Insulation resistance detection circuit, method and device

Abstract

An insulation resistance detection circuit, method and device, the method comprising: when a state control unit is in a first state, controlling a low-voltage direct current source not to charge a second voltage-dividing branch and a second resistor in the insulation resistance detection circuit, obtaining a first voltage value of the first voltage-dividing branch and a second voltage value of the second voltage-dividing branch in the insulation resistance detection circuit; when the state control unit is in a second state, controlling the low-voltage direct current source to charge the second voltage-dividing branch and the second resistor, obtaining a third voltage value of the first voltage-dividing branch and a fourth voltage value of the second voltage-dividing branch, and a fifth voltage value of the third voltage-dividing branch; the first resistor and the second resistor are two resistors connected in series in a device to be detected; according to the first voltage value, the second voltage value, the third voltage value, the fourth voltage value and the fifth voltage value, determining the resistance value of the first resistor and the resistance value of the second resistor, the scheme can efficiently detect the resistance value of the insulation resistance in the device to be detected.

Description

Technical Field

[0001] The present application relates to the field of communication technology, and in particular to an insulation resistance detection circuit, method, and device. Background Art

[0002] In the field of electric vehicles, it is very important to ensure that the insulation impedance between high voltage and low voltage is normal. If the insulation impedance in the car drops to a certain value, the high voltage circuit needs to be disconnected to avoid personal injury. Therefore, it is very important to be able to quickly and accurately determine the insulation impedance of the high voltage system to the low voltage system. This is one of the core contents of ensuring the safety and reliability of the high voltage circuit of electric vehicles.

[0003] In the prior art, the bridge method and the DC injection method are usually used to detect the insulation impedance of the high voltage system to the low voltage system. The detection accuracy is low, and it is impossible to quickly detect the insulation resistance value and locate the fault position. Therefore, it is urgent to propose a new insulation resistance detection method to efficiently detect the insulation resistance value. Summary of the invention

[0004] The present application provides an insulation resistance detection circuit, method, and device for efficiently detecting the insulation resistance of a high voltage system to a low voltage system in an electric vehicle.

[0005] In a first aspect, the present application provides an insulation resistance detection circuit, which can be connected to a device to be detected, and is used to detect the device to be detected including a first resistor and a second resistor connected in series, and identify whether the insulation fault in the device to be detected occurs at the positive or negative pole of the power supply of the device to be detected. Specifically, the insulation resistance detection circuit may include: the first voltage dividing branch is used to be connected in parallel with the first resistor, and is used to divide the voltage across the first resistor; the second voltage dividing branch is used to be connected in parallel with the second resistor, and is used to divide the voltage across the second resistor; the third voltage dividing branch is connected between the positive pole of the low-voltage DC source and the ground, and is used to determine the current value of the low-voltage DC source; the state control unit is used to be connected between the positive and negative poles of the power supply of the device to be detected, and when the state control unit is in a first state, the low-voltage DC source is controlled not to supply current to the second voltage dividing branch and the third voltage dividing branch. The state control unit is configured to charge two resistors, and when the state control unit is in the second state, the low-voltage DC source is controlled to charge the second voltage-dividing branch and the second resistor; the processor is respectively connected to the state control unit, the first voltage-dividing branch, the second voltage-dividing branch and the third voltage-dividing branch, and is used to control the state control unit to switch between the first state and the second state; when the state control unit is in the first state, the first voltage value of the first voltage-dividing branch and the second voltage value of the second voltage-dividing branch are obtained; when the state control unit is in the second state, the third voltage value of the first voltage-dividing branch and the fourth voltage value of the second voltage-dividing branch, as well as the fifth voltage value of the third voltage-dividing branch are obtained; and the resistance value of the first resistor and the resistance value of the second resistor are determined according to the first voltage value, the second voltage value, the third voltage value, the fourth voltage value and the fifth voltage value.

[0006] With the above circuit structure, the processor controls the state control unit to switch between the first state and the second state, so as to control the low-voltage DC source to charge the second voltage-dividing branch and the second resistor. When the control state control unit is in the first state, the low-voltage DC source does not charge the second voltage-dividing branch and the second resistor, and obtains the first voltage value of the first voltage-dividing branch and the second voltage value of the second voltage-dividing branch. When the control state control unit is in the second state, the low-voltage DC source charges the second voltage-dividing branch and the second resistor, and obtains the third voltage value of the first voltage-dividing branch, the fourth voltage value of the second voltage-dividing branch, and the fifth voltage value of the third voltage-dividing branch. Further, the processor determines the resistance value of the first resistor and the resistance value of the second resistor according to the first voltage value, the second voltage value, the third voltage value, the fourth voltage value and the fifth voltage value. This solution avoids the defects of the prior art solution, so that the resistance value of the insulation resistor can be efficiently detected.

[0007] In a possible design, the detection circuit further includes a sampling unit, which is connected to the first voltage-dividing branch, the second voltage-dividing branch, the third voltage-dividing branch and the processor respectively, and is used to collect the first voltage value of the first voltage-dividing branch and the second voltage value of the second voltage-dividing branch when the state control unit is in the first state, and send them to the processor; when the state control unit is in the second state, collect the third voltage value of the first voltage-dividing branch and the fourth voltage value of the second voltage-dividing branch, as well as the fifth voltage value of the third voltage-dividing branch, and send them to the processor. With this circuit structure, the sampling unit can effectively collect the voltage values ​​of each voltage-dividing branch and send them to the processor to perform calculation processing.

[0008] In a possible design, the first end of the first resistor is connected to the positive electrode of the power supply, the second end of the first resistor is connected to the first end of the second resistor, and the second end of the second resistor is connected to the negative electrode of the power supply. With this circuit structure, by detecting the resistance value of the first resistor and the resistance value of the second resistor, it is possible to identify whether the insulation fault occurs in the positive electrode or the negative electrode of the power supply of the device to be detected.

[0009] In a possible design, the detection circuit further includes an anti-reverse unit, the first end of which is connected to the state control unit, and the second end is used to connect to the positive pole of the power supply of the device to be detected, so as to control the influence of the high voltage on the low voltage of the device to be detected. With this circuit structure, the detection circuit includes an anti-reverse unit, which can prevent the low-voltage DC source from inputting current in the opposite direction, ensure that the low-voltage DC source is always charged in one direction, and thus prevent the power supply of the device to be detected from interfering with the low-voltage DC source.

[0010] In a possible design, the anti-reverse unit includes at least one diode, and the at least one diode is connected in series. With the above circuit structure, the anti-reverse unit includes at least one diode connected in series, thereby ensuring that the low-voltage DC source is charged in one direction, and preventing the low-voltage DC source from charging in the opposite direction, which causes the power supply of the device to be detected to interfere with the low-voltage DC source.

[0011] In a possible design, the first voltage-dividing branch includes a third resistor and a fourth resistor, the first end of the third resistor is used to be connected to the positive electrode of the power supply of the device to be detected, the second end of the third resistor is connected to the first end of the fourth resistor, and the second end of the fourth resistor is grounded. With this circuit structure, the first voltage-dividing branch includes the third resistor and the fourth resistor, and the voltage across the first resistor is divided, so that the voltage on the first resistor can be determined by collecting the voltage value of the first voltage-dividing branch.

[0012] In a possible design, the second voltage-dividing branch includes a fifth resistor and a sixth resistor; the first end of the fifth resistor is grounded, the second end of the fifth resistor is connected to the first end of the sixth resistor, and the second end of the sixth resistor is used to be connected to the negative electrode of the power supply of the device to be detected. With this circuit structure, the second voltage-dividing branch includes the fifth resistor and the sixth resistor, and the voltage across the second resistor is divided, so that the voltage on the second resistor can be determined by collecting the voltage value of the second voltage-dividing branch.

[0013] In a possible design, the third voltage-dividing branch includes: a seventh resistor, a first end of the seventh resistor is grounded, and a second end of the seventh resistor is connected to the positive electrode of the low-voltage DC source. With this circuit structure, the voltage of the third voltage-dividing branch can be collected to determine the total current value input by the low-voltage DC source to the second voltage-dividing branch and the second resistor, while also preventing the third voltage-dividing branch from causing a short circuit.

[0014] In a possible design, the state control unit includes: a first switch and an eighth resistor; the first end of the eighth resistor is connected to the negative electrode of the low-voltage DC source, the second end of the eighth resistor is connected to the first end of the first switch, the second end of the first switch is connected to the first end of the anti-reverse unit, and the control end of the first switch is connected to the processor; when the processor controls the first switch to be disconnected, the state control unit is in the first state; when the processor controls the first switch to be closed, the state control unit is in the second state. With this circuit structure, the low-voltage DC source is controlled to charge the second voltage-dividing branch and the second resistor respectively by controlling the working state of the first switch, thereby realizing accurate control of the state control unit switching between the first state and the second state. At the same time, the eighth resistor is used for current limiting, thereby preventing the first switch from short-circuiting the positive electrode of the power supply to the ground.

[0015] In a possible design, the resistance value of the first resistor and the resistance value of the second resistor determined by the processor may meet the requirements of the following formula:

[0016]

[0017]

[0018] Among them, U 1 represents the first voltage value, U 2 represents the second voltage value, U 3 represents the third voltage value, U 4 represents the fourth voltage value, U 5 represents the fifth voltage value, R 1 represents the resistance value of the first resistor, R 2Represents the resistance value of the second resistor, R 3 +R 4 represents the resistance value of the first voltage divider branch, R 5 +R 6 represents the resistance value of the second voltage divider branch, R 7 Represents the resistance value of the third voltage dividing branch.

[0019] Through this design, according to the above two formulas, the resistance value of the insulating first resistor and the resistance value of the second resistor can be efficiently calculated.

[0020] In a second aspect, an embodiment of the present application provides an insulation resistance detection method, the execution subject of the method may be a processor in the insulation resistance circuit provided in the first aspect of the present embodiment or other processors that are communicatively connected to the device to be detected, and the method specifically includes the following steps:

[0021] A control state control unit is switched between a first state and a second state. When the state control unit is in the first state, the low-voltage DC source is controlled not to charge the second voltage-dividing branch and the second resistor in the insulation resistance detection circuit. When the state control unit is in the second state, the low-voltage DC source is controlled to charge the second voltage-dividing branch and the second resistor, and the second resistor is connected in parallel with the second voltage-dividing branch.

[0022] When the state control unit is in the first state, a first voltage value of the first voltage-dividing branch and a second voltage value of the second voltage-dividing branch in the insulation resistance detection circuit are obtained; when the state control unit is in the second state, a third voltage value of the first voltage-dividing branch and a fourth voltage value of the second voltage-dividing branch, as well as a fifth voltage value of the third voltage-dividing branch are obtained; the first voltage-dividing branch is connected in parallel with the first resistor, and the third voltage-dividing branch is connected across the positive electrode of the low-voltage DC source and the ground; the first resistor and the second resistor are two resistors connected in series in the device to be detected;

[0023] The resistance value of the first resistor and the resistance value of the second resistor are determined according to the first voltage value, the second voltage value, the third voltage value, the fourth voltage value, and the fifth voltage value.

[0024] Through this design, the processor controls the state control unit to switch between the first state and the second state, and controls the low-voltage DC source to charge the second voltage-dividing branch and the second resistor. When the control state control unit is in the first state, the low-voltage DC source does not charge the second voltage-dividing branch and the second resistor, and obtains the first voltage value of the first voltage-dividing branch and the second voltage value of the second voltage-dividing branch. When the control state control unit is in the second state, the low-voltage DC source charges the second voltage-dividing branch and the second resistor, and obtains the third voltage value of the first voltage-dividing branch and the fourth voltage value of the second voltage-dividing branch, as well as the fifth voltage value of the third voltage-dividing branch. Further, the processor determines the resistance value of the first resistor and the resistance value of the second resistor according to the first voltage value, the second voltage value, the third voltage value, the fourth voltage value and the fifth voltage value. This solution can avoid the defects of the existing technical solution, so that the resistance value of the insulation resistor can be efficiently detected.

[0025] In a possible design, the determined resistance value of the first resistor and the determined resistance value of the second resistor may meet the requirements of the following formula:

[0026]

[0027]

[0028] Among them, U 1 represents the first voltage value, U 2 represents the second voltage value, U 3 represents the third voltage value, U 4 represents the fourth voltage value, U 5 represents the fifth voltage value, R 1 represents the resistance value of the first resistor, R 2 Represents the resistance value of the second resistor, R 3 +R 4 represents the resistance value of the first voltage divider branch, R 5 +R 6 represents the resistance value of the second voltage divider branch, R 7 Represents the resistance value of the third voltage dividing branch.

[0029] Through this design, the processor can efficiently calculate the resistance value of the first insulating resistor and the resistance value of the second resistor according to the above formula.

[0030] In a third aspect, an embodiment of the present application also provides an electric vehicle, which includes a power module and an insulation resistance detection circuit of the first aspect or any possible design of the first aspect, wherein the insulation resistance detection circuit is connected between the positive output terminal and the negative output terminal of the power module and is used to detect the insulation resistance between the positive and negative electrodes of the power module.

[0031] In a fourth aspect, an embodiment of the present application also provides a power management system, which includes an insulation resistance detection circuit of the first aspect or any possible design of the first aspect, wherein the insulation resistance detection circuit is used to detect the insulation resistance between the positive and negative poles of the managed power module.

[0032] In a fifth aspect, an embodiment of the present application provides an insulation resistance detection device, the insulation resistance detection device comprising: a processor and a memory. The memory stores a computer program, instruction or data, and the processor is used to call the computer program, instruction or data stored in the memory to execute the method of the second aspect or any possible design of the second aspect.

[0033] In the sixth aspect, an embodiment of the present application also provides a computer-readable storage medium, in which computer-readable instructions are stored. When the computer-readable instructions are run on a computer, a method such as the second aspect or any possible design in the second aspect is executed.

[0034] The technical effects that can be achieved in the third and fourth aspects can refer to the technical effects that can be achieved in the first aspect or any one of the designs in the first aspect, and the technical effects that can be achieved in the fifth and sixth aspects can refer to the technical effects that can be achieved in the second aspect or any one of the designs in the second aspect. No further details will be given here. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a structural schematic diagram of an application scenario of an insulation resistance detection device in an embodiment of the present application;

[0036] Figure 2A It is a circuit diagram of insulation resistance detection based on the bridge method in the existing detection technology;

[0037] Figure 2B A circuit diagram for detecting insulation resistance based on a DC injection method in existing detection technology;

[0038] Figure 3 This is a schematic diagram of the structure of an insulation resistance detection circuit in an embodiment of the present application;

[0039] Figure 4 A schematic diagram of the circuit structure of an insulation resistance detection circuit in an embodiment of the present application;

[0040] Figure 5 A schematic diagram of a flow chart of an insulation resistance detection method in an embodiment of the present application;

[0041] Figure 6 This is an example flow chart of an insulation resistance detection method in an embodiment of the present application;

[0042] Figure 7 This is a schematic diagram of the structure of an insulation resistance detection device in an embodiment of the present application;

[0043] Figure 8 This is a structural schematic diagram of an insulation resistance detection device in an embodiment of the present application. DETAILED DESCRIPTION

[0044] The embodiments of the present application provide an insulation resistance detection circuit, method, device and storage medium thereof. The method and device are based on the same or similar technical concepts. Since the method and device solve the problem in a similar manner, the implementation of the device and the method can refer to each other, and the repeated parts will not be repeated.

[0045] It should be noted that in the description of the embodiments of the present application, "and / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent three situations: A exists alone, A and B exist at the same time, and B exists alone. "Connection" describes the connection relationship between two objects, and can represent two connection relationships. For example, A and B are connected, which can represent two situations: A is directly connected to B, and A is connected to B through C.

[0046] The character " / " generally indicates that the objects before and after are in an "or" relationship. In the present application, at least one refers to one or more; and a plurality refers to two or more.

[0047] In addition, it should be understood that in the description of this application, words such as "first", "second", and "third" are only used for the purpose of distinguishing the description, and cannot be understood as indicating or implying relative importance, nor can they be understood as indicating or implying order.

[0048] References to "one embodiment" or "some embodiments" etc. described in this specification mean that one or more embodiments of the present application include a particular feature, structure or characteristic described in conjunction with the embodiment. Thus, in this specification, the terms "include", "comprises", "has" and their variations all mean "including but not limited to", unless otherwise specifically emphasized.

[0049] The symbol of division in the formula of the embodiment of the present application can be represented by “ / ”, and the symbol of parallel connection in the circuit can be represented by “||”.

[0050] The insulation resistance detection circuit, method, and device provided in the embodiments of the present application can be applied to electric vehicles, CNC machine tools, wind power generation systems, photovoltaic power generation systems, and other devices that use high-voltage power supply, and can be used to detect whether the insulation resistance between the positive and negative poles of the power supply in the device to be detected is failed.

[0051] The embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0052] Figure 1 An example of an application scenario of an electric vehicle is shown. Figure 1 As shown, the electric vehicle at least includes: a power module, a high-voltage upper and lower power module and a high-voltage load. Among them, the power module includes a plurality of battery packs for supplying power to the high-voltage load, and the high-voltage upper and lower power module is used to control the connection between the power module and the high-voltage load. As the battery voltage of electric vehicles becomes higher and higher, in order to ensure that the high-voltage battery of the electric vehicle does not cause leakage safety to the human body, the prior art provides an insulation resistance detection circuit that can be connected between the positive output terminal HVDC+ and the negative output terminal HVDC- of the power supply of the power module in the electric vehicle, and is used to detect the insulation resistance between the positive and negative electrodes of the power module, and then take corresponding measures to disconnect the high-voltage circuit in the electric vehicle according to the resistance value of the insulation resistance, so as to avoid causing harm to the human body.

[0053] The existing detection schemes mainly include two schemes. The first scheme is a method based on the bridge method to detect insulation resistance. The specific detection circuit can be referred to Figure 2A As shown, the high-voltage system to be detected includes a power supply E, an insulation resistor R1 to be detected, and an insulation resistor R2 to be detected. The first resistor is connected in parallel with the resistor R1 to be detected in the high-voltage system to be detected. The first sampling branch includes a first capacitor, and the first sampling branch is connected in parallel with the first resistor. The second sampling branch includes a second capacitor, and the second sampling branch is connected in parallel with the second resistor R2. When the first switch S1 is closed and the second switch is opened, the voltage value across the first resistor R1 is collected through the first sampling branch, and a formula 1 is obtained. When the first switch S1 is opened and the second switch is closed, the voltage value across the second resistor R2 is collected through the second sampling branch, and another formula 2 is obtained. Further, according to formula 1 and formula 2, the resistance value of the insulating first resistor R1 and the resistance value of the insulating second resistor R2 can be obtained.

[0054] However, in the first solution, since each switch switching causes the insulating first resistor R1 and the second resistor R2 to change, the bus voltage fluctuates to a low level due to the capacitance in the sampling branch, and a delay is required before adoption, resulting in a slower detection speed.

[0055] The second solution is an insulation detection method based on the DC injection method. The detection circuit can be found in Figure 2BAs shown, in the first step: a DC power supply (voltage value is represented by U) injects a DC voltage into the left battery system (the voltage value of the battery is represented by HV), collects the voltage U1 across the insulated second resistor R2 in the device to be detected, and obtains the current I on the second resistor R2. At this time, according to the circuit, formula 1 is obtained: (U+HV) / I-(R1+R2)=Rz. In the second step: the DC power supply is passed through the reverse power supply circuit to obtain a reverse voltage (voltage value is represented by -U). At this time, according to the circuit, formula 2 is obtained: (HV-U) / I-(R1+R2)=Rz, where Rz is the total resistance value of R1 and R2 in parallel. Then, according to formula 1 and formula 2, Rz is calculated, and then the resistance value of the insulated first resistor R1 and the resistance value of the second resistor R2 are obtained according to Rz.

[0056] However, in the second solution, even if the resistance of the first insulating resistor R1 and the second insulating resistor R2 are detected, it is not possible to distinguish the resistance of the positive and negative electrodes of the battery system to the low voltage ground. Moreover, it is more complicated to design a power supply capable of positive and negative conversion, and the DC injection circuit will cause the system impedance to decrease.

[0057] In summary, the detection scheme in the prior art still has corresponding defects, and thus cannot efficiently detect the resistance value of the insulation resistance in the electric vehicle.

[0058] Therefore, the present application provides an insulation resistance detection circuit, see Figure 3 As shown, it is a structural schematic diagram of an insulation resistance detection circuit provided by the present application. The insulation resistance detection circuit 300 can be connected to the positive pole of the power supply of the device to be detected and the negative pole of the power supply, and is used to quickly and accurately detect the resistance value of the first insulation resistor R1 between the positive pole of the power supply of the device to be detected and the ground and the resistance value of the second insulation resistor R2 between the negative pole of the power supply of the device to be detected and the ground, and thus can also identify the insulation fault occurring at the positive and negative poles of the high voltage system.

[0059] Specifically, the insulation resistance detection circuit 300 may include: a first voltage dividing branch 301 , a second voltage dividing branch 302 , a third voltage dividing branch 303 , a state control unit 304 , a low voltage DC power supply 305 , an anti-reverse unit 306 , a collection unit 307 and a processor 308 .

[0060] The first voltage-dividing branch 301 is connected in parallel with the first resistor R1, and is used to divide the voltage across the first resistor R1; the voltage value across the first resistor R1 is equal to the total voltage value on the first voltage-dividing branch 301, and therefore, the voltage value across the first resistor R1 can be determined by collecting the voltage value on the first voltage-dividing branch 301.

[0061] The second voltage-dividing branch 302 is connected in parallel with the second resistor R2, and is used to divide the voltage across the second resistor R2; the voltage value across the second resistor R2 is equal to the total voltage value on the second voltage-dividing branch 302, therefore, the voltage value across the second resistor can be determined by collecting the voltage value on the second voltage-dividing branch 302.

[0062] The third voltage-dividing branch 303 is used to bridge between the positive pole of the low-voltage DC source and the ground, and is used to determine the current value of the low-voltage DC source input; the low-voltage DC source charges the insulation resistance detection circuit through the third voltage-dividing branch 303, so the total current value of the low-voltage DC source input can be determined by collecting the voltage value on the third voltage-dividing branch 303.

[0063] The state control unit 304 is used to bridge between the positive and negative electrodes of the power supply of the device to be detected. When the state control unit 304 is in the first state, it includes but is not limited to: controlling the low-voltage DC source 305 not to charge the second voltage-dividing branch 302 and the second resistor R2. When the state control unit 304 is in the second state, it includes but is not limited to: controlling the low-voltage DC source 305 to charge the second voltage-dividing branch 302 and the second resistor R2.

[0064] The low-voltage DC power supply 305 includes a positive and a negative electrode, the positive electrode of the low-voltage DC power supply 305 is connected to the third voltage-dividing branch, and the negative electrode of the low-voltage DC power supply 305 is connected to the state control unit 304, and is controlled by the state control unit 304 to execute or not execute current injection. The low-voltage DC power supply 305 can be used to detect insulation resistance when injecting a low-voltage DC signal into the detection circuit, and specifically, the low-voltage DC source 305 can inject a low-voltage DC current into the second voltage-dividing branch 302 and the second resistor R2.

[0065] It should be noted that when the state control unit 304 is in the second state, the low-voltage DC source 305 injects a low-voltage DC current into the second voltage dividing branch 302 and the second resistor R2 through the third voltage dividing branch 303 .

[0066] The first end of the anti-reverse unit 306 is used to be connected to the state control unit 304, and the second end of the anti-reverse unit 306 is used to be connected to the negative pole of the power supply of the device to be detected, so as to prevent the low-voltage DC source 305 from flowing into the circuit to be detected in the opposite direction, so as to ensure that the low-voltage DC source 305 passes through in a single direction, thereby also controlling the influence of the high voltage on the low voltage of the device to be detected.

[0067] The sampling unit 307 is connected to the first voltage division branch 301 , the second voltage division branch 302 , the third voltage division branch 303 and the processor 308 respectively.

[0068] The sampling unit 307 is used to collect the first voltage value of the first voltage dividing branch 301 and the second voltage value of the second voltage dividing branch 302 when the state control unit 304 is in the first state, and send them to the processor 308; when the state control unit 304 is in the second state, collect the third voltage value of the first voltage dividing branch 301, the fourth voltage value of the second voltage dividing branch 302 and the fifth voltage value of the third voltage dividing branch 303, and send them to the processor 308.

[0069] The processor 308 is connected to the state control unit 304 and the sampling unit 307 respectively.

[0070] The processor 308 can be used to control the state control unit 304 to switch between the first state and the second state; when the state control unit 304 is in the first state, the first voltage value of the first voltage dividing branch 301 and the second voltage value of the second voltage dividing branch 302 can be obtained from the sampling unit 307; when the state control unit 304 is in the second state, the third voltage value of the first voltage dividing branch 301 and the fourth voltage value of the second voltage dividing branch 302, as well as the fifth voltage value of the third voltage dividing branch 303 can be obtained from the sampling unit 307; and then the resistance value of the first resistor and the resistance value of the second resistor are determined according to the first voltage value, the second voltage value, the third voltage value, the fourth voltage value and the fifth voltage value.

[0071] In a specific implementation, the processor 308 may be connected to the state control unit 304 and send a control signal to the state control unit 304. After receiving the control signal, the state control unit 304 controls the state control unit 304 to switch between the first state and the second state in response to the control signal.

[0072] In specific implementation, the processor 204 can be any one of a microcontroller unit (MCU), a central processing unit (CPU), and a digital signal processor (DSP). Of course, the specific form of the processor is not limited to the above examples.

[0073] See also Figure 3As shown, the specific structures of the first voltage-dividing branch 301, the second voltage-dividing branch 302, the third voltage-dividing branch 303, the state control unit 304, the low-voltage DC power supply 305, the anti-reverse unit 306, the sampling unit 307 and the processor 308 in the insulation detection circuit 300 are respectively introduced in detail below.

[0074] 1. First voltage dividing branch 301

[0075] The first voltage-dividing branch 301 is connected in parallel with the first resistor R1 in the device to be detected, and the first voltage-dividing branch 301 may include but is not limited to: a third resistor R3 and a fourth resistor R4, wherein the first end of the third resistor R3 is used to be connected to the positive electrode of the power supply of the device to be detected, the second end of the third resistor R3 is connected to the first end of the fourth resistor R4, and the second end of the fourth resistor R4 is grounded.

[0076] 2. First voltage dividing branch 302

[0077] The second voltage-dividing branch 302 is connected in parallel with the first resistor R2 in the device to be detected. The second voltage-dividing branch 302 may include but is not limited to: a fifth resistor R5 and a sixth resistor R6; the first end of the fifth resistor R5 is grounded, the second end of the fifth resistor R5 is connected to the first end of the sixth resistor R6, and the second end of the sixth resistor R6 is used to be connected to the negative electrode of the power supply of the device to be detected.

[0078] 3. The third voltage dividing branch 303

[0079] The third voltage dividing branch 303 may include but is not limited to: a seventh resistor; a first end of the seventh resistor R7 is grounded, and a second end of the seventh resistor is connected to the positive electrode of the low-voltage DC source.

[0080] 4. State Control Unit 304

[0081] The state control unit 304 may also include but is not limited to: a first switch and an eighth resistor.

[0082] The first end of the eighth resistor R8 is connected to the negative electrode of the low-voltage DC source 305, the second end of the eighth resistor R8 is connected to the first end of the first switch K1, the second end of the first switch K1 is connected to the first end of the anti-reverse unit 306, and the control end of the first switch K1 is connected to the processor 308.

[0083] When the processor 308 controls the first switch K1 to be opened, the state control unit 304 is in the first state; when the processor 308 controls the first switch K1 to be closed, the state control unit 304 is in the second state.

[0084] Among them, the function of setting the first switch K1 is: by changing the state of the first switch K1, the low-voltage DC power supply 305 is controlled not to charge the second voltage dividing branch 302 and the second resistor R2, or the low-voltage DC power supply 305 is controlled to charge the second voltage dividing branch 302 and the second resistor R2.

[0085] Specifically, the first switch can be a switch tube. If the first switch is a metal oxide semiconductor (MOS) tube, the gate of the MOS tube can be the control end of the first switch connected to the processor 308, and the processor 308 can control the on-off of the MOS tube to realize the switching of the control state control unit 304 between the first state and the second state; if the first switch is a bipolar junction transistor (BJT), the base of the BJT can be the control end of the first switch connected to the processor 308, and the processor 308 can control the on-off of the BJT to realize the switching of the control state control unit 304 between the first state and the second state.

[0086] The working state of the state switching unit 304 is described in detail below.

[0087] See also Figure 3 As shown, when the first switch K1 is disconnected under the control of the processor 308, the state control unit 304 is in a non-operating state (a first state), that is, the low-voltage DC power supply 305 does not inject current into the second resistor R2 and the second voltage-dividing branch 302. When the first switch K1 is closed under the control of the processor 308, the state control unit 304 is in an operating state (a second state), that is, the low-voltage DC power supply 305 injects current into the second resistor R2 and the second voltage-dividing branch 302.

[0088] For details, see Figure 3 As shown, point A and point B serve as input terminals of the state switching unit 304 to control the low-voltage DC power supply. Point A may be located between the first resistor and the second resistor in the device to be detected, and point B may be located between the first voltage-dividing branch and the second voltage-dividing branch. When the first switch K1 is closed by the control of the processor 308, the state switching unit 304 may control the low-voltage DC power supply 305 to inject a DC current into the second resistor R2 through point A, and to inject a DC current into the second voltage-dividing branch 302 through point B.

[0089] Of course, the above introduction to the structure of the state control unit 304 is only an example. In actual applications, the state control unit 304 may also adopt other structures. For example, the state control unit 304 may adopt a relay, and the state control unit 304 is in the first state and the second state by changing the input quantity of the relay.

[0090] 5. Low voltage DC source 305

[0091] The low voltage DC source 305 is connected between the third voltage dividing branch 303 and the state control unit 304. The low voltage DC source 305 may output a constant current, and the current output by the low voltage DC source 305 may include but is not limited to a DC current with constant magnitude and direction.

[0092] 6. Anti-reverse unit 306

[0093] The first end of the anti-reverse unit 306 is connected to the state control unit 304, and the second end is used to connect to the negative pole of the power supply of the device to be detected. The anti-reverse unit 306 includes at least one diode, and the at least one diode is connected in series. The anti-reverse unit 306 is used to control the influence of the high voltage of the device to be detected on the low voltage.

[0094] VII. Sampling Unit 307

[0095] Optionally, the sampling unit 307 may be a voltage sampling chip, and the sampling unit 307 may transmit information to the processor 308 via inter-chip communication.

[0096] The sampling unit 307 performs voltage sampling on the first voltage division branch 301 , the second voltage division branch 302 , and the third voltage division branch 303 respectively (corresponding to voltage sampling 1 , voltage sampling 2 , and voltage sampling 3 , respectively).

[0097] When the state control unit 304 is in the first state, a first voltage value of the first voltage dividing branch 301 and a second voltage value of the second voltage dividing branch 302 are acquired, and the first voltage value and the second voltage value are sent to the processor 308 .

[0098] When the state control unit 305 is in the second state, the third voltage value of the first voltage division branch 301, the fourth voltage value of the second voltage division branch 302, and the fifth voltage value of the third voltage division branch 303 are obtained, and the third voltage value, the fourth voltage value, and the fifth voltage value are sent to the processor 308.

[0099] 8. Processor 308

[0100] The processor 308 is connected to the state control unit 304 and the sampling unit 307 respectively.

[0101] When the state control unit 304 is in the first state, the first voltage value of the first voltage dividing branch 301 and the second voltage value of the second voltage dividing branch 302 are obtained from the sampling unit 307; when the state control unit 304 is in the second state, the third voltage value of the first voltage dividing branch 301 and the fourth voltage value of the second voltage dividing branch 302, as well as the fifth voltage value of the third voltage dividing branch 303 are obtained from the sampling unit 307; the resistance value of the first resistor and the resistance value of the second resistor are determined according to the first voltage value, the second voltage value, the third voltage value, the fourth voltage value and the fifth voltage value.

[0102] Among them, the first resistor is the insulation resistance between the positive pole of the power supply of the device to be detected and the ground, and the second resistor is the insulation resistance between the negative pole of the power supply of the device to be detected and the ground. The resistance value of the first resistor and the resistance value of the second resistor can be used to determine whether an insulation resistance fault occurs in the device to be detected, and the resistance value of the first resistor and the resistance value of the second resistor can also be used to identify whether the insulation resistance fault occurs at the positive pole or negative pole of the power supply of the device to be detected.

[0103] The processor 308 can also be used to: control the first switch in the state control unit 304 to close and open; and in the first state and the second state, respectively obtain the total voltage value on the first voltage dividing branch 301 and the total voltage value on the second voltage dividing branch 302 from the sampling unit, and calculate the parallel resistance value of the first resistor and the second resistor. The parallel resistance value can be used to determine whether an insulation resistance fault occurs in the device to be detected.

[0104] It should be understood that since it is necessary to obtain the first voltage and the second voltage, the third voltage value, the fourth voltage value and the fifth voltage value in real time or periodically, and calculate the resistance value of the first resistor and the resistance value of the second resistor, or the parallel resistance value of the first resistor and the second resistor, the insulation resistance detection circuit 300 may also include a memory for storing data.

[0105] In combination with the above description, for example, Figure 4 , which is a circuit structure diagram of an insulation resistance detection circuit provided in an embodiment of the present application.

[0106] The insulation resistance detection circuit includes: a first voltage-dividing branch, a second voltage-dividing branch, a third voltage-dividing branch, a state control unit, a low-voltage direct current source, an anti-reverse unit, a sampling unit, a processor, and a memory.

[0107] The first voltage-dividing branch may include a third resistor R3 and a fourth resistor R4, wherein a first end of the third resistor R3 is connected to a positive electrode of a power supply of the device to be detected, a second end of the third resistor R3 is connected to a first end of the fourth resistor R4, and a second end of the fourth resistor R4 is grounded. The resistance values ​​of the third resistor R3 and the fourth resistor R4 are both known.

[0108] In one implementation, the sampling unit collects the voltage value of the first voltage dividing branch, which may specifically include but is not limited to the following:

[0109] like Figure 4 As shown in the figure, point a is located between the third resistor R3 and the fourth resistor R4, point b is located between the fourth resistor R4 and the second voltage divider branch, and the sampling unit can be connected to point a and point b respectively, and perform voltage sampling (voltage sampling 1) between point a and point b to obtain a sampled voltage value 1, which is the voltage value across the fourth resistor R4. Further, according to the voltage value across the fourth resistor R4, the total voltage value of the first voltage divider branch can be determined.

[0110] The first voltage-dividing branch is connected in parallel with the first resistor R1 , so the total voltage of the first voltage-dividing branch is equal to the voltage value of the first resistor R1 .

[0111] The second voltage divider branch may include a fifth resistor R5 and a sixth resistor R6; the first end of the fifth resistor R5 is grounded, the second end of the fifth resistor R5 is connected to the first end of the sixth resistor R6, and the second end of the sixth resistor R6 is used to be connected to the negative pole of the power supply of the device to be detected.

[0112] In one implementation, the sampling unit collects the voltage value of the second voltage dividing branch, which may specifically include but is not limited to the following:

[0113] like Figure 4 As shown in the figure, point c is located between the fifth resistor R5 and the sixth resistor R6, and the sampling unit can be connected to point b and point c respectively, and perform voltage sampling (voltage sampling 2) between point b and point c to obtain a sampled voltage value 2, which is the voltage value across the fifth resistor R5. Further, based on the voltage value across the fifth resistor R5, the total voltage value of the second voltage divider branch can be determined.

[0114] The second voltage-dividing branch is connected in parallel with the second resistor R2 , so the total voltage of the second voltage-dividing branch is equal to the voltage value of the second resistor R2 .

[0115] The third voltage-dividing branch may include a seventh resistor R7; the first end of the seventh resistor R7 is grounded (the process of connecting the first end of the seventh resistor R7 to the ground passes through points A and B), and the second end of the seventh resistor R7 is connected to the positive electrode of the low-voltage DC source.

[0116] In one implementation, the sampling unit collects the voltage value of the third voltage-dividing branch, which may specifically include but is not limited to the following:

[0117] like Figure 4 As shown in , point d is located between the first end of the seventh resistor R7 and point B (point B is located between the first voltage-dividing branch and the second voltage-dividing branch), and point e is located between the second end of the seventh resistor R7 and the positive electrode of the low-voltage DC source. The sampling unit can be connected to point d and point e respectively, and perform voltage sampling (voltage sampling 3) between point d and point e to obtain a sampled voltage value 3, which is the voltage value at both ends of the seventh resistor R7, and then according to the voltage value at both ends of the seventh resistor R7, the total voltage value of the third voltage-dividing branch can be determined.

[0118] The current value in the third voltage dividing branch is determined according to the total voltage value of the third voltage dividing branch and the resistance value of the third voltage dividing branch. The current value in the third voltage dividing branch is equal to the total current value charged by the low voltage DC source to the second voltage dividing branch and the second resistor R2.

[0119] The state control unit includes an eighth resistor R8 and a first switch K1.

[0120] A first end of the eighth resistor R8 is connected to the negative electrode of the low voltage DC source, a second end of the eighth resistor R8 is connected to the first end of the first switch K1, and a second end of the first switch K1 is connected to the first end of the anti-reverse unit.

[0121] The processor may be connected to a control terminal C of the first switch K1 to control the first switch K1 to be opened or closed.

[0122] When the processor controls the first switch K1 to be opened, the state control unit is in the first state; when the processor controls the first switch to be closed, the state control unit is in the second state.

[0123] However, the present application is not limited to controlling the state of the first switch by a processor. In actual use, the first switch can also be controlled to be opened or closed by manual operation of a user, and the present application does not make specific limitations.

[0124] The anti-reverse unit includes at least one diode, and at least one diode is connected in series. The first end of the anti-reverse unit is connected to the state control unit, and the second end is used to connect to the negative pole of the power supply of the device to be detected or to ground. The anti-reverse unit is mainly used to prevent the low-voltage DC source from reverse charging, and to control the influence of the high voltage on the low voltage of the device to be detected.

[0125] In the processor, the processor is connected to the state control unit, the sampling unit, and the memory respectively.

[0126] The processor can control the working state of the state control unit, that is, control the state control unit to switch between the first state and the second state. The processor and the sampling unit can communicate with each other through chips to obtain the voltage values ​​of the first voltage division branch, the second voltage division branch and the third voltage division branch from the sampling unit.

[0127] The memory may be connected to the processor for storing data, programs, instructions or codes.

[0128] In the embodiment of the present application, Figure 4 When the insulation resistance detection circuit shown detects the first resistor R1 and the second resistor R2, A and B serve as single-phase input terminals. When the low-voltage DC power supply can inject current into the second resistor R2 through point A, the low-voltage DC power supply can inject current into the second voltage divider branch through point B, and the sum of the current injected into the second resistor R2 and the current injected into the second voltage divider branch is equal to the total output current of the low-voltage DC power supply.

[0129] Combine the following Figure 4 , the working principle of the insulation resistance detection circuit provided in the embodiment of the present application is explained.

[0130] The following description is made by taking the first switch K1 being disconnected as switch state 1 and the first switch K1 being closed as switch state 2 as an example. The first switch K1 switches between switch state 1 and switch state 2 under the control of the processor.

[0131] It should be understood that in the embodiments of the present application, the switching of the switch state is not limited to being controlled by a processor, but can also be set to be manually switched by a user.

[0132] The above switching between state 1 and switch state 2 may specifically include the following two steps:

[0133] Step 1: The processor sends a control signal to the first switch, and the first switch responds to the control signal and is in switch state 1. At this time, the low-voltage DC source does not charge the second voltage divider branch and the second resistor, that is, the circuit path in the device to be detected, and the power supply in the device to be detected supplies power to the first resistor and the second resistor.

[0134] The processor obtains the first voltage value (total voltage) of the first voltage-dividing branch and the second voltage value (total voltage) of the second voltage-dividing branch. The first voltage-dividing branch is connected in parallel with the first resistor, and the second voltage-dividing branch is connected in parallel with the second resistor. At this time, the voltage value on the first resistor is equal to the first voltage value of the first voltage-dividing branch, and the voltage value on the second resistor is equal to the second voltage value of the second voltage-dividing branch.

[0135] It should be understood that reference Figure 4As shown, the first voltage-dividing branch and the first resistor can be regarded as a whole, that is, the resistors in the first voltage-dividing branch (the third resistor and the fourth resistor) and the first resistor are connected in parallel to form a total resistor (the first total resistor).

[0136] The second voltage-dividing branch and the second resistor can be regarded as another whole, that is, the resistors in the second voltage-dividing branch (the fifth resistor and the sixth resistor) and the second resistor are connected in parallel to form a total resistor (a second total resistor).

[0137] At this time, the current on the first total resistor is equal to the current on the second total resistor, that is, the sum of the current value on the first voltage divider branch and the current value on the first resistor R1 is equal to the sum of the current value on the second voltage divider branch and the current value on the second resistor. Specifically, the following formula is satisfied:

[0138] U x / ((R 3 +R 4 ) / / R 1 )=U y / ((R 5 +R 6 ) / / R 2 ) Formula 1

[0139] Among them, " / " means division and " / / " is the parallel symbol. x Represents the voltage value on the first resistor, U y represents the voltage value on the second resistor, and U 1 The value is equal to the first voltage value, U 2 The value of is equal to the second voltage value. (R 3 +R 4 ) / / R 1 Represents the first total resistance value, (R 5 +R 6 ) / / R 2 Represents the second total resistance value.

[0140] Concrete the formula 1, that is, satisfy the following formula:

[0141]

[0142] R 1 Represents the resistance of the first resistor, R 2 Represents the resistance of the second resistor, R 3 +R 4 Represents the total resistance value in the first voltage divider branch, R 5 +R 6 Represents the total resistance value in the second voltage divider branch.

[0143] Step 2: The processor sends a control signal to the first switch K1, and the first switch K1 responds to the control signal and is in switch state 2. At this time, the low-voltage DC source charges the second voltage-dividing branch and the second resistor, that is, the low-voltage DC source charges the second resistor in the device to be detected through point A and charges the second voltage-dividing branch through point B. The circuit in the device to be detected is also a passage, and the power supply in the device to be detected charges the first resistor and the second resistor.

[0144] The third voltage value (total voltage) of the first voltage-dividing branch, the fourth voltage value (total voltage) of the second voltage-dividing branch, and the fifth voltage value (total voltage) of the third voltage-dividing branch are obtained by the processor. Since the first voltage-dividing branch is connected in parallel with the first resistor, and the second voltage-dividing branch is connected in parallel with the second resistor, at this time, the voltage value on the first resistor is equal to the third voltage value of the first voltage-dividing branch, and the voltage value on the second resistor is equal to the fourth voltage value of the second voltage-dividing branch.

[0145] According to Kirchhoff's law, the sum of the current value on the first resistor, the current value in the first voltage-dividing branch, and the current value in the third voltage-dividing branch is equal to the sum of the current value on the second resistor and the current value in the second voltage-dividing branch. Specifically, the following formula is satisfied:

[0146] I x +I 1 +I 3 =I y +I Formula 2

[0147] Among them, I x Represents the current value on the first resistor, I y Represents the current value on the second resistor, I 1 Represents the current value in the first voltage divider branch, I 2 Indicates the current value in the second voltage divider branch, I 3 Indicates the current value in the third voltage-dividing branch.

[0148] Among them, the current value on the first resistor can be expressed as: The current value on the second resistor can be expressed as:

[0149] Since the first resistor is connected in parallel with the first voltage-dividing branch, and the second resistor is connected in parallel with the second voltage-dividing branch, the voltage value on the first resistor is equal to the third voltage value, and the voltage value on the second resistor is equal to the fourth voltage value, that is, U x =U 3 , U y =U 4 .

[0150] Then the current value on the first resistor can be expressed as: The current value on the second resistor can be expressed as: The current value in the first voltage divider branch can be expressed as: The current value in the second voltage divider branch can be expressed as: The current value in the third voltage divider branch can be expressed as: U 5 Represents the voltage value of the third voltage divider branch, R 7 It is represented by the total resistance value of the third voltage-dividing branch (when the third voltage-dividing branch includes the seventh resistor, U 5 Represents the voltage value on the seventh resistor, R 7 is the resistance value of the seventh resistor).

[0151] The above values ​​I x ,I y ,I 1 ,I 2 ,I 3 Substituting into the second formula, the following formula is satisfied:

[0152]

[0153] Therefore, the processor determines the resistance value of the first resistor and the resistance value of the second resistor according to the acquired first voltage value, second voltage value, third voltage value, fourth voltage value and fifth voltage value.

[0154] The resistance value of the first resistor R1 and the resistance value of the second resistor R2 determined by the processor meet the requirements of the following formula:

[0155]

[0156]

[0157] Among them, U 1 Indicates the first voltage value, U 2 Indicates the second voltage value, U 3 Indicates the third voltage value, U 4 Indicates the fourth voltage value, U 5 represents the fifth voltage value, R 1 Represents the resistance of the first resistor, R 2 Represents the resistance of the second resistor, R 3 +R 4 Represents the total resistance value of the first voltage divider branch, R 5 +R 6 Represents the total resistance value of the second voltage divider branch, R 7 Represents the total resistance of the third voltage dividing branch.

[0158] Among them, the first resistor is the insulation resistance between the positive pole of the power supply of the device to be detected and the ground, and the second resistor is the insulation resistance between the negative pole of the power supply of the device to be detected and the ground. Therefore, based on the calculated resistance values ​​of the first resistor and the second resistor, it is determined whether an insulation resistance fault occurs in the device to be detected.

[0159] In summary, the insulation resistance detection circuit provided in the present application is connected to the positive pole of the power supply of the device to be detected and the negative pole of the power supply, and can quickly and accurately detect the resistance value of the first insulation resistor between the positive pole of the power supply of the device to be detected and the ground and the resistance value of the second insulation resistor between the negative pole of the power supply of the device to be detected and the ground, and then identify the insulation fault occurring at the positive and negative poles of the high-voltage system based on the detected resistance value of the first resistor and the resistance value of the second resistor.

[0160] It should be noted that, based on the different structures of the first voltage-dividing branch, the second voltage-dividing branch, the third voltage-dividing branch and the state control unit provided in the aforementioned embodiments, the insulation resistance detection circuit provided in the embodiments of the present application also has several other structures. The principles of other circuit structures are the same, and this application will not introduce them in detail one by one.

[0161] Based on the same technical concept, the present application embodiment also provides an insulation resistance detection method, such as Figure 5 As shown, the insulation resistance detection method provided by the embodiment of the present application is as follows. The method can be Figure 4 The processor shown may also be executed with Figure 4 The insulation resistance detection circuit shown communicates with other processors for execution.

[0162] S501: When the processor controls the state control unit to be in the first state, a first voltage value of a first voltage dividing branch and a second voltage value of a second voltage dividing branch in the insulation resistance detection circuit are obtained.

[0163] Specifically, the processor can control the state control unit to switch between a first state and a second state. When the state control unit is in the first state, the low-voltage DC source is controlled not to charge the second voltage divider branch and the second resistor in the insulation resistance detection circuit. When the state control unit is in the second state, the low-voltage DC source is controlled to charge the second voltage divider branch and the second resistor in the insulation resistance detection circuit.

[0164] The first voltage-dividing branch in the insulation resistance detection circuit is connected in parallel with the first resistor in the device to be detected, and the second voltage-dividing branch in the insulation resistance detection circuit is connected in parallel with the second resistor in the device to be detected. The first resistor is connected in series with the second resistor.

[0165] In one implementation, when the processor controls the state control unit to be in the first state, the sampling unit collects a first voltage value of the first voltage division branch and a second voltage value of the second voltage division branch, and sends them to the processor.

[0166] It should be noted that the processor may obtain the first voltage value of the first voltage dividing branch in the insulation resistance detection circuit in a manner that includes but is not limited to the following manners:

[0167] Method 1: directly collect the total voltage value on the first voltage divider branch.

[0168] Method 2: Obtain the current value on the first voltage-dividing branch, and then determine the total voltage value on the first voltage-dividing branch according to the current value on the first voltage-dividing branch and the total resistance in the first voltage-dividing branch.

[0169] Method three: Obtain the voltage value on any resistor in the first voltage divider branch, and determine the current value on the voltage divider branch based on the resistance value of the resistor and the voltage value across the resistor; then, determine the total voltage value on the first voltage divider branch based on the current value on the voltage divider branch and the total resistance value in the first voltage divider branch.

[0170] Optionally, the way in which the processor obtains the second voltage value of the second voltage-dividing branch in the insulation resistance detection circuit can refer to the way in which the processor obtains the first voltage value of the first voltage-dividing branch, which will not be described in detail here.

[0171] S502: When the processor controls the state control unit to be in the second state, a third voltage value of the first voltage division branch, a fourth voltage value of the second voltage division branch, and a fifth voltage value of the third voltage division branch in the insulation resistance detection circuit are obtained.

[0172] Optionally, when the processor control state control unit is in the second state, the sampling unit collects the third voltage value of the first voltage-dividing branch, the fourth voltage value of the second voltage-dividing branch, and the fifth voltage of the third voltage-dividing branch, and sends them to the processor. The third voltage-dividing branch is connected between the positive pole and the ground of the low-voltage DC source to determine the current value of the low-voltage DC source. The sampling unit is respectively connected to the first voltage-dividing branch, the second voltage-dividing branch, the third voltage-dividing branch and the processor.

[0173] Optionally, the processor obtains the third voltage value of the first voltage dividing branch, the fourth voltage value of the second voltage dividing branch, and the fifth voltage value of the third voltage dividing branch in the insulation resistance detection circuit. Please refer to step S501 for details, which will not be described in detail here.

[0174] S503: The processor determines the resistance value of the first resistor and the resistance value of the second resistor in the device to be detected according to the first voltage value, the second voltage value, the third voltage value, the fourth voltage value and the fifth voltage value.

[0175] In one embodiment, when the processor controls the state control unit to be in the first state, the processor determines the voltage value on the first resistor and the voltage value on the second resistor according to the first voltage value and the second voltage value. At this time, the sum of the current value on the first voltage dividing branch and the current value on the first resistor is equal to the sum of the current value on the second voltage dividing branch and the current value on the second resistor. That is, the following formula 1 is satisfied:

[0176]

[0177] When the processor control state control unit is in the second state, at this time, according to Kirchhoff's law, the sum of the current value on the first resistor, the current value in the first voltage divider branch, and the current value in the third voltage divider branch is equal to the sum of the current value on the second resistor and the current value in the second voltage divider branch. That is, the following formula 2 is satisfied:

[0178]

[0179] Among them, U 1 Indicates the first voltage value, U 2 Indicates the second voltage value, U 3 Indicates the third voltage value, U 4 Indicates the fourth voltage value, U 5 Indicates the fifth voltage value, R 1 Represents the resistance of the first resistor, R 2 Represents the resistance of the second resistor, R 3 +R 4 Represents the total resistance value of the first voltage divider branch, R 5 +R 6 Represents the total resistance value of the second voltage divider branch, R 7 Indicates the total resistance value of the third voltage-dividing branch.

[0180] In the above formulas 1 and 2, R 3 , R 4 , R 5 , R 6 , R 7 are all known values, U 1 , U 2 , U 3 , U 4 Therefore, the processor can solve the first resistor R according to the above formula 1 and formula 2. 1 and the resistance of the second resistor.

[0181] Therefore, according to the insulation resistance detection method provided by the present application, the resistance value of the first insulation resistor between the positive pole of the power supply of the device to be detected and the ground and the resistance value of the second insulation resistor between the negative pole of the power supply of the device to be detected and the ground can be efficiently detected, and then the insulation fault occurring at the positive and negative poles of the high-voltage system can be identified based on the detected resistance value of the first resistor and the second resistor.

[0182] Based on the insulation resistance detection method provided in the above embodiment, the present application also provides the following specific examples to explain the method of the present application in detail. The method is mainly executed by a processor, and the specific flow chart can be referred to Figure 6 .

[0183] S601: Turn off the first switch K1.

[0184] The processor controls the first switch K1 in the state control unit to be disconnected, that is, the state control unit is in the first state, and the low-voltage direct current source does not charge the second voltage dividing branch and the second resistor.

[0185] S602: Obtaining a first voltage value U of the first voltage dividing branch 1 and the second voltage value U of the second voltage dividing branch 2 ..

[0186] When executing step S602, the processor may collect the first voltage value U of the first voltage dividing branch through the sampling unit. 1 and the second voltage U of the second voltage dividing branch 2 The sampling unit may be connected to the first voltage division branch, the second voltage division branch, the third voltage division branch and the processor.

[0187] S603: Calculate and obtain the voltage value Ux of the first resistor and the voltage value Uy of the second resistor.

[0188] Since the first voltage-dividing branch is connected in parallel with the first resistor, and the second voltage-dividing branch is connected in parallel with the second resistor, at this time, U x =U 1 , U y =U 2 .

[0189] S604: Obtain a conversion formula between the first resistor and the second resistor, ie, a first formula, according to the voltage value Ux of the first resistor and the voltage value Uy of the second resistor.

[0190] The first formula satisfies the following:

[0191] U x / ((R 3 +R 4 ) / / R 1 )=U y / ((R 5 +R6 ) / / R 2 )

[0192] Concrete the formula 1, that is, satisfy the following formula:

[0193]

[0194] Among them, " / " means division and " / / " is the parallel symbol. x Represents the voltage value on the first resistor, U y represents the voltage value on the second resistor, and U 1 The value is equal to the first voltage value, U 2 The value of is equal to the second voltage value. (R 3 +R 4 ) / / R 1 Represents the first total resistance value, (R 5 +R 6 ) / / R 2 Represents the second total resistance value.

[0195] S605: Close the first switch K1.

[0196] The processor controls the first switch K1 in the state control unit to be closed, that is, the state control unit is in the second state, and the low-voltage direct current source charges the second voltage dividing branch and the second resistor.

[0197] S606: Obtaining a third voltage value U of the first voltage dividing branch 3 and the fourth voltage value U of the second voltage dividing branch 4 and the fifth voltage value U of the third voltage dividing branch 5 .

[0198] Since the first resistor is connected in parallel with the first voltage-dividing branch, and the second resistor is connected in parallel with the second voltage-dividing branch, at this time, U x =U 3 , U y =U 4 .

[0199] When executing step S606, reference may be made to step S602, which will not be described in detail here.

[0200] S607: Calculate the current value I of the first resistor x and the current value of the second resistor I y , the first voltage dividing branch current I 1 , the second voltage dividing branch current I 2 , the current I in the state control unit 3 .

[0201] The current on the first resistor can be expressed as: The current on the second resistor can be expressed as: The current value in the first voltage divider branch can be expressed as The current value in the second voltage divider branch can be expressed as The current value in the third voltage-dividing branch can be expressed as U 5 Represents the voltage value of the third voltage divider branch, R 7 Indicates the resistance value of the third voltage divider branch. 5 When the voltage value on the seventh resistor is represented by 7 It can be expressed as the resistance value of the seventh resistor.

[0202] S608: According to Kirchhoff's law, we get I x +I 1 +I 3 =I y +I 2 , that is, the second formula is obtained.

[0203] The second formula satisfies the following:

[0204]

[0205] S609: Obtain the resistance value of the first resistor and the resistance value of the second resistor according to the first formula and the second formula.

[0206] In Formula 1 and Formula 2, U 1 , U 2 , U 3 , U 4 , R 3 , R 4 , R 5 , R 6 , R 7 are all known values, R 1 and R 2 is unknown, according to formula 1 and formula 2, R can be calculated 1 and R 2 The value of .

[0207] Based on the same technical concept, such as Figure 7 As shown, the embodiment of the present application further provides an insulation resistance detection device, the insulation resistance detection device 700. In one design, the insulation resistance detection device 700 may include a communication unit 701, a processing unit 702, and a storage unit 703.

[0208] The communication unit 701 can be used to obtain a first voltage value of a first voltage dividing branch and a second voltage value of a second voltage dividing branch when the state control unit is in a first state; and to obtain a third voltage value of the first voltage dividing branch, a fourth voltage value of the second voltage dividing branch, and a fifth voltage value of the third voltage dividing branch when the state control unit is in a second state.

[0209] The processing unit 702 may be configured to determine a resistance value of the first resistor and a resistance value of the second resistor according to the first voltage value, the second voltage value, the third voltage value, the fourth voltage value, and the fifth voltage value.

[0210] The storage unit 703 may be used to store data, programs, instructions or codes.

[0211] Based on the same technical concept, such as Figure 8 As shown, the embodiment of the present application further provides an insulation resistance detection device, the insulation resistance detection device 800. In one design, the insulation resistance detection device 800 may include a communication interface 801, a processor 802, and a memory 803.

[0212] The communication interface 801 can be used to obtain a first voltage value of a first voltage dividing branch and a second voltage value of a second voltage dividing branch when the state control unit is in a first state; and to obtain a third voltage value of the first voltage dividing branch, a fourth voltage value of the second voltage dividing branch, and a fifth voltage value of the third voltage dividing branch when the state control unit is in a second state.

[0213] The processor 802 may be configured to determine a resistance value of the first resistor and a resistance value of the second resistor according to the first voltage value, the second voltage value, the third voltage value, the fourth voltage value, and the fifth voltage value.

[0214] The memory 803 may be used to store data, programs, instructions or codes.

[0215] The division of modules in the embodiments of the present application is schematic and is only a logical function division. There may be other division methods in actual implementation. In addition, each functional module in each embodiment of the present application may be integrated into a processor, or may exist physically separately, or two or more modules may be integrated into one module. The above-mentioned integrated modules may be implemented in the form of hardware or in the form of software functional modules.

[0216] An embodiment of the present application provides a computer-readable storage medium storing a computer program, wherein the computer program includes instructions for executing the above method embodiment.

[0217] An embodiment of the present application provides a computer program product including instructions, which, when executed on a computer, enables the computer to execute the above method embodiment.

[0218] Through the description of the above implementation mode, it can be clearly understood by those skilled in the art that the embodiments of the present application can be implemented by hardware, firmware, or a combination thereof. When software is used for implementation, the above functions can be stored in a computer-readable medium or transmitted as one or more instructions or codes on a computer-readable medium. Computer-readable media include computer storage media and communication media, wherein the communication media include any medium that facilitates the transmission of a computer program from one place to another. The storage medium can be any available medium that a computer can access. Taking this as an example but not limited to: a computer-readable medium can include RAM, ROM, electrically erasable programmable read only memory (EEPROM), compact disc read-only memory (CD-ROM) or other optical disc storage, disk storage medium or other magnetic storage device, or any other medium that can be used to carry or store a desired program code in the form of an instruction or data structure and can be accessed by a computer. In addition. Any connection can be appropriately a computer-readable medium. For example, if the software is transmitted from a website, server, or other remote source using coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, wireless, and microwave are included in the fixation of the medium. As used in the embodiments of the present application, disk and disc include compact disc (CD), laser disc, optical disc, digital video disc (DVD), floppy disk, and Blu-ray disc, where disks usually copy data magnetically and discs use lasers to copy data optically. The above combinations should also be included in the scope of protection of computer-readable media.

[0219] In short, the above description is only an embodiment of the present application and is not intended to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. made according to the disclosure of the present application shall be included in the protection scope of the present application.

Claims

1. An insulation resistance detection circuit for detecting a device to be detected comprising a first resistor and a second resistor connected in series, It is characterized in that include: A first voltage-dividing branch, a second voltage-dividing branch, a third voltage-dividing branch, a state control unit, and a processor; The first voltage-dividing branch is connected in parallel with the first resistor, and is used to divide the voltage across the first resistor; the second voltage-dividing branch is connected in parallel with the second resistor, and is used to divide the voltage across the second resistor; the third voltage-dividing branch is connected between the positive electrode of the low-voltage DC source and the ground, and is used to determine the current value of the low-voltage DC source; wherein the low-voltage DC source and the ground are between the first voltage-dividing branch and the second voltage-dividing branch, and the negative electrode of the low-voltage DC power supply is connected to the state control unit; The state control unit is used to bridge between the positive electrode and the negative electrode of the power supply of the device to be detected. When the state control unit is in a first state, the low-voltage DC source is controlled not to charge the second voltage-dividing branch and the second resistor. When the state control unit is in a second state, the low-voltage DC source is controlled to charge the second voltage-dividing branch and the second resistor. The processor is respectively connected to the state control unit, the first voltage dividing branch, the second voltage dividing branch and the third voltage dividing branch, and is used to control the state control unit to switch between the first state and the second state; when the state control unit is in the first state, the first voltage value of the first voltage dividing branch and the second voltage value of the second voltage dividing branch are obtained; when the state control unit is in the second state, the third voltage value of the first voltage dividing branch, the fourth voltage value of the second voltage dividing branch, and the fifth voltage value of the third voltage dividing branch are obtained; according to the first voltage value, the second voltage value, the third voltage value, the fourth voltage value and the fifth voltage value, the resistance value of the first resistor and the resistance value of the second resistor are determined.

2. The circuit as claimed in claim 1, It is characterized in that The device further comprises a sampling unit, which is connected to the first voltage-dividing branch, the second voltage-dividing branch, the third voltage-dividing branch and the processor respectively, and is used for collecting a first voltage value of the first voltage-dividing branch and a second voltage value of the second voltage-dividing branch when the state control unit is in the first state, and sending the collected data to the processor; When the state control unit is in the second state, a third voltage value of the first voltage division branch, a fourth voltage value of the second voltage division branch, and a fifth voltage value of the third voltage division branch are collected and sent to the processor.

3. The circuit as claimed in claim 1, It is characterized in that The first end of the first resistor is connected to the positive electrode of the power supply, the second end of the first resistor is connected to the first end of the second resistor, and the second end of the second resistor is connected to the negative electrode of the power supply.

4. The circuit as claimed in claim 1, It is characterized in that The insulation resistance detection circuit also includes: an anti-reverse unit, a first end of which is connected to the state control unit, and a second end is used to connect to the positive pole of the power supply of the device to be detected, so as to control the influence of the high voltage of the device to be detected on the low voltage.

5. The circuit as claimed in claim 4, It is characterized in that The anti-reverse unit includes: at least one diode, and the at least one diode is connected in series.

6. A circuit as claimed in any one of claims 1 to 5, It is characterized in that The first voltage dividing branch includes: a third resistor and a fourth resistor, wherein the first end of the third resistor is used to be connected to the positive electrode of the power supply of the device to be detected, the second end of the third resistor is connected to the first end of the fourth resistor, and the second end of the fourth resistor is grounded.

7. A circuit as claimed in any one of claims 1 to 5, It is characterized in that The second voltage dividing branch includes: a fifth resistor and a sixth resistor; the first end of the fifth resistor is grounded, the second end of the fifth resistor is connected to the first end of the sixth resistor, and the second end of the sixth resistor is used to be connected to the negative pole of the power supply of the device to be detected.

8. A circuit as claimed in any one of claims 1 to 5, It is characterized in that The third voltage-dividing branch includes: a seventh resistor; a first end of the seventh resistor is grounded, and a second end of the seventh resistor is connected to the positive electrode of the low-voltage DC source.

9. The circuit as claimed in claim 4, It is characterized in that The state control unit includes: a first switch and an eighth resistor; The first end of the eighth resistor is connected to the negative electrode of the low-voltage DC source, the second end of the eighth resistor is connected to the first end of the first switch, the second end of the first switch is connected to the first end of the anti-reverse unit, and the control end of the first switch is connected to the processor; When the processor controls the first switch to be opened, the state control unit is in the first state; when the processor controls the first switch to be closed, the state control unit is in the second state.

10. The circuit according to any one of claims 1 to 5, It is characterized in that The resistance value of the first resistor and the resistance value of the second resistor determined by the processor meet the requirements of the following formula: Among them, U 1 represents the first voltage value, U 2 represents the second voltage value, U 3 represents the third voltage value, U 4 represents the fourth voltage value, U 5 represents the fifth voltage value, R 1 represents the resistance value of the first resistor, R 2 The resistance value of the second resistor, R 3 +R 4 represents the resistance value of the first voltage divider branch, R 5 +R 6 represents the resistance value of the second voltage divider branch, R 7 Represents the resistance value of the third voltage dividing branch.

11. A method for detecting insulation resistance, applied to the insulation resistance detection circuit according to any one of claims 1 to 10, It is characterized in that include: A control state control unit is switched between a first state and a second state. When the state control unit is in the first state, the low-voltage DC source is controlled not to charge the second voltage-dividing branch and the second resistor in the insulation resistance detection circuit. When the state control unit is in the second state, the low-voltage DC source is controlled to charge the second voltage-dividing branch and the second resistor, and the second resistor is connected in parallel with the second voltage-dividing branch. When the state control unit is in a first state, obtaining a first voltage value of a first voltage dividing branch and a second voltage value of the second voltage dividing branch in the insulation resistance detection circuit; When the state control unit is in the second state, obtaining a third voltage value of the first voltage division branch, a fourth voltage value of the second voltage division branch, and a fifth voltage value of the third voltage division branch; The first voltage-dividing branch is connected in parallel with the first resistor, and the third voltage-dividing branch is connected between the positive electrode of the low-voltage DC source and the ground; the first resistor and the second resistor are two resistors connected in series in the device to be detected; wherein the low-voltage DC source and the ground are between the first voltage-dividing branch and the second voltage-dividing branch; The resistance value of the first resistor and the resistance value of the second resistor are determined according to the first voltage value, the second voltage value, the third voltage value, the fourth voltage value, and the fifth voltage value.

12. The method according to claim 11, It is characterized in that The determined resistance values ​​of the first resistor and the second resistor meet the requirements of the following formula: Among them, U 1 represents the first voltage value, U 2 represents the second voltage value, U 3 represents the third voltage value, U 4 represents the fourth voltage value, U 5 represents the fifth voltage value, R 1 represents the resistance value of the first resistor, R 2 The resistance value of the second resistor, R 3 +R 4 represents the resistance value of the first voltage divider branch, R 5 +R 6 represents the resistance value of the second voltage divider branch, R 7 Represents the resistance value of the third voltage dividing branch.

13. An insulation impedance detection device, It is characterized in that The device comprises: Memory, used to store data, programs, instructions or codes; A processor, configured to execute the program, instruction or code in the memory to complete the method according to claim 11 or 12.

14. An electric vehicle, It is characterized in that It comprises a power module and an insulation resistance detection circuit as described in any one of claims 1 to 10, wherein the insulation resistance detection circuit is connected between the positive output terminal and the negative output terminal of the power module and is used to detect the insulation resistance between the positive and negative electrodes of the power module.

15. A power management system, It is characterized in that It comprises the insulation resistance detection circuit as claimed in any one of claims 1 to 10, wherein the insulation resistance detection circuit is used to detect the insulation resistance between the positive electrode and the negative electrode of the managed power module.

16. A non-volatile computer-readable storage medium, It is characterized in that A computer program is stored, and the computer program is loaded by a processor to execute the method according to claim 11 or 12.

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