the second end of the protection circuit 300 is connected to the other end of the negative contactor 200, the third end of the protection circuit 300 is connected to the positive output terminal of the battery pack, and the fourth end of the protection circuit 300 is connected to the negative output terminal of the battery pack, and is used to perform current limiting control on the high-voltage circuit of the battery pack when the insulation resistance value is less than the preset resistance value and the positive contactor 100 and / or the negative contactor 200 are stuck.

[0039] Optionally, in an embodiment of the present application, the protection circuit 300 includes a first insulation redundancy circuit and a second insulation redundancy circuit. Among them, one end of the first insulation redundancy circuit is connected to the output terminal of the positive contactor, and the other end of the first insulation redundancy circuit is connected to the positive output interface of the battery pack; one end of the second insulation redundancy circuit is connected to the output terminal of the negative contactor, and the other end of the second insulation redundancy circuit is connected to the negative output interface of the battery pack.

[0040] Among them, the preset resistance value can be set by those skilled in the art according to actual design requirements, or can be determined through a limited number of computer simulations, and no specific limitation is made here.

[0041] Specifically, as Figure 5As shown in the figure, the protection circuit 10 of the battery pack according to the embodiment of the present application mainly includes a battery module, a BMS, a positive contactor 100, a negative contactor 200, a protection circuit 300 (i.e., an insulation redundancy circuit), and a battery pack output interface. Among them, one end of the positive contactor 100 according to the embodiment of the present application is connected to the positive electrode of the battery module, one end of the negative contactor 200 is connected to the negative electrode of the battery module, the protection circuit 300 includes a first insulation redundancy circuit and a second insulation redundancy circuit. One end of the first insulation redundancy circuit is connected to the output end of the positive contactor, and the other end of the first insulation redundancy circuit is connected to the positive output interface of the battery pack. One end of the second insulation redundancy circuit is connected to the output end of the negative contactor, and the other end of the second insulation redundancy circuit is connected to the negative output interface of the battery pack. By adding an insulation redundancy circuit between the positive contactor 100, the negative contactor 200, and the battery pack output interface, when the insulation resistance value is less than the preset resistance value, the positive contactor 100 and the negative contactor 200 are in the off state, and when the positive contactor 100 and / or the negative contactor 200 are stuck, that is, when the positive contactor 100 is stuck, or the negative contactor 200 is stuck, or both the positive contactor 100 and the negative contactor 200 are stuck, current limiting control is performed on the high-voltage circuit of the battery pack, thereby improving the safety of users in the vehicle.

[0042] Optionally, in an embodiment of the present application, both the first insulation redundancy circuit and the second insulation redundancy circuit include: an insulation judgment circuit, which is connected to the battery management system BMS and is used to generate a first electrical signal when the insulation resistance value is less than a preset resistance value; a contactor judgment circuit, which is respectively connected to the insulation judgment circuit and the battery management system, and is used to generate a first electrical signal when the current contactor is not disconnected and generate a second electrical signal when the current contactor is disconnected, wherein the levels of the first electrical signal and the second electrical signal are opposite; a delay control circuit, which is connected to the contactor judgment circuit, and when the contactor judgment circuit generates the first electrical signal, the delay control circuit generates a first level signal, and when the contactor judgment circuit generates the second electrical signal, the delay control circuit generates a second level signal; the high-voltage circuit protection circuit includes a redundant protection switch, a protection resistor, and a first switch. One end of the redundant protection switch is connected to the output end of the contactor, the other end of the redundant protection switch is connected to the battery pack output interface, one end of the protection resistor is connected to one end of the redundant protection switch, the other end of the protection resistor is connected to one end of the first switch, and the other end of the first switch is connected to the other end of the redundant protection switch. The control end of the high-voltage circuit protection circuit is connected to the insulation judgment circuit. When the delay control circuit generates the second level signal, the first switch is in the off state and the redundant protection switch is in the on state, and the battery pack supplies power to the load. When the delay control circuit generates the first level signal, the first switch is in the on state and the redundant protection switch is in the off state, and the protection resistor of the insulation redundancy circuit is used to limit the current of the high-voltage circuit of the battery pack.

[0043] Optionally, in an embodiment of the present application, the insulation judgment circuit includes: a first AND gate, the first input end of the first AND gate is connected to the first output end of the battery management system, and the output end of the first AND gate is connected to the contactor judgment circuit; a first voltage-reducing component, the first end of the first voltage-reducing component is connected to the power access node, and the second end of the first voltage-reducing component is connected to the grounding node; a first capacitor, one end of the first capacitor is connected to the first end of the first voltage-reducing component, and the other end of the first capacitor is connected to the grounding node; a second capacitor, one end of the second capacitor is connected to the third end of the first voltage-reducing component, and the other end of the second capacitor is connected to the grounding node; a first resistor, one end of the first resistor is connected to the fourth output end of the battery management system; a second resistor, one end of the second resistor is connected to the other end of the first resistor, and the other end of the second resistor is connected to the grounding node; a first comparator, the non-inverting input end of the first comparator is connected to the second output end of the battery management system, the inverting input end of the first comparator is connected to the connection node between the first resistor and the second resistor, the power input end of the first comparator is connected to the third end of the first voltage-reducing component, the grounding end of the first comparator is connected to the grounding node, and the output end of the first comparator is connected to the second input end of the first AND gate.

[0044] Specifically, asFigure 4 As shown in the insulation judgment circuit part in [reference], the insulation judgment circuit mainly includes a first AND gate (AND gate chip 1), a first step-down component (AH8027 step-down chip 1), a first capacitor (C1-1), a second capacitor (C1-2), a first resistor (R1-1), a second resistor (R1-2), and a first comparator (B1). Among them, the first input terminal of the first AND gate (AND gate chip 1) is connected to the first output terminal (insulation fault level) of the battery management system. The output terminal of the first AND gate (AND gate chip 1) is connected to the contactor judgment circuit. One end of the first capacitor (C1-1) is connected to the first end of the first step-down component, and the other end of the first capacitor (C1-1) is connected to the ground node. One end of the second capacitor (C1-2) is connected to the third end of the first step-down component, and the other end of the second capacitor (C1-2) is connected to the ground node. One end of the first resistor (R1-1) is connected to the fourth output terminal (detection voltage of the insulation detection loop) of the battery management system. One end of the second resistor (R1-2) is connected to the other end of the first resistor (R1-1), and the other end of the second resistor (R1-2) is connected to the ground node. The non-inverting input terminal (+) of the first comparator (B1) is connected to the second output terminal (resistance voltage division of the insulation detection loop) of the battery management system. The inverting input terminal (-) of the first comparator (B1) is connected to the connection node between the first resistor (R1-1) and the second resistor (R1-2). The power input terminal of the first comparator (B1) is connected to the third end of the first step-down component. The ground terminal of the first comparator (B1) is connected to the ground node. The output terminal of the first comparator (B1) is connected to the second input terminal of the first AND gate (AND gate chip 1), that is, connected through line 6.

[0045] Furthermore, in the insulation judgment circuit, its main function is to judge the magnitude of the current insulation resistance value of the high voltage to the low voltage and the preset resistance value, and generate a first electrical signal when the insulation resistance value is less than the preset resistance value, that is, output a high level. Line 2 is the voltage for the BMS to detect the insulation resistance value. The BMS internally judges the resistance value through the voltage division method. The voltage of this line is the voltage value after the resistance value of the loop is divided. Line 4 is the reference voltage for the BMS to detect the insulation resistance value, that is, the voltage before the resistance value is divided. The first resistor (R1-1) and the second resistor (R1-2) are set with the same proportion of resistance values according to the required magnitude of the high voltage loop resistance value. When the high voltage loop resistance value detected by the BMS becomes smaller, the voltage output by line 2 becomes larger. When the voltage is higher than the voltage at line 5, the first comparator (B1) will make line 6 become high level. Otherwise, line 6 is always at low level. At the same time, judge the insulation fault level output by the BMS. That is, when the BMS judges that the insulation resistance value is too low, it will make line 1 become high level, otherwise it is low level. When both line 1 and line 6 are high levels, through the judgment of the first AND gate (AND gate chip 1), line 7 outputs a high level, otherwise it outputs a low level.

[0046] Optionally, in an embodiment of the present application, the contactor judgment circuit includes: a second AND gate, the first input end of the second AND gate is connected to the output end of the first AND gate; a second voltage dropping component, the first end of the second voltage dropping component is connected to the power access node, the second end of the second voltage dropping component is connected to the ground node; a third capacitor, one end of the third capacitor is connected to the first end of the second voltage dropping component, the other end of the third capacitor is connected to the ground node; a fourth capacitor, one end of the fourth capacitor is connected to the third end of the second voltage dropping component, the other end of the fourth capacitor is connected to the ground node; a third resistor, one end of the third resistor is connected to the power access node; a fourth resistor, one end of the fourth resistor is connected to the other end of the third resistor, and the other end of the fourth resistor is connected to the ground node; a second comparator, the non-inverting input end of the second comparator is connected to the third output end of the battery management system, the inverting input end of the second comparator is connected to the connection node between the third resistor and the fourth resistor, the power input end of the second comparator is connected to the third end of the second voltage dropping component, the ground end of the second comparator is connected to the ground node, and the output end of the second comparator is connected to the second input end of the second AND gate.

[0047] Specifically, as Figure 4 shown in the contactor judgment circuit part in

[0048] Further, in the contactor judgment circuit, its main function is to judge whether the current contactor is disconnected. When the current contactor is not disconnected, a first electrical signal is generated, that is, a high level is output. When the current contactor is disconnected, a second electrical signal is generated, that is, a low level is output. Among them, the levels of the first electrical signal and the second electrical signal are opposite. Among them, line 3 is the contactor drive voltage. When the contactor is closed, the voltage at line 3 is 12V, and when it is disconnected, it is 0. Line 8 is the voltage after the 12V power supply of the battery is divided by the third resistor (R2-1) and the fourth resistor (R2-2). The resistance value is set proportionally according to the magnitude of the contactor disconnection voltage. When the contactor is not disconnected, the voltage of line 3 is higher than the voltage of line 8, and the output of the second comparator (B2) is high level, that is, line 9 is high level. When the contactor is disconnected, line 9 outputs low level. When both line 9 and line 7 are high levels, it is judged by the second AND gate (AND gate chip 2), and line 10 outputs high level, otherwise it outputs low level.

[0049] Optionally, in an embodiment of the present application, the delay control circuit includes: a fifth to an eighth resistor, an amplifier, a fifth capacitor, a sixth capacitor and a first diode. One end of the fifth resistor is connected to the output end of the second AND gate, and the other end of the fifth resistor is connected to one end of the fifth capacitor; the other end of the fifth capacitor is connected to the negative input terminal of the amplifier; one end of the sixth capacitor is connected to the negative input terminal of the amplifier, and the other end of the sixth capacitor is connected to the ground node; one end of the sixth resistor is connected to one end of the sixth capacitor; the anode of the first diode is connected to one end of the sixth resistor, and the cathode of the sixth diode is connected to the other end of the sixth resistor; one end of the seventh resistor is connected to the ground node, and the other end of the seventh resistor is connected to the eighth resistor; the other end of the eighth resistor is connected to the other end of the sixth resistor; the positive input terminal of the amplifier is connected to the connection node between the seventh resistor and the eighth resistor, the first end of the amplifier is connected to the output end of the second AND gate, the second end of the amplifier is connected to the ground node, and the output end of the amplifier is connected to the high-voltage circuit protection circuit.

[0050] Specifically, as Figure 4As shown in the delay control circuit part, the delay control circuit mainly includes a fifth resistor (R3-1), a sixth resistor (R3-2), a seventh resistor (R3-3), an eighth resistor (R3-4), an amplifier (IC), a fifth capacitor (C3-1), a sixth capacitor (C3-2) and a first diode (M1). Among them, one end of the fifth resistor (R3-1) is connected to the output end of the second AND gate (AND gate chip 2), the other end of the fifth resistor (R3-1) is connected to one end of the fifth capacitor (R3-1), the other end of the fifth capacitor (R3-1) is connected to the negative input terminal of the amplifier (IC), one end of the sixth capacitor (R3-2) is connected to the negative input terminal of the amplifier (IC), the other end of the sixth capacitor (R3-2) is connected to the ground node, one end of the sixth resistor (R3-2) is connected to one end of the sixth capacitor (R3-2), the anode of the first diode (M1) is connected to one end of the sixth resistor (R3-2), the cathode of the first diode (M1) is connected to the other end of the sixth resistor (R3-2), one end of the seventh resistor (R3-3) is connected to the ground node, the other end of the seventh resistor (R3-3) is connected to the eighth resistor (R3-4), the other end of the eighth resistor (R3-4) is connected to the other end of the sixth resistor (R3-2), the positive input terminal of the amplifier (IC) is connected to the connection node between the seventh resistor (R3-3) and the eighth resistor (R3-4), the first end of the amplifier (IC) is connected to the output end of the second AND gate (AND gate chip 2), the second end of the amplifier (IC) is connected to the ground node, and the output end of the amplifier (IC) is connected to the high-voltage loop protection circuit, that is, connected through line 11.

[0051] Further, in the delay control circuit, its main function is to delay the disconnection of K4 after K3 in the high-voltage loop protection circuit is closed, that is, first connect the high-voltage loop protection resistor and then disconnect the main circuit to prevent the high-voltage loop protection resistor from short-circuiting. Under normal conditions, when the voltage of line 10 is low, the output of the amplifier (IC) is low, that is, the voltage of line 11 is low. When the voltage of line 10 becomes high, a negative pulse is input to the inverting terminal through the capacitor C1. At this time, the potential of the inverting terminal is lower than that of the non-inverting terminal, and the output of the amplifier (IC) becomes high. After the voltage of line 11 becomes high, it is divided by the seventh resistor (R3-3) and the eighth resistor (R3-4), and the voltage is applied to the non-inverting terminal of the amplifier (IC), making the potential of the non-inverting terminal higher than that of the inverting terminal, so as to keep the high-level output of line 11.

[0052] Optionally, in an embodiment of the present application, the high-voltage loop protection circuit further includes: a third AND gate, the first input end of the third AND gate is connected to the first output end of the battery management system, and the second input end of the third AND gate is connected to the output end of the amplifier; a NOT gate, the input end of the NOT gate is connected to the output end of the third AND gate; a first triode, the base of the first triode is connected to the output end of the second AND gate, the collector of the first triode is connected to the control end of the first switch, and the emitter of the first triode is connected to the power access node; a second triode, the base of the second triode is connected to the output end of the NOT gate, the collector of the second triode is connected to the control end of the redundant protection switch, and the emitter of the second triode is connected to the power access node.

[0053] Specifically, as Figure 4 shown in the high-voltage loop protection circuit part of

[0054] Further, in the high-voltage circuit protection circuit, its main function is to control the access of the high-voltage circuit protection resistor in the high-voltage circuit. When line 12 is at a high level, the first triode (K1) is closed. At this time, the voltage of line 13 is equal to the V+ voltage, driving the first switch (K3) to close; when line 12 is at a low level, the first switch (K3) is in an open state. After the first switch (K3) closes, the high-voltage circuit protection resistor (R4) is connected to the circuit. At this time, since the redundant protection switch (K4) is not disconnected, a short circuit is formed. When both line 11 and line 14 are at a high level, after passing through the third AND gate, line 15 is at a high level. After passing through the NOT gate chip, line 16 becomes a low level, and the second triode (K2) is disconnected. Line 17 is disconnected from the V+ power supply and becomes 0V, and the redundant protection switch (K4) is disconnected. At this time, the high-voltage circuit must pass through the connected high-voltage circuit protection resistor, thereby realizing the function of accessing the resistance value. When either line 11 or line 14 is at a low level, line 16 is at a high level, the second triode (K2) is closed, and the redundant protection switch (K4) is closed. That is, under normal conditions, the redundant protection switch (K4) is in a closed state and does not affect the high-voltage circuit path.

[0055] Preferably, to improve the flexibility of circuit design, make the voltage adaptability stronger, and the compatibility better, the first triode (K1) and the second triode (K2) in the embodiment of the present application can both be selected as PNP (PNP Transistor, PNP type triode) type triodes.

[0056] Optionally, in an embodiment of the present application, the above-mentioned protection circuit of the battery pack further includes: a power supply component, which is connected to the power input node and is used to supply power to the high-voltage circuit protection circuit, the insulation judgment circuit, the contactor judgment circuit, and the delay control circuit.

[0057] Specifically, the power supply component plays a crucial role in an electronic device, especially in a complex system such as the redundant design of power battery anti-electric shock. It can provide a stable power supply for the entire circuit to ensure that each component can work normally. In the embodiment of the present application, through the AH8027 step-down chips 1 and 2, the power supply component can convert the input 12V voltage into a 5V voltage suitable for the operation of devices such as B1 and B2. This voltage conversion ensures that each part of the circuit can obtain a voltage suitable for its normal operation, thereby ensuring the continuity and reliability of the circuit operation and preventing system failures caused by voltage fluctuations.

[0058] Further, as Figure 4As shown in the figure, the circuit operation of the embodiments of the present application will be introduced below. As a feasible implementation, when the BMS does not detect an insulation too low fault, the high-voltage loop protection resistor is not connected in any case. The circuit operation is as follows: the voltage at line 1 is low. When the voltage at line 6 is high or low, the output of the first AND gate (AND gate chip 1) is low, and the output of the second AND gate (AND gate chip 2) is also low. At this time, the voltage at line 12 is always low, the first triode (K1) will not close, the output of the third AND gate is always low, and the output of the NOT gate chip is always high. At this time, the second triode (K2) is always closed, the voltage at line 17 is 12V, and the redundant protection switch (K4) is always closed. In summary, when the BMS does not detect an insulation fault, that is, the insulation fault level is always low, the first switch (K3) is open, and the redundant protection switch (K4) is closed, which will not affect the normal battery pack discharge function.

[0059] As another feasible implementation, when the BMS detects an insulation too low fault and the actual resistance value is less than the preset resistance value, and the main contactor drive is in the off state, the high-voltage loop protection resistor is not connected at this time. The circuit operation is as follows: the voltage at line 1 is high; since the actual resistance value is less than the preset resistance value, the voltage at line 2 is higher than the voltage at line 5, and the first comparator will output a high level, that is, the voltage at line 6 is high, and the first AND gate (AND gate chip 1) will output a high level, that is, the voltage at line 7 is high; since the contactor drive is off and the drive voltage is 0, the voltage at line 3 is lower than the voltage at line 8, and the first comparator will output a low level, that is, the voltage at line 9 is low. Since the input of the second AND gate (AND gate chip 2) is one high and one low, it will output a low level. At this time, the voltage at line 10 is always low, the first triode (K1) will not close. Since the voltage at line 10 is low, the amplifier (IC) continuously outputs a low level, that is, the voltage at line 11 is low. Since the input of the third AND gate is one high and one low, it will output a low level, and the output of the NOT gate chip is always high. At this time, the second triode (K2) is always closed, the voltage at line 17 is 12V, and the redundant protection switch (K4) is always closed. In summary, when the BMS detects an insulation too low fault, the loop resistance is less than the preset resistance value, but the contactor drive is already off, the first switch (K3) is open, and the redundant protection switch (K4) is closed. At this time, since the main contactor and the high-voltage loop are already disconnected, there is no need to connect the high-voltage loop protection resistor, and the high-voltage loop protection resistor is not connected.

[0060] As another implementable way, when the BMS detects an insulation too low fault and the actual resistance value is less than the preset resistance value, and the main contactor drive is in the closed state, the high-voltage circuit protection resistor is connected at this time. The working condition of its circuit is that the voltage at Line 1 is high. Since the actual resistance value is less than the preset resistance value, the voltage at Line 2 is higher than the voltage at Line 5, and the first comparator will output a high level, that is, the voltage at Line 6 is high; the first AND gate (AND gate chip 1) will output a high level. Since the contactor drive is closed and the drive voltage is 12, the voltage at Line 3 is higher than the voltage at Line 8, and the second comparator will output a high level, that is, the voltage at Line 9 is high; the second AND gate (AND gate chip 2) will output a high level because both inputs are high levels. At this time, the voltage at Line 10 is always high, the first triode (K1) is closed, and at this time, the circuit between Line 13 and the V+ power supply is connected, and the first switch (K3) is closed; since the voltage at Line 10 is high, the amplifier (IC) will delay and output a high level, and the delay time is set by the specifications of the fifth resistor and the fifth capacitor. At this time, that is, the voltage at Line 11 is low; the third AND gate will output a high level because both inputs are high levels, that is, the voltage at Line 15 is high; the output of the NOT gate chip becomes low, and at this time, the second triode (K2) will change from closed to open, and at this time, the voltage at Line 17 is 0V, and the redundant protection switch (K4) changes from closed to open. In summary, when the BMS detects an insulation too low fault, the loop resistance is lower than the preset value, and the contactor drive is not disconnected, the first switch (K3) is closed, and the redundant protection switch (K4) is delayed to disconnect. At this time, the high-voltage circuit protection resistor is connected to the high-voltage circuit.

[0061] Thus, in the embodiment of the present application, an insulation redundancy circuit is directly added to the output interface of the contactor and the battery pack. When the BMS detects an insulation resistance fault and the contactor is not disconnected, the insulation redundancy circuit for BMS detection is placed in this circuit, so that the resistance in the loop increases and the current decreases, thereby improving the safety of vehicle personnel.

[0062] In summary, the protection circuit of the battery pack according to the embodiments of the present application is used for the positive contactor and the negative contactor that are in an open state when the insulation resistance value is less than a preset resistance value. One end of the positive contactor is connected to the positive electrode of the battery module, and one end of the negative contactor is connected to the negative electrode of the battery module. The protection circuit is used for current limiting control of the high-voltage circuit of the battery pack when the insulation resistance value is less than the preset resistance value and the positive contactor and / or the negative contactor are stuck. Its first end is connected to the other end of the positive contactor, the second end is connected to the other end of the negative contactor, the third end is connected to the positive output terminal of the battery pack, and the fourth end is connected to the negative output terminal of the battery pack. It solves the problem in the related art that when a failure such as sticking occurs in the high-voltage contactor, when the resistance value is detected to be too low, only the BMS controls the disconnection of the high-voltage contactor, which easily causes the high-voltage contactor to fail to disconnect effectively, thereby increasing the risk of electric shock to vehicle users and potential safety hazards. By directly adding an insulation redundancy circuit at the output interface of the high-voltage contactor and the battery pack, when the BMS detects an insulation resistance failure and the high-voltage contactor is not disconnected, this circuit can be used to increase the loop resistance, thereby reducing the risk of electric shock caused by the high-voltage contactor failure and increasing the safety of vehicle users.

[0063] Furthermore, the present application provides a vehicle, including the protection circuit of the battery pack in the above embodiment, which solves the problem in the related art that when a failure such as sticking occurs in the high-voltage contactor, when the resistance value is detected to be too low, only the BMS controls the disconnection of the high-voltage contactor, which easily causes the high-voltage contactor to fail to disconnect effectively, thereby increasing the risk of electric shock to vehicle users and potential safety hazards. By directly adding an insulation redundancy circuit at the output interface of the high-voltage contactor and the battery pack, when the BMS detects an insulation resistance failure and the high-voltage contactor is not disconnected, this circuit can be used to increase the loop resistance, thereby reducing the risk of electric shock caused by the high-voltage contactor failure and increasing the safety of vehicle users.

Claims

1. A protection circuit for a battery pack, characterized in that, Including: A positive contactor, one end of which is connected to the positive electrode of the battery module and is used to be in an open state when the insulation resistance value is less than a preset resistance value; A negative contactor, one end of which is connected to the negative electrode of the battery module and is used to be in an open state when the insulation resistance value is less than the preset resistance value; A protection circuit, the first end of which is connected to the other end of the positive contactor, the second end of which is connected to the other end of the negative contactor, the third end of which is connected to the positive output terminal of the battery pack, and the fourth end of which is connected to the negative output terminal of the battery pack, and is used to perform current limiting control on the high-voltage circuit of the battery pack when the insulation resistance value is less than the preset resistance value and the positive contactor and / or the negative contactor is / are adhered.

2. The protection circuit of the battery pack according to claim 1, characterized in that The protection circuit includes a first insulation redundancy circuit and a second insulation redundancy circuit, wherein, One end of the first insulation redundancy circuit is connected to the output terminal of the positive contactor, and the other end of the first insulation redundancy circuit is connected to the positive output interface of the battery pack; One end of the second insulation redundancy circuit is connected to the output terminal of the negative contactor, and the other end of the second insulation redundancy circuit is connected to the negative output interface of the battery pack.

3. The protection circuit of the battery pack according to claim 2, characterized in that, Both the first insulation redundancy circuit and the second insulation redundancy circuit include: An insulation judgment circuit, which is connected to the battery management system and is used to generate a first electrical signal when the insulation resistance value is less than a preset resistance value; A contactor judgment circuit, which is respectively connected to the insulation judgment circuit and the battery management system and is used to generate the first electrical signal when the current contactor is not open and generate a second electrical signal when the current contactor is open, wherein the levels of the first electrical signal and the second electrical signal are opposite; A delay control circuit, which is connected to the contactor judgment circuit. When the contactor judgment circuit generates the first electrical signal, the delay control circuit generates a first level signal, and when the contactor judgment circuit generates the second electrical signal, the delay control circuit generates a second level signal; High-voltage circuit protection circuit, the high-voltage circuit protection circuit includes a redundant protection switch, a protection resistor and a first switch. One end of the redundant protection switch is connected to the output end of the contactor, the other end of the redundant protection switch is connected to the battery pack output interface, one end of the protection resistor is connected to one end of the redundant protection switch, the other end of the protection resistor is connected to one end of the first switch, the other end of the first switch is connected to the other end of the redundant protection switch, and the control end of the high-voltage circuit protection circuit is connected to the insulation judgment circuit. When the delay control circuit generates the second level signal, the first switch is in the off state and the redundant protection switch is in the on state, and the battery pack supplies power to the load. When the delay control circuit generates the first level signal, the first switch is in the on state and the redundant protection switch is in the off state, and the protection resistor of the protection circuit of the battery pack is used to limit the current of the high-voltage circuit of the battery pack.

4. The protection circuit of the battery pack according to claim 3, wherein, The insulation judgment circuit includes: A first AND gate, the first input terminal of the first AND gate is connected to the first output terminal of the battery management system, and the output terminal of the first AND gate is connected to the contactor judgment circuit; A first voltage-reducing component, the first end of the first voltage-reducing component is connected to the power access node, and the second end of the first voltage-reducing component is connected to the ground node; A first capacitor, one end of the first capacitor is connected to the first end of the first voltage-reducing component, and the other end of the first capacitor is connected to the ground node; A second capacitor, one end of the second capacitor is connected to the third end of the first voltage-reducing component, and the other end of the second capacitor is connected to the ground node; A first resistor, one end of the first resistor is connected to the fourth output terminal of the battery management system; A second resistor, one end of the second resistor is connected to the other end of the first resistor, and the other end of the second resistor is connected to the ground node; A first comparator, the non-inverting input terminal of the first comparator is connected to the second output terminal of the battery management system, the inverting input terminal of the first comparator is connected to the connection node between the first resistor and the second resistor, the power input terminal of the first comparator is connected to the third end of the first voltage-reducing component, the ground terminal of the first comparator is connected to the ground node, and the output terminal of the first comparator is connected to the second input terminal of the first AND gate.

5. The protection circuit of the battery pack according to claim 4, characterized in that, The contactor judgment circuit includes: A second AND gate, the first input terminal of the second AND gate is connected to the output terminal of the first AND gate; A second voltage-reducing component, the first end of the second voltage-reducing component is connected to the power access node, and the second end of the second voltage-reducing component is connected to the ground node; A third capacitor, one end of the third capacitor is connected to the first end of the second voltage-reducing component, and the other end of the third capacitor is connected to the ground node; A fourth capacitor, one end of the fourth capacitor is connected to the third end of the second voltage-reducing component, and the other end of the fourth capacitor is connected to the ground node; A third resistor, one end of the third resistor is connected to the power access node; A fourth resistor, one end of the fourth resistor is connected to the other end of the third resistor, and the other end of the fourth resistor is connected to the grounding node; A second comparator, the non-inverting input terminal of the second comparator is connected to the third output terminal of the battery management system, the inverting input terminal of the second comparator is connected to the connection node between the third resistor and the fourth resistor, the power input terminal of the second comparator is connected to the third terminal of the second voltage reducing component, the grounding terminal of the second comparator is connected to the grounding node, and the output terminal of the second comparator is connected to the second input terminal of the second AND gate.

6. The protection circuit of the battery pack according to claim 5, wherein, The delay control circuit includes: a fifth to an eighth resistor, an amplifier, a fifth capacitor, a sixth capacitor and a first diode, wherein, One end of the fifth resistor is connected to the output terminal of the second AND gate, and the other end of the fifth resistor is connected to one end of the fifth capacitor; The other end of the fifth capacitor is connected to the negative input terminal of the amplifier; One end of the sixth capacitor is connected to the negative input terminal of the amplifier, and the other end of the sixth capacitor is connected to the grounding node; One end of the sixth resistor is connected to one end of the sixth capacitor; The anode of the first diode is connected to one end of the sixth resistor, and the cathode of the first diode is connected to the other end of the sixth resistor; One end of the seventh resistor is connected to the grounding node, and the other end of the seventh resistor is connected to the eighth resistor; The other end of the eighth resistor is connected to the other end of the sixth resistor; The positive input terminal of the amplifier is connected to the connection node between the seventh resistor and the eighth resistor, the first terminal of the amplifier is connected to the output terminal of the second AND gate, the second terminal of the amplifier is connected to the grounding node, and the output terminal of the amplifier is connected to the high-voltage loop protection circuit.

7. The protection circuit of the battery pack according to claim 6, wherein The high-voltage loop protection circuit further includes: A third AND gate, the first input terminal of the third AND gate is connected to the first output terminal of the battery management system, and the second input terminal of the third AND gate is connected to the output terminal of the amplifier; A NOT gate, the input terminal of the NOT gate is connected to the output terminal of the third AND gate; A first triode, the base of the first triode is connected to the output terminal of the second AND gate, the collector of the first triode is connected to the control terminal of the first switch, and the emitter of the first triode is connected to the power supply access node; A second triode, the base of the second triode is connected to the output terminal of the NOT gate, the collector of the second triode is connected to the control terminal of the redundant protection switch, and the emitter of the second triode is connected to the power supply access node.

8. The protection circuit of the battery pack according to claim 7, characterized in that, Both the first triode and the second triode are PNP type triodes.

9. The protection circuit of the battery pack according to any one of claims 1-8, characterized in that, Further included: A power supply component, the power supply component is connected to the power input node and is used to supply power to the high-voltage loop protection circuit, the insulation judgment circuit, the contactor judgment circuit and the delay control circuit.

10. A vehicle, characterized in that, Including: The protection circuit of the battery pack according to any one of claims 1-8.

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