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

Abstract

The application discloses a sampling point voltage determination method and system, a power battery insulation detection method and an automobile. The method adopts a double filtering mode to filter the collected data, and can improve the filtering accuracy. When the filtering fails, instead of collecting m times, only k times are collected, and the collected k voltage values are stored in an array U[m] based on the first-in first-out principle, and then the filtering is performed again, so that the insulation detection time can be effectively shortened, and the insulation detection efficiency can be improved. Noise signals in the special case of short ground of the negative electrode to ground insulation resistance are identified and filtered. If U xadc1 is greater than or equal to U xmin , insulation resistance calculation is performed, and if U xadc1 is less than U xmin , it is directly determined that there is an insulation fault. Thus, the influence of the uncertainty caused by the noise signal participating in the calculation on the insulation detection accuracy can be avoided, and the insulation detection accuracy can be improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of power battery detection, and particularly relates to a sampling point voltage determination method and system, a power battery insulation detection method, and an automobile. BACKGROUND

[0002] The power system of an electric vehicle is a high-voltage system. Ideally, the system is a closed system and is completely insulated from the vehicle body, but problems such as cable aging, vibration, temperature and humidity changes, acid and alkali corrosion, etc. can cause insulation to be damaged, causing the insulation performance of the entire vehicle to decrease. 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 ECUs on the vehicle, but also may threaten the personal safety of the driver and passengers. Therefore, the insulation performance of the power battery needs to be monitored.

[0003] Currently, methods such as a balanced bridge are generally used for insulation detection. To ensure that the calculation results are more accurate, the collected voltages are generally filtered. CN114646808A discloses a battery pack insulation resistance detection device and method, which collects 66 samples, takes the last 50 for averaging, and then compares the 50 sample values with the average value. If the difference from the average value is within a certain range, subsequent calculation is performed, and the average value of the last 5 stored sampling values is output as the collection value, otherwise, re-sampling calculation is performed. It can prevent calculation errors caused by large changes in insulation resistance within an insulation detection period, ensure that each insulation detection period is detected under the condition that the insulation resistance is relatively stable, and ensure the accuracy of the detection.

[0004] However, it still has the following problems: (1) In actual application scenarios, for a group of collected voltages, some may become extremely large due to the influence of some pulse signals, while the actual voltages are in a stable state and can meet the needs of participating in insulation calculation, but since individual signals have a greater impact on the calculation of the average value, filtering will not pass when filtering is performed in this way, and data collection needs to be performed again, then calculation is performed, reducing the efficiency of the entire insulation calculation. (2) Once the filtering does not pass, the way of re-collecting 66 voltage values is also extremely time-consuming, and there may be a situation where only the first few voltages are unstable and the last dozens of voltages are stable in the last 66 voltage values. This way will waste a lot of time. In addition, in the case of an extreme main negative terminal to ground (i.e. negative to ground insulation resistance R nWhen the short circuit occurs, the voltage value of the sampling point of the main negative end is theoretically 0, but in actual conditions, the voltage value of the sampling point of the main negative end collected is not completely 0 due to the influence of some noise signals. If this condition is not considered, the voltage of the random noise signal may be brought into operation, resulting in random calculation results, affecting the accuracy of insulation detection, and there is a risk of causing serious safety problems. SUMMARY

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

[0006] In a first aspect, the present application provides a sampling point voltage determination method, which comprises:

[0007] Step one, collecting m times of voltage at the sampling point according to the preset sampling period, and storing the collected m voltage values into an array U[m], and then executing step two.

[0008] Step two, averaging the m voltage values in the array U[m] to obtain a first voltage average value U avg1 , and then executing step three.

[0009] Step three, filtering the m voltage values in the array U[m], and filtering out n1 voltage values whose difference from the first voltage average value U avg1 is greater than U th , that is, the number n1 of voltage values in the array U[m] whose difference from the first voltage average value U avg1 is greater than U th , and then executing step four; wherein U th represents a preset filtering threshold value, and n1

[0010] Step four, determining whether n1 is less than or equal to i1, if yes, executing step five, otherwise executing step eight; wherein i1 represents a preset first filtering number, and i1

[0011] Step five, averaging the remaining m-n1 voltage values after filtering to obtain a second voltage average value U avg2 , and then executing step six.

[0012] Step six, filtering the remaining m-n1 voltage values after filtering, and filtering out n2 voltage values whose difference from the second voltage average value U avg2 is greater than U th , that is, the number n2 of voltage values in the remaining m-n1 voltage values after filtering whose difference from the second voltage average value U avg2 is greater than U thThe number n2) is then executed, and step seven is performed; 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 filtered 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; where k<i1.

[0015] Step 9: Select the latest j voltage values ​​(i.e., the j voltage values ​​with the latest storage time among the m-n1-n2 voltage values ​​remaining 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 10: Use the root mean square value rms as the sampling point voltage, and then end.

[0017] Preferably, the preset first filtering number The preset second filtering number described Among them, int() represents the floor 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 configured to execute the above 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 with one end connected to the positive electrode of the power battery and the other end connected to the negative electrode of the power battery. 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 chassis ground, and the resistor R c With resistor R d The connection point of the resistor R is used as the main negative sampling point A, which is connected to the controller; 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 the balanced bridge 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 be closed / opened. The method includes:

[0021] In the first step, the controller controls the controllable switch SW to be disconnected, 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 xadc1 And the voltage U of the balanced bridge sampling point batadc1 , then proceed to step 2.

[0022] In the second step, the controller determines whether the main negative terminal sampling point voltage U xadc1 Less than U xmin If yes, execute step 3, otherwise execute step 4; 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 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 of the negative electrode to ground 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 Indicates that twice the insulation resistance acquisition error is used as the insulation resistance of the negative electrode to ground, and this 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, where 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 of the negative electrode to ground and the insulation resistance R n The resistance value is:

[0030] Using the formula: Calculate the positive electrode to ground insulation resistance R p The resistance of the negative electrode to ground 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 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, which can filter more effectively and accurately, thereby improving the accuracy of filtering.

[0035] (2) When the 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 negative electrode to ground insulation resistance short ground (ie 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 calculation is performed, if U xadc1 Less than U xmin , it is directly determined that there is an insulation fault; this can avoid 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 Flowchart of a method for determining 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 insulation detection device in an embodiment of the present invention when the controllable switch SW 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 This is a flow chart of a power battery insulation detection method according to 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 with reference to the accompanying drawings. The accompanying 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 commonly understood by those skilled in the art to which the present invention pertains. The terms used herein are for the purpose of describing embodiments of the present invention only and are not intended to limit the present invention.

[0044] In the following description, reference is made to “some embodiments”, which describes 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 a preset sampling period, store the m collected voltage values ​​in an array U[m], and then proceed to step 2. In some embodiments, the preset sampling period ranges from 9 milliseconds to 11 milliseconds, and the value of m ranges from 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 , 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 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 n1), then perform step 4; where U th In some embodiments, U th The value range of is 1mV to 5mV. As an example, here U th =3 mV.

[0049] Step 4: Determine whether n1 is less than or equal to i1. If yes, proceed to step 5, otherwise proceed to step 8; wherein i1 represents the preset first filtered 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 , then proceed to step 6.

[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 ​​in 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) is then executed, and step seven is performed; wherein, n2<m-n1.

[0052] Step 7: Determine whether n2 is less than or equal to i2. If yes (indicating that the filtering passes), execute step 9; otherwise (indicating that the filtering fails), execute step 8; wherein i2 represents the preset second filtered number, i2<i1. In some embodiments, As an example, here i2=5.

[0053] Step 8: Collect k voltages at the sampling points according to a preset sampling period, and store the k collected voltage values ​​into the array U[m] based on the first-in-first-out principle (i.e., use the k voltage values ​​to replace the first k voltage values ​​stored in the array U[m]), and then return to step 2; wherein k < i1. In some embodiments, As an example, k=5 here.

[0054] Step 9: Select the latest j voltage values ​​(i.e., the j voltage values ​​with the latest storage time among the m-n1-n2 voltage values ​​remaining 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。作为示例,此处j=5。

[0055] Step 10: Use the root mean square value rms as the sampling point voltage, and then end.

[0056] In the process of determining the sampling point voltage, the first filtering condition is relatively wide, and the maximum number of points that can be filtered out is i1. It 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 the individual points with large differences have been filtered out. The condition is relatively narrow, and the maximum number of voltage values ​​allowed to be filtered out is i2. It can perform filtering more effectively and accurately, and improve the accuracy of filtering.

[0057] When the 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.

[0058] In addition, the sampling point voltage determination system in the embodiment of the present invention includes a controller, which is configured to perform the following steps: Figure 1 The method for determining the sampling point voltage is shown in FIG.

[0059] An embodiment of the present invention further provides a car, which includes the above-mentioned 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 of the resistor R is connected to the chassis ground. c With resistor R d The connection point of the resistor R is used as the main negative sampling point A, which 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 be closed / opened.

[0061] like Figure 5 As shown, the power battery insulation detection method in the embodiment of the present invention is executed by the 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 , then proceed to step 2.

[0063] The second step is to determine whether the main negative terminal sampling point voltage U xadc1 Less than U xmin If yes, execute step 3, otherwise execute step 4; where U xmin Indicates the preset threshold voltage.

[0064] In some embodiments, the preset threshold voltage U xmin =U xadc0 Among them, U xadc0 Indicates that twice the insulation resistance acquisition error is used as the insulation resistance of the negative electrode to ground, and this 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, where δ represents the insulation resistance acquisition error. As an example, the insulation resistance acquisition error δ 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), random noise signals may be introduced into the calculation, affecting the result. Therefore, the present invention adopts the threshold value interception method to filter out the influence of the noise voltage, setting a smaller threshold voltage (i.e., U xmin ) to judge, 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 of the main negative terminal sampling point (U xadc0 ) the smaller the voltage value, 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 xmin When the noise signal is involved in the calculation, the insulation resistance calculation is performed normally; this can avoid the influence of the uncertainty caused by the participation of noise signals in the calculation on the accuracy of insulation detection, and improve the accuracy of insulation detection.

[0067] Step 3: Determine if 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 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 p The resistance of the negative electrode to ground 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 of the negative electrode to ground and the insulation resistance R n The resistance value is:

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

[0072] The above description is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with this technical field within the technical scope disclosed in the present invention should be covered by the scope of protection 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 the preset sampling period, and store the collected m voltage values ​​into the 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 three; Step 3: Filter the m voltage values ​​in the array U[m] to remove the voltage values ​​and U[m]. avg1 The difference is greater than U th n1 voltage values, and then execute step 4; where U th Indicates the preset filtering threshold; Step 4: Determine whether n1 is less than or equal to i1. If so, proceed to step 5; otherwise, proceed to step 8. Wherein, i1 represents the preset first filtered 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 values ​​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 so, proceed to step 9; otherwise, proceed to step 8; wherein i2 represents the preset second filtered 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 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; where 1 <j<i1; Step 10: Use the root mean square value rms as the sampling point voltage, and then end.

2. The method for determining the sampling point voltage according to claim 1, wherein: described described described Among them, int() represents the floor function.

3. The method for determining the sampling point voltage according to claim 2, wherein: 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 with one end connected to the positive electrode of the power battery and the other end connected to the negative electrode of the power battery. 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 chassis ground, and the resistor R c With resistor R d The connection point of the resistor R is used as the main negative sampling point A and connected to the controller; e With resistor R f Connect in series and connect 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 the 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 be closed / opened; it is characterized in that, The method includes: In the first step, the controller controls the controllable switch SW to be turned off, 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 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 step 3, otherwise execute step 4; 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; In the fourth step, 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 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 of the negative electrode to ground 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 Indicates that twice the insulation resistance acquisition error is used as the insulation resistance of the negative electrode to ground, and this 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, where 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 the ground is calculated p The resistance of the negative electrode to ground and the insulation resistance R n The resistance value is: Using the formula: Calculate the positive electrode to ground insulation resistance R p The resistance of the negative electrode to ground and the insulation resistance R n 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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