A charging pile insulation resistance verification method and system for common mode interference

Abstract

The application provides a charging pile insulation resistance verification method and system for common mode interference in the technical field of direct current charging piles, and the method comprises the following steps: step S10, opening and closing switch S1 and switch S2 to obtain the voltage V1' and V2' measured by voltmeter 1 and the voltage V1 and V2 measured by voltmeter 2; step S20, calculating the negative pole-to-ground insulation resistance Ri1 and the positive pole-to-ground insulation resistance Ri2 based on the V1', V2', V1 and V2; step S30, performing common mode interference verification based on the Ri1 and Ri2; step S40, collecting the positive pole-to-ground voltage and the negative pole-to-ground voltage through voltmeter 1 and voltmeter 2, and calculating the difference Vbus between the positive pole-to-ground voltage and the negative pole-to-ground voltage; and step S50, verifying the Ri1 and Ri2 based on the V1', V2', V1, V2 and Vbus. The application has the advantage that the abnormality of the insulation resistance of the direct current charging pile can be verified.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of direct current charging piles, and particularly relates to a charging pile insulation resistance verification method and system for common mode interference. BACKGROUND

[0002] A direct current charging pile is a special direct current device directly connecting an electric vehicle to an alternating current / direct current power grid (power supply) side, and is provided with a control guide device to ensure reliable connection and charging safety between the direct current charging pile and the electric vehicle, and is also integrated with a man-machine interaction system, a charging management system, a local communication interface and a remote communication interface and other functional modules for use and management of people.

[0003] The direct current charging pile provides direct current electric energy for a battery pack of the electric vehicle to realize energy supply for the electric vehicle under management of a vehicle-mounted BMS system. The existing direct current charging pile generally follows the GB / T18487 standard, and a principle diagram thereof is shown in Figure 3 .

[0004] The direct current charging pile is generally composed of a charging cabinet and a charging gun (including a charging cable). During charging, the charging gun is inserted into a charging seat of the electric vehicle, insulation detection is performed by an IMD (intelligent metering device), K1 and K2 are disconnected after the insulation detection is completed, and after a handshake between a guide circuit and a control program, charging service is started. An unbalanced bridge insulation detection principle of the existing direct current charging pile is shown in Figure 4 , wherein R0 and R1 are known resistances, Ri1 is a negative pole-to-ground insulation resistance, Ri2 is a positive pole-to-ground insulation resistance, and DC1 is a charging pile DC-DC output direct current voltage source. For insulation detection of the direct current charging pile, the following method is traditionally adopted:

[0005] Step 1: when switches S2 and S1 are disconnected, a voltmeter 1 measures a voltage V1', and a voltmeter 2 measures a voltage V1. According to equal loop currents, the following is obtained:

[0006] V1' / Ri2=-V1 / Ri1---------------------Equation 1

[0007] Step 2: when an absolute value of V1' is greater than an absolute value of V1, switch S1 is disconnected, switch S2 is closed, the voltmeter 1 measures a voltage V2', and the voltmeter 2 reads a voltage V2. According to equal loop currents, the following is obtained:

[0008] V2' / (Ri2||R1)=-V2 / Ri1---------------Equation 2

[0009] According to Equation 1 and Equation 2, the following is obtained:

[0010] Ri2=((V1'*V2) / (V2'*V1)-1)*R1-------Equation 3

[0011] Ri1 = -(V1 * Ri2 / V1 ')-----------------Formula 4

[0012] Step 3: When the absolute value of V1' is less than or equal to the absolute value of V1, switch S2 is opened, S1 is closed, and voltmeter 1 measures the voltage as V2', and voltmeter 2 reads the voltage as V2, according to the equal loop current:

[0013] V2' / Ri2 = -V2 / (Ri1 || R0)----------------Formula 5

[0014] According to Formula 1 and Formula 2:

[0015] Ri1 = ((V2' * V1) / (V1' * V2) - 1) * R0-------Formula 6

[0016] Ri2 = -(V1' * Ri1 / V1)-----------------Formula 7

[0017] In the case of no common-mode interference in the ground, the traditional method can accurately calculate the positive-to-ground insulation resistance Ri2 and the negative-to-ground insulation resistance Ri1. However, in actual use, the switching noise of the energy storage converter and the DC converter is generally discharged to the ground through the Y capacitor, resulting in common-mode interference on the ground. After the ground appears common-mode interference, the negative-to-ground voltage is likely to appear negative voltage, that is, one of V1 and V2 appears negative voltage, and thus accurate insulation detection cannot be performed.

[0018] For example, under common-mode interference, the actual detected voltage values are: V1' = 360920.8125mv, V1 = 161430.6563mv, V2' = 142048mv, V2 = -57292.71875mv; R0 and R1 are 1MΩ, V1' > V1, according to Formula 3 and Formula 4, Ri2 = -1.902MΩ; Ri1 = 0.85MΩ;

[0019] Since Ri2 appears a negative resistance value, it cannot be used to determine whether the insulation resistance is qualified. This phenomenon can cause a DC charging pile with actual insulation to be misjudged as unqualified insulation resistance, and cannot provide normal charging service.

[0020] Therefore, how to provide a charging pile insulation resistance verification method and system for common-mode interference, to verify the abnormality of the DC charging pile insulation resistance, has become a technical problem to be solved. SUMMARY

[0021] The technical problem solved by the present application is to provide a charging pile insulation resistance verification method and system for common mode interference, and to realize verification of abnormal DC charging pile insulation resistance.

[0022] In a first aspect, the present application provides a charging pile insulation resistance verification method for common mode interference, comprising the following steps:

[0023] In step S10, the on-off switch S1 and the switch S2 are opened to obtain the voltage V1' measured by the voltmeter 1 and the voltage V2' measured by the voltmeter 2, and the voltage V1 measured by the voltmeter 2 and the voltage V2 measured by the voltmeter 1.

[0024] In step S20, the negative pole-to-ground insulation resistance Ri1 and the positive pole-to-ground insulation resistance Ri2 are calculated based on the V1', V2', V1 and V2.

[0025] In step S30, common mode interference verification is performed based on the Ri1 and the Ri2.

[0026] In step S40, the positive pole-to-ground voltage and the negative pole-to-ground voltage are collected by the voltmeter 1 and the voltmeter 2, and the difference Vbus between the positive pole-to-ground voltage and the negative pole-to-ground voltage is calculated.

[0027] In step S50, the Ri1 and the Ri2 are verified based on the V1', V2', V1, V2 and Vbus.

[0028] Further, the step S10 is specifically:

[0029] The switch S1 and the switch S2 are opened, and the voltage V1' measured by the voltmeter 1 and the voltage V1 measured by the voltmeter 2 are obtained.

[0030] When |V1'|>|V1|, the switch S1 is opened, the switch S2 is closed, the voltage V2' measured by the voltmeter 1 and the voltage V2 measured by the voltmeter 2 are obtained.

[0031] When |V1'|≤|V1|, the switch S1 is closed, the switch S2 is opened, the voltage V2' measured by the voltmeter 1 and the voltage V2 measured by the voltmeter 2 are obtained.

[0032] Further, in the step S20, the calculation formulas of the negative pole-to-ground insulation resistance Ri1 and the positive pole-to-ground insulation resistance Ri2 are:

[0033] Ri2= ((V1'*V2) / (V2'*V1)-1)*R1;

[0034] Ri1=-(V1*Ri2 / V1').

[0035] Further, the step S30 is specifically:

[0036] It is judged whether Ri1 or Ri2 is less than 0, if yes, it is indicated that there is common mode interference, and step S40 is entered; if not, it is indicated that there is no common mode interference, and the measurement values of Ri1 and Ri2 are normal.

[0037] Further, the step S50 specifically comprises:

[0038] Step S51, the values of Ri1 and Ri2 are judged, when Ri1 is less than 0, step S52 is entered, when Ri2 is less than 0, step S54 is entered;

[0039] Step S52, it is judged whether |V1'-V2'|>Vbus / 2 and |V1-V2|>Vbus / 2 are simultaneously satisfied, if yes, it is indicated that the measurement value of Ri1 is normal; if not, step S53 is entered;

[0040] Step S53, it is judged whether Ri2>0, Ri2 / Vbus<100K and |V2| / Vbus>0.99 are simultaneously satisfied, if yes, it is indicated that the measurement value of Ri1 is normal; if not, it is indicated that the measurement value of Ri1 is abnormal;

[0041] Step S54, it is judged whether |V1'-V2'|>Vbus / 2 and |V1-V2|>Vbus / 2 are simultaneously satisfied, if yes, it is indicated that the measurement value of Ri2 is normal; if not, step S55 is entered;

[0042] Step S55, it is judged whether Ri1>0, Ri1 / Vbus<100K and |V2'| / Vbus>0.99 are simultaneously satisfied, if yes, it is indicated that the measurement value of Ri2 is normal; if not, it is indicated that the measurement value of Ri2 is abnormal.

[0043] In a second aspect, the present application provides a charging pile insulation resistance verification system for common mode interference, comprising the following modules:

[0044] A voltage measurement module is used for opening and closing switch S1 and switch S2 to obtain the voltages V1' and V2' measured by voltmeter 1 and the voltages V1 and V2 measured by voltmeter 2.

[0045] An insulation resistance calculation module is used for calculating negative pole-to-ground insulation resistance Ri1 and positive pole-to-ground insulation resistance Ri2 based on V1', V2', V1 and V2.

[0046] A common mode interference verification module is used for verifying common mode interference based on Ri1 and Ri2.

[0047] A Vbus calculation module is used for collecting positive pole-to-ground voltage and negative pole-to-ground voltage through voltmeter 1 and voltmeter 2, and calculating the difference Vbus between the positive pole-to-ground voltage and the negative pole-to-ground voltage.

[0048] The insulation resistance verification module is configured to verify Ri1 and Ri2 based on V1', V2', V1, V2 and Vbus.

[0049] Further, the voltage measurement module is specifically configured to:

[0050] open the switch S1 and the switch S2, and acquire the voltage V1' measured by the voltmeter 1 and the voltage V1 measured by the voltmeter 2;

[0051] when |V1'| > |V1|, the switch S1 is opened, the switch S2 is closed, the voltage V2' measured by the voltmeter 1 and the voltage V2 measured by the voltmeter 2 are acquired;

[0052] when |V1'| ≤ |V1|, the switch S1 is closed, the switch S2 is opened, the voltage V2' measured by the voltmeter 1 and the voltage V2 measured by the voltmeter 2 are acquired.

[0053] Further, in the insulation resistance calculation module, the calculation formulae of the negative electrode-to-ground insulation resistance Ri1 and the positive electrode-to-ground insulation resistance Ri2 are as follows:

[0054] Ri2 = ((V1'*V2) / (V2'*V1)-1)*R1;

[0055] Ri1 = -(V1*Ri2 / V1').

[0056] Further, the common-mode interference verification module is specifically configured to:

[0057] determine whether the Ri1 or the Ri2 is less than 0, if yes, it indicates that there is common-mode interference, and the Vbus calculation module is entered; if not, it indicates that there is no common-mode interference, and the measurement values of Ri1 and Ri2 are normal.

[0058] Further, the insulation resistance verification module specifically comprises:

[0059] a value judgment unit configured to judge the values of Ri1 and Ri2, when the Ri1 is less than 0, the Ri1 first verification unit is entered, and when the Ri2 is less than 0, the Ri2 first verification unit is entered;

[0060] the Ri1 first verification unit is configured to determine whether |V1'-V2'| > Vbus / 2 and |V1-V2| > Vbus / 2 are simultaneously satisfied, if yes, it indicates that the measurement value of Ri1 is normal; if not, step S53 is entered;

[0061] Ri1 is a second checking unit for judging whether Ri1>0, Ri1 / Vbus<100K and |V2| / Vbus>0.99 are satisfied simultaneously, if yes, it is indicated that the measured value of Ri1 is normal, if not, it is indicated that the measured value of Ri1 is abnormal.

[0062] Ri2 is a first checking unit for judging whether |V1'-V2'|>Vbus / 2 and |V1-V2|>Vbus / 2 are satisfied simultaneously, if yes, it is indicated that the measured value of Ri2 is normal, if not, step S55 is entered.

[0063] Ri2 is a second checking unit for judging whether Ri1>0, Ri1 / Vbus<100K and |V2'| / Vbus>0.99 are satisfied simultaneously, if yes, it is indicated that the measured value of Ri2 is normal, if not, it is indicated that the measured value of Ri2 is abnormal.

[0064] The present application has the advantages of:

[0065] The voltage V1' and V2' measured by the voltmeter 1 and the voltage V1 and V2 measured by the voltmeter 2 are obtained through the on-off switch S1 and the switch S2, the negative pole-to-ground insulation resistance Ri1 and the positive pole-to-ground insulation resistance Ri2 are calculated based on V1', V2', V1 and V2, when Ri1 or Ri2 is less than 0, it is indicated that there is common mode interference, then the positive pole-to-ground voltage and the negative pole-to-ground voltage are collected by the voltmeter 1 and the voltmeter 2 and the difference Vbus is calculated, finally, Ri1 and Ri2 are checked based on V1', V2', V1, V2 and Vbus, that is, the voltage amplitude is judged, so as to check whether the negative pole-to-ground insulation resistance Ri1 and the positive pole-to-ground insulation resistance Ri2 are abnormal, that is, the abnormality of the insulation resistance of the direct current charging pile is checked, and the accuracy of the insulation resistance detection of the charging pile is greatly improved. BRIEF DESCRIPTION OF DRAWINGS

[0066] The present application will be further described below with reference to the accompanying drawings and embodiments.

[0067] Figure 1 It is a flow chart of the charging pile insulation resistance checking method for common mode interference of the present application.

[0068] Figure 2 It is a structural schematic diagram of the charging pile insulation resistance checking system for common mode interference of the present application.

[0069] Figure 3 It is a principle diagram of the direct current charging pile of the present application.

[0070] Figure 4 It is an unbalanced bridge insulation detection principle diagram of the present application. DETAILED DESCRIPTION

[0071] Referring to Figures 1 to 4 A preferred embodiment of the charging pile insulation resistance verification method against common mode interference provided by the application comprises the following steps:

[0072] Step S10, open and close switch S1 and switch S2 to obtain the voltage V1' measured by voltmeter 1 and the voltage V2' measured by voltmeter 2, and obtain the voltage V1 measured by voltmeter 1 and the voltage V2 measured by voltmeter 2;

[0073] Step S20, based on V1', V2', V1 and V2, calculate the negative pole-to-ground insulation resistance Ri1 and the positive pole-to-ground insulation resistance Ri2;

[0074] Step S30, based on Ri1 and Ri2, perform common mode interference verification;

[0075] Step S40, collect the positive pole-to-ground voltage and the negative pole-to-ground voltage by voltmeter 1 and voltmeter 2, and calculate the difference Vbus between the positive pole-to-ground voltage and the negative pole-to-ground voltage;

[0076] Step S50, based on V1', V2', V1, V2 and Vbus, verify Ri1 and Ri2, that is, use the voltage amplitude judgment method to verify whether Ri1 and Ri2 are abnormal.

[0077] The step S10 specifically comprises:

[0078] Open switch S1 and switch S2, obtain the voltage V1' measured by voltmeter 1 and the voltage V1 measured by voltmeter 2;

[0079] When |V1'|>|V1|, open switch S1 and close switch S2, obtain the voltage V2' measured by voltmeter 1 and the voltage V2 measured by voltmeter 2;

[0080] When |V1'|≤|V1|, close switch S1 and open switch S2, obtain the voltage V2' measured by voltmeter 1 and the voltage V2 measured by voltmeter 2.

[0081] In the step S20, the calculation formula of the negative pole-to-ground insulation resistance Ri1 and the positive pole-to-ground insulation resistance Ri2 is:

[0082] Ri2= ((V1'*V2) / (V2'*V1)-1)*R1;

[0083] Ri1=-(V1*Ri2 / V1').

[0084] The step S30 specifically comprises:

[0085] Judge whether Ri1 or Ri2 is less than 0, if yes, it indicates that there is common mode interference, and step S40 is entered; if not, it indicates that there is no common mode interference, and the measured values of Ri1 and Ri2 are normal. That is, when the ground wire has common mode interference, the ground insulation resistance will be negative.

[0086] The step S50 specifically includes:

[0087] Step S51, judging the values of Ri1 and Ri2, when Ri1 is less than 0, step S52 is entered, and when Ri2 is less than 0, step S54 is entered;

[0088] Step S52, judging whether |V1'-V2'|>Vbus / 2 and |V1-V2|>Vbus / 2 are satisfied at the same time, if yes, it indicates that the measured value of Ri1 is normal; if not, step S53 is entered;

[0089] Step S53, judging whether Ri2>0, Ri2 / Vbus<100K and |V2| / Vbus>0.99 are satisfied at the same time, if yes, it indicates that the measured value of Ri1 is normal; if not, it indicates that the measured value of Ri1 is abnormal;

[0090] Step S54, judging whether |V1'-V2'|>Vbus / 2 and |V1-V2|>Vbus / 2 are satisfied at the same time, if yes, it indicates that the measured value of Ri2 is normal; if not, step S55 is entered;

[0091] Step S55, judging whether Ri1>0, Ri1 / Vbus<100K and |V2'| / Vbus>0.99 are satisfied at the same time, if yes, it indicates that the measured value of Ri2 is normal; if not, it indicates that the measured value of Ri2 is abnormal.

[0092] The preferred embodiment of the charging pile insulation resistance verification system for common mode interference provided by the application includes the following modules:

[0093] The voltage measurement module is used for turning on and off the switches S1 and S2 to obtain the voltages V1' and V2' measured by the voltmeter 1 and the voltages V1 and V2 measured by the voltmeter 2.

[0094] The insulation resistance calculation module is used for calculating the negative ground insulation resistance Ri1 and the positive ground insulation resistance Ri2 based on V1', V2', V1 and V2.

[0095] The common mode interference verification module is used for verifying common mode interference based on Ri1 and Ri2.

[0096] A Vbus calculation module is configured to acquire the positive electrode-ground voltage and the negative electrode-ground voltage through the voltmeter 1 and the voltmeter 2, and calculate the difference Vbus between the positive electrode-ground voltage and the negative electrode-ground voltage.

[0097] An insulation resistance verification module is configured to verify Ri1 and Ri2 based on V1', V2', V1, V2 and Vbus, that is, to verify whether Ri1 and Ri2 are abnormal by using the voltage amplitude judgment method.

[0098] The voltage measurement module is specifically configured to:

[0099] The switch S1 and the switch S2 are disconnected, and the voltage V1' measured by the voltmeter 1 and the voltage V1 measured by the voltmeter 2 are acquired.

[0100] When |V1'|>|V1|, the switch S1 is disconnected, the switch S2 is closed, and the voltage V2' measured by the voltmeter 1 and the voltage V2 measured by the voltmeter 2 are acquired.

[0101] When |V1'|≤|V1|, the switch S1 is closed, the switch S2 is disconnected, and the voltage V2' measured by the voltmeter 1 and the voltage V2 measured by the voltmeter 2 are acquired.

[0102] In the insulation resistance calculation module, the calculation formulae of the negative electrode-ground insulation resistance Ri1 and the positive electrode-ground insulation resistance Ri2 are as follows:

[0103] Ri2= ((V1'*V2) / (V2'*V1)-1)*R1;

[0104] Ri1=-(V1*Ri2 / V1').

[0105] The common-mode interference verification module is specifically configured to:

[0106] It is judged whether Ri1 or Ri2 is less than 0. If yes, it indicates that there is common-mode interference, and the Vbus calculation module is entered. If no, it indicates that there is no common-mode interference, and the measurement values of Ri1 and Ri2 are normal. That is, when the ground wire has common-mode interference, the ground insulation resistance will be negative.

[0107] The insulation resistance verification module specifically includes:

[0108] A value judgment unit is configured to judge the values of Ri1 and Ri2. When Ri1 is less than 0, the Ri1 first verification unit is entered. When Ri2 is less than 0, the Ri2 first verification unit is entered.

[0109] Ri1 first checking unit, for judging whether |V1'-V2'|>Vbus / 2 and |V1-V2|>Vbus / 2 are satisfied simultaneously, if yes, it is indicated that the measurement value of Ri1 is normal, if not, step S53 is entered;

[0110] Ri1 second checking unit, for judging whether Ri2>0, Ri2 / Vbus<100K and |V2| / Vbus>0.99 are satisfied simultaneously, if yes, it is indicated that the measurement value of Ri1 is normal, if not, it is indicated that the measurement value of Ri1 is abnormal;

[0111] Ri2 first checking unit, for judging whether |V1'-V2'|>Vbus / 2 and |V1-V2|>Vbus / 2 are satisfied simultaneously, if yes, it is indicated that the measurement value of Ri2 is normal, if not, step S55 is entered;

[0112] Ri2 second checking unit, for judging whether Ri1>0, Ri1 / Vbus<100K and |V2'| / Vbus>0.99 are satisfied simultaneously, if yes, it is indicated that the measurement value of Ri2 is normal, if not, it is indicated that the measurement value of Ri2 is abnormal.

[0113] In summary, the advantages of the present application are:

[0114] Through on-off switch S1 and switch S2, the voltage V1' and V2' measured by voltmeter 1 and the voltage V1 and V2 measured by voltmeter 2 are obtained, the negative pole-to-ground insulation resistance Ri1 and the positive pole-to-ground insulation resistance Ri2 are calculated based on V1', V2', V1 and V2, when Ri1 or Ri2 is less than 0, it is indicated that there is common mode interference, then the positive pole-to-ground voltage and the negative pole-to-ground voltage are collected by voltmeter 1 and voltmeter 2 and the difference Vbus is calculated, finally, Ri1 and Ri2 are checked based on V1', V2', V1, V2 and Vbus, that is, voltage amplitude judgment is carried out, so as to check whether the negative pole-to-ground insulation resistance Ri1 and the positive pole-to-ground insulation resistance Ri2 are abnormal, that is, the abnormality of the insulation resistance of the direct current charging pile is checked, and the accuracy of the insulation resistance detection of the charging pile is greatly improved.

[0115] Although the specific embodiments of the present application are described above, those skilled in the art should understand that the specific embodiments described are only illustrative, and are not intended to limit the scope of the present application, and equivalent modifications and changes made by those skilled in the art in accordance with the spirit of the present application should be covered within the scope of the claims of the present application.

Claims

1. A method for verifying the insulation resistance of charging piles in response to common-mode interference, characterized in that: Includes the following steps: Step S10, switch S1 and switch S2 to obtain the voltages V1' and V2' measured by voltmeter 1, and obtain the voltages V1 and V2 measured by voltmeter 2; Step S20: Based on V1', V2', V1 and V2, calculate the insulation resistance Ri1 of the negative electrode to ground and the insulation resistance Ri2 of the positive electrode to ground; Step S30: Perform common-mode interference verification based on Ri1 and Ri2; Step S40: Collect the positive terminal voltage to ground and the negative terminal voltage to ground using voltmeter 1 and voltmeter 2, and calculate the difference Vbus between the positive terminal voltage to ground and the negative terminal voltage to ground. Step S50: Verify Ri1 and Ri2 based on V1', V2', V1, V2 and Vbus; Step S50 specifically includes: Step S51: Determine the values ​​of Ri1 and Ri2. If Ri1 is less than 0, proceed to step S52. If Ri2 is less than 0, proceed to step S54. Step S52: Determine whether |V1'-V2'|>Vbus / 2 and |V1-V2|>Vbus / 2 are satisfied simultaneously. If yes, it means that the measured value of Ri1 is normal; if not, proceed to step S53. Step S53: Determine whether Ri2 > 0, Ri2 / Vbus < 100K and |V2| / Vbus > 0.99 are satisfied simultaneously. If yes, it means that the measured value of Ri1 is normal; if no, it means that the measured value of Ri1 is abnormal. Step S54: Determine whether |V1'-V2'|>Vbus / 2 and |V1-V2|>Vbus / 2 are satisfied simultaneously. If yes, it means that the measured value of Ri2 is normal; if not, proceed to step S55. Step S55: Determine whether Ri1 > 0, Ri1 / Vbus < 100K and |V2'| / Vbus > 0.99 are satisfied simultaneously. If yes, it means that the measured value of Ri2 is normal; if no, it means that the measured value of Ri2 is abnormal.

2. The method for verifying the insulation resistance of a charging pile against common-mode interference as described in claim 1, characterized in that: Step S10 specifically involves: Disconnect switches S1 and S2, and obtain the voltage V1' measured by voltmeter 1 and the voltage V1 measured by voltmeter 2; When |V1'|>|V1|, open switch S1 and close switch S2 to obtain the voltage V2' measured by voltmeter 1 and the voltage V2 measured by voltmeter 2. When |V1'|≤|V1|, close switch S1 and open switch S2 to obtain the voltage V2' measured by voltmeter 1 and the voltage V2 measured by voltmeter 2.

3. The method for verifying the insulation resistance of a charging pile against common-mode interference as described in claim 1, characterized in that: In step S20, the calculation formulas for the negative electrode-to-ground insulation resistance Ri1 and the positive electrode-to-ground insulation resistance Ri2 are as follows: When the absolute value of V1' is greater than the absolute value of V1: Ri2=((V1'*V2) / (V2'*V1)-1)*R1; Ri1 = -(V1 * Ri2 / V1'); When the absolute value of V1' is less than or equal to the absolute value of V1: Ri2 = -(V1'*Ri1 / V1); Ri1=((V2'*V1) / (V1'*V2)-1)*R0.

4. The method for verifying the insulation resistance of a charging pile against common-mode interference as described in claim 1, characterized in that: Step S30 specifically involves: Determine whether Ri1 or Ri2 is less than 0. If yes, it indicates the presence of common-mode interference, and proceed to step S40; if no, it indicates the absence of common-mode interference, and the measured values ​​of Ri1 and Ri2 are normal.

5. A charging pile insulation resistance verification system for common-mode interference, characterized in that: Includes the following modules: The voltage measurement module is used to switch on and off switch S1 and switch S2 to obtain the voltages V1' and V2' measured by voltmeter 1 and the voltages V1 and V2 measured by voltmeter 2. An insulation resistance calculation module is used to calculate the negative electrode-to-ground insulation resistance Ri1 and the positive electrode-to-ground insulation resistance Ri2 based on V1', V2', V1 and V2. A common-mode interference verification module is used to perform common-mode interference verification based on Ri1 and Ri2. The Vbus calculation module is used to collect the positive-to-ground voltage and the negative-to-ground voltage through voltmeter 1 and voltmeter 2, and calculate the difference Vbus between the positive-to-ground voltage and the negative-to-ground voltage. An insulation resistance verification module is used to verify Ri1 and Ri2 based on V1', V2', V1, V2 and Vbus; The insulation resistance verification module specifically includes: The value judgment unit is used to judge the values ​​of Ri1 and Ri2. When Ri1 is less than 0, it enters the first verification unit of Ri1, and when Ri2 is less than 0, it enters the first verification unit of Ri2. The first verification unit Ri1 is used to determine whether |V1'-V2'|>Vbus / 2 and |V1-V2|>Vbus / 2 are satisfied at the same time. If yes, it means that the measurement value of Ri1 is normal; if no, proceed to step S53. The second verification unit Ri1 is used to determine whether Ri2 > 0, Ri2 / Vbus < 100K and |V2| / Vbus > 0.99 are satisfied simultaneously. If so, it means that the measured value of Ri1 is normal; if not, it means that the measured value of Ri1 is abnormal. The first verification unit of Ri2 is used to determine whether |V1'-V2'|>Vbus / 2 and |V1-V2|>Vbus / 2 are satisfied at the same time. If yes, it means that the measurement value of Ri2 is normal; if no, proceed to step S55. The second verification unit Ri2 is used to determine whether Ri1 > 0, Ri1 / Vbus < 100K and |V2'| / Vbus > 0.99 are satisfied simultaneously. If so, it means that the measured value of Ri2 is normal; if not, it means that the measured value of Ri2 is abnormal.

6. The charging pile insulation resistance verification system for common-mode interference as described in claim 5, characterized in that: The voltage measurement module is specifically used for: Disconnect switches S1 and S2, and obtain the voltage V1' measured by voltmeter 1 and the voltage V1 measured by voltmeter 2; When |V1'|>|V1|, open switch S1 and close switch S2 to obtain the voltage V2' measured by voltmeter 1 and the voltage V2 measured by voltmeter 2. When |V1'|≤|V1|, close switch S1 and open switch S2 to obtain the voltage V2' measured by voltmeter 1 and the voltage V2 measured by voltmeter 2.

7. The charging pile insulation resistance verification system for common-mode interference as described in claim 5, characterized in that: In the insulation resistance calculation module, the calculation formulas for the negative electrode-to-ground insulation resistance Ri1 and the positive electrode-to-ground insulation resistance Ri2 are as follows: When the absolute value of V1' is greater than the absolute value of V1: Ri2=((V1'*V2) / (V2'*V1)-1)*R1; Ri1 = -(V1 * Ri2 / V1'); When the absolute value of V1' is less than or equal to the absolute value of V1: Ri2 = -(V1'*Ri1 / V1); Ri1=((V2'*V1) / (V1'*V2)-1)*R0.

8. The charging pile insulation resistance verification system for common-mode interference as described in claim 5, characterized in that: The common-mode interference verification module is specifically used for: Determine whether Ri1 or Ri2 is less than 0. If yes, it indicates the presence of common-mode interference, and proceed to the Vbus calculation module. If no, it indicates the absence of common-mode interference, and the measured values ​​of Ri1 and Ri2 are normal.

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