A simulation analysis method and system for AC conducted emission of on-board charger

Abstract

The present invention provides a simulation and analysis method and system for AC conducted emissions of an on-board charger, comprising: step S1, generating an inductor equivalent circuit model, a three-dimensional finite element model, and a capacitor equivalent circuit model; step S2, performing correlation to obtain a field-circuit co-simulation circuit model for the EMI filter circuit; step S3, correlating this with pre-established PFC circuit models, LLC circuit models, AC mains models, and LISN circuit models to form a field-circuit co-simulation model for the on-board charger's AC conducted emissions; step S4, performing simulation calculations to obtain simulation results; comparing the simulation results with the peak limits of the test standard to generate a comparison result; and step S5, outputting an AC conducted emissions solution for the on-board charger based on the comparison results. The present invention ensures that the conducted noise suppression trend is consistent with actual measurements and also closely matches the magnitude, improving simulation accuracy and enabling full-band simulation calculations and predictions.

Description

Technical Field

[0001] The present invention relates to the technical field of AC conducted emission analysis of an on-board charger for a new energy electric vehicle, and in particular to a simulation analysis method and system for the AC conducted emission of an on-board charger. Background Art

[0002] An electric vehicle's integrated power system (IPS) not only charges the battery but also provides the vehicle's 12V DC power supply, making it an essential component for EVs. The onboard charger (OBC) includes EMI filtering, PFC (power factor control), LLC (resonant voltage conversion), and a low-voltage converter. AC conducted emissions from the OBC are a key electromagnetic compatibility (EMC) test item for onboard power supplies. CISPR 25 is the standard for testing the EMC performance of OBCs, specifying limits and test methods for AC conducted emissions from OBCs. The test frequency range is 150kHz to 108MHz. Currently, AC conducted emissions in EV systems are predicted through circuit simulation of the EMI filtering circuit. Parameter sweeps of the capacitors in this circuit are performed to identify trends in their impact on conducted emissions and propose remediation plans. However, design engineers often find that these AC conducted emissions are inaccurately predicted in the high-frequency band, and adjusting the capacitors fails to mitigate excess charging conduction emissions at low frequencies. This has led many designers to prefer physical measurements of the OBC and empirically adjust the components to address these issues.

[0003] Because the topology of EMI filter circuits is composed of inductors and capacitors, modifying the inductor and capacitor parameters can effectively filter noise in the corresponding frequency band. Predicting and evaluating AC conducted emissions from electric vehicle on-board chargers is typically achieved through circuit modeling and simulation of EMI filter circuits. However, due to the difficulty of building a three-dimensional model of an EMI filter circuit, in practice, only circuit construction and simulation of the EMI filter circuit are performed. This lack of consideration of the parasitic parameters and Q value of the common-mode inductor, the distributed parameters of the capacitors, and the parasitic parameters of the PCB board leads to significant deviations from actual results in the high-frequency range (1MHz-108MHz) of conducted emissions, sometimes even failing to match the trend. Without the addition of active circuits such as PFC and LLC, adjustments to the EMI filter circuit have no effect on the low-frequency range (150kHz-1MHz) of conducted emissions. This severely impacts the accuracy of AC conducted emissions predictions for electric vehicle on-board chargers, limiting their practical application. Summary of the Invention

[0004] The purpose of the present invention is to propose a simulation analysis method and system for the AC conducted emission of an on-board charger, so as to solve the technical problem that the existing method only simulates the EMI circuit for the AC conducted emission of the on-board charger, resulting in a large deviation between the simulation results and the actual results and low accuracy.

[0005] On the one hand, a simulation analysis method for AC conducted emission of an on-board charger is provided, comprising the following steps:

[0006] Step S1: determining the inductance, resistance, and parasitic capacitance of the common-mode inductor using a pre-established three-dimensional finite element model of the common-mode inductor, and generating an inductor equivalent circuit model based on the determined inductance, resistance, and parasitic capacitance of the common-mode inductor; generating a three-dimensional finite element model based on PCB design data; and generating a capacitor equivalent circuit model based on capacitor specification data.

[0007] Step S2, associating the inductor equivalent circuit model, the three-dimensional finite element model and the capacitor equivalent circuit model to obtain a field-circuit collaborative simulation circuit model of the EMI filter circuit;

[0008] Step S3, associating the field-circuit collaborative simulation circuit model of the EMI filter circuit with the pre-established PFC circuit model, LLC circuit model, AC mains model, and LISN circuit model to form an AC conducted emission field-circuit collaborative simulation model of the on-board charger;

[0009] Step S4, performing simulation calculations based on the on-board charger AC conduction emission field-circuit collaborative simulation model to obtain simulation calculation results; comparing the simulation calculation results with the peak limit of the test standard to generate a comparison result;

[0010] Step S5: Based on the comparison results, the on-board charger AC conduction emission field-circuit collaborative simulation model is output as the on-board charger AC conduction emission solution. Alternatively, the on-board charger AC conduction emission field-circuit collaborative simulation model is adjusted and simulation calculations are performed until the adjusted simulation calculation results do not exceed the peak limit of the test standard, and the adjusted on-board charger AC conduction emission field-circuit collaborative simulation model is output as the on-board charger AC conduction emission solution.

[0011] Preferably, in step S1, the specific process of pre-establishing the three-dimensional finite element model of the common mode inductor is:

[0012] Obtain specification data or physical data of the common-mode inductor, determine the number of wire turns parameters and the size parameters of the magnetic core based on the specification data or physical data of the common-mode inductor; and establish a three-dimensional finite element model of the common-mode inductor based on the number of wire turns parameters and the size parameters of the magnetic core.

[0013] Preferably, in step S1, generating a three-dimensional finite element model specifically includes: obtaining design data of the PCB board, exporting the design data through a corresponding export interface, and simplifying the data according to calculation time parameters, complexity parameters and result accuracy parameters to obtain a three-dimensional finite element model.

[0014] Preferably, in step S1, generating a capacitor equivalent circuit model specifically includes: obtaining device specification data of the capacitor; converting the capacitance value, parasitic inductance and parasitic resistance value and parasitic capacitance value determined according to the device specification data of the capacitor into corresponding equivalent devices; and associating all equivalent devices to form a capacitor equivalent circuit model.

[0015] Preferably, in step S3, the specific process of pre-establishing the PFC circuit model, the LLC circuit model, the AC mains model, and the LISN circuit model is as follows:

[0016] Obtain the switching device data in the on-board charger and establish the PFC circuit model and LLC circuit model through the nonlinear model of the switching device;

[0017] Obtaining LISN circuit data of the on-board charger and establishing a LISN circuit model based on the LISN circuit data;

[0018] Obtain the mains data connected to the on-board charger and establish an AC mains model based on the mains data.

[0019] Preferably, in step S4, generating the comparison result specifically includes: obtaining a peak limit value of conducted emission in a device-level test by querying an international standard for testing electromagnetic compatibility performance of an on-board charger, and using the peak limit value as the peak limit value of the test standard; comparing the simulation calculation result with the peak limit value of the test standard, and when the simulation calculation result exceeds the peak limit value of the test standard, generating a comparison result as exceeding the peak limit value of the speed measurement standard;

[0020] The simulation calculation result is compared with the peak value limit of the test standard. When the simulation calculation result is lower than the peak value limit of the test standard, a comparison result is generated as not exceeding the peak value limit of the test standard.

[0021] Preferably, step S5 includes:

[0022] When the comparison result exceeds the peak limit of the test standard, the Y capacitor or common-mode inductor in the EMI filter circuit is adjusted, and an adjusted on-board charger AC conduction emission field-circuit collaborative simulation model is obtained based on the adjusted EMI filter circuit. Simulation calculation is performed based on the adjusted on-board charger AC conduction emission field-circuit collaborative simulation model to obtain adjusted simulation calculation results.

[0023] Preferably, the step S5 further includes: when the price comparison result does not exceed the peak limit of the test standard, outputting the on-board charger AC conduction emission field-circuit collaborative simulation model as the on-board charger AC conduction emission solution.

[0024] On the other hand, a simulation analysis system for AC conducted emissions of an on-board charger is provided, which is used to implement the simulation analysis method for AC conducted emissions of an on-board charger, including:

[0025] A model building module is used to determine the inductance, resistance, and parasitic capacitance of the common-mode inductor using a pre-established three-dimensional finite element model of the common-mode inductor, and obtain an inductor equivalent circuit model based on the determined inductance, resistance, and parasitic capacitance of the common-mode inductor; generate a three-dimensional finite element model based on PCB design data; and generate a capacitor equivalent circuit model based on capacitor specification data;

[0026] A model association module is used to associate the inductor equivalent circuit model, the three-dimensional finite element model, and the capacitor equivalent circuit model to obtain a field-circuit collaborative simulation circuit model of the EMI filter circuit; and the field-circuit collaborative simulation circuit model of the EMI filter circuit is associated with the pre-established PFC circuit model, LLC circuit model, AC mains model, and LISN circuit model to form an AC conducted emission field-circuit collaborative simulation model of the on-board charger;

[0027] A simulation calculation module is used to perform simulation calculations based on the on-board charger AC conduction emission field-circuit collaborative simulation model to obtain simulation calculation results; compare the simulation calculation results with the peak limits of the test standard to generate a comparison result; and output the on-board charger AC conduction emission field-circuit collaborative simulation model as an on-board charger AC conduction emission scheme based on the comparison result; or adjust the on-board charger AC conduction emission field-circuit collaborative simulation model and perform simulation calculations until the adjusted simulation calculation results do not exceed the peak limits of the test standard, and output the adjusted on-board charger AC conduction emission field-circuit collaborative simulation model as the on-board charger AC conduction emission scheme.

[0028] Preferably, the system further includes a model preprocessing module for obtaining common-mode inductor specification data or physical data, determining the number of wire turns parameters and the size parameters of the magnetic core according to the common-mode inductor specification data or physical data; and establishing a three-dimensional finite element model of the common-mode inductor according to the number of wire turns parameters and the size parameters of the magnetic core;

[0029] It is also used to obtain the switching device data in the on-board charger and establish the PFC circuit model and LLC circuit model through the nonlinear model of the switching device; obtain the LISN circuit data of the on-board charger and establish the LISN circuit model based on the LISN circuit data; obtain the mains data connected to the on-board charger and establish the AC mains model based on the mains data;

[0030] And it is used to obtain design data of the PCB board, export the design data through the corresponding export interface, and simplify it according to the calculation time parameter, complexity parameter and result accuracy parameter to obtain a three-dimensional finite element model; obtain the device specification data of the capacitor; convert the capacitance value, parasitic inductance and parasitic resistance value and parasitic capacitance value determined according to the device specification data of the capacitor into corresponding equivalent devices; and associate all equivalent devices to form a capacitor equivalent circuit model.

[0031] In summary, the implementation of the embodiments of the present invention has the following beneficial effects:

[0032] The simulation and analysis method and system for AC conducted emissions from on-board chargers provided by this invention employs a detailed three-dimensional model of the common-mode inductor, incorporating a three-dimensional model of the PCB board and a capacitor equivalent circuit model to form a complete simulation model of the EMI filter circuit. This model not only ensures that the conducted noise suppression trends in the corresponding frequency bands are consistent with those measured, but also closely matches the magnitude.

[0033] Active circuit components such as PFC and LLC were incorporated into the simulation process, allowing for the simulation of the switching noise generated by the active switching circuit, a crucial component of the on-board charger's AC conducted emission noise. This enabled simulation and prediction of the on-board charger's AC conducted emission noise level across the entire frequency range of 150kHz-108MHz, rather than simply predicting the trend of the on-board charger's AC conducted emission noise in the high-frequency band (1MHz-108MHz) through EMI filter circuit simulation. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, without paying any creative work, other drawings obtained based on these drawings still fall within the scope of the present invention.

[0035] Figure 1 The figure is a schematic diagram of the main process of a simulation analysis method for AC conducted emission of an on-board charger according to an embodiment of the present invention.

[0036] Figure 2 The figure is a logic diagram of a simulation analysis method of AC conducted emission of an on-board charger according to an embodiment of the present invention.

[0037] Figure 3 Schematic diagram of a simulation analysis system for AC conducted emissions of an on-board charger according to an embodiment of the present invention. DETAILED DESCRIPTION

[0038] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention will be described in further detail below with reference to the accompanying drawings.

[0039] like Figure 1 and Figure 2 FIG. 1 is a schematic diagram of an embodiment of a simulation analysis method for AC conducted emissions of an on-board charger provided by the present invention. In this embodiment, the method includes the following steps:

[0040] Step S1, determining the inductance value, resistance value and parasitic capacitance value of the common-mode inductor through a pre-established three-dimensional finite element model of the common-mode inductor, and generating an inductor equivalent circuit model based on the determined inductance value, resistance value and parasitic capacitance value of the common-mode inductor; generating a three-dimensional finite element model based on the PCB design data; generating a capacitor equivalent circuit model based on the capacitor specification data; it is understandable that the capacitor equivalent circuit model is constructed according to the capacitor device specification sheet or the device equivalent model provided by the device manufacturer is directly used; and exporting and simplifying the three-dimensional finite element model based on the layout file of the PCB board.

[0041] In a specific embodiment, the specific process of pre-establishing a three-dimensional finite element model of a common-mode inductor is as follows: obtaining the specification data or physical data of the common-mode inductor, determining the number of wire turns parameters and the size parameters of the magnetic core based on the specification data or physical data of the common-mode inductor; and establishing a three-dimensional finite element model of the common-mode inductor based on the number of wire turns parameters and the size parameters of the magnetic core. It is understandable that a series of detailed parameters about the common-mode inductor, such as geometric parameters and material parameters such as the number of wire turns and the size of the magnetic core, can be obtained through the specification sheet or physical object of the common-mode inductor, and a detailed three-dimensional finite element model can be built based on the geometric parameters and material parameters such as the number of wire turns and the size of the magnetic core. By establishing a three-dimensional finite element model of the common-mode inductor, the simplification of the magnetic core inductor and the PCB (Printed Circuit Board) board and the joint simulation of the two can be achieved, and the parasitic inductance and parasitic capacitance inside the circuit can be accurately calculated. The simulation results are in good agreement with the actual measurement in the frequency range of 1MHz-108MHz.

[0042] Specifically, the design data of the PCB board is obtained, the design data is exported through the corresponding export interface, and simplified according to the calculation time parameter, complexity parameter and result accuracy parameter to obtain a three-dimensional finite element model. The device specification data of the capacitor is obtained; the capacitance value, parasitic inductance and parasitic resistance value and parasitic capacitance value determined according to the device specification data of the capacitor are converted into corresponding equivalent devices; all equivalent devices are associated to form a capacitor equivalent circuit model. It is understandable that by determining the accurate capacitance parameters (inductance value, resistance value and parasitic capacitance value) and the parameters of the PCB board, the equivalent devices can be added to the simulation calculation model, effectively supplementing the previous method's neglect of factors such as capacitance, making the simulation calculation more accurate.

[0043] In step S2, the inductor equivalent circuit model, the three-dimensional finite element model, and the capacitor equivalent circuit model are associated to obtain a field-circuit collaborative simulation circuit model of the EMI (Electromagnetic Interference) filter circuit; a complete EMI filter circuit is formed by the inductor equivalent circuit model, the three-dimensional finite element model, and the capacitor equivalent circuit model, effectively considering the influence of devices such as capacitors on the circuit simulation calculation, so that the simulation results are closer to the actual situation.

[0044] Step S3, the field-circuit collaborative simulation circuit model of the EMI filter circuit is associated with the pre-established PFC (Power Factor Correction, power factor correction) circuit model, LLC (resonant circuit) circuit model, AC mains model, and LISN (Line Impedance Stabilization Network, line impedance stabilization network) circuit model to form an on-board charger AC conduction emission field-circuit collaborative simulation model; it can be understood that the nonlinear model of the switching device is used to build a circuit-level model of circuits such as PFC and LLC, and the EMI filter circuit field-circuit collaborative model, the capacitor equivalent circuit model, the PFC and LLC circuit-level models, the AC mains model, and the LISN circuit-level model are combined to form a complete electric vehicle on-board charger AC conduction emission field-circuit collaborative simulation model for simulation calculation.

[0045] In a specific embodiment, the specific process for pre-establishing the PFC circuit model, LLC circuit model, AC mains model, and LISN circuit model is as follows: obtaining data on the switching devices within the onboard charger, establishing the PFC circuit model and LLC circuit model using the nonlinear models of the switching devices. It is understood that to ensure the integrity of the output waveform when the active switching circuit is in operation, the active switching devices in the circuit require active circuit models, or a nonlinear switching device model is constructed using software based on the characteristic curves of the active devices; obtaining data on the LISN circuit of the onboard charger, and establishing the LISN circuit model based on the LISN circuit data; obtaining data on the mains connected to the onboard charger, and establishing the AC mains model based on the mains data. Specifically, by incorporating active circuit components such as PFC and LLC, the switching noise generated by the active switching circuit is incorporated into the conducted noise results. This not only enables the prediction of the electromagnetic compatibility performance of the onboard charger of electric vehicles across the full frequency band (150kHz-108MHz) of AC conducted emissions, but also achieves high accuracy.

[0046] Step S4: Perform simulation calculations based on the on-board charger AC conduction emission field-circuit collaborative simulation model to obtain simulation calculation results; compare the simulation calculation results with the peak limit of the test standard to generate a comparison result; specifically, during the simulation calculation process, the AC conduction emission focus frequency band is 150kHz-108MHz, and the field-circuit collaborative circuit is simulated. The simulation time must be greater than 6.7uS and the time interval must be less than 9nS.

[0047] In a specific embodiment, by querying the international standards for testing the electromagnetic compatibility performance of on-board chargers, the peak limit of the conducted emission of the equipment-level test is obtained as the peak limit of the test standard; it can be understood that the peak limit of the test standard can be directly found in the international standards and is divided into 5 levels, which can be selected according to different equipment requirements and usage environments. There are two types of limits, one is the voltage limit (the main test standard of this embodiment), and the other is the current limit (which is also applicable to this embodiment)

[0048] , compare the simulation calculation results with the peak limit of the test standard. When the simulation calculation results exceed the peak limit of the test standard, the comparison result is generated as exceeding the peak limit of the test standard; compare the simulation calculation results with the peak limit of the test standard. When the simulation calculation results are lower than the peak limit of the test standard, the comparison result is generated as not exceeding the peak limit of the test standard.

[0049] In step S5, based on the comparison results, the on-board charger AC conducted emission field-circuit collaborative simulation model is output as the on-board charger AC conducted emission solution. Alternatively, the on-board charger AC conducted emission field-circuit collaborative simulation model is adjusted and simulated until the adjusted simulation result does not exceed the peak limit of the test standard, and the adjusted on-board charger AC conducted emission field-circuit collaborative simulation model is output as the on-board charger AC conducted emission solution. It is understood that by extracting the noise voltage value time domain waveform at the same position as the LISN in the CISPR25 test method and performing spectrum transformation to obtain a noise voltage frequency domain curve, the AC conducted emission simulation result (i.e., the noise voltage frequency domain curve) is compared with the peak limit in CISPR25 to directly predict the electromagnetic compatibility performance of the electric vehicle on-board charger AC conducted emission. When the result exceeds the threshold, the Y capacitor (safety capacitor) or even the common-mode inductor in the EMI filter circuit needs to be adjusted. This can accurately predict the improvement of the on-board charger AC conducted emission caused by the adjustment, providing an effective solution for the rectification of electric vehicle on-board chargers and even the charging conducted emission of electric vehicles.

[0050] In a specific embodiment, when the price comparison result exceeds the peak limit of the test standard, the Y capacitor or common-mode inductor in the EMI filter circuit is adjusted, and an adjusted on-board charger AC conducted emission field-circuit co-simulation model is obtained based on the adjusted EMI filter circuit. Simulation calculations are performed based on the adjusted on-board charger AC conducted emission field-circuit co-simulation model to obtain adjusted simulation calculation results. When the price comparison result does not exceed the peak limit of the test standard, the on-board charger AC conducted emission field-circuit co-simulation model is output as the on-board charger AC conducted emission scheme. This simplifies the workload of the on-board charger design for electric vehicles. The AC conducted electromagnetic compatibility performance of the on-board charger of an electric vehicle can be fully and accurately predicted using only the design circuit diagram, PCB layout files, and the device specifications of the common-mode inductor. During the rectification process, the device values ​​in the adjusted simulation circuit are highly consistent with the actual adjusted device values, which can greatly reduce the difficulty of rectification and significantly reduce the human and material costs of rectification.

[0051] like Figure 3 As shown, an embodiment of the present invention further provides a simulation analysis system for AC conducted emissions of an on-board charger, which is used to implement the simulation analysis method for AC conducted emissions of an on-board charger, including:

[0052] The model building module is used to determine the inductance, resistance, and parasitic capacitance of the common-mode inductor using a pre-established three-dimensional finite element model of the common-mode inductor, and obtain an inductor equivalent circuit model based on the determined inductance, resistance, and parasitic capacitance of the common-mode inductor; generate a three-dimensional finite element model based on PCB design data; and generate a capacitor equivalent circuit model based on capacitor specification data.

[0053] The model association module is used to associate the inductor equivalent circuit model, the three-dimensional finite element model and the capacitor equivalent circuit model to obtain a field-circuit collaborative simulation circuit model of the EMI filter circuit; and associate the field-circuit collaborative simulation circuit model of the EMI filter circuit with the pre-established PFC circuit model, LLC circuit model, AC mains model, and LISN circuit model to form an AC conducted emission field-circuit collaborative simulation model of the on-board charger.

[0054] A simulation calculation module is used to perform simulation calculations based on the on-board charger AC conduction emission field-circuit collaborative simulation model to obtain simulation calculation results; compare the simulation calculation results with the peak limits of the test standard to generate a comparison result; and output the on-board charger AC conduction emission field-circuit collaborative simulation model as an on-board charger AC conduction emission scheme based on the comparison result; or adjust the on-board charger AC conduction emission field-circuit collaborative simulation model and perform simulation calculations until the adjusted simulation calculation results do not exceed the peak limits of the test standard, and output the adjusted on-board charger AC conduction emission field-circuit collaborative simulation model as the on-board charger AC conduction emission scheme.

[0055] A model preprocessing module is used to obtain common-mode inductor specification data or physical data, determine the wire turn parameters and core size parameters based on the common-mode inductor specification data or physical data; establish a three-dimensional finite element model of the common-mode inductor based on the wire turn parameters and core size parameters; and also to obtain switching device data in the on-board charger, and establish a PFC circuit model and an LLC circuit model through the nonlinear model of the switching device; obtain LISN circuit data of the on-board charger, and establish a LISN circuit model based on the LISN circuit data; obtain mains power data connected to the on-board charger, and establish an AC mains power model based on the mains power data; and to obtain PCB design data, export the design data through the corresponding export interface, and simplify it based on calculation time parameters, complexity parameters, and result accuracy parameters to obtain a three-dimensional finite element model; obtain capacitor device specification data; convert the capacitance value, parasitic inductance, parasitic resistance value, and parasitic capacitance value determined based on the capacitor device specification data into corresponding equivalent devices; and associate all equivalent devices to form a capacitor equivalent circuit model.

[0056] The specific implementation process of the simulation analysis system for the AC conducted emission of the on-board charger can refer to the specific process of the simulation analysis method for the AC conducted emission of the on-board charger described above, which will not be repeated here.

[0057] In summary, the implementation of the embodiments of the present invention has the following beneficial effects:

[0058] The simulation and analysis method and system for AC conducted emissions from on-board chargers provided by this invention employs a detailed three-dimensional model of the common-mode inductor, incorporating a three-dimensional model of the PCB board and a capacitor equivalent circuit model to form a complete simulation model of the EMI filter circuit. This model not only ensures that the conducted noise suppression trends in the corresponding frequency bands are consistent with those measured, but also closely matches the magnitude.

[0059] Active circuit components such as PFC and LLC were incorporated into the simulation process, allowing for the simulation of the switching noise generated by the active switching circuit, a crucial component of the on-board charger's AC conducted emission noise. This enabled simulation and prediction of the on-board charger's AC conducted emission noise level across the entire frequency range of 150kHz-108MHz, rather than simply predicting the trend of the on-board charger's AC conducted emission noise in the high-frequency band (1MHz-108MHz) through EMI filter circuit simulation.

[0060] The above disclosure is merely a preferred embodiment of the present invention and 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. A simulation analysis method for AC conducted emission of an on-board charger, characterized in that: The following steps are involved: Step S1: determining the inductance, resistance, and parasitic capacitance of the common-mode inductor using a pre-established three-dimensional finite element model of the common-mode inductor, and generating an inductor equivalent circuit model based on the determined inductance, resistance, and parasitic capacitance of the common-mode inductor; generating a three-dimensional finite element model based on PCB design data; and generating a capacitor equivalent circuit model based on capacitor specification data. Step S2, associating the inductor equivalent circuit model, the three-dimensional finite element model generated according to the PCB design data, and the capacitor equivalent circuit model to obtain a field-circuit collaborative simulation circuit model of the EMI filter circuit; Step S3, associating the field-circuit collaborative simulation circuit model of the EMI filter circuit with the pre-established PFC circuit model, LLC circuit model, AC mains model, and LISN circuit model to form an AC conducted emission field-circuit collaborative simulation model of the on-board charger; Step S4, performing simulation calculations based on the on-board charger AC conduction emission field-circuit collaborative simulation model to obtain simulation calculation results; comparing the simulation calculation results with the peak limit of the test standard to generate a comparison result; Step S5: When the comparison result shows that the peak value does not exceed the test standard, the on-board charger AC conduction emission field-circuit collaborative simulation model is output as the on-board charger AC conduction emission solution. Alternatively, when the comparison result shows that the peak value exceeds the test standard, the on-board charger AC conduction emission field-circuit collaborative simulation model is adjusted and simulation calculations are performed until the adjusted simulation calculation result does not exceed the test standard peak value limit, and the adjusted on-board charger AC conduction emission field-circuit collaborative simulation model is output as the on-board charger AC conduction emission solution.

2. The method according to claim 1, wherein In step S1, the specific process of pre-establishing the three-dimensional finite element model of the common mode inductor is: Obtain specification data or physical data of the common-mode inductor, determine the number of wire turns parameters and the size parameters of the magnetic core based on the specification data or physical data of the common-mode inductor; and establish a three-dimensional finite element model of the common-mode inductor based on the number of wire turns parameters and the size parameters of the magnetic core.

3. The method according to claim 2, wherein In step S1, generating a three-dimensional finite element model specifically includes: Obtain the design data of the PCB board, export the design data through the corresponding export interface, and simplify it according to the calculation time parameters, complexity parameters, and result accuracy parameters to obtain a three-dimensional finite element model.

4. The method according to claim 3, wherein In step S1, generating a capacitor equivalent circuit model specifically includes: Obtain device specification data of the capacitor; convert the capacitance value, parasitic inductance, parasitic resistance value, and parasitic capacitance value determined according to the device specification data of the capacitor into corresponding equivalent devices; and associate all equivalent devices to form a capacitor equivalent circuit model.

5. The method according to claim 4, wherein In step S3, the specific process of pre-establishing the PFC circuit model, LLC circuit model, AC mains model, and LISN circuit model is as follows: Obtain the switching device data in the on-board charger and establish the PFC circuit model and LLC circuit model through the nonlinear model of the switching device; Obtaining LISN circuit data of the on-board charger and establishing a LISN circuit model based on the LISN circuit data; Obtain the mains data connected to the on-board charger and establish an AC mains model based on the mains data.

6. The method according to claim 5, wherein In step S4, generating the comparison result specifically includes: By querying the international standards for testing the electromagnetic compatibility performance of on-board chargers, the peak limit of conducted emissions for equipment-level testing was obtained and used as the peak limit of the test standard; Comparing the simulation calculation result with the peak value limit of the test standard, when the simulation calculation result exceeds the peak value limit of the test standard, generating a comparison result as exceeding the peak value limit of the test standard; The simulation calculation result is compared with the peak value limit of the test standard. When the simulation calculation result is lower than the peak value limit of the test standard, a comparison result is generated as not exceeding the peak value limit of the test standard.

7. The method according to claim 6, wherein The step S5 comprises: When the comparison result exceeds the peak limit of the test standard, the Y capacitor or common-mode inductor in the EMI filter circuit is adjusted, and an adjusted on-board charger AC conduction emission field-circuit collaborative simulation model is obtained based on the adjusted EMI filter circuit. Simulation calculation is performed based on the adjusted on-board charger AC conduction emission field-circuit collaborative simulation model to obtain adjusted simulation calculation results.

8. The method according to claim 6, wherein The step S5 further includes: When the comparison result shows that the peak value of the test standard is not exceeded, the on-board charger AC conducted emission field-circuit collaborative simulation model is output as the on-board charger AC conducted emission solution.

9. A simulation and analysis system for AC conducted emission of an on-board charger, used to implement the method according to any one of claims 1 to 8, characterized in that: include: A model building module is used to determine the inductance, resistance, and parasitic capacitance of the common-mode inductor using a pre-established three-dimensional finite element model of the common-mode inductor, and obtain an inductor equivalent circuit model based on the determined inductance, resistance, and parasitic capacitance of the common-mode inductor; generate a three-dimensional finite element model based on PCB design data; and generate a capacitor equivalent circuit model based on capacitor specification data; A model association module is used to associate the inductor equivalent circuit model, the three-dimensional finite element model generated based on the PCB design data, and the capacitor equivalent circuit model to obtain a field-circuit collaborative simulation circuit model of the EMI filter circuit; and the field-circuit collaborative simulation circuit model of the EMI filter circuit is associated with the pre-established PFC circuit model, LLC circuit model, AC mains model, and LISN circuit model to form an AC conducted emission field-circuit collaborative simulation model of the on-board charger; A simulation calculation module is configured to perform simulation calculations based on the on-board charger AC conduction emission field-circuit collaborative simulation model to obtain simulation calculation results; compare the simulation calculation results with the peak limit of the test standard to generate a comparison result; and when the comparison result shows that the peak limit of the test standard is within the limit, output the on-board charger AC conduction emission field-circuit collaborative simulation model as the on-board charger AC conduction emission scheme; or when the comparison result shows that the peak limit of the test standard is beyond the limit, adjust the on-board charger AC conduction emission field-circuit collaborative simulation model and perform simulation calculations until the adjusted simulation calculation results do not exceed the peak limit of the test standard, and output the adjusted on-board charger AC conduction emission field-circuit collaborative simulation model as the on-board charger AC conduction emission scheme.

10. The system according to claim 9, wherein: Also includes: A model preprocessing module is used to obtain common-mode inductor specification data or physical data, and determine the number of wire turns parameters and the size parameters of the magnetic core based on the common-mode inductor specification data or physical data; A three-dimensional finite element model of the common-mode inductor is established based on the parameters of the number of turns of the wire and the size parameters of the magnetic core; It is also used to obtain the switching device data in the on-board charger and establish the PFC circuit model and LLC circuit model through the nonlinear model of the switching device; obtain the LISN circuit data of the on-board charger and establish the LISN circuit model based on the LISN circuit data; obtain the mains data connected to the on-board charger and establish the AC mains model based on the mains data; And it is used to obtain design data of the PCB board, export the design data through the corresponding export interface, and simplify it according to the calculation time parameter, complexity parameter and result accuracy parameter to obtain a three-dimensional finite element model; obtain the device specification data of the capacitor; convert the capacitance value, parasitic inductance and parasitic resistance value and parasitic capacitance value determined according to the device specification data of the capacitor into corresponding equivalent devices; and associate all equivalent devices to form a capacitor equivalent circuit model.

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