An insulation detection circuit and calibration method based on tri-state switching

Abstract

The application provides an insulation detection circuit and a calibration method based on tri-state switching, and relates to the technical field of circuit detection. In the insulation detection circuit, when the first relay, the second relay and the third relay are all disconnected, the first resistor, the second resistor, the third resistor and the fourth resistor are connected in series; when the first relay is disconnected, and the second relay and the third relay are closed, the first resistor, the second resistor and the third resistor are connected in series, and then are connected in parallel with a positive electrode insulation resistor to form a first loop; the fourth resistor is connected in parallel with a negative electrode insulation resistor to form a second loop; the first loop and the second loop are connected in series; when the second relay is disconnected, and the first relay and the third relay are closed, the first resistor is connected in parallel with the positive electrode insulation resistor to form a third loop; the second resistor, the third resistor and the fourth resistor are connected in series, and then are connected in parallel with the negative electrode insulation resistor to form a fourth loop; and the third loop and the fourth loop are connected in series.

Description

Technical Field

[0001] The present invention relates to the technical field of circuit detection, and in particular to an insulation detection circuit and calibration method based on tri-state switching. Background Art

[0002] With the increasing popularization of electric vehicles, the safety of matching charging piles is of critical importance. As a high-power electric energy conversion device, the insulation performance between the output busbar of its gun line and the ground is a core indicator directly related to personal safety and equipment safety. The national standard GB / T 18487.1-2023 explicitly stipulates that the insulation resistance of off-board power supply equipment must be detected, and hierarchical control shall be carried out according to the ratio of insulation resistance to busbar voltage (R / V); a safe state is defined when R / V>500Ω / V; an insulation abnormality alarm is required when 100Ω / V<R / V≤500Ω / V; and an insulation fault must be determined and charging shall be stopped when R / V<100Ω / V. The standard particularly emphasizes that measurement accuracy must be reliably guaranteed in the critical threshold interval close to the alarm and fault points.

[0003] At present, the mainstream technology mostly adopts the unbalanced bridge method for insulation detection. However, the following problems exist in practical engineering applications: the amplification of inherent systematic errors. Resistance elements in the detection bridge have initial tolerances, and the voltage sampling circuit also has gain and zero-point errors. In the calculation of the bridge method, the resistance value of the insulation resistance is obtained through complex operations of the measured voltage and multiple reference voltages. This calculation process will significantly amplify these errors. Especially when the detected insulation resistance is as high as hundreds of kiloohms to megaohms, the final calculated value may have a large deviation from the true value. This deviation is extremely harmful when the insulation resistance is close to the critical threshold for alarm or fault, and is very likely to cause false alarms or missed alarms. In addition, there are coupling and interference problems in the measurement of positive and negative insulation resistances. In the existing unbalanced bridge scheme, the positive insulation resistance RP and the negative insulation resistance RN are coupled to each other in the calculation model. When the resistance values of the two are greatly different or both are at a low level, this coupling calculation leads to ill-conditioned equations and increased solution errors. Although some improved schemes attempt to add switches to obtain more schemes, they still detect the voltages of at least two resistors with unfixed resistance values, which additionally introduces detection errors by the added detection circuit. Meanwhile, the change of the circuit topology is not sufficient, it cannot provide a truly independent measurement dimension, cannot fundamentally decouple RP and RN, and increases the calibration cost. Summary of the Invention

[0004] In view of this, the present invention proposes an insulation detection circuit and calibration method based on tri-state switching.

[0005] The technical solution of this invention is implemented as follows: The first aspect of this invention provides an insulation detection circuit based on three-state switching, comprising: a power supply, a first resistor, a second resistor, a third resistor, a fourth resistor, a first relay, a second relay, and a third relay, and a voltage acquisition module connected in parallel with the third resistor; wherein, When the first relay, the second relay, and the third relay are all disconnected, the first resistor, the second resistor, the third resistor, and the fourth resistor are connected in series; When the first relay is open and the second and third relays are closed, the first, second, and third resistors are connected in series and then connected in parallel with the positive insulation resistor to form a first circuit; the fourth resistor is connected in parallel with the negative insulation resistor to form a second circuit; the first circuit and the second circuit are connected in series. When the second relay is open and the first and third relays are closed, the first resistor is connected in parallel with the positive insulation resistor to form a third circuit, and the second, third, and fourth resistors are connected in series and then connected in parallel with the negative insulation resistor to form a fourth circuit; the third and fourth circuits are connected in series.

[0006] Based on the above technical solutions, preferably, the resistance values ​​of the first resistor, the second resistor, and the fourth resistor are the same.

[0007] Based on the above technical solutions, preferably, the first resistor, the second resistor, and the fourth resistor are all obtained by connecting multiple sub-resistors in series and in parallel.

[0008] More preferably, a second aspect of the present invention provides a calibration method based on three-state switching, applied to the insulation detection circuit described in the first aspect, characterized in that it includes: A standard resistor with a known resistance value is connected to the insulation detection circuit to replace the positive and negative insulation resistors. Adjust the opening and closing states of the first relay, the second relay, and the third relay, and use the insulation detection circuit to detect the standard resistor to obtain multiple sets of detection resistance values ​​corresponding to the standard resistor; The calibration parameters are determined by performing linear mapping or model parameter inversion based on the average value of multiple sets of detected resistance values ​​and the actual resistance value of the standard resistor.

[0009] Based on the above technical solution, preferably, the step of adjusting the opening and closing states of the first relay, the second relay, and the third relay, and using the insulation detection circuit to detect the standard resistor and obtain multiple sets of detection resistance values ​​corresponding to the standard resistor further includes: When the first relay, the second relay, and the third relay are all disconnected, the bus voltage is obtained; With the first relay open and the second and third relays closed, establish a first equation relating the voltage across the standard resistor to the first resistor, the second resistor, the third resistor, the fourth resistor, and the bus voltage. When the second relay is open and the first and third relays are closed, establish a second equation relating the voltage across the standard resistor to the first resistor, the second resistor, the third resistor, the fourth resistor, and the bus voltage. By combining the first equation and the second equation, the detection resistance values ​​of the positive electrode insulation resistance and the negative electrode insulation resistance are determined.

[0010] Based on the above technical solutions, preferably, the step of determining calibration parameters by performing linear mapping or model parameter inversion based on the average value of multiple sets of detected resistance values ​​and the actual resistance value of the standard resistor includes: The average value of the multiple sets of detected resistance values ​​and the actual resistance value of the standard resistor are input into the initial linear model, and the least squares method is used to perform linear fitting to determine the calibration parameters.

[0011] Based on the above technical solutions, preferably, the step of determining calibration parameters by performing linear mapping or model parameter inversion based on the average value of multiple sets of detected resistance values ​​and the actual resistance value of the standard resistor includes: Obtain multiple resistors connected in parallel with the standard resistor under different opening and closing states of the first relay, the second relay, and the third relay, as well as the equivalent equation parameters corresponding to the total resistance of the first resistor, the second resistor, the third resistor, and the fourth resistor; A nonlinear relationship is created between the equivalent equation parameters, the detected resistance value, and the actual resistance value. The calibration parameters are then determined through iterative optimization using the lsqcurvefit function.

[0012] More preferably, a third aspect of the present invention provides a calibration system based on three-state switching, including the insulation detection circuit described in the first aspect, and further including: a resistor replacement module, a resistance detection module, and a resistance calibration module; wherein, The resistor replacement module is configured to connect a standard resistor with a known resistance value to the insulation detection circuit to replace the third resistor. The resistance detection module is configured to adjust the opening and closing states of the first relay, the second relay and the third relay, and use the insulation detection circuit to detect the standard resistor to obtain multiple sets of detection resistance values ​​corresponding to the standard resistor. The resistance calibration module is configured to determine calibration parameters by performing linear mapping or model parameter inversion based on the average value of multiple sets of detected resistance values ​​and the actual resistance value of the standard resistor. It also includes a resistance replacement module, a resistance detection module, and a resistance calibration module. The resistor replacement module is configured to connect a standard resistor with a known resistance value to the insulation detection circuit to replace the third resistor. The resistance detection module is configured to adjust the opening and closing states of the first relay, the second relay and the third relay, and use the insulation detection circuit to detect the standard resistor to obtain multiple sets of detection resistance values ​​corresponding to the standard resistor. The resistance calibration module is configured to determine calibration parameters by performing linear mapping or model parameter inversion based on the average value of multiple sets of detected resistance values ​​and the actual resistance value of the standard resistor.

[0013] More preferably, a fourth aspect of the present invention provides an electronic device, including a processor and a memory; the memory has a computer program stored therein, wherein the computer program, when executed by the processor, implements the calibration method based on three-state switching as described in the second aspect.

[0014] More preferably, a fourth aspect of the present invention provides a non-transitory computer-readable storage medium having a computer program stored thereon, wherein the computer program, when executed by a processor, implements the calibration method based on three-state switching as described in the second aspect.

[0015] The insulation detection circuit and calibration method based on three-state switching of the present invention have the following advantages over the prior art: 1. By acquiring the voltage across a single sampling resistor through a specific combination of multiple relays, the resistance values ​​of the positive insulation resistance RP and the negative insulation resistance RN can be obtained. Deep decoupling of the measurement fundamentally suppresses the propagation and amplification of errors during the measurement process, resolving the mutual coupling problem between the positive and negative insulation resistances in the calculation. Even under extreme conditions of severe imbalance or low values ​​for both RP and RN, the accuracy and stability of the measurement are guaranteed, avoiding misjudgments. Furthermore, offline high-precision calibration compensates for the inherent bias of the system, greatly improving the measurement accuracy of the insulation resistance.

[0016] 2. Under specific relay open or closed states, equations are directly established for the voltage across the standard resistor and related resistors and bus voltages, avoiding complex multiple calculations and reducing error propagation stages, thereby reducing the amplification of systematic inherent errors. Even if the voltage sampling circuit has certain gain and zero-point errors, these can be mutually canceled or weakened to some extent during the equation solving process, thus improving the accuracy of the detection results and reducing the deviation between the final calculated value and the true value caused by error amplification.

[0017] 3. By creating equivalent equation parameters and nonlinear relationships between the detected resistance and the true resistance, the structure and characteristics of the resistor network are described from multiple perspectives. Furthermore, using iterative optimization methods, the errors of the voltage sampling circuit can be taken into account. During the optimization process, calibration parameters are continuously adjusted to make the calculated detected resistance closer to the true resistance, thereby effectively correcting the gain and zero-point errors of the voltage sampling circuit and reducing their impact on the detection results. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 A schematic diagram of an insulation detection circuit based on three-state switching is provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the first detection state of the insulation detection circuit provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of the second detection state of the insulation detection circuit provided in an embodiment of the present invention; Figure 4 A schematic diagram of the third detection state of the insulation detection circuit provided in an embodiment of the present invention; Figure 5 A schematic flowchart of a calibration method based on three-state switching provided in an embodiment of the present invention; Figure 6 A schematic diagram of a calibration system based on three-state switching provided in an embodiment of the present invention; Figure 7 This is a schematic diagram of the structure of an electronic device provided in an embodiment of the present invention. Detailed Implementation

[0020] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0021] In some embodiments, such as Figure 1 As shown, Figure 1 This is a schematic diagram of an insulation detection circuit based on three-state switching provided by an embodiment of the present invention. The insulation detection circuit based on three-state switching provided by the present invention includes: a power supply, a first resistor, a second resistor, a third resistor, a fourth resistor, a first relay, a second relay, and a third relay, as well as a voltage acquisition module connected in parallel with the third resistor; wherein, When the first, second, and third relays are all disconnected, the first, second, third, and fourth resistors are connected in series; When the first relay is open and the second and third relays are closed, the first, second, and third resistors are connected in series and then connected in parallel with the positive insulation resistor to form the first circuit. The fourth resistor is connected in parallel with the negative insulation resistor to form the second circuit. The first and second circuits are connected in series. When the second relay is open and the first and third relays are closed, the first resistor is connected in parallel with the positive insulation resistor to form the third circuit, and the second, third and fourth resistors are connected in series and then connected in parallel with the negative insulation resistor to form the fourth circuit; the third circuit and the fourth circuit are connected in series.

[0022] In this embodiment, the insulation detection circuit includes four fixed resistors: R1, R2, R3, and R4, and three controlled relays: relay A, relay B, and relay Y. By controlling the relays, three specific circuit states are generated. In each state, the voltage is measured across the same sampling resistor, R3. Using the voltage data from the three states, and combining circuit theory, an independent set of equations is established to accurately determine the resistance values ​​of the positive insulation resistance RP and the negative insulation resistance RN.

[0023] In an alternative embodiment, please refer to Figure 2 , Figure 2 This is a schematic diagram of the first detection state of the insulation detection circuit provided in an embodiment of the present invention; the first relay A, the second relay B, and the third relay Y are all disconnected. At this time, R1-R4 are connected in series between the positive and negative terminals of the DC bus. By measuring the voltage V0 across R3 and combining it with the resistance ratio, the total bus voltage V1 can be accurately deduced. This state does not involve the insulation resistances RP and RN.

[0024] In another alternative embodiment, please refer to Figure 3 , Figure 3 This is a schematic diagram of the second detection state of the insulation detection circuit provided in an embodiment of the present invention; the first relay A is open, and the second relay B and the third relay Y are closed. At this time, the positive insulation resistance RP is connected in parallel with the network formed by R1, R2, and R3, and the negative insulation resistance RN is connected in parallel with R4, forming a specific unbalanced bridge. The voltage VB of R3 can be measured in this state.

[0025] In yet another alternative embodiment, please refer to Figure 4 , Figure 4 This is a schematic diagram of the third detection state of the insulation detection circuit provided in an embodiment of the present invention; the second relay B is open, and the first relay A and the third relay Y are closed. At this time, the circuit topology becomes: RP is connected in parallel with R1, and RN is connected in parallel with the network formed by R2, R3, and R4, forming another different unbalanced bridge. In this state, the voltage VA of R3 can be measured.

[0026] Based on Kirchhoff's laws, circuit equations are written for the second and third detection states respectively. Both equations include the bus voltage V1, the measured voltage VB or VA, and the unknowns RP and RN. Since the two equations originate from different circuit topologies and are independent, their unique true values ​​can be directly calculated by solving them together. Deep decoupling of the measurement fundamentally suppresses the propagation and amplification of errors during the measurement process, and solves the problem of mutual coupling between the positive and negative insulation resistances in the calculation. Even under extreme conditions of severe imbalance or low values ​​for both RP and RN, the accuracy and stability of the measurement are guaranteed, avoiding misjudgments.

[0027] For example, the system starts the insulation detection program and enters the first detection state. The MCU controls relays A, B, and Y to all disconnect, and R1, R2, R3, and R4 are connected in series. The voltage across R3 is measured using an ADC to obtain V0. According to the voltage divider principle, the bus voltage... .

[0028] The system initiates the insulation detection program, entering the second detection state. The MCU controls relays A to open and B and Y to close. Resistors RP and RN are the equivalent insulation resistances between the positive and negative terminals of the high-voltage DC power supply V1 and ground. The voltage divider circuit is equivalent to a bridge circuit at this time. The value measured by the sampling circuit is the voltage across the 820Ω resistor R3. At this time, RP is connected in parallel with R1, R2, and R3 between the positive terminal and ground, and RN is connected in parallel with R4 between the negative terminal and ground. The measured voltage across resistor R3 is VB, the voltage across resistor RP is VPB, and the voltage across resistor RN is VNB. Combining this with the calculated V1, the voltages VPB and VNB can be obtained as follows:

[0029] ; .

[0030] The system initiates the insulation detection program, entering the third detection state. The MCU controls relay B to open, while relays A and Y both close. The values ​​of resistors RP and RN are exactly the same as those in the second bridge state. The voltage divider circuit is now equivalent to another bridge, and the value measured by the sampling circuit is still the voltage across the 820Ω resistor R3. In this case, the measured voltage across R3 is VA, the voltage across resistor RP is VPA, and the voltage across resistor RN is VNA. Combining this with the calculated V1, the expressions for VNA and VPA can be obtained:

[0031] ; .

[0032] The system starts the insulation detection program and enters the state solution state. Based on the circuit connections of the second and third detection states, the MCU can derive the following equations based on the current flowing through the bridge: ; ; Combining the three states mentioned above, RP, RN, voltages V0, VA, VB, and electrical groups R1, R2, R3, R4 can be calculated. First, define the intermediate variables and coefficients:

[0033] make , , ; The expressions for RN and RP are given by the following formulas: ; .

[0034] In some embodiments, the first resistor, the second resistor, and the fourth resistor have the same resistance value.

[0035] Here, the first, second, and fourth resistors have the same resistance value. On one hand, when constructing the insulation detection bridge circuit, resistors with the same resistance value make it easier to set the initial balance of the bridge, simplifying the initial circuit debugging, reducing the computational load, and improving detection efficiency. On the other hand, when the first, second, and fourth resistors have the same resistance value, their tolerances have a certain symmetry in their impact on the circuit. This symmetry allows the influence of resistance tolerances on the output signal to cancel each other out or decrease, thereby reducing the impact of resistance tolerances on the insulation resistance measurement results and improving the accuracy of the measurement.

[0036] In some embodiments, the first resistor, the second resistor, and the fourth resistor are all obtained by connecting multiple sub-resistors in series and in parallel.

[0037] Each sub-resistor has a certain initial tolerance, meaning there is a deviation between the actual resistance value and the nominal resistance value. By connecting multiple sub-resistors in series and parallel to form the target resistor, the initial tolerances of the sub-resistors can be offset to some extent according to the calculation formulas for series and parallel resistances. Furthermore, using multiple sub-resistors in series and parallel can distribute power across all sub-resistors, preventing individual resistors from overheating due to excessive power. This results in relatively smaller temperature variations for each sub-resistor, better stability of the resistance value, and thus reduced resistance value errors caused by power loss, improving the measurement accuracy of the circuit.

[0038] In one example, resistors R1, R2, and R4 are all 200K resistors. Four 100K resistors are connected in series in pairs and then in parallel to form a single 100K resistor. Another set of four 100K resistors are then connected in series in pairs and then in parallel to form another 100K resistor. These four 100K resistors are then connected in series in pairs to form a single 100K resistor. Finally, two sets of 100K resistors are connected in series to form a 200K resistor. When using 100KΩ resistors from the same batch and of the same model, their error and temperature drift are consistent. The resistance is 200KΩ after being connected in series in pairs. Two sets of 200KΩ resistors are then connected in parallel to obtain a 100KΩ resistor. Finally, two sets of 100KΩ resistors are connected in series to obtain a 200KΩ resistor. Errors are offset by statistical averaging effects, significantly reducing the total error after combination. Temperature drift is also compensated for by the consistent resistor characteristics, resulting in a much lower total temperature drift coefficient than a single resistor. This leads to better resistance stability over a wide temperature range. For high-voltage, high-power circuits, fixed-value resistors have greater error, while combined resistors offer a larger power margin, better heat dissipation, and higher accuracy due to their distributed resistance. In addition, a resistor composed of multiple sub-resistors will not pose a significant risk of circuit failure even if one of the sub-resistors fails.

[0039] In some embodiments, such as Figure 5 As shown, Figure 5 This is a flowchart illustrating a calibration method based on three-state switching provided by an embodiment of the present invention; the calibration method based on three-state switching provided by the present invention is applied to the above-mentioned insulation detection circuit, including: S510, connect a standard resistor with a known resistance value to the insulation detection circuit to replace the positive and negative insulation resistors.

[0040] S520 adjusts the opening and closing states of the first, second, and third relays, and uses the insulation detection circuit to detect the standard resistors, obtaining the detection resistance values ​​corresponding to multiple sets of standard resistors.

[0041] The S530 determines calibration parameters by performing linear mapping or model parameter inversion based on the average value of multiple sets of detected resistance values ​​and the actual resistance value of the standard resistor.

[0042] Considering the high precision requirements for insulation testing, besides the high precision requirements of the circuit and its components, the entire insulation resistance calculation relies heavily on the measurement of the voltage across the tested resistor. Generally, taking ADC sampling as an example, the accuracy of the ADC sampling value is crucial to the final calculation; therefore, ADC sampling needs to be calibrated. The calculation formula is:

[0043] ; It is through the voltage of the operational amplifier. K is the magnification factor. These are the ADC sample values ​​from the MCU, where N is the resolution. This is the reference voltage for the ADC.

[0044] In some embodiments, adjusting the opening and closing states of the first relay, the second relay, and the third relay, and using an insulation detection circuit to detect standard resistors to obtain multiple sets of detected resistance values ​​corresponding to standard resistors, further includes: The bus voltage is obtained when the first, second, and third relays are all disconnected. With the first relay open and the second and third relays closed, establish the first equations relating the voltage across the standard resistor to the first resistor, the second resistor, the third resistor, the fourth resistor, and the bus voltage, respectively. With the second relay open and the first and third relays closed, establish second equations relating the voltages across the standard resistor to the first resistor, the second resistor, the third resistor, the fourth resistor, and the bus voltage, respectively. Solve the first and second equations together to determine the detection resistance values ​​of the positive and negative insulation resistances.

[0045] In this embodiment, taking a 1000V DC output voltage as an example, the device to be calibrated is connected to the calibration platform. The device sends a calibration command to the MCU. The MCU controls the relay to enter the first detection state, the second detection state, and the third detection state in sequence, and records multiple sets of voltage data. Each set includes V0, VA, and VB. During this process, the average value is taken multiple times for each standard resistor combination. The calibration platform runs a calibration algorithm, such as output linear mapping or model parameter inversion, to calculate the optimal calibration parameters, such as proportional coefficients KP and KN, offsets BP and BN, or equivalent equation parameters. , , Finally, the calibration parameters are burned into the Flash memory of the device's MCU.

[0046] In some embodiments, calibration parameters are determined by performing linear mapping or model parameter inversion based on the average value of multiple sets of detected resistance values ​​and the actual resistance value of a standard resistor, including: The average value of multiple sets of detected resistance values ​​and the actual resistance value of the standard resistor are input into the initial linear model, and the least squares method is used to perform linear fitting to determine the calibration parameters.

[0047] In this embodiment, for positive and negative calibration, the calibration voltages V0_i, VB_i, VA_i and the corresponding actual resistance values ​​are substituted into the uncalibrated original model, and the formula is obtained by linear fitting using the least squares method. The calibration parameters, such as proportional coefficients KP and KN, and offsets BP and BN, are then determined.

[0048] In some embodiments, calibration parameters are determined by performing linear mapping or model parameter inversion based on the average value of multiple sets of detected resistance values ​​and the actual resistance value of a standard resistor, including: Obtain the equivalent equation parameters corresponding to the total resistance of the first, second, third, and fourth resistors connected in parallel with the standard resistor under different opening and closing states of the first, second, and third relays; A nonlinear relationship is established between the equivalent equation parameters, the detected resistance, and the true resistance. The calibration parameters are then determined through iterative optimization using the lsqcurvefit function.

[0049] In this embodiment, the optimization objective is set as: finding a set of equivalent equation parameters. , , This ensures that for all N sets of calibration data, the equivalent equation parameters of the calibration voltage V0_i, VB_i, and VA_i for each set of data are... , , After being incorporated into the model, the overall error between the calculated detected resistance and the true resistance is minimized. This is a nonlinear optimization problem, which the calibration platform can solve using the lsqcurvefit algorithm, yielding a set of equivalent equation parameters. , , These are the calibration parameters, which directly replace the equation coefficients in the original model of the equipment.

[0050] In some embodiments, please refer to Figure 6 , Figure 6 This is a schematic diagram of a calibration system based on three-state switching provided by an embodiment of the present invention. The present invention provides a calibration system 600 based on three-state switching, including the aforementioned insulation detection circuit, and further including: a resistor replacement module 610, a resistance detection module 620, and a resistance calibration module 630; wherein,

[0051] The resistor replacement module 610 is configured to connect a standard resistor with a known resistance value to the insulation detection circuit to replace the third resistor. The resistance detection module 620 is configured to adjust the opening and closing states of the first relay, the second relay and the third relay, and to use the insulation detection circuit to detect the standard resistors and obtain the detection resistance values ​​corresponding to multiple sets of standard resistors. The resistance calibration module 630 is configured to determine calibration parameters by performing linear mapping or model parameter inversion based on the average value of multiple sets of detected resistance values ​​and the actual resistance value of a standard resistor.

[0052] In some embodiments, the resistance detection module 620 is specifically configured as follows: The bus voltage is obtained when the first, second, and third relays are all disconnected. With the first relay open and the second and third relays closed, establish the first equations relating the voltage across the standard resistor to the first resistor, the second resistor, the third resistor, the fourth resistor, and the bus voltage, respectively. With the second relay open and the first and third relays closed, establish a second equation relating the negative voltage across the standard resistor to the first resistor, the second resistor, the third resistor, the fourth resistor, and the bus voltage, respectively. Solve the first and second equations together to determine the detection resistance values ​​of the positive and negative insulation resistances.

[0053] In some embodiments, the resistance calibration module 630 is specifically configured as follows: The average value of multiple sets of detected resistance values ​​and the actual resistance value of the standard resistor are input into the initial linear model, and the least squares method is used to perform linear fitting to determine the calibration parameters.

[0054] In some embodiments, the resistance calibration module 630 is specifically configured as follows: Obtain the equivalent equation parameters corresponding to the total resistance of the first, second, third, and fourth resistors connected in parallel with the standard resistor under different opening and closing states of the first, second, and third relays; A nonlinear relationship is established between the equivalent equation parameters, the detected resistance, and the true resistance. The calibration parameters are then determined through iterative optimization using the lsqcurvefit function.

[0055] It should be noted that the calibration system based on three-state switching provided in this application embodiment and the insulation detection circuit based on three-state switching provided in this application embodiment are based on the same application concept. Therefore, the specific implementation of this embodiment can refer to the aforementioned implementation of the insulation detection circuit based on three-state switching, and the repeated parts will not be described again.

[0056] In some embodiments, please refer to Figure 7 , Figure 7 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this application. The electronic device 700 provided in this application includes a processor 710 and a memory 720; the memory 720 stores a computer program, wherein the computer program, when executed by the processor, implements the aforementioned calibration method based on three-state switching.

[0057] Specifically, processor 710 may include, for example, a general-purpose microprocessor, an instruction set processor and / or an associated chipset and / or a special-purpose microprocessor (e.g., an application-specific integrated circuit (ASIC)), etc. Processor 710 may also include onboard memory for caching purposes. Processor 710 may be a single processing unit or multiple processing units for performing different actions of the method flow according to embodiments of this application.

[0058] The memory 720 can be any medium capable of containing, storing, transmitting, propagating, or transmitting instructions. For example, the memory 720 can be, but is not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, device, apparatus, or propagation medium. Specific examples of the memory 720 include: magnetic storage devices such as magnetic tape or hard disk drives (HDDs); optical storage devices such as optical discs (CD-ROMs); and also random access memory (RAM) or flash memory; and / or wired / wireless communication links.

[0059] This application also provides a non-transitory computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements the aforementioned calibration method based on three-state switching. This computer-readable medium may be included in the device / apparatus / system described in the above embodiments; or it may exist independently and not assembled into the device / apparatus / system. The aforementioned computer-readable medium carries one or more programs, which, when executed, implement the method according to the embodiments of this application.

[0060] According to embodiments of this application, a computer-readable medium may be a computer-readable signal medium or a computer-readable storage medium, or any combination thereof. A computer-readable storage medium may be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples of a computer-readable storage medium may include, but are not limited to: an electrical connection having one or more wires, a portable computer disk, a hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage device, magnetic storage device, or any suitable combination thereof. In this application, a computer-readable storage medium may be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, apparatus, or device. In this application, a computer-readable signal medium may include a data signal propagated in baseband or as part of a carrier wave, carrying computer-readable program code. Such propagated data signals may take various forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination thereof. Computer-readable signal media can also be any computer-readable medium other than computer-readable storage media, which can send, propagate, or transmit a program for use by or in connection with an instruction execution system, apparatus, or device. The program code contained on the computer-readable medium can be transmitted using any suitable medium, including but not limited to: wireless, wired, optical fiber, radio frequency signals, etc., or any suitable combination thereof.

[0061] Those skilled in the art will understand that the features described in the various embodiments and / or claims of this application can be combined and / or combined in various ways, even if such combinations or combinations are not explicitly described in this application. In particular, the features described in the various embodiments and / or claims of this application can be combined and / or combined in various ways without departing from the spirit and teachings of this application. All such combinations and / or combinations fall within the scope of this application. Therefore, the scope of this application should not be limited to the above embodiments, but should be defined not only by the appended claims, but also by their equivalents. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this invention should be included within the protection scope of this invention.

Claims

1. An insulation detection circuit based on three-state switching, characterized in that, include: The system includes a power supply, a first resistor, a second resistor, a third resistor, a fourth resistor, a first relay, a second relay, and a third relay, as well as a voltage acquisition module connected in parallel with the third resistor; wherein, When the first relay, the second relay, and the third relay are all disconnected, the first resistor, the second resistor, the third resistor, and the fourth resistor are connected in series; When the first relay is open and the second and third relays are closed, the first, second, and third resistors are connected in series and then connected in parallel with the positive insulation resistor to form a first circuit; the fourth resistor is connected in parallel with the negative insulation resistor to form a second circuit; the first circuit and the second circuit are connected in series. When the second relay is open and the first and third relays are closed, the first resistor is connected in parallel with the positive insulation resistor to form a third circuit, and the second, third, and fourth resistors are connected in series and then connected in parallel with the negative insulation resistor to form a fourth circuit; the third and fourth circuits are connected in series.

2. The insulation detection circuit based on three-state switching as described in claim 1, characterized in that, The first resistor, the second resistor, and the fourth resistor have the same resistance value.

3. The insulation detection circuit based on three-state switching as described in claim 1, characterized in that, The first resistor, the second resistor, and the fourth resistor are all obtained by connecting multiple sub-resistors in series and in parallel.

4. A calibration method based on three-state switching, applied to the insulation detection circuit according to any one of claims 1-3, characterized in that, include: A standard resistor with a known resistance value is connected to the insulation detection circuit to replace the positive and negative insulation resistors. Adjust the opening and closing states of the first relay, the second relay, and the third relay, and use the insulation detection circuit to detect the standard resistor to obtain multiple sets of detection resistance values ​​corresponding to the standard resistor; The calibration parameters are determined by performing linear mapping or model parameter inversion based on the average value of multiple sets of detected resistance values ​​and the actual resistance value of the standard resistor.

5. The calibration method based on three-state switching as described in claim 4, characterized in that, The step of adjusting the opening and closing states of the first relay, the second relay, and the third relay, and using the insulation detection circuit to detect the standard resistor and obtain multiple sets of detection resistance values ​​corresponding to the standard resistor, further includes: When the first relay, the second relay, and the third relay are all disconnected, the bus voltage is obtained; With the first relay open and the second and third relays closed, establish a first equation relating the voltage across the standard resistor to the first resistor, the second resistor, the third resistor, the fourth resistor, and the bus voltage. When the second relay is open and the first and third relays are closed, establish a second equation relating the voltage across the standard resistor to the first resistor, the second resistor, the third resistor, the fourth resistor, and the bus voltage. By combining the first equation and the second equation, the detection resistance values ​​of the positive electrode insulation resistance and the negative electrode insulation resistance are determined.

6. The calibration method based on three-state switching as described in claim 4, characterized in that, The determination of calibration parameters based on the average value of multiple sets of detected resistance values ​​and the actual resistance value of the standard resistor through linear mapping or model parameter inversion includes: The average value of the multiple sets of detected resistance values ​​and the actual resistance value of the standard resistor are input into the initial linear model, and the least squares method is used to perform linear fitting to determine the calibration parameters.

7. The calibration method based on three-state switching as described in claim 4, characterized in that, The determination of calibration parameters based on the average value of multiple sets of detected resistance values ​​and the actual resistance value of the standard resistor through linear mapping or model parameter inversion includes: Obtain multiple resistors connected in parallel with the standard resistor under different opening and closing states of the first relay, the second relay, and the third relay, as well as the equivalent equation parameters corresponding to the total resistance of the first resistor, the second resistor, the third resistor, and the fourth resistor; A nonlinear relationship is created between the equivalent equation parameters, the detected resistance value, and the actual resistance value. The calibration parameters are then determined through iterative optimization using the lsqcurvefit function.

8. A calibration system based on three-state switching, comprising the insulation detection circuit according to any one of claims 1-3, characterized in that, Also includes: The system includes a resistor replacement module, a resistance detection module, and a resistor calibration module; among which, The resistor replacement module is configured to connect a standard resistor with a known resistance value to the insulation detection circuit to replace the third resistor. The resistance detection module is configured to adjust the opening and closing states of the first relay, the second relay and the third relay, and use the insulation detection circuit to detect the standard resistor to obtain multiple sets of detection resistance values ​​corresponding to the standard resistor. The resistance calibration module is configured to determine calibration parameters by performing linear mapping or model parameter inversion based on the average value of multiple sets of detected resistance values ​​and the actual resistance value of the standard resistor.

9. An electronic device comprising a processor and a memory; said memory storing a computer program, wherein, When the computer program is executed by the processor, it implements the calibration method based on three-state switching as described in any one of claims 4 to 7.

10. A non-transitory computer-readable storage medium, characterized in that, It stores a computer program, wherein the computer program, when executed by a processor, implements the calibration method based on three-state switching as described in any one of claims 4 to 7.

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