Insulation resistance testing method

Abstract

The invention provides an insulation resistance testing method, which comprises the following steps of: when detecting that each switch in all resistance switching structures is switched off, acquiring initial sampling voltages at two ends of a negative electrode ground insulation resistor RN and a positive electrode ground insulation resistor RP; if the initial sampling voltage of the RP is greater than or equal to the initial sampling voltage of the RN, determining a first switching sequence corresponding to each switch in a resistor switching structure connected to the two ends of the RP in parallel after resistors connected with the switches are arranged from large to small according to resistance values; sequentially performing closing operation on the corresponding switches and detecting the sampling voltage at the two ends of the RN after the operation until the sampling voltage at the two ends of the RN is greater than the offset voltage threshold value; and the resistors correspondingly connected in parallel at the two ends of the RP and the resistance values of the resistors are obtained, and the sizes of the RP and the RN are calculated by combining the voltage of the power supply UBAT, the initial sampling voltages of the RP and the RN, the last sampling voltage of the RN and the resistance values of the sampling resistors R3-R5. According to the invention, the resistance detection result can be improved.

Description

Technical Field

[0001] The invention relates to the technical field of electronic components, and in particular to an insulation resistance testing method. Background Art

[0002] like Figure 1 As shown, by connecting 3.9M, 7.8M, 30M, 50M, 100MΩ resistors (such as resistor R3) in combination to switch the insulation resistance detection, once the connected resistance is too small or the resistance difference is too large, it will cause the voltage across the positive electrode to ground insulation resistance RP or the negative electrode to ground insulation resistance RN of the power supply UBAT to be close to saturation or imbalance, thereby affecting the actual resistance detection result.

[0003] Therefore, it is necessary to improve the existing insulation resistance test method to improve the resistance detection result. Summary of the invention

[0004] The technical problem to be solved by the embodiments of the present invention is to provide an insulation resistance testing method which can improve the resistance detection result.

[0005] In order to solve the above technical problems, an embodiment of the present invention provides an insulation resistance testing method, which is used in a circuit including a power supply UBAT, a positive electrode to ground insulation resistance RP, a negative electrode to ground insulation resistance RN, a sampling resistor R3, a sampling resistor R4, a sampling resistor R5, and a plurality of resistance switching structures connected in parallel to both ends of the positive electrode to ground insulation resistance RP and the negative electrode to ground insulation resistance RN; wherein each resistance switching structure includes a resistor and a switch connected in series therewith; the method includes the following steps:

[0006] When it is detected that all switches in all resistance switching structures are disconnected, the initial sampling voltage across the negative electrode to ground insulation resistance RN is obtained, and combined with the output voltage of the power supply UBAT, the initial sampling voltage across the positive electrode to ground insulation resistance RP is obtained;

[0007] If the initial sampling voltage across the positive electrode-to-ground insulation resistance RP is greater than or equal to the initial sampling voltage across the negative electrode-to-ground insulation resistance RN, then confirming and connecting the first switching sequence corresponding to each switch in the resistance switching structure across the positive electrode-to-ground insulation resistance RP after the connected resistors are arranged in descending order according to the resistance value, and based on the first switching sequence, sequentially performing closing operations on the corresponding switches, and detecting the sampling voltage across the negative electrode-to-ground insulation resistance RN after each switch closing operation, until the sampling voltage across the negative electrode-to-ground insulation resistance RN after a certain switch closing operation is greater than the preset offset voltage threshold;

[0008] Obtain the corresponding parallel resistor and its resistance value when the switch connected to both ends of the positive electrode-to-ground insulation resistance RP is closed, and combine the voltage of the power supply UBAT, the initial sampling voltage across the positive electrode-to-ground insulation resistance RP, the initial sampling voltage across the negative electrode-to-ground insulation resistance RN and its last sampling voltage, and the resistance values ​​of the sampling resistors R3 to R5 to calculate the size of the positive electrode-to-ground insulation resistance RP and the negative electrode-to-ground insulation resistance RN.

[0009] Among them, the specific steps of obtaining the corresponding parallel resistance and its resistance value when the switch connected to both ends of the positive electrode to ground insulation resistance RP is closed, and combining the voltage of the power supply UBAT, the initial sampling voltage across the positive electrode to ground insulation resistance RP, the initial sampling voltage across the negative electrode to ground insulation resistance RN and the last sampling voltage, and the resistance values ​​of the sampling resistors R3 to R5 to calculate the size of the positive electrode to ground insulation resistance RP and the negative electrode to ground insulation resistance RN include:

[0010] The total resistance RP′ across the positive electrode-to-ground insulation resistance RP and the total resistance RN′ across the negative electrode-to-ground insulation resistance RN after the last switch closing operation are calculated by the formula RP′=(RQ*VNN*VP―RQ*VN*VPP) / (VN*VPP) and the formula RN′=(RQ*VNN*VP―RQ*VN*VPP) / (VP*VPP), respectively; wherein RQ represents the total resistance value of the resistance connected in parallel to the positive electrode-to-ground insulation resistance RP, which is calculated by the sampling resistor R3 connected in parallel and the resistance of each switch when it is in the closed state; / / represents parallel connection; VP = VBAT - VN; VBAT is the voltage of the power supply UBAT; VN is the initial sampling voltage across the negative electrode insulation resistance RN, and VP is the initial sampling voltage across the positive electrode insulation resistance RP; VR5 is the initial sampling voltage of the sampling resistor R5, which is the fixed value directly measured by the sampler before the switch closing operation; ZR5 is the resistance value of the sampling resistor R5; ZR4 is the resistance value of the sampling resistor R4; VPP = VBAT-VNN; VNN is the sampling voltage across the negative electrode insulation resistance RN after the last switch closing operation, and VPP is the sampled voltage across the positive electrode-to-ground insulation resistance RP after the last switch closing operation; VRR5 is the sampled voltage obtained by the sampler directly measuring the sampling resistor R5 after the last switch closing operation, which is a fixed value;

[0011] The magnitude of the positive electrode to ground insulation resistance RP is calculated based on the calculated total resistance RP′ at both ends of the positive electrode to ground insulation resistance RP and combined with the total resistance RQ of the resistance connected to both ends of the positive electrode to ground insulation resistance RP;

[0012] The magnitude of the negative electrode-to-ground insulation resistance RN is calculated based on the calculated total resistance RN′ across the negative electrode-to-ground insulation resistance RN and the resistance values ​​of the sampling resistors R4 to R5 connected in parallel to the negative electrode-to-ground insulation resistance RN.

[0013] Wherein, the method further comprises:

[0014] If the initial sampling voltage across the positive electrode-to-ground insulation resistance RP is less than the initial sampling voltage across the negative electrode-to-ground insulation resistance RN, then confirming and connecting the switches in the resistance switching structure across the negative electrode-to-ground insulation resistance RN, the second switching sequence corresponding to the switches after the connected resistors are arranged in descending order according to the resistance value, and based on the second switching sequence, sequentially performing closing operations on the corresponding switches, and detecting the sampling voltage across the negative electrode-to-ground insulation resistance RN after each switch closing operation, until the sampling voltage across the negative electrode-to-ground insulation resistance RN after a certain switch closing operation is greater than the preset offset voltage threshold;

[0015] Obtain the corresponding parallel resistor and its resistance value when the switch connected to the negative electrode to ground insulation resistance RN is closed, and combine the voltage of the power supply UBAT, the initial sampling voltage across the positive electrode to ground insulation resistance RP, the initial sampling voltage across the negative electrode to ground insulation resistance RN and its last sampling voltage, and the resistance values ​​of the sampling resistors R3 to R5 to calculate the size of the positive electrode to ground insulation resistance RP and the negative electrode to ground insulation resistance RN.

[0016] Among them, the specific steps of obtaining the corresponding parallel-connected resistance and its resistance value when the switch connected to the negative electrode to ground insulation resistance RN is closed, and combining the voltage of the power supply UBAT, the initial sampling voltage across the positive electrode to ground insulation resistance RP, the initial sampling voltage across the negative electrode to ground insulation resistance RN and the last sampling voltage, and the resistance values ​​of the sampling resistors R3 to R5 to calculate the size of the positive electrode to ground insulation resistance RP and the negative electrode to ground insulation resistance RN include:

[0017] By formula RP ′ =―(RQ′*VNN*VP―RQ′*VN*VPP) / (VN*VNN) and formula RN ′ =―(RQ′*VNN*VP―RQ′*VN*VPP) / (VP*VNN), respectively calculate the total resistance RP′ across the positive electrode to ground insulation resistance RP and the total resistance RN′ across the negative electrode to ground insulation resistance RN after the last switch closing operation; wherein RQ′ represents the total resistance value of the resistance connected in parallel to the negative electrode to ground insulation resistance RN, which is calculated by the parallel-connected sampling resistors R4 to R5 and the resistance of each switch when it is in the closed state; / / represents parallel connection; VP = VBAT - VN; VBAT is the voltage of the power supply UBAT; VN is the initial sampling voltage across the negative electrode insulation resistance RN, and VP is the initial sampling voltage across the positive electrode insulation resistance RP; VR5 is the initial sampling voltage of the sampling resistor R5, which is the fixed value directly measured by the sampler before the switch closing operation; ZR5 is the resistance value of the sampling resistor R5; ZR4 is the resistance value of the sampling resistor R4; VPP = VBAT-VNN; VNN is the sampling voltage across the negative electrode insulation resistance RN after the last switch closing operation, and VPP is the sampled voltage across the positive electrode-to-ground insulation resistance RP after the last switch closing operation; VRR5 is the sampled voltage obtained by the sampler directly measuring the sampling resistor R5 after the last switch closing operation, which is a fixed value;

[0018] The magnitude of the positive electrode-to-ground insulation resistance RP is calculated based on the calculated total resistance RP′ at both ends of the positive electrode-to-ground insulation resistance RP and the resistance value of the sampling resistor R3 connected in parallel to both ends of the positive electrode-to-ground insulation resistance RP;

[0019] The magnitude of the negative electrode-to-ground insulation resistance RN is calculated based on the calculated total resistance RN′ across the negative electrode-to-ground insulation resistance RN and combined with the total resistance RQ′ connected to the two ends of the negative electrode-to-ground insulation resistance RN.

[0020] Implementing the embodiments of the present invention has the following beneficial effects:

[0021] The present invention measures the total resistance RP at both ends of the positive electrode to ground insulation resistance RP and the negative electrode to ground insulation resistance RN by connecting a plurality of resistance switching structures in parallel and switching them in sequence according to a predetermined order until the sampling voltage at both ends of the negative electrode to ground insulation resistance RN is greater than the offset voltage threshold. ′ The total resistance RN′ at both ends of the negative electrode to ground insulation resistance RN can be used to quickly calculate the size of the positive electrode to ground insulation resistance RP and the negative electrode to ground insulation resistance RN, thereby improving the resistance detection result. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, without paying creative labor, other drawings obtained based on these drawings still belong to the scope of the present invention.

[0023] Figure 1 The following is a circuit logic connection structure diagram of an existing insulation resistance test method;

[0024] Figure 2 A circuit logic connection structure diagram of an insulation resistance testing method provided by an embodiment of the present invention;

[0025] Figure 3 A flowchart of an insulation resistance testing method provided by an embodiment of the present invention;

[0026] Figure 4 An application scenario diagram of an insulation resistance testing method provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0027] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention will be further described in detail below with reference to the accompanying drawings.

[0028] The inventors found that when 3.9M, 7.8M, 30M, 50M, 100MΩ and other resistor combinations are connected, the most serious error exceeds 25%. Therefore, it can be concluded that based on the switching resistor method, multiple resistance value gears of different orders of magnitude can be added to the switching resistor to adapt to applications with a large measurement range.

[0029] Therefore, the inventors have made improvements on the circuit of the existing insulation resistance test method. Figure 2 As shown, the circuit is based on the original source UBAT, the positive electrode to ground insulation resistor RP, the negative electrode to ground insulation resistor RN, the sampling resistor R3, the sampling resistor R4, the sampling resistor R5, the sampler (such as an amplifier), etc., by connecting a plurality of resistance switching structures L with different resistance levels in parallel at both ends of the positive electrode to ground insulation resistor RP and the negative electrode to ground insulation resistor RN, and each of the resistance switching structures L includes a resistor Ri and a switch Ki connected in series therewith.

[0030] like Figure 3 As shown in the embodiment of the present invention, the inventors based on Figure 3 A new insulation resistance test method is proposed for a circuit, which includes the following steps:

[0031] Step S1, when it is detected that all switches in all resistance switching structures are disconnected, the initial sampling voltage across the negative electrode to ground insulation resistance RN is obtained, and the initial sampling voltage across the positive electrode to ground insulation resistance RP is obtained in combination with the output voltage of the power supply UBAT;

[0032] The specific process is to first ensure that all switches in the resistance switching structure are disconnected, so as to measure the initial sampling voltage VN across the negative electrode to ground insulation resistance RN; it should be noted that, given that the sampling resistor R4 and the sampling resistor R5 form a voltage divider circuit, and the sampler collects the output voltage across the sampling resistor R5. Therefore, it can be obtained by the formula The initial sampling voltage VN across the negative electrode-to-ground insulation resistance RN is obtained. Among them, VR5 is the initial sampling voltage of the sampling resistor R5, which is the fixed value directly measured by the sampler before the switch is closed; ZR5 is the resistance value of the sampling resistor R5; and ZR4 is the resistance value of the sampling resistor R4.

[0033] Secondly, according to the formula VP = VBAT - VN, the initial sampling voltage VP across the positive electrode-to-ground insulation resistance RP is calculated, where VBAT is the voltage of the power supply UBAT.

[0034] Step S2, if the initial sampling voltage across the positive electrode-to-ground insulation resistance RP is greater than or equal to the initial sampling voltage across the negative electrode-to-ground insulation resistance RN, then confirm and connect the first switching sequence corresponding to each switch in the resistance switching structure across the positive electrode-to-ground insulation resistance RP after the connected resistors are arranged in descending order according to the resistance value, and based on the first switching sequence, sequentially close the corresponding switches, and detect the sampling voltage across the negative electrode-to-ground insulation resistance RN after each switch closing operation, until the sampling voltage across the negative electrode-to-ground insulation resistance RN after a certain switch closing operation is greater than the preset offset voltage threshold; or

[0035] If the initial sampling voltage across the positive electrode-to-ground insulation resistance RP is less than the initial sampling voltage across the negative electrode-to-ground insulation resistance RN, then confirming and connecting the switches in the resistance switching structure across the negative electrode-to-ground insulation resistance RN, the second switching sequence corresponding to the switches after the connected resistors are arranged in descending order according to the resistance value, and based on the second switching sequence, sequentially performing closing operations on the corresponding switches, and detecting the sampling voltage across the negative electrode-to-ground insulation resistance RN after each switch closing operation, until the sampling voltage across the negative electrode-to-ground insulation resistance RN after a certain switch closing operation is greater than the preset offset voltage threshold;

[0036] The specific process is that according to the comparison result of the initial sampling voltage VP across the positive electrode insulation resistance RP and the initial sampling voltage VN across the negative electrode insulation resistance RN, a resistance switching structure connected in parallel across the two ends is selected to perform resistance switching, as follows:

[0037] (21) When the initial sampling voltage VP across the positive electrode-to-ground insulation resistor RP is greater than or equal to the initial sampling voltage VN across the negative electrode-to-ground insulation resistor RN, firstly, the first switching sequence corresponding to each switch in the resistance switching structure L connected to the positive electrode-to-ground insulation resistor RP after the connected resistors are arranged in descending order according to the resistance value is determined, that is, the resistors are connected to the positive electrode-to-ground insulation resistor RP in descending order; secondly, based on the above-mentioned first switching sequence, the corresponding switches (that is, the switches connected in parallel to the positive electrode-to-ground insulation resistor RP) are closed in turn, and after each switch closing operation, the sampling voltage across the negative electrode-to-ground insulation resistor RN is detected to further determine whether the sampling voltage across the negative electrode-to-ground insulation resistor RN is greater than the preset offset voltage threshold; if so, the switch closing operation is stopped; if not, the next switch is replaced for closing operation until the sampling voltage across the negative electrode-to-ground insulation resistor RN is greater than the preset offset voltage threshold.

[0038] (22) When the initial sampling voltage VP across the positive electrode to ground insulation resistor RP is less than the initial sampling voltage VN across the negative electrode to ground insulation resistor RN, firstly, the second switching sequence corresponding to each switch in the resistance switching structure connected to the two ends of the negative electrode to ground insulation resistor RN is determined after the connected resistors are arranged in descending order, that is, the resistors are connected to the two ends of the negative electrode to ground insulation resistor RN in descending order; secondly, based on the above second switching sequence, the corresponding switches (that is, the switches connected in parallel to the two ends of the negative electrode to ground insulation resistor RN) are closed in turn, and after each switch closing operation, the sampling voltage across the two ends of the negative electrode to ground insulation resistor RN is detected to further determine whether the sampling voltage across the two ends of the negative electrode to ground insulation resistor RN is greater than the aforementioned offset voltage threshold; if so, the switch closing operation is stopped; if not, the next switch is replaced for closing operation until the sampling voltage across the two ends of the negative electrode to ground insulation resistor RN is greater than the preset offset voltage threshold.

[0039] It should be noted that, based on the above-mentioned first switching sequence and the second switching sequence, the corresponding switches are closed in sequence. The closing operation of the current switch can be performed while retaining the closure of the switch of the previous operation, or the closing operation of the current switch can be performed without retaining the switch of the previous operation (i.e., restoring to the original open state).

[0040] It is understandable that the first switching order and the second switching order can be flexibly adjusted according to actual conditions, including but not limited to sorting from large to small, from small to large, etc., or other preset switching orders.

[0041] Step S3, obtaining the corresponding parallel resistor and its resistance value when the switch connected to both ends of the positive electrode to ground insulation resistance RP is closed, and combining the voltage of the power supply UBAT, the initial sampling voltage across the positive electrode to ground insulation resistance RP, the initial sampling voltage across the negative electrode to ground insulation resistance RN and the last sampling voltage, and the resistance values ​​of the sampling resistors R3 to R5, to calculate the size of the positive electrode to ground insulation resistance RP and the negative electrode to ground insulation resistance RN; or

[0042] Obtain the corresponding parallel resistor and its resistance value when the switch connected to the negative electrode to ground insulation resistance RN is closed, and combine the voltage of the power supply UBAT, the initial sampling voltage across the positive electrode to ground insulation resistance RP, the initial sampling voltage across the negative electrode to ground insulation resistance RN and its last sampling voltage, and the resistance values ​​of the sampling resistors R3 to R5 to calculate the size of the positive electrode to ground insulation resistance RP and the negative electrode to ground insulation resistance RN.

[0043] The specific process is to calculate the size of the positive electrode to ground insulation resistance RP and the negative electrode to ground insulation resistance RN respectively according to the corresponding parallel resistance and its resistance value when the switch connected to the two ends of the positive electrode to ground insulation resistance RP is closed, and the corresponding parallel resistance and its resistance value when the switch connected to the negative electrode to ground insulation resistance RN is closed, as follows:

[0044] (31) The corresponding parallel resistor and its resistance value when the switch connected to both ends of the positive electrode insulation resistance RP is closed:

[0045] First, the sampled voltage across the positive electrode to ground insulation resistance RP after the last switch closing operation is obtained by the formula VPP=VBAT-VNN; wherein VNN is the sampled voltage across the negative electrode to ground insulation resistance RN after the last switch closing operation, and VRR5 is the sampling voltage obtained by the sampler directly measuring the sampling resistor R5 after the last switch closing operation, which is a fixed value;

[0046] Secondly, the total resistance RP′ at both ends of the positive electrode-to-ground insulation resistance RP and the total resistance RN′ at both ends of the negative electrode-to-ground insulation resistance RN after the last switch closing operation are calculated by the formula RP′=(RQ*VNN*VP―RQ*VN*VPP) / (VN*VPP) and the formula RN′=(RQ*VNN*VP―RQ*VN*VPP) / (VP*VPP); wherein RQ represents the total resistance value of the resistance connected in parallel to both ends of the positive electrode-to-ground insulation resistance RP, which is calculated by the sampling resistor R3 connected in parallel and the resistance of each switch when it is in the closed state; / / Represents parallel connection;

[0047] Next, the magnitude of the positive electrode-to-ground insulation resistance RP is calculated based on the calculated total resistance RP′ across the positive electrode-to-ground insulation resistance RP and the total resistance RQ of the resistances connected to the positive electrode-to-ground insulation resistance RP;

[0048] Finally, the magnitude of the negative electrode-to-ground insulation resistance RN is calculated based on the calculated total resistance RN′ across the negative electrode-to-ground insulation resistance RN and the resistance values ​​of the sampling resistors R4 to R5 connected in parallel to the negative electrode-to-ground insulation resistance RN.

[0049] (32) The corresponding parallel resistor and its resistance value when the switch connected to the negative electrode insulation resistance RN is closed:

[0050] First, using the same formula VPP=VBAT-VNN in step (31), the sampled voltage across the positive electrode-to-ground insulation resistance RP after the last switch closing operation is obtained;

[0051] Secondly, through the formula RP ′ =―(RQ′*VNN*VP―RQ′*VN*VPP) / (VN*VNN) and formula RN ′ =―(RQ′*VNN*VP―RQ′*VN*VPP) / (VP*VNN), respectively calculate the total resistance RP′ across the positive electrode to ground insulation resistance RP and the total resistance RN′ across the negative electrode to ground insulation resistance RN after the last switch closing operation; wherein RQ′ represents the total resistance value of the resistance connected in parallel to the negative electrode to ground insulation resistance RN, which is calculated by the parallel-connected sampling resistors R4 to R5 and the resistance of each switch when it is in the closed state;

[0052] Next, the magnitude of the positive electrode-to-ground insulation resistance RP is calculated based on the calculated total resistance RP′ across the positive electrode-to-ground insulation resistance RP and the resistance value of the sampling resistor R3 connected to the positive electrode-to-ground insulation resistance RP;

[0053] Finally, the magnitude of the negative electrode-to-ground insulation resistance RN is calculated based on the calculated total resistance RN′ across the negative electrode-to-ground insulation resistance RN and the total resistance RQ′ connected to the two ends of the negative electrode-to-ground insulation resistance RN.

[0054] It should be noted that the total resistance RP′ at both ends of the positive electrode-to-ground insulation resistance RP and the total resistance RN′ at both ends of the negative electrode-to-ground insulation resistance RN are used to calculate the size of the positive electrode-to-ground insulation resistance RP and the negative electrode-to-ground insulation resistance RN. This is achieved by using common technical means in the field (such as reverse calculation of parallel resistance calculation method), which will not be repeated here.

[0055] like Figure 4As shown, the application scenario of an insulation resistance testing method provided in an embodiment of the present invention is further described as follows:

[0056] exist Figure 4 In the example, it is assumed that there are three gears, the first gear has a switching resistor of 10M (i.e., switching resistors R1 and R2 = 10M), the second gear has a switching resistor of 1M (i.e., switching resistors R6 and R7 = 1M), the third gear has a switching resistor of 500K (i.e., switching resistors R8 and R9 = 500K), the sampling voltage divider resistor is 1:18.4 (i.e., sampling resistor R4: sampling resistor R5 = 18.4:1), the resistor R3 is the sampling resistor, and its value = sampling resistor R4 + sampling resistor R5, the offset voltage threshold is set to 0.5V, and the voltage UBAT of the battery VBAT = 55.2V. At this time, the op amp U1A is a sampler.

[0057] At the same time, the first switching sequence and the second switching sequence are both set to switch the resistors connected to the switches in a descending order, that is, the first switching sequence = SP1->SP2->SP3; the second switching sequence = SN1->SN2->SN3.

[0058] When Count=1, there is no switch closed at present, VN=1.854mV*18.4=34.1mV<0.5V, at this time VN is obviously insufficient and is in an unregulated state, VP=55.2-VN=55.166, so Count++;

[0059] When Count=2, switch SP1 is closed. In the current circuit, only SP1 is in the closed state, VNN=16.766mV*18.4=0.308V<0.5V. At this time, VNN is in the unregulated state, VPP=55.2-VN=54.892, so Count++;

[0060] When Count=3, switch SP2 is closed. In the current circuit, switches SP1 and SP2 are both closed. VNN=0.158V*18.4=2.909V>0.5V, which means it is not out of regulation. Then VPP=55.2-VNN=52.291V can be substituted into the formula to calculate RP'=89998Ω, RN'=50010Ω.

[0061] At the same time, considering RP'=RP / / 10M(R1) / / 1M(R6) / / 423M(R3), RP=114285024Ω is derived; and considering RN'=RN / / 423M(R4+R5), RN=50016 is derived. Since the initial RP=100M and RN=50K, the final errors are 14.29% and 0.03% respectively.

[0062] Implementing the embodiments of the present invention has the following beneficial effects:

[0063] The present invention measures the total resistance RP at both ends of the positive electrode to ground insulation resistance RP and the negative electrode to ground insulation resistance RN by connecting a plurality of resistance switching structures in parallel and switching them in sequence according to a predetermined order until the sampling voltage at both ends of the negative electrode to ground insulation resistance RN is greater than the offset voltage threshold. ′ The total resistance RN′ at both ends of the negative electrode to ground insulation resistance RN can be used to quickly calculate the size of the positive electrode to ground insulation resistance RP and the negative electrode to ground insulation resistance RN, thereby improving the resistance detection result.

[0064] A person skilled in the art can understand that all or part of the steps in the above-mentioned embodiment method can be completed by instructing related hardware through a program, and the program can be stored in a computer-readable storage medium, such as ROM / RAM, disk, CD-ROM, etc.

[0065] The above disclosure is only a preferred embodiment of the present invention, which certainly cannot be used to limit the scope of the present invention. Therefore, equivalent changes made according to the claims of the present invention are still within the scope of the present invention.

Claims

1. An insulation resistance testing method, characterized in that: Used in a circuit including a power supply UBAT, a positive electrode to ground insulation resistor RP, a negative electrode to ground insulation resistor RN, a sampling resistor R3, a sampling resistor R4, a sampling resistor R5, and a plurality of resistance switching structures connected in parallel to both ends of the positive electrode to ground insulation resistor RP and the negative electrode to ground insulation resistor RN; wherein each resistance switching structure includes a resistor and a switch connected in series therewith; the method includes the following steps: When it is detected that all switches in all resistance switching structures are disconnected, the initial sampling voltage across the negative electrode to ground insulation resistance RN is obtained, and combined with the output voltage of the power supply UBAT, the initial sampling voltage across the positive electrode to ground insulation resistance RP is obtained; If the initial sampling voltage across the positive electrode-to-ground insulation resistance RP is greater than or equal to the initial sampling voltage across the negative electrode-to-ground insulation resistance RN, then confirming and connecting the first switching sequence corresponding to each switch in the resistance switching structure across the positive electrode-to-ground insulation resistance RP after the connected resistors are arranged in descending order according to the resistance value, and based on the first switching sequence, sequentially performing closing operations on the corresponding switches, and detecting the sampling voltage across the negative electrode-to-ground insulation resistance RN after each switch closing operation, until the sampling voltage across the negative electrode-to-ground insulation resistance RN after a certain switch closing operation is greater than the preset offset voltage threshold; Obtain the corresponding parallel resistor and its resistance value when the switch connected to both ends of the positive electrode-to-ground insulation resistance RP is closed, and combine the voltage of the power supply UBAT, the initial sampling voltage across the positive electrode-to-ground insulation resistance RP, the initial sampling voltage across the negative electrode-to-ground insulation resistance RN and its last sampling voltage, and the resistance values ​​of the sampling resistors R3 to R5 to calculate the size of the positive electrode-to-ground insulation resistance RP and the negative electrode-to-ground insulation resistance RN.

2. The insulation resistance testing method according to claim 1, characterized in that: The specific steps of obtaining the corresponding parallel resistor and its resistance value when the switch connected to both ends of the positive electrode to ground insulation resistance RP is closed, and combining the voltage of the power supply UBAT, the initial sampling voltage across the positive electrode to ground insulation resistance RP, the initial sampling voltage across the negative electrode to ground insulation resistance RN and the last sampling voltage, and the resistance values ​​of the sampling resistors R3 to R5 to calculate the magnitude of the positive electrode to ground insulation resistance RP and the negative electrode to ground insulation resistance RN include: The total resistance RP′ across the positive electrode-to-ground insulation resistance RP and the total resistance RN′ across the negative electrode-to-ground insulation resistance RN after the last switch closing operation are calculated by the formula RP′=(RQ*VNN*VP―RQ*VN*VPP) / (VN*VPP) and the formula RN′=(RQ*VNN*VP―RQ*VN*VPP) / (VP*VPP), respectively; wherein RQ represents the total resistance value of the resistance connected in parallel to the positive electrode-to-ground insulation resistance RP, which is calculated by the sampling resistor R3 connected in parallel and the resistance of each switch when it is in the closed state; / / represents parallel connection; VP = VBAT - VN; VBAT is the voltage of the power supply UBAT; VN is the initial sampling voltage across the negative electrode insulation resistance RN, and VP is the initial sampling voltage across the positive electrode insulation resistance RP; VR5 is the initial sampling voltage of the sampling resistor R5, which is the fixed value directly measured by the sampler before the switch closing operation; ZR5 is the resistance value of the sampling resistor R5; ZR4 is the resistance value of the sampling resistor R4; VPP = VBAT-VNN; VNN is the sampling voltage across the negative electrode insulation resistance RN after the last switch closing operation, and VPP is the sampled voltage across the positive electrode-to-ground insulation resistance RP after the last switch closing operation; VRR5 is the sampled voltage obtained by the sampler directly measuring the sampling resistor R5 after the last switch closing operation, which is a fixed value; The magnitude of the positive electrode to ground insulation resistance RP is calculated based on the calculated total resistance RP′ at both ends of the positive electrode to ground insulation resistance RP and combined with the total resistance RQ of the resistance connected to both ends of the positive electrode to ground insulation resistance RP; The magnitude of the negative electrode-to-ground insulation resistance RN is calculated based on the calculated total resistance RN′ across the negative electrode-to-ground insulation resistance RN and the resistance values ​​of the sampling resistors R4 to R5 connected in parallel to the negative electrode-to-ground insulation resistance RN.

3. The insulation resistance testing method according to claim 1, characterized in that: The method further comprises: If the initial sampling voltage across the positive electrode-to-ground insulation resistance RP is less than the initial sampling voltage across the negative electrode-to-ground insulation resistance RN, then confirming and connecting the switches in the resistance switching structure across the negative electrode-to-ground insulation resistance RN, the second switching sequence corresponding to the switches after the connected resistors are arranged in descending order according to the resistance value, and based on the second switching sequence, sequentially performing closing operations on the corresponding switches, and detecting the sampling voltage across the negative electrode-to-ground insulation resistance RN after each switch closing operation, until the sampling voltage across the negative electrode-to-ground insulation resistance RN after a certain switch closing operation is greater than the preset offset voltage threshold; Obtain the corresponding parallel resistor and its resistance value when the switch connected to the negative electrode to ground insulation resistance RN is closed, and combine the voltage of the power supply UBAT, the initial sampling voltage across the positive electrode to ground insulation resistance RP, the initial sampling voltage across the negative electrode to ground insulation resistance RN and its last sampling voltage, and the resistance values ​​of the sampling resistors R3 to R5 to calculate the size of the positive electrode to ground insulation resistance RP and the negative electrode to ground insulation resistance RN.

4. The insulation resistance testing method according to claim 3, characterized in that: The specific steps of obtaining the parallel-connected resistance and its resistance value when the switch connected to the negative electrode-to-ground insulation resistance RN is closed, and combining the voltage of the power supply UBAT, the initial sampling voltage across the positive electrode-to-ground insulation resistance RP, the initial sampling voltage across the negative electrode-to-ground insulation resistance RN and the last sampling voltage, and the resistance values ​​of the sampling resistors R3 to R5 to calculate the magnitude of the positive electrode-to-ground insulation resistance RP and the negative electrode-to-ground insulation resistance RN include: By formula RP ′ =―(RQ′*VNN*VP―RQ′*VN*VPP) / (VN*VNN) and formula RN ′ =―(RQ′*VNN*VP―RQ′*VN*VPP) / (VP*VNN), respectively calculate the total resistance RP′ across the positive electrode to ground insulation resistance RP and the total resistance RN′ across the negative electrode to ground insulation resistance RN after the last switch closing operation; wherein RQ′ represents the total resistance value of the resistance connected in parallel to the negative electrode to ground insulation resistance RN, which is calculated by the parallel-connected sampling resistors R4 to R5 and the resistance of each switch when it is in the closed state; / / represents parallel connection; VP = VBAT - VN; VBAT is the voltage of the power supply UBAT; VN is the initial sampling voltage across the negative electrode insulation resistance RN, and VP is the initial sampling voltage across the positive electrode insulation resistance RP; VR5 is the initial sampling voltage of the sampling resistor R5, which is the fixed value directly measured by the sampler before the switch closing operation; ZR5 is the resistance value of the sampling resistor R5; ZR4 is the resistance value of the sampling resistor R4; VPP = VBAT-VNN; VNN is the sampling voltage across the negative electrode insulation resistance RN after the last switch closing operation, and VPP is the sampled voltage across the positive electrode-to-ground insulation resistance RP after the last switch closing operation; VRR5 is the sampled voltage obtained by the sampler directly measuring the sampling resistor R5 after the last switch closing operation, which is a fixed value; The magnitude of the positive electrode-to-ground insulation resistance RP is calculated based on the calculated total resistance RP′ at both ends of the positive electrode-to-ground insulation resistance RP and the resistance value of the sampling resistor R3 connected in parallel to both ends of the positive electrode-to-ground insulation resistance RP; The magnitude of the negative electrode-to-ground insulation resistance RN is calculated based on the calculated total resistance RN′ across the negative electrode-to-ground insulation resistance RN and combined with the total resistance RQ′ connected to the two ends of the negative electrode-to-ground insulation resistance RN.

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