Sampling point voltage determination method and system, power battery insulation detection method and automobile

Abstract

The invention discloses a sampling point voltage determination method and system, a power battery insulation detection method and an automobile, and the method employs a dual filtering mode to filter collected data, and can improve the filtering accuracy. When filtering is not passed, collection is not carried out for m times again, collection is only carried out for k times, the collected k voltage values are stored in an array U [m] based on the first-in first-out principle, then filtering is carried out again, the insulation detection time can be effectively shortened, and the insulation detection efficiency is improved; noise signals under the special condition that the negative electrode ground insulation resistance is short to the ground are recognized and filtered, if Uxadc1 is larger than or equal to Uxmin, the insulation resistance value is calculated, and if Uxadc1 is smaller than Uxmin, it is directly judged that an insulation fault exists; therefore, the influence of uncertainty caused by the participation of noise signals in calculation on the insulation detection accuracy can be avoided, and the insulation detection accuracy is improved.

Description

Technical Field

[0001] The present invention belongs to the field of power battery detection, and in particular relates to a sampling point voltage determination method and system, a power battery insulation detection method, and a vehicle. Background Art

[0002] The power system of electric vehicles is a high-voltage system. Ideally, the system is a closed system that is completely insulated from the vehicle body. However, it cannot be ruled out that cable aging, vibration, temperature and humidity changes, acid-base corrosion and other problems may cause insulation damage, resulting in a decrease in the insulation performance of the entire vehicle. If a leakage current loop is formed between the power battery and the vehicle body, it will not only affect the normal operation of low-voltage electrical appliances and the ECU on the vehicle, but may also threaten the personal safety of the driver and passengers. Therefore, it is necessary to monitor the insulation performance of the power battery.

[0003] At present, insulation detection is generally performed using methods such as a balanced bridge. In order to ensure that the calculation result is more accurate, the collected voltage is generally filtered. CN114646808A discloses a detection device and method for the insulation resistance of a battery pack, which collects 66 samples, takes the last 50 samples for averaging, and then compares the 50 sample values ​​with the average value. If the difference with the average value is within a certain range, subsequent calculations are performed, and the average value of the last 5 stored sample values ​​is output as the collected value, otherwise the sample calculation is performed again. It can prevent calculation errors caused by large changes in insulation resistance within an insulation detection cycle, ensure that each insulation detection cycle is detected under the condition that the insulation resistance is relatively stable, and ensure the accuracy of the detection.

[0004] However, the following problems still exist: (1) In actual application scenarios, for a set of collected voltages, some may become extremely large due to the influence of some pulse signals, while in fact other voltages are in a stable state and can meet the requirements of participating in insulation calculations. However, since individual signals will have a greater impact on the calculation of the average value, when this method is used for filtering, the filtering will fail and it is necessary to re-collect data and then calculate again, which reduces the efficiency of the entire insulation calculation. (2) Once the filtering fails, the method of re-collecting 66 voltage values ​​is also extremely time-consuming. There may be a situation where only the first few voltages of the last 66 voltage values ​​are still unstable, while the following dozens of voltages are already stable. Using this method will waste a lot of time. In addition, in the event of an extreme main negative terminal short to ground (that is, the negative electrode to ground insulation resistance R nIn the case of a short circuit, the voltage value of the main negative terminal sampling point is theoretically 0, but in actual situations, due to the influence of some noise signals, the collected voltage value of the main negative terminal sampling point is not completely 0. If such working conditions are not taken into account, the voltage of the random noise signal may be brought into the calculation, resulting in random calculation results, affecting the accuracy of insulation detection, and there is a risk of causing serious safety problems. Summary of the invention

[0005] The purpose of the present invention is to provide a sampling point voltage determination method and system, a power battery insulation detection method, and a vehicle, so as to improve the accuracy of filtering and enhance the accuracy and efficiency of insulation detection.

[0006] In a first aspect, the present invention provides a method for determining a sampling point voltage, comprising:

[0007] Step 1: collect voltage m times at the sampling point according to a preset sampling period, and store the collected m voltage values ​​into an array U[m], and then execute step 2.

[0008] Step 2: Average the m voltage values ​​in the array U[m] to obtain the first voltage average value U avg1 , and then proceed to step 3.

[0009] Step 3: Filter the m voltage values ​​in the array U[m] to remove the voltage values ​​and the first voltage average value U avg1 The difference is greater than U th The n1 voltage values ​​(i.e., the voltage values ​​in the statistical array U[m] and the first voltage average value U avg1 The difference is greater than U th The number of n1), and then execute step 4; wherein, U th Represents the preset filtering threshold value, n1<m.

[0010] Step 4: determine whether n1 is less than or equal to i1. If yes, execute step 5, otherwise execute step 8; wherein i1 represents the preset first filtering number, i1<m.

[0011] Step 5: Average the remaining m-n1 voltage values ​​after filtering to obtain the second voltage average value U avg2 , and then proceed to step six.

[0012] Step 6: Filter the remaining m-n1 voltage values ​​after filtering to remove the voltage values ​​and the second voltage average value U avg2 The difference is greater than U th The n2 voltage values ​​(i.e., the voltage values ​​among the m-n1 voltage values ​​remaining after statistical filtering and the second voltage average value U avg2 The difference is greater than U thThe number of n2), and then execute step seven; wherein, n2<m-n1.

[0013] Step 7, determine whether n2 is less than or equal to i2, if so (indicating that the filtering passes), execute step 9, otherwise (indicating that the filtering fails), execute step 8; wherein i2 represents the preset second filtering number, i2<i1.

[0014] Step 8. Collect voltage k times at the sampling point according to the preset sampling period, and store the collected k voltage values ​​into the array U[m] based on the first-in-first-out principle (i.e., use the k voltage values ​​to shift and replace the first k voltage values ​​stored in the array U[m]), and then return to execute step 2; wherein k<i1.

[0015] Step 9: Select the latest j voltage values ​​(i.e., the j voltage values ​​with the latest storage time among the remaining m-n1-n2 voltage values ​​after filtering) from the remaining m-n1-n2 voltage values ​​after filtering to calculate the root mean square value rms, and then execute step 10; wherein, 1 <j<i1。

[0016] Step ten: taking the root mean square value rms as the sampling point voltage, and then ending.

[0017] Preferably, the preset first filtering number The preset second filtering number Said Among them, int() represents the floor rounding function.

[0018] Preferably, the value range of m is 45 to 55, the value range of the preset sampling period is 9 milliseconds to 11 milliseconds, and the preset filtering threshold value U is th The value range is 1 mV to 5 mV.

[0019] In a second aspect, the present invention provides a sampling point voltage determination system, which includes a controller, wherein the controller is configured to execute the sampling point voltage determination method.

[0020] In a third aspect, the present invention provides a power battery insulation detection method, wherein the insulation detection device used includes a controller, a resistor R a , resistor R b , resistor R c , resistor R d , resistor R e , resistor R f and controllable switch SW; resistor R a , resistor R b , resistor R c , resistor R dThe controllable switch SW is connected in series in sequence and connected to the positive electrode of the power battery at one end and the negative electrode of the power battery at the other end as a whole; one end of the controllable switch SW is connected to the resistor R a With resistor R b The other end is connected to the negative electrode of the power battery; the resistor R b With resistor R c The connection point is connected to the shell ground, and the resistor R c With resistor R d The connection point of is used as the main negative terminal sampling point A, and the main negative terminal sampling point A is connected to the controller; the resistor R e With resistor R f Connect in series and as a whole, one end is connected to the positive electrode of the power battery and the other end is connected to the negative electrode of the power battery; the resistor R e With resistor R f The connection point of is used as a balanced bridge sampling point B, the balanced bridge sampling point B is connected to the controller; the controller is connected to the controllable switch SW, and controls the controllable switch SW to be closed / opened. The method includes:

[0021] In the first step, the controller controls the controllable switch SW to be disconnected, and the above sampling point voltage determination method is used for both the main negative terminal sampling point A and the balanced bridge sampling point B to obtain the main negative terminal sampling point voltage U xadc1 And the voltage U of the balanced bridge sampling point batadc1 , and then proceed to step 2.

[0022] In the second step, the controller determines whether the voltage U xadc1 Less than U xmin If yes, execute the third step, otherwise execute the fourth step; where U xmin Indicates the preset threshold voltage.

[0023] In the third step, the controller determines that there is an insulation fault in the power battery and then ends.

[0024] Step 4: The controller controls the controllable switch SW to close, and uses the above sampling point voltage determination method for both the main negative terminal sampling point A and the balanced bridge sampling point B to obtain the main negative terminal sampling point voltage U xadc2 And the voltage U of the balanced bridge sampling point batadc2 , then proceed to step 5.

[0025] Step 5: Controller uses U xadc1 , U batadc1 , U xadc2 , U batadc2 And the resistor R a , R b , R c , R d , R e , R f Calculate the insulation resistance R of the positive electrode to groundp The resistance value and the insulation resistance R n resistance value, and then end.

[0026] Preferably, the preset threshold voltage U xmin =U xadc0 Among them, U xadc0 It means that twice the insulation resistance acquisition error is used as the insulation resistance of the negative electrode to the ground, and is substituted into the preset main negative terminal sampling point voltage calculation formula to calculate the main negative terminal sampling point voltage value.

[0027] Preferably, the preset main negative terminal sampling point voltage calculation formula is: Among them, U pack+ Indicates the voltage value of the power battery. R n =2δ, δ represents the insulation resistance acquisition error.

[0028] Preferably, the insulation resistance acquisition error δ=5KΩ.

[0029] Preferably, in the fifth step, the positive electrode to ground insulation resistance R is calculated p The resistance value and the insulation resistance R n The resistance value is:

[0030] Using the formula: Calculate the insulation resistance R of the positive electrode to ground p The resistance value and the insulation resistance R n resistance value.

[0031] in,

[0032] In a fourth aspect, the present invention provides an automobile, comprising the above-mentioned sampling point voltage determination system.

[0033] Compared with the prior art, the present invention has the following effects:

[0034] (1) The collected data are filtered by double filtering. The first filtering condition is relatively wide, which can effectively filter out individual points with large differences, and prevent these points with large differences from causing filtering failure due to their large impact on the average value calculation. The second filtering is performed again after filtering out individual points with large differences. The condition is relatively narrow, which can filter more effectively and accurately, thereby improving the accuracy of filtering.

[0035] (2) When filtering fails, instead of re-collecting m times, only k times are collected, and the k collected voltage values ​​are stored in the array U[m] based on the first-in-first-out principle, and then filtered again; in this way, a relatively stable voltage value can be obtained in time after the voltage stabilizes, which effectively shortens the insulation detection time and improves the insulation detection efficiency.

[0036] (3) For the short insulation resistance of the negative electrode to the ground (i.e. R n short circuit) special case of noise signal identification and filtering, if U xadc1 Greater than or equal to U xmin , then the insulation resistance is calculated. If U xadc1 Less than U xmin , it is directly determined that there is an insulation fault; thereby avoiding the influence of uncertainty caused by the participation of noise signals in the calculation on the accuracy of insulation detection, thereby improving the accuracy of insulation detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 Flow chart of a method for determining a sampling point voltage in an embodiment of the present invention.

[0038] Figure 2 Schematic diagram of the circuit principle of the insulation detection device in an embodiment of the present invention.

[0039] Figure 3 Schematic diagram of the controllable switch SW of the insulation detection device in the embodiment of the present invention when it is in the off state.

[0040] Figure 4 Schematic diagram of the controllable switch SW of the insulation detection device in the embodiment of the present invention when it is in a closed state.

[0041] Figure 5 The figure is a flow chart of a power battery insulation detection method in an embodiment of the present invention. DETAILED DESCRIPTION

[0042] In order to enable a more detailed understanding of the features and technical contents of the embodiments of the present invention, the implementation of the embodiments of the present invention is described in detail below in conjunction with the accompanying drawings. The attached drawings are for reference only and are not intended to limit the embodiments of the present invention.

[0043] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. The terms used herein are only for the purpose of describing the embodiments of the present invention and are not intended to limit the present invention.

[0044] In the following description, reference is made to “some embodiments”, which describe a subset of all possible embodiments, but it will be understood that “some embodiments” may be the same subset or different subsets of all possible embodiments and may be combined with each other without conflict.

[0045] like Figure 1 As shown, the method for determining the sampling point voltage in the embodiment of the present invention includes:

[0046] Step 1: collect voltage m times at the sampling point according to the preset sampling period, and store the collected m voltage values ​​into the array U[m], and then execute step 2. In some embodiments, the preset sampling period ranges from 9 milliseconds to 11 milliseconds, and the value range of m is 45 to 55. As an example, here, the preset sampling period is 10 milliseconds, and m=50.

[0047] Step 2: Average the m voltage values ​​in the array U[m] to obtain the first voltage average value U avg1 , and then proceed to step 3.

[0048] Step 3: Filter the m voltage values ​​in the array U[m] to remove the voltage values ​​and the first voltage average value U avg1 The difference is greater than U th The n1 voltage values ​​(i.e., the voltage values ​​in the statistical array U[m] and the first voltage average value U avg1 The difference is greater than U th The number of n1), and then execute step 4; wherein, U th represents a preset filtering threshold value, n1<m. In some embodiments, U th The value range of is 1 millivolt to 5 millivolts. As an example, here U th =3 mV.

[0049] Step 4: Determine whether n1 is less than or equal to i1. If yes, execute step 5, otherwise execute step 8; wherein i1 represents the preset first filtering number, i1<m. In some embodiments, int() represents a floor function. As an example, here i1=10.

[0050] Step 5: Average the remaining m-n1 voltage values ​​after filtering to obtain the second voltage average value U avg2 , and then proceed to step six.

[0051] Step 6: Filter the remaining m-n1 voltage values ​​after filtering to remove the voltage values ​​and the second voltage average value U avg2 The difference is greater than U th The n2 voltage values ​​(i.e., the voltage values ​​among the m-n1 voltage values ​​remaining after statistical filtering and the second voltage average value Uavg2 The difference is greater than U th (the number n2), and then step seven is executed; where n2 < m - n1.

[0052] Step seven, determine whether n2 is less than or equal to i2. If so, (indicating that the filtering passes) step nine is executed; otherwise (indicating that the filtering fails) step eight is executed; where i2 represents a preset second filtering number, and i2 < i1. In some embodiments, As an example, here i2 = 5.

[0053] Step eight, collect the voltage k times at the sampling point according to the preset sampling period, and store the k collected voltage values into the array U[m] based on the first-in-first-out principle (that is, use these k voltage values to shift and replace the first k voltage values stored in the array U[m]), and then return to execute step two; where k < i1. In some embodiments, As an example, here k = 5.

[0054] Step nine, among the remaining m - n1 - n2 voltage values after filtering, select the latest j voltage values (that is, the j voltage values with the latest storage time among the remaining m - n1 - n2 voltage values after filtering) to calculate the root mean square, and obtain the root mean square value rms, and then step ten is executed; where 1 < j < i1. As an example, here j = 5.

[0055] Step ten, use the root mean square value rms as the voltage at the sampling point, and then end.

[0056] During the process of the sampling point voltage determination method, the first filtering condition is relatively wide, and the maximum number of points that can be filtered is i1. It can effectively filter out individual points with large differences, preventing these points with large differences from causing filtering failure due to their great influence on the average value calculation. The second filtering is performed again after filtering out individual points with large differences. The condition is relatively narrow, and the maximum number of voltage values that can be filtered is i2, which can perform filtering more effectively and accurately, improving the accuracy of filtering.

[0057] When the filtering fails, m times of re - collection are not performed, but only k times of collection are performed, and the k collected voltage values are stored into the array U[m] based on the first - in - first - out principle, and then the filtering is performed again; in this way, a relatively stable voltage value can be obtained in time after the voltage is stable, effectively shortening the time of insulation detection and improving the insulation detection efficiency.

[0058] In addition, the sampling point voltage determination system in the embodiments of the present invention includes a controller, and the controller is configured to execute the Figure 1 sampling point voltage determination method as shown.

[0059] An embodiment of the present invention further provides a car, which includes the sampling point voltage determination system.

[0060] like Figure 2 As shown, the power battery insulation detection method in the embodiment of the present invention adopts an insulation detection device including a controller (not shown in the figure), a resistor R a , resistor R b , resistor R c , resistor R d , resistor R e , resistor R f and controllable switch SW. Resistor R a , resistor R b , resistor R c , resistor R d They are connected in series in sequence, and as a whole, one end is connected to the positive electrode of the power battery and the other end is connected to the negative electrode of the power battery. One end of the controllable switch SW is connected to the resistor R a With resistor R b The other end is connected to the negative electrode of the power battery. b With resistor R c The connection point is connected to the shell ground. c With resistor R d The connection point of is used as the main negative sampling point A, and the main negative sampling point A is connected to the controller. e With resistor R f Connected in series, with one end connected to the positive pole of the power battery and the other end connected to the negative pole of the power battery as a whole. e With resistor R f The connection point of is used as a balanced bridge sampling point B, and the balanced bridge sampling point B is connected to the controller. The controller is connected to the controllable switch SW to control the controllable switch SW to close / open.

[0061] like Figure 5 As shown, the power battery insulation detection method in the embodiment of the present invention is executed by a controller and includes:

[0062] The first step is to control the controllable switch SW to be disconnected (see Figure 3 ), and the above sampling point voltage determination method is used for both the main negative terminal sampling point A and the balanced bridge sampling point B to obtain the main negative terminal sampling point voltage U xadc1 And the voltage U of the balanced bridge sampling point batadc1 , and then proceed to step 2.

[0063] Step 2: Determine whether the voltage at the main negative terminal sampling point is U xadc1 Less than U xmin If yes, execute the third step, otherwise execute the fourth step; where U xmin Indicates the preset threshold voltage.

[0064] In some embodiments, the preset threshold voltage U xmin =U xadc0 Among them, U xadc0 It means that twice the insulation resistance acquisition error is used as the insulation resistance of the negative electrode to the ground, and is substituted into the preset main negative terminal sampling point voltage calculation formula to calculate the main negative terminal sampling point voltage value.

[0065] In some embodiments, the preset main negative terminal sampling point voltage calculation formula is: Among them, U pack+ Indicates the voltage value of the power battery (known quantity), R n =2δ, δ represents the insulation resistance value acquisition error. As an example, the insulation resistance value acquisition error δ here is 5KΩ.

[0066] like Figure 2 As shown, in this circuit, the main negative terminal is short-circuited (i.e. R n When the voltage at the main negative terminal sampling point is short-circuited), the voltage at the main negative terminal sampling point may bring in random noise signals into the calculation, affecting the result. Therefore, the present invention adopts a threshold value interception method to filter out the influence of the noise voltage and sets a smaller threshold voltage (i.e., U xmin ) to make a judgment, when the voltage value of the main negative terminal sampling point is less than U xmin When R n The resistance value is too small, which indicates that insulation failure has occurred. p When the circuit is open, the more voltage the main positive terminal receives, the smaller the voltage value of the main negative terminal sampling point is; therefore, we assume that R p Circuit breaker. U pack+ Indicates the voltage value of the power battery (known quantity), When R n When it is smaller, the voltage at the main negative terminal sampling point (U xadc0 ) is smaller, assuming R n =2δ, δ represents the insulation resistance acquisition error, which can be used to calculate a U xadc0 The value of xmin When the controllable switch SW is disconnected and the voltage value collected at the main negative terminal sampling point is less than U xmin When R n Less than 2δ, the insulation fault condition is met; when the controllable switch SW is disconnected and the voltage collected at the main negative terminal sampling point is greater than or equal to U xminWhen the insulation resistance value is calculated normally, the influence of the uncertainty caused by the participation of noise signals in the calculation on the accuracy of insulation detection can be avoided, thereby improving the accuracy of insulation detection.

[0067] The third step is to determine whether there is an insulation fault in the power battery, and then end.

[0068] Step 4: Control the controllable switch SW to close (see Figure 4 ), and the above sampling point voltage determination method is used for both the main negative terminal sampling point A and the balanced bridge sampling point B to obtain the main negative terminal sampling point voltage U xadc2 And the voltage U of the balanced bridge sampling point batadc2 , then proceed to step 5.

[0069] Step 5: Use U xadc1 , U batadc1 , U xadc2 , U batadc2 And the resistor R a , R b , R c , R d , R e , R f The resistance value (known quantity) is used to calculate the insulation resistance R of the positive electrode to ground. p The resistance value and the insulation resistance R n resistance value, and then end.

[0070] In some embodiments, the fifth step of calculating the positive electrode to ground insulation resistance R p The resistance value and the insulation resistance R n The resistance value is:

[0071] Using the formula: Calculate the insulation resistance R of the positive electrode to ground p The resistance value and the insulation resistance R n The resistance value of

[0072] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for determining a sampling point voltage, characterized in that: include: Step 1: collect voltage m times at the sampling point according to a preset sampling period, and store the collected m voltage values ​​into an array U[m], and then execute step 2; Step 2: Average the m voltage values ​​in the array U[m] to obtain the first voltage average value U avg1 , then proceed to step 3; Step 3: Filter the m voltage values ​​in the array U[m] to remove the voltage values ​​and U avg1 The difference is greater than U th n1 voltage values, and then execute step 4; where U th Indicates the preset filtering threshold value; Step 4: determine whether n1 is less than or equal to i1. If yes, execute step 5, otherwise execute step 8; wherein i1 represents the preset first filtering number, i1<m; Step 5: Average the remaining m-n1 voltage values ​​after filtering to obtain the second voltage average value U avg2 , then proceed to step six; Step 6: Filter the remaining m-n1 voltage values ​​after filtering to remove the voltage value and U avg2 The difference is greater than U th n2 voltage values, and then execute step 7; Step 7: Determine whether n2 is less than or equal to i2. If yes, execute step 9, otherwise execute step 8; wherein i2 represents the preset second filtering number, i2<i1; Step 8: collect k voltages at the sampling points according to a preset sampling period, and store the collected k voltage values ​​into an array U[m] based on a first-in-first-out principle, and then return to execute step 2; wherein k < i1; Step 9: Select the latest j voltage values ​​from the remaining m-n1-n2 voltage values ​​after filtering to calculate the root mean square value rms, and then execute step 10; wherein, 1 <j<i1; Step ten: taking the root mean square value rms as the sampling point voltage, and then ending.

2. The method for determining the sampling point voltage according to claim 1, characterized in that: Said Said Said Among them, int() represents the floor rounding function.

3. The method for determining the sampling point voltage according to claim 2, characterized in that: The value range of m is 45 to 55, the value range of the preset sampling period is 9 milliseconds to 11 milliseconds, and the U th The value range is 1 mV to 5 mV.

4. A sampling point voltage determination system, comprising a controller, characterized in that: The controller is configured to execute the sampling point voltage determination method according to any one of claims 1 to 3.

5. A power battery insulation detection method, the insulation detection device used includes a controller, a resistor R a , resistor R b , resistor R c , resistor R d , resistor R e , resistor R f and controllable switch SW; resistor R a , resistor R b , resistor R c , resistor R d The controllable switch SW is connected in series in sequence and connected to the positive electrode of the power battery at one end and the negative electrode of the power battery at the other end as a whole; one end of the controllable switch SW is connected to the resistor R a With resistor R b The other end is connected to the negative electrode of the power battery; the resistor R b With resistor R c The connection point is connected to the shell ground, and the resistor R c With resistor R d The connection point of is used as the main negative sampling point A and connected to the controller; the resistor R e With resistor R f Connect in series and connect one end to the positive electrode of the power battery as a whole. The other end is connected to the negative electrode of the power battery; the resistor R e With resistor R f The connection point of is used as a balanced bridge sampling point B, which is connected to the controller; the controller is connected to the controllable switch SW to control the controllable switch SW to close / open; it is characterized in that, The method includes: In the first step, the controller controls the controllable switch SW to be turned off, and the sampling point voltage determination method as described in any one of claims 1 to 3 is used for both the main negative terminal sampling point A and the balanced bridge sampling point B to obtain the main negative terminal sampling point voltage U xadc1 And the voltage U of the balanced bridge sampling point batadc1 , then execute the second step; Step 2: The controller determines whether U xadc1 Less than U xmin If yes, execute the third step, otherwise execute the fourth step; where U xmin Indicates the preset threshold voltage; Step 3: The controller determines that there is an insulation fault in the power battery, and then ends; Step 4: The controller controls the controllable switch SW to close, and adopts the sampling point voltage determination method as described in any one of claims 1 to 3 for both the main negative terminal sampling point A and the balanced bridge sampling point B to obtain the main negative terminal sampling point voltage U xadc2 And the voltage U of the balanced bridge sampling point batadc2 , then execute step 5; Step 5: Controller uses U xadc1 , U batadc1 , U xadc2 , U batadc2 And the resistor R a , R b , R c , R d , R e , R f Calculate the insulation resistance R of the positive electrode to ground p The resistance value and the insulation resistance R n resistance value, and then end.

6. The power battery insulation detection method according to claim 5, characterized in that: Stated U xmin = U xadc0 ; Among them, U xadc0 It means that twice the insulation resistance acquisition error is used as the insulation resistance of the negative electrode to the ground, and is substituted into the preset main negative terminal sampling point voltage calculation formula to calculate the main negative terminal sampling point voltage value.

7. The power battery insulation detection method according to claim 6, characterized in that: The preset main negative terminal sampling point voltage calculation formula is: Among them, U pack+ Indicates the voltage value of the power battery. R n =2δ, δ represents the insulation resistance acquisition error.

8. The power battery insulation detection method according to claim 7, characterized in that: The insulation resistance acquisition error δ=5KΩ.

9. The power battery insulation detection method according to any one of claims 5 to 8, characterized in that: In the fifth step, the insulation resistance R of the positive electrode to ground is calculated. p The resistance value and the insulation resistance R n The resistance value is: Using the formula: Calculate the insulation resistance R of the positive electrode to ground p The resistance value and the insulation resistance R n The resistance value; in, 10. An automobile, characterized in that: The method comprises the sampling point voltage determination system as claimed in claim 4.

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