Insulation impedance detection device and method for power battery system

Abstract

The present application discloses an insulation impedance detection device and method for a power battery system, which relates to the field of automotive electronic technology. The device includes: a detection module, a first resistor, a second resistor and an isolation capacitor. The pulse output end of the detection module is connected to the first end of the isolation capacitor through the first resistor and the second resistor connected in series in sequence, and the second end of the isolation capacitor is connected to the negative electrode of the power battery pack; the grounding end of the detection module is grounded; the detection module is used to output a pulse voltage signal through the pulse output end, and obtain a first voltage sampling signal between the first resistor and the second resistor, and a second voltage sampling signal between the negative output end of the power battery pack and the ground; the detection module is also used to obtain the insulation impedance of the power battery system according to the pulse voltage signal, the first voltage sampling signal, the second voltage sampling signal and the resistance value of the first resistor. By using this device, the influence of the capacitor on the insulation impedance detection is reduced, and the accuracy of the insulation impedance detection is improved.

Description

Technical Field

[0001] The present application relates to the field of automotive electronic technology, and in particular to an insulation impedance detection device and method for a power battery system. Background Art

[0002] With the increasing energy shortage and environmental pollution in modern society, electric vehicles have attracted wide attention from all walks of life. Electric vehicles use the on-board power battery pack as a power source to drive the motor, so that the motor drives the wheels to rotate, and then drives the vehicle to travel.

[0003] Monitoring the high-voltage insulation impedance of the battery system of electric vehicles is an important means to ensure the safe operation of the vehicle. When performing insulation measurement, the Y capacitor in the power battery pack will affect the accuracy of insulation impedance detection, resulting in low accuracy of insulation impedance detection. Therefore, reducing the interference of capacitance while performing insulation impedance detection has always been a hot research issue. Summary of the invention

[0004] In order to solve the above-mentioned technical problems existing in the prior art, the present application provides an insulation impedance detection device and method for a power battery system, which reduces the influence of capacitance on insulation impedance detection and improves the accuracy of insulation impedance detection.

[0005] The present application provides an insulation impedance detection device for a power battery system, the power battery system comprising a power battery pack, the device comprising: a detection module, a first resistor, a second resistor and an isolation capacitor;

[0006] The pulse output end of the detection module is connected to the first end of the isolation capacitor through a first resistor and a second resistor connected in series in sequence, and the second end of the isolation capacitor is connected to the negative electrode of the power battery pack;

[0007] The grounding terminal of the detection module is grounded;

[0008] The detection module is used to output a pulse voltage signal through the pulse output terminal, and obtain a first voltage sampling signal between the first resistor and the second resistor, and a second voltage sampling signal between the negative output terminal of the power battery pack and the ground;

[0009] The detection module is also used to obtain the insulation impedance of the power battery system according to the pulse voltage signal, the first voltage sampling signal, the second voltage sampling signal and the resistance value of the first resistor.

[0010] Optionally, the detection module specifically includes: a sampling module and a pulse generator;

[0011] The sampling module is used to convert the acquired first voltage sampling signal and the second voltage sampling signal into a first voltage digital signal and a second voltage digital signal respectively;

[0012] The pulse generator is used to output the pulse voltage signal.

[0013] Optionally, the detection module specifically includes a processor;

[0014] The processor is used to obtain the insulation impedance of the power battery system according to the pulse voltage signal, the first voltage digital signal, the second voltage digital signal and the resistance value of the first resistor.

[0015] Optionally, the processor is used to obtain the insulation impedance of the power battery system according to the pulse voltage signal, the first voltage digital signal, the second voltage digital signal and the resistance value of the first resistor, specifically including:

[0016] The processor obtains an equation satisfied by a preset number of the pulse voltage signals, the first voltage digital signal, the second voltage digital signal, the resistance value of the first resistor, the capacitance value of the Y capacitor, and the insulation impedance of the power battery system within a preset time period, and the preset number of the first voltage digital signals and the second voltage digital signals of the equation correspond to different groups of sampled data;

[0017] The processor is further configured to use the preset number of equations to obtain the insulation impedance of the power battery system through a least squares method.

[0018] Optionally, the processor is further used to obtain the capacitance value of the Y capacitor by using the preset number of equations through a least squares method.

[0019] Optionally, the pulse generator is also used to output different pulse voltage signals, so that the sampling module converts the first voltage sampling signal and the second voltage sampling signal corresponding to the different pulse voltage signals into the first voltage digital signal and the second voltage digital signal corresponding to the different pulse voltage signals respectively.

[0020] Optionally, the pulse generator obtains different pulse voltage signals by changing the period and / or duty cycle of the pulse voltage signal.

[0021] Optionally, the pulse voltage signal, the first voltage digital signal, the second voltage digital signal, the resistance value of the first resistor, the capacitance value of the Y capacitor, and the insulation impedance of the power battery system satisfy the equation, specifically:

[0022]

[0023] Among them, U sourceis the pulse voltage signal, U1 is the first voltage digital signal, U2 is the second voltage digital signal, R1 is the resistance value of the first resistor, C Y is the capacitance value of the total capacitance of the Y capacitor, R i is the total insulation resistance.

[0024] The embodiment of the present application further provides an insulation impedance detection method for a power battery system, wherein a first resistor and a second resistor are connected to a first end of an isolation capacitor, and a second end of the isolation capacitor is connected to a negative electrode of a power battery pack, comprising:

[0025] sequentially passing a pulse voltage signal to the negative output terminal of the power battery pack through a first resistor, a second resistor and an isolation capacitor, and obtaining a first voltage sampling signal between the first resistor and the second resistor, and a second voltage sampling signal between the negative output terminal of the power battery pack and ground;

[0026] The insulation impedance of the power battery system is obtained according to the pulse voltage signal, the first voltage sampling signal, the second voltage sampling signal and the resistance value of the first resistor.

[0027] Optionally, obtaining the insulation impedance of the power battery system according to the pulse voltage signal, the first voltage sampling signal, the second voltage sampling signal and the resistance value of the first resistor specifically includes:

[0028] Acquire an equation satisfied by a preset number of the pulse voltage signals, the first voltage digital signal, the second voltage digital signal, the resistance value of the first resistor, the capacitance value of the Y capacitor, and the insulation impedance of the power battery system within a preset time period, wherein the preset number of the first voltage digital signals and the second voltage digital signals of the equation correspond to different groups of sampled data;

[0029] The insulation impedance of the power battery system is obtained by using the preset number of equations through a least square method.

[0030] An embodiment of the present application further provides an electric vehicle, which includes the insulation impedance detection device of the power battery system.

[0031] The device provided by the present application has at least the following advantages:

[0032] The device includes a detection module, a first resistor, a second resistor and an isolation capacitor. The pulse output end of the detection module is connected to the first end of the isolation capacitor through the first resistor and the second resistor connected in series in sequence, the second end of the isolation capacitor is connected to the negative electrode of the power battery pack, and the ground end of the detection module is grounded. The detection module is used to output a pulse voltage signal through the pulse output end, and obtain a first voltage sampling signal between the first resistor and the second resistor, and a second voltage sampling signal between the negative output end of the power battery pack and the ground. The detection module is also used to obtain the insulation impedance of the power battery system according to the pulse voltage signal, the first voltage sampling signal, the second voltage sampling signal and the resistance value of the first resistor. The circuit design of the device is capable of sampling between the negative electrode of the power battery pack and the vehicle body ground, and can obtain a group of equations satisfied by a pulse voltage signal, a first voltage sampling signal, a second voltage sampling signal, the resistance value of the first resistor, the capacitance value of the Y capacitor, and the insulation impedance of the power battery system, wherein the capacitance value of the Y capacitor and the insulation impedance of the power battery system are unknown, and thus the group of equations is a two-variable linear equation. By obtaining and solving the two-variable linear equations satisfied by multiple groups of test data, the insulation impedance of the power battery system can be obtained. Therefore, this method can more accurately obtain the insulation impedance of the power battery system, and reduces the influence of the capacitor on the insulation impedance detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0034] Figure 1 A schematic diagram of a circuit for insulation impedance detection;

[0035] Figure 2 A schematic diagram of an insulation impedance detection device for a power battery system provided in an embodiment of the present application;

[0036] Figure 3 Flow chart of the insulation impedance detection method of the power battery system provided in the embodiment of the present application

[0037] Figure 4 A schematic diagram of an electric vehicle provided in an embodiment of the present application. DETAILED DESCRIPTION

[0038] In order to enable those skilled in the art to better understand the technical solution of the present application, the insulation impedance method of the current power battery system is first described below.

[0039] See also Figure 1, the figure is a schematic diagram of a circuit for insulation impedance detection.

[0040] The high voltage part 20 includes a power battery system of a battery, including a power battery pack 201 of an electric vehicle.

[0041] When the low-frequency pulse injection method is used to detect the insulation impedance of the power battery system, an isolation capacitor C is used to isolate the detection circuit 10 from the high-voltage part 20, and a pulse waveform is injected into the high-voltage part 20 by the detection circuit 10, and the wavelength is sampled. The insulation resistance of the power battery system is determined by the changes in the sampled waveform.

[0042] However, due to the existence of Y capacitance in the power battery pack, that is, the structural capacitance between the positive and negative electrodes of the battery and the metal shell of the battery or the internal cooling pipeline, the accuracy of the insulation resistance measurement will be reduced.

[0043] In order to solve the above technical problems existing in the prior art, the present application provides an insulation impedance detection device and method for a power battery system, which adds sampling between the negative electrode of the high-voltage power battery pack and the vehicle body ground, and uses the least squares method to fit the obtained circuit equation, thereby reducing the influence of capacitance on insulation impedance detection and improving the accuracy of insulation impedance detection.

[0044] In order to enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0045] It will be understood that the terms “first”, “second”, etc. in the embodiments of the present application are only used for convenience of description and do not constitute a limitation on the embodiments of the present application.

[0046] Embodiment 1:

[0047] An embodiment of the present application provides an insulation impedance detection device for a power battery system, which is applied to an electric vehicle, wherein the power battery system includes a power battery pack, which is described in detail below with reference to the accompanying drawings.

[0048] See also Figure 2 , which is a schematic diagram of an insulation impedance detection device for a power battery system provided in an embodiment of the present application.

[0049] The device comprises: a detection module 101, a first resistor R1, a second resistor R2 and an isolation capacitor C.

[0050] Among them, the pulse output end of the detection module 101 is connected to the first end of the isolation capacitor C through the first resistor R1 and the second resistor R2 connected in series in sequence, and the second end of the isolation capacitor C is connected to the negative electrode of the power battery pack 201. Since the negative electrode of the power battery pack is grounded, the second end of the isolation capacitor C is actually also grounded, that is, the voltage of the second end of the isolation capacitor C is the voltage of the negative electrode of the power battery pack to the ground.

[0051] The ground terminal of the detection module 101 is grounded.

[0052] The detection module 101 is used to output a pulse voltage signal through the pulse output terminal, and obtain a first voltage sampling signal between the first resistor R1 and the second resistor R2, and a second voltage sampling signal between the negative output terminal of the power battery pack 201 and the ground.

[0053] The pulse voltage signal may be a PWM (Pulse Width Modulation) signal, and the detection module 101 may control the period and duty cycle of the pulse voltage signal.

[0054] The detection module 101 is further used to obtain the insulation impedance of the power battery system according to the pulse voltage signal, the first voltage sampling signal, the second voltage sampling signal and the resistance value of the first resistor.

[0055] The working principle of the detection module 101 is described in detail below.

[0056] Specifically, the detection module 101 includes: a sampling module 101a and a pulse generator 101b.

[0057] The sampling module 101a is used to convert the acquired first voltage sampling signal and second voltage sampling signal into a first voltage digital signal and a second voltage digital signal respectively.

[0058] During the time period of sending the pulse voltage signal, the sampling module 101a can perform sampling according to a preset sampling frequency, thereby being able to obtain multiple groups of first voltage sampling signals and second voltage sampling signals.

[0059] The pulse generator 101b is used to output the pulse voltage signal. In addition, the pulse signal generator 101b can also adjust the period and duty cycle of the output pulse voltage signal to obtain different pulse voltage signals.

[0060] When the pulse voltage signal is changed, the first voltage sampling signal and the second voltage sampling signal are also changed accordingly, and then the first voltage digital signal and the second voltage digital signal converted by the sampling module 101a are also changed accordingly.

[0061] Furthermore, the detection module specifically includes a processor (not shown in the figure), and the processor is used for performing data processing.

[0062] Specifically, the processor obtains the insulation impedance of the power battery system according to the pulse voltage signal, the first voltage digital signal, the second voltage digital signal and the resistance value of the first resistor.

[0063] See also Figure 2 In the circuit shown, the Y capacitor of the power battery system can be equivalent to the Y capacitor shown in the figure. The insulation impedance of the power battery system is equivalent to the insulation impedance Ri to ground. When an insulation fault occurs, the insulation impedance Ri will divide the first resistor R1 and the second resistor R2, causing the peak value of the collected pulse voltage signal to change, and when the Y capacitor is present, the time constant of the waveform will change accordingly. For high-voltage power battery packs and high-voltage vehicle capacitors, it can be regarded as a short-circuit state. According to Kirchhoff's current law, the entire system satisfies the following equation at this time:

[0064]

[0065] Among them, i source is the current change caused by the pulse voltage signal, U2 is the voltage between the negative electrode of the high-voltage battery and the vehicle body ground, which corresponds to the second voltage digital signal, C Y is the capacitance of all Y capacitors, R i is the resistance value of the absolute impedance. source It is impossible to measure directly, so the two ends of equation (1) are multiplied by the resistance value of the first resistor R1 to transform it, and then the following equation can be obtained:

[0066]

[0067] This equation is the pulse voltage signal U obtained by the processor source , the first voltage digital signal U1, the second voltage digital signal U2, the resistance value R1 of the first resistor, the capacitance value C of the Y capacitor Y And the insulation resistance R of the power battery system i Satisfied equation.

[0068] The pulse voltage signal U source , the resistance value of the first resistor R1, the capacitance value of the Y capacitor C Y And the insulation resistance R of the power battery system i It can be considered as a fixed value during the detection process, and the first voltage digital signal U1 and the second voltage digital signal U2 are obtained within a preset time period, so the equation is a binary linear equation.

[0069] The sampling module 101 a acquires a preset number of first voltage digital signals U1 and second voltage digital signals U2 within a preset period.

[0070] Then, the processor can obtain a preset number of equations within a preset time, that is, obtain a preset number of binary linear equations. The first voltage digital signals and the second voltage digital signals of the preset number of equations correspond to different groups of sampled data.

[0071] The processor is also used to use the preset number of equations to obtain the insulation impedance of the power battery system through a least squares method.

[0072] The following is a detailed description of the process of using the least squares method to obtain the solution of the system of equations. The system of equations is represented by the following mathematical form:

[0073]

[0074] Where m represents m equations, n represents n unknowns β, m>n, and the value of the unknown n in this application is 2, that is, the unknowns include the capacitance value C of the Y capacitor. Y And the insulation resistance R of the power battery system i , which is vectorized to:

[0075] Xβ=y

[0076]

[0077] Obviously, this system of equations generally has no solution, so in order to select the most appropriate β, the residual sum of squares function S is introduced:

[0078] S(β)=||Xβ-y|| 2

[0079] (In statistics, the residual sum of squares function can be viewed as n times the mean square error MSE)

[0080] when When , S(β) takes the minimum value, which is written as: By differentiating S(β) to find the maximum value, we can get: If the matrix X T If X is non-singular, then β has a unique solution:

[0081] Therefore, C can be obtained by least squares Y and R i The optimal solution of .

[0082] In addition, since the pulse generator can adjust the period and duty cycle of the pulse voltage signal, the best solution effect can be achieved by changing the period and duty cycle, and multiple verifications can be performed to reduce the probability of false alarms.

[0083] In summary, the pulse output end of the detection module of the device provided in the embodiment of the present application is connected to the first end of the isolation capacitor through the first resistor and the second resistor in series in sequence, the second end of the isolation capacitor is connected to the negative pole of the power battery pack, and the ground end of the detection module is grounded. The detection module is used to output a pulse voltage signal through the pulse output end, and obtain a first voltage sampling signal between the first resistor and the second resistor, and a second voltage sampling signal between the negative output end of the power battery pack and the ground. The detection module is also used to obtain the insulation impedance of the power battery system according to the pulse voltage signal, the first voltage sampling signal, the second voltage sampling signal and the resistance value of the first resistor. The device has a circuit design for sampling between the negative pole of the power battery pack and the vehicle body ground, and can obtain a pulse voltage signal, a first voltage sampling signal, a second voltage sampling signal, the resistance value of the first resistor, the capacitance value of the Y capacitor and the insulation impedance of the power battery system. The capacitance value of the Y capacitor and the insulation impedance of the power battery system are unknown, so the equation group is a binary linear equation, and the binary linear equations satisfied by multiple groups of test data are obtained and solved, that is, the insulation impedance of the power battery system can be obtained, so the method can more accurately obtain the insulation impedance of the power battery system, reducing the influence of the capacitor on the insulation impedance detection.

[0084] Embodiment 2:

[0085] Based on the insulation impedance detection device of the power battery system provided in the above embodiment, the second embodiment of the present application also provides an insulation impedance detection method of the power battery system. When the method is applied, the pulse output end of the detection module of the insulation impedance detection device of the power battery system is connected to the first end of the isolation capacitor through the first resistor and the second resistor connected in series in sequence, the second end of the isolation capacitor is connected to the negative electrode of the power battery pack, and the ground end of the detection module is grounded. The following is a detailed description in conjunction with the accompanying drawings.

[0086] See also Figure 3 , which is a flow chart of an insulation impedance detection method for a power battery system provided in an embodiment of the present application.

[0087] The method described in the embodiment of the present application comprises the following steps:

[0088] S301: Pass a pulse voltage signal to the negative output terminal of the power battery pack through the first resistor, the second resistor and the isolation capacitor in sequence, and obtain a first voltage sampling signal between the first resistor and the second resistor, and a second voltage sampling signal between the negative output terminal of the power battery pack and ground.

[0089] Since the negative electrode of the power battery pack is grounded, the second end of the isolation capacitor C is actually also grounded, that is, the voltage of the second end of the isolation capacitor C is the voltage of the negative electrode of the power battery pack to ground.

[0090] S302: Obtaining the insulation impedance of the power battery system according to the pulse voltage signal, the first voltage sampling signal, the second voltage sampling signal and the resistance value of the first resistor.

[0091] Specifically, when the detection module includes a sampling module and a pulse generator.

[0092] The first voltage sampling signal and the second voltage sampling signal acquired may be converted into a first voltage digital signal and a second voltage digital signal respectively by using a sampling module.

[0093] The pulse voltage signal can be outputted by a pulse generator. In addition, the pulse signal generator can be used to adjust the period and duty cycle of the output pulse voltage signal to obtain different pulse voltage signals.

[0094] Furthermore, when the detection module includes a processor, the processor can be used to obtain an equation satisfied by a preset number of the pulse voltage signals, the first voltage digital signal, the second voltage digital signal, the resistance value of the first resistor, the capacitance value of the Y capacitor and the insulation impedance of the power battery system within a preset time period, the first voltage digital signal and the second voltage digital signal of the preset number of the equations correspond to different groups of sampling data, and the processor is used to obtain the insulation impedance of the power battery system through the least squares method based on the preset number of equations.

[0095] The specific equation is:

[0096]

[0097] U in the equation source is the pulse voltage signal, U1 is the first voltage digital signal, U2 is the second voltage digital signal, R1 is the resistance value of the first resistor, C Y is the capacitance value of the Y capacitor.

[0098] A preset number of first voltage digital signals U1 and second voltage digital signals U2 are acquired within a preset period.

[0099] Then, within a preset time, a preset number of equations can be obtained, that is, a preset number of binary linear equations can be obtained. The first voltage digital signals and the second voltage digital signals of the preset number of equations correspond to different groups of sampled data.

[0100] The specific process of determining the solution of a system of linear equations of two variables by the least squares method can be found in Example 1, and the embodiments of the present application will not be repeated here.

[0101] The method provided in the embodiment of the present application adds sampling between the negative electrode of the power battery pack and the vehicle body ground, and can obtain a group of equations satisfied by the pulse voltage signal, the first voltage sampling signal, the second voltage sampling signal, the resistance value of the first resistor, the capacitance value of the Y capacitor, and the insulation impedance of the power battery system, wherein the capacitance value of the Y capacitor and the insulation impedance of the power battery system are unknown, so the group of equations is a two-variable linear equation. The two-variable linear equations satisfied by multiple groups of test data are obtained and solved, that is, the insulation impedance of the power battery system can be obtained. Therefore, this method can more accurately obtain the insulation impedance of the power battery system and reduce the influence of capacitance on insulation impedance detection.

[0102] Embodiment three:

[0103] Based on the insulation impedance detection device of the power battery system provided in the above embodiment, the second embodiment of the present application further provides an electric vehicle, which is described in detail below with reference to the accompanying drawings.

[0104] See also Figure 4 , which is a schematic diagram of an electric vehicle provided in an embodiment of the present application.

[0105] The electric vehicle 400 includes the insulation impedance detection device 10 of the power battery system described in the first embodiment, which is used to detect the insulation resistance of the power battery pack of the electric vehicle.

[0106] For the specific description of the detection device 10, please refer to the relevant description in the first embodiment, and the embodiment of the present application will not be repeated here.

[0107] The electric vehicle provided in the application example includes a detection module whose pulse output end is connected to the first end of the isolation capacitor through the first resistor and the second resistor connected in series in sequence, and the second end of the isolation capacitor is connected to the negative electrode of the power battery pack. The grounding end of the detection module is grounded, and the detection module is used to output a pulse voltage signal through the pulse output end, and obtain a first voltage sampling signal between the first resistor and the second resistor, and a second voltage sampling signal between the negative output end of the power battery pack and the ground. The detection module is also used to obtain the insulation impedance of the power battery system according to the pulse voltage signal, the first voltage sampling signal, the second voltage sampling signal and the resistance value of the first resistor. In terms of circuit design, the device has the ability to sample between the negative electrode of the power battery pack and the vehicle body ground, and can obtain the equation group satisfied by the pulse voltage signal, the first voltage sampling signal, the second voltage sampling signal, the resistance value of the first resistor, the capacitance value of the Y capacitor and the insulation impedance of the power battery system, wherein the capacitance value of the Y capacitor and the insulation impedance of the power battery system are unknown, so the equation group is a binary linear equation, and the binary linear equation satisfied by multiple sets of test data is obtained and solved, that is, the insulation impedance of the power battery system can be obtained, so the detection device can more accurately obtain the insulation impedance of the power battery system, reducing the influence of the capacitor on the insulation impedance detection.

[0108] It should be understood that in the present application, "at least one (item)" means one or more, and "plurality" means two or more. "And / or" is used to describe the association relationship of associated objects, indicating that three relationships may exist. For example, "A and / or B" can mean: only A exists, only B exists, and A and B exist at the same time, where A and B can be singular or plural. The character " / " generally indicates that the objects associated before and after are in an "or" relationship. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single or plural items. For example, at least one of a, b or c can mean: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, c can be single or multiple.

[0109] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the device embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment. The device embodiment described above is merely schematic, and the units and modules described as separate components may or may not be physically separated. In addition, some or all of the units and modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Ordinary technicians in this field can understand and implement it without paying creative work.

[0110] The above is only a specific implementation of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application. These improvements and modifications should also be regarded as the scope of protection of the present application.

Claims

1. An insulation impedance detection device for a power battery system, characterized in that: The power battery system includes a power battery pack, and the device includes: a detection module, a first resistor, a second resistor and an isolation capacitor; The pulse output end of the detection module is connected to the first end of the isolation capacitor through a first resistor and a second resistor connected in series in sequence, and the second end of the isolation capacitor is connected to the negative electrode of the power battery pack; The grounding terminal of the detection module is grounded; The detection module is used to output a pulse voltage signal through the pulse output terminal, and obtain a first voltage sampling signal between the first resistor and the second resistor, and a second voltage sampling signal between the negative output terminal of the power battery pack and the ground; The detection module is also used to form a preset number of equations based on the pulse voltage signal, the first voltage sampling signal, the second voltage sampling signal, the resistance value of the first resistor, the capacitance value of the Y capacitor and the insulation impedance of the power battery system, where the equation is a linear equation of two variables, and the linear equation of two variables satisfied by multiple sets of test data is obtained and solved to obtain the insulation impedance of the power battery system.

2. The detection device according to claim 1, characterized in that: The detection module specifically includes: a sampling module and a pulse generator; The sampling module is used to convert the acquired first voltage sampling signal and second voltage sampling signal into a first voltage digital signal and a second voltage digital signal respectively; The pulse generator is used to output the pulse voltage signal.

3. The detection device according to claim 2, characterized in that: The detection module specifically includes a processor; The processor is used to obtain the insulation impedance of the power battery system according to the pulse voltage signal, the first voltage digital signal, the second voltage digital signal and the resistance value of the first resistor.

4. The detection device according to claim 3, characterized in that: The processor is used to obtain the insulation impedance of the power battery system according to the pulse voltage signal, the first voltage digital signal, the second voltage digital signal and the resistance value of the first resistor, specifically including: The processor obtains an equation satisfied by a preset number of the pulse voltage signals, the first voltage digital signal, the second voltage digital signal, the resistance value of the first resistor, the capacitance value of the Y capacitor, and the insulation impedance of the power battery system within a preset time period, and the preset number of the first voltage digital signals and the second voltage digital signals of the equation correspond to different groups of sampled data; The processor is further configured to use the preset number of equations to obtain the insulation impedance of the power battery system through a least squares method.

5. The detection device according to claim 4, characterized in that: The processor is further configured to obtain the capacitance value of the Y capacitor by using the preset number of equations through a least square method.

6. The detection device according to claim 2, characterized in that: The pulse generator is also used to output different pulse voltage signals, so that the sampling module converts the first voltage sampling signal and the second voltage sampling signal corresponding to the different pulse voltage signals into the first voltage digital signal and the second voltage digital signal corresponding to the different pulse voltage signals respectively.

7. The detection device according to claim 6, characterized in that: The pulse generator obtains different pulse voltage signals by changing the period and / or duty cycle of the pulse voltage signal.

8. The detection device according to claim 4, characterized in that: The equation satisfied by the pulse voltage signal, the first voltage digital signal, the second voltage digital signal, the resistance value of the first resistor, the capacitance value of the Y capacitor and the insulation impedance of the power battery system is specifically: Among them, U source is the pulse voltage signal, U1 is the first voltage digital signal, U2 is the second voltage digital signal, R1 is the resistance value of the first resistor, C Y is the capacitance value of all the Y capacitors, R i is the total insulation resistance.

9. A method for detecting insulation impedance of a power battery system, characterized in that: The first resistor and the second resistor are connected to a first end of the isolation capacitor, and the second end of the isolation capacitor is connected to the negative electrode of the power battery pack, including: sequentially passing a pulse voltage signal to the negative output terminal of the power battery pack through a first resistor, a second resistor and an isolation capacitor, and obtaining a first voltage sampling signal between the first resistor and the second resistor, and a second voltage sampling signal between the negative output terminal of the power battery pack and ground; According to the equation group satisfied by the pulse voltage signal, the first voltage sampling signal, the second voltage sampling signal, the resistance value of the first resistor, the capacitance value of the Y capacitor and the insulation impedance of the power battery system, the equation group is a two-variable linear equation, the two-variable linear equation satisfied by multiple sets of test data is obtained and solved to obtain the insulation impedance of the power battery system.

10. An electric vehicle, characterized in that: The electric vehicle comprises the insulation impedance detection device of the power battery system according to any one of claims 1-7.

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