Modeling and suppression method of common-mode interference of electric vehicle multi-in-one drive module

Abstract

The application discloses a modeling and suppression method for common mode interference of a multi-in-one drive module of an electric vehicle. According to different component characteristics on a conducted electromagnetic interference coupling path of the multi-in-one drive module of the electric vehicle, a specific modeling method is adopted to establish a wideband common mode equivalent circuit model, and on the basis, a complete common mode interference simulation circuit model of the multi-in-one drive module of the electric vehicle is established according to a conducted electromagnetic interference mechanism. The common mode resonance loop and mechanism are analyzed by relying on the equivalent circuit model, and a suppression method based on electromagnetic compatibility quantitative design is proposed. The application can accelerate the simulation analysis speed of the conducted electromagnetic interference, thereby quickly evaluating the conducted electromagnetic interference level of the multi-in-one drive module of the electric vehicle, and through simulation analysis on the change rule of the system conducted electromagnetic interference level under different circuit parameters, a basis is provided for positive design of electromagnetic compatibility of the multi-in-one drive module of the electric vehicle.

Description

Technical Field

[0001] The present invention belongs to the technical field of electromagnetic interference simulation and suppression, and specifically relates to a modeling and suppression method for common-mode interference of an all-in-one drive module of an electric vehicle. Background Art

[0002] All-in-one (ALL-IN-ONE) drive modules for electric vehicles are widely used in new energy vehicles. Initially, the electromagnetic compatibility (EMC) design of automotive electric drive systems was relatively simple. However, to improve efficiency while reducing production costs and system size, automakers have begun introducing all-in-one (ALL-IN-ONE) modules that integrate inverter, control, and charging functions. This has led to increasingly severe common-mode electromagnetic interference (EMI) issues within the system, particularly due to common-mode current resonance, which can cause current method testing and monopole antenna radiation tests to exceed standards. Therefore, it is crucial to construct an accurate common-mode interference model for all-in-one drive modules and study the mechanism of common-mode current resonance. Furthermore, to suppress common-mode current EMI resonance, quantitative EMC design of all-in-one drive modules is necessary.

[0003] There are two common approaches for modeling and simulating the common-mode electromagnetic interference (CMEMI) of all-in-one drive modules: frequency domain and time domain. The frequency domain method, after the interference source spectrum is known or calculated, establishes an impedance-frequency model of the CMEMI coupling path and performs a sweep-frequency simulation directly in the frequency domain. This method can quickly determine the CMEMI spectrum characteristics of the system. However, accurate frequency domain modeling requires a clear understanding of the conducted interference source and the interference loop. The time domain method, based on a high-frequency equivalent circuit model of each component in the conducted CMEMI loop of the all-in-one drive module, uses circuit simulation to obtain the time-domain waveforms of voltage and current at key nodes. These waveforms are then converted into a spectrum using a fast Fourier transform. This method is relatively straightforward, but establishing component circuit models is complex and difficult, and can result in slow simulation speeds or even non-convergence issues. The challenges of high-frequency modeling and interference suppression in all-in-one drive module systems lie in accurately extracting the DC busbar stray inductance in the three-phase inverter, high-frequency modeling of multi-port busbar capacitance, and resonance suppression based on quantitative electromagnetic compatibility design.

[0004] Regarding the modeling and simulation methods for conducted electromagnetic interference (EMI) in drive modules, Zhou Zuojian et al. from Huazhong University of Science and Technology proposed a simplified calculation model and suppression method for conducted EMI in traditional inverter systems in the paper "Research on Modeling and Suppression Technology of Conducted EMI in Inverter Power Systems [D]. Huazhong University of Science and Technology, 2019." However, this paper did not consider the high-frequency model of the passive component capacitance within the all-in-one module, nor did it explain the extraction method for the high-frequency parameters of each component. Niu Jianfeng et al. from Zhejiang University proposed a method for extracting DC busbar stray parameters based on SiC devices in the paper "Analysis and Design of Laminated Busbars for ANPC Converters Based on High-Voltage SiC MOSFET Modules [D]. Zhejiang University, 2023. DOI: 10.27461 / d.cnki.gzjdx.2023.000207." However, this paper did not consider the influence of high-frequency parameters in the test circuit. Summary of the Invention

[0005] In view of the above, the present invention provides a modeling and suppression method for common-mode interference of an electric vehicle's all-in-one drive module, which can accelerate the simulation and analysis speed of conducted electromagnetic interference, thereby quickly evaluating the conducted electromagnetic interference level of the electric vehicle's all-in-one drive module. By simulating and analyzing the changing pattern of the system's conducted electromagnetic interference level under different circuit parameters, a basis is provided for the forward design of electromagnetic compatibility of the electric vehicle's all-in-one drive module.

[0006] A method for modeling and suppressing common-mode interference of an electric vehicle all-in-one drive module, wherein the electric vehicle all-in-one drive module is composed of a DC power supply, an artificial power network, a DC cable, an electromagnetic interference filter, a fast charging cable, a multi-port bus capacitor, an inverter, a DC busbar, and a motor connected in sequence, and the modeling and suppression method includes the following steps:

[0007] (1) Establish an electromagnetic interference source model for common-mode interference of the drive module;

[0008] (2) Establish a high-frequency circuit model of the cable that drives the common-mode interference of the module;

[0009] (3) Establish a filter for common-mode interference of the drive module and a high-frequency equivalent circuit model of the motor;

[0010] (4) Establish a high-frequency impedance model of the DC busbar for common-mode interference of the drive module;

[0011] (5) Establish a multi-port busbar capacitor high-frequency circuit model for common-mode interference of the driving module;

[0012] (6) Connecting the models established in the above steps to obtain a full-circuit simulation model of the common-mode interference of the electric vehicle all-in-one drive module, adding voltage and current measurement devices to the DC and AC side ports of the inverter, and analyzing the resonant path and mechanism of the full-circuit simulation model;

[0013] (7) Based on the analysis results of step (6), the common mode interference of the electric vehicle all-in-one drive module is suppressed through electromagnetic compatibility quantitative design.

[0014] Furthermore, the specific implementation method of step (1) is as follows: first, the voltage change rate and current change rate generated by the switching action of the IGBT module in the inverter are used as interference sources, and the waveform characteristics under different output voltage and current conditions are extracted; then, the model dynamic parameters of the IGBT module are extracted according to the turn-on and turn-off characteristic parameters in the device data manual, and the device parameterized feature modeling tool is used to interpolate and fit the output change waveform of the IGBT module under different voltages and currents to obtain the model static parameters of the IGBT module, thereby generating an IGBT module device-level behavior model that can be imported into a circuit simulation platform, and finally, combining it with the SVPWM modulation adopted by the drive module to obtain the electromagnetic interference source model of the drive module.

[0015] Furthermore, the specific implementation method of step (2) is as follows: first, a three-dimensional structural dimension model of the cable is established in the three-dimensional mechanical design software, and the model is imported into the high-frequency parasitic parameter simulation software; then, a finite element sweep frequency simulation analysis is performed in a wide frequency band to obtain a high-frequency circuit model of the structural component within the frequency range of the conducted electromagnetic interference, wherein the sweep frequency range is 150kHz to 30MHz, covering the entire common-mode conducted electromagnetic interference frequency range, and the sweep frequency step is 10kHz, ensuring that high-frequency parasitic parameter data at sufficient frequency points are used for model fitting; and then, high-frequency parasitic parameters that can reflect the high-frequency characteristics of the cable are extracted through finite element sweep frequency simulation, thereby obtaining a high-frequency circuit model of the cable per unit length; finally, a high-frequency circuit model of the actual length of the cable is established by cascading multiple high-frequency circuit models of cables per unit length.

[0016] Furthermore, the specific implementation method of step (3) is as follows: first, an impedance analyzer is used to test the common-mode and differential-mode impedance frequency characteristic curves of the electromagnetic interference filter and the motor, and then a vector matching method is used in combination with an equivalent circuit of a network function to convert the partial fractions in the approximate rational function expression Z(s) of the impedance frequency characteristic curve into circuit models for series connection, and a high-frequency equivalent circuit model of the electromagnetic interference filter and the motor is constructed according to the number and type of resonant points in the impedance frequency characteristic curve;

[0017]

[0018] Among them: the extreme point p n The number N is greater than or equal to the number of resonant points in the impedance frequency characteristic curve. The constant term d and the first-order term h correspond to the equivalent circuits of resistors in series and inductors in series, respectively. The residue r n is a real number or a conjugate complex number, and s is the Laplace operator.

[0019] Furthermore, the specific implementation of step (4) is as follows: first, a dual-pulse test platform is built, and the oscillation frequency information in the on-off current waveform of the IGBT module in the platform is used as the resonant frequency f0 of the DC busbar high-frequency impedance model, and then the stray inductance of the DC busbar is calculated and extracted. Specifically:

[0020] The double pulse test platform is composed of the stray inductance L of the DC busbar. busbar , DC support capacitor C, resonant circuit resistance R S , power device module inductor L S And two IGBT modules T1 and T2 with anti-parallel diodes are connected in series, and an equivalent capacitor C is connected in parallel at both ends of T1. j , T2 has an air-core inductor L in parallel at both ends, and the DC support capacitor C is an RLC series high-frequency equivalent circuit, which consists of the equivalent inductor L C , equivalent capacitance C C , equivalent resistance R C The air-core inductor L is composed of an RLC parallel high-frequency equivalent circuit, which consists of an equivalent resistor R L , equivalent inductance L L , equivalent capacitance C L There is a lead inductance L between the positive electrode of the air-core inductor L and the collector of T2. lead , the collector of T1 and the negative electrode of the air-core inductor L are provided with current measurement ports for testing the current spectrum; the DC bus high-frequency impedance model is composed of a step voltage source V step , the total distributed resistance R of the test circuit sum , additional distributed inductance L sum , additional distributed capacitance C sum , the equivalent capacitance C of the air-core inductor L And the stray inductance L of the DC busbar busbar Finally, the measured f0, C L and L sum Substitute the following expression into the calculated DC busbar stray inductance L busbar ;

[0021]

[0022] Among them: additional distributed inductance L sum It is the parasitic inductance of DC support capacitor, air-core inductor lead and IGBT module.

[0023] Furthermore, the specific implementation method of step (5) is as follows: first, a three-dimensional structural dimension model of the copper busbar of the multi-port busbar capacitor is established in the three-dimensional mechanical design software, and the model is imported into the high-frequency parasitic parameter simulation software, and the conductor and the insulator are given corresponding electrical properties. Then, a finite element simulation analysis is performed within a wide frequency band to obtain a high-frequency circuit model of the copper busbar; then, a genetic algorithm is used to fit the input end impedance test results to obtain a high-frequency equivalent model of the embedded capacitor; finally, the high-frequency circuit model of the multi-port busbar capacitor is obtained by connecting the high-frequency circuit model of the copper busbar in parallel with the high-frequency equivalent model of the embedded capacitor.

[0024] Furthermore, in step (6), after measuring the voltage and current time domain waveforms, the voltage and current time domain waveforms are converted into frequency spectra by fast Fourier transform, so as to realize rapid simulation analysis of the common mode interference of the driving module; then, in view of the influence of circuit parameters on the common mode interference level of the system, by doubling the step size in the full circuit simulation model or changing the model parameter value according to the actual optional parameter value, a variable parameter simulation analysis is performed to obtain the simulation results of the system conducted electromagnetic common mode interference level under different model parameters, summarize the change rules, and provide a basis for the electromagnetic compatibility forward design of the electric vehicle all-in-one driving module; finally, the full circuit simulation model is simplified, and the electrical parameters in the simplified circuit are subjected to sensitivity analysis to judge the main electrical parameters affecting the resonant frequency, determine the resonant path, and obtain the common mode interference resonance mechanism based on the resonant path.

[0025] Furthermore, in step (7), a filter is designed for the system based on the insertion loss principle, that is, the electromagnetic interference insertion loss expression is obtained according to the common-mode interference resonance mechanism, and the topology and parameter selection of the filter are determined according to the minimum limit requirement of the insertion loss, and then a filter is added at the connection between the fast charging cable and the multi-port bus capacitor to suppress the electromagnetic interference resonance of the system.

[0026] Based on the above technical solution, the present invention has the following beneficial technical effects and values:

[0027] 1. This paper systematically proposes a common-mode interference modeling and suppression method for an all-in-one drive module for electric vehicles. Based on the characteristics of different components in the conducted electromagnetic interference coupling path of the all-in-one drive module for electric vehicles, a specific modeling method is used to establish broadband common-mode equivalent circuit models. To address the difficulties and large errors in extracting DC busbar stray inductance using existing methods, this paper proposes a current oscillation frequency method to calculate stray inductance.

[0028] 2. In order to solve the problem of inconsistent impedance of each port of the multi-port bus capacitor of the all-in-one module, the present invention constructs a high-frequency model of the multi-port bus capacitor that conforms to the actual physical structure. On this basis, according to the mechanism of conducted electromagnetic interference, a common-mode interference simulation circuit model of the all-in-one drive module of electric vehicles suitable for the frequency range of 150kHz to 30MHz is established, and the simulation error in the key frequency band is less than 6dB; the present invention relies on the equivalent simulation circuit model to analyze the common-mode resonant circuit and mechanism, and proposes a suppression method based on electromagnetic compatibility quantitative design. The provided suppression method has a margin of more than 6dB.

[0029] 3. The present invention provides an accurate method for obtaining stray parameters. By selecting specific voltage and current simulation initial values ​​for key nodes of the simulation circuit, the simulation analysis speed of conducted electromagnetic interference is accelerated by 60%, thereby quickly evaluating the common-mode electromagnetic interference level of the electric vehicle's all-in-one drive module. By simulating and analyzing the changing pattern of the system's conducted electromagnetic interference level under different circuit parameters, a basis for the forward design of electromagnetic compatibility of the electric vehicle's all-in-one drive module is provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 Schematic diagram of the process of modeling and suppressing common-mode interference of an all-in-one drive module of an electric vehicle according to the present invention.

[0031] Figure 2 Schematic diagram of the cable model for the all-in-one drive module of an electric vehicle.

[0032] Figure 3 (a) is a schematic diagram comparing the measured and fitted results of the common-mode impedance amplitude-frequency characteristic curve of the electromagnetic interference filter.

[0033] Figure 3 (b) is a schematic diagram comparing the measured and fitted results of the differential mode impedance amplitude-frequency characteristic curve of the electromagnetic interference filter.

[0034] Figure 3 (c) is a schematic diagram comparing the measured and fitted results of the common-mode impedance amplitude-frequency characteristic curve of the motor.

[0035] Figure 3 (d) is a schematic diagram comparing the measured and fitted results of the differential mode impedance amplitude-frequency characteristic curve of the motor.

[0036] Figure 4 This is a structural diagram of the DC busbar stray inductance extraction platform and the DC busbar high-frequency impedance model.

[0037] Figure 5 (a) and Figure 5 (b) Schematic diagrams of impedance fitting at the input and output ends of the multi-port bus capacitor.

[0038] Figure 6This is a schematic diagram of the example structure of an all-in-one drive module for electric vehicles.

[0039] Figure 7 Schematic diagram of the full circuit simulation model for common-mode interference of an electric vehicle's all-in-one drive module.

[0040] Figure 8 This is a schematic diagram comparing the common-mode current simulation results and measured results of the electric vehicle all-in-one drive module.

[0041] Figure 9 Schematic diagram comparing the simulated and measured common-mode current results after adding a quantitatively designed Y capacitor to the all-in-one electric vehicle drive module. DETAILED DESCRIPTION

[0042] In order to describe the present invention more specifically, the technical solution of the present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0043] like Figure 1 As shown, the modeling and suppression method of the common-mode interference of the electric vehicle all-in-one drive module of the present invention includes the following specific steps:

[0044] (1) Establish an electromagnetic interference source model for common-mode interference of electric vehicle all-in-one drive modules. The dv / dt and di / dt generated by the switching action of the IGBT module in the inverter of the electric vehicle all-in-one drive module are used as interference sources. Using the device parameter feature modeling tool, according to the relevant device parameter information in the device data sheet, the output waveform of the IGBT module under different voltages and currents is interpolated and fitted to generate an IGBT module device-level behavior model that can be imported into the circuit simulation platform.

[0045] In this example, the electric vehicle all-in-one drive module uses a CRRC TG650FF0852-S5A02 three-phase full-bridge IGBT module as the power switching device. The test obtains the IGBT turn-off and turn-on voltage waveforms at a rated voltage of 400V and an operating power of 20kW. The transfer characteristic curve, output characteristic curve, and freewheeling diode forward characteristic curve from the data sheet are used to extract the static parameters of the IGBT module device-level behavioral model. The turn-on and turn-off time, turn-on and turn-off energy, reverse recovery charge, and reverse recovery current peak from the data sheet are used to extract the dynamic parameters of the IGBT module device-level behavioral model. Finally, a device-level behavioral model of the IGBT module is generated that can be imported into circuit simulation software. Combined with the SVPWM modulation used by the electric vehicle all-in-one drive module, an electromagnetic interference source model of the electric vehicle all-in-one drive module is obtained.

[0046] (2) Establish a high-frequency circuit model of the DC cable and fast-charging cable for the common-mode electromagnetic interference path of the electric vehicle's all-in-one drive module. A three-dimensional model of the power supply cable per unit length is established in the high-frequency parasitic parameter simulation software. Finite element simulation analysis is performed to obtain a high-frequency circuit model of the power supply cable per unit length. By cascading multiple high-frequency circuit models of power supply cables per unit length, a high-frequency circuit model of the actual length of the power supply cable is established.

[0047] This example takes the DC power supply cable as an example and establishes a 0.5m long unit length cable model in Ansys Q3D Extractor high-frequency parasitic parameter simulation software. Figure 2 As shown, by performing finite element sweep simulation analysis in a wide frequency band, a high-frequency circuit model of the structural parts within the frequency range of conducted electromagnetic interference is obtained, wherein the sweep range is 150kHz~30MHz, covering the entire common-mode conducted electromagnetic interference frequency range, and the sweep step is 10kHz, ensuring that the high-frequency parasitic parameter data at sufficient frequency points are used for model fitting, thereby obtaining a high-frequency model of the DC cable and fast charging cable so that the extracted high-frequency parasitic parameters can reflect the high-frequency characteristics of the cable, and performing finite element sweep simulation to extract the high-frequency parasitic parameters to obtain a high-frequency circuit model of the power supply cable per unit length, and by cascading multiple high-frequency circuit models of power supply cables per unit length, a high-frequency circuit model of the actual length of the power supply cable is established.

[0048] (3) Establish the electromagnetic interference filter and motor high-frequency impedance model of the electric vehicle all-in-one module conduction electromagnetic interference path. Use an impedance analyzer to test the common mode and differential mode impedance frequency characteristic curves of the electromagnetic interference filter and motor, such as Figure 3 (a)~ Figure 3 As shown in (d), the vector matching method is then combined with the equivalent circuit of the network function to construct a high-frequency impedance circuit model of the motor according to the number and type of resonant points in the impedance-frequency characteristic curve. The approximate rational function expression of the impedance-frequency characteristic curve obtained by the vector matching method is as follows:

[0049]

[0050] Among them: the extreme point p n The number N should be greater than or equal to the number of resonant points in the impedance frequency characteristic curve.

[0051] At the same time, combined with the equivalent circuit of the network function, the partial fractions of the rational function expression are equivalent to the circuit model and connected in series to obtain the equivalent circuit model that can reflect the impedance frequency characteristic curve. Specifically: the constant term d and the first-order term h correspond to the equivalent circuit of the resistor and inductor in series, where the resistor and inductor are d and h respectively, and the residue r n and the extreme point p n are all real numbers or complex conjugate numbers.

[0052] (4) Establish a high-frequency circuit model for the DC busbar of an all-in-one electric drive system for electric vehicles. Build a dual-pulse test platform and use the oscillation frequency information in the IGBT module's on-off current waveform to obtain the resonant frequency of the equivalent circuit model. Then, calculate the stray inductance of the DC busbar and extract the stray parameters of the DC busbar.

[0053] like Figure 4 As shown in the figure, the present invention proposes to use the current oscillation triggered by the switching process during the double pulse test to extract the busbar stray parameters based on the current spectrum characteristics. The figure shows the application of the DC busbar under test mainly composed of inductors. When performing frequency domain analysis, the busbar capacitor and air-core inductor cannot be regarded as ideal voltage and current sources as in time domain analysis. The busbar capacitor can be regarded as an RLC series high-frequency equivalent circuit, R C is the equivalent series resistance, L C is the equivalent series inductance, C C As an equivalent series capacitor, the air-core inductor can be regarded as an RLC parallel high-frequency equivalent circuit, R L is the equivalent parallel resistance, L L is the equivalent parallel inductance, C L is the equivalent parallel capacitance. In addition, other high-frequency parasitic parameters need to be considered, such as L S is the power device module inductance, R S is the resonant circuit resistance, L lead is the lead inductance of the air-core inductor, L busbar is the required busbar stray inductance, C j is the equivalent parallel capacitance.

[0054] The dual-pulse test platform consists of a DC link capacitor, a diode, and an IGBT module connected in series. An air-core inductor is connected in parallel across the diode. Current measurement ports are located at the collector of the IGBT module and the negative electrode of the air-core inductor to test the circuit spectrum. The DC link capacitor is represented by C, the diode by D, and the air-core inductor by L. The equivalent circuit model represents the turn-on and turn-off processes of the IGBT in the dual-pulse test platform for the IGBT module. It includes a series-connected step voltage source, the total distributed resistance of the test loop, the additional distributed inductance, the additional distributed capacitance, the equivalent parallel capacitance of the air-core inductor, and the stray inductance of the DC busbar. Figure 4 The medium step voltage source is represented by V step , the total distributed resistance of the test loop is expressed as R sum , the additional distributed inductance is represented by L sum , the additional distributed capacitance is expressed as C sum , the equivalent parallel capacitance of the air-core inductor is expressed as C L , the stray inductance of the DC busbar is expressed as L busbar , the resonant frequency of the equivalent circuit model is related as follows:

[0055]

[0056] Where: f0 is the current resonant frequency, L busbar is the stray inductance of the DC busbar, L sum is the parasitic inductance of the DC support capacitor, air-core inductor leads and IGBT module, C L is the equivalent parallel capacitance of the air-core inductor; the measured f0, C L and L sum By substituting this into the formula, the stray inductance of the DC busbar can be calculated.

[0057] (5) Establish a high-frequency impedance model for the multi-port busbar capacitor of the all-in-one module of electric vehicles. A three-dimensional structural dimension model of the copper busbar of the multi-port busbar capacitor is established in the three-dimensional mechanical design software and imported into the high-frequency parasitic parameter simulation software. After the design is completed, the three-dimensional structure is imported into the Ansys Q3D Extractor high-frequency parasitic parameter simulation software to assign corresponding electrical properties to the conductor and insulator, including relative dielectric constant, relative magnetic permeability, bulk conductivity and dielectric loss factor; then, the excitation source is set according to the current or power flow direction and the actual current contact surface of the port, and a sweep frequency setting is added. By performing finite element sweep frequency simulation analysis in a wide frequency band, the sweep frequency results within the frequency range of the conducted electromagnetic interference are obtained.

[0058] In the high-frequency parasitic parameter simulation software, a three-dimensional busbar model of the multi-port busbar capacitor is established, and a finite element simulation analysis is performed to obtain a high-frequency circuit model of the multi-port busbar capacitor busbar, ensuring that the high-frequency parasitic parameter data at sufficient frequency points are used for model fitting; at the same time, high-performance computing tools are enabled to enable all computing cores of the computer, and finite element sweep simulation parallel calculations are performed to extract high-frequency parasitic parameters, and obtain a high-frequency parasitic parameter model of the multi-port busbar capacitor busbar within the frequency range of conducted electromagnetic interference. The input impedance test results are fitted with a genetic algorithm to obtain a high-frequency equivalent model of the internal capacitor. During the impedance fitting process, the internal capacitor can be regarded as two RLC series structures with consistent high-frequency characteristics. The feasibility of the method is verified by comparing the actual output impedance test results with the model fitting results. Figure 5 (a) and Figure 5 As shown in (b); finally, by connecting the busbar high-frequency circuit of the multi-port bus capacitor in parallel with the embedded capacitor, the high-frequency circuit model of the actual multi-port bus capacitor can be obtained.

[0059] (6) Establish a complete full-circuit simulation model of the common-mode electromagnetic interference of the electric vehicle all-in-one drive module. According to the conducted electromagnetic interference mechanism of the electric vehicle all-in-one drive module, the models established in the above steps are connected to establish a full-circuit simulation model of the conducted electromagnetic interference of the electric vehicle all-in-one drive module, and a voltage and current measurement device is added to the DC input port of the electric vehicle all-in-one drive module.

[0060] The IGBT module drive signal of the simulation circuit at the switching frequency of the electric vehicle all-in-one drive module is extracted as the control signal for turning on and off the IGBT module in the inverter of the electric vehicle all-in-one drive module. In this example, the drive signal of the simulation circuit at the fast-off frequency of the electric vehicle all-in-one drive module is exported and imported into Ansys Simplorer with the help of AnsoftSFunction, the joint simulation interface between Ansys Simplorer and Simulink software, to control the turning on and off of the IGBT module.

[0061] This example targets Figure 6 The electric vehicle all-in-one drive module shown in the figure is used to establish a complete full-circuit simulation model of the common-mode electromagnetic interference of the drive module in the Ansys Simplorer simulation platform. Figure 7 As shown in Figure 1, the simulation model mainly consists of the following subcircuits: (1) power supply; (2) artificial power network (LISN); (3) cable; (4) all-in-one module; (5) motor; (6) drive waveform output. Voltage and current measurement devices are added to the DC input port of the all-in-one drive module. By setting the initial simulation values ​​of voltage and current at key circuit nodes, the transition process from transient to steady state is accelerated. The voltage and current time domain waveforms at the key ports are converted into frequency spectra with the help of fast Fourier transform, realizing the rapid simulation analysis of common-mode electromagnetic interference of the all-in-one drive module of electric vehicles.

[0062] This example sets the initial simulation values ​​for some key components based on the steady-state value of the switching frequency simulation circuit of the electric vehicle all-in-one drive module, so as to accelerate the electric vehicle all-in-one drive module conducted electromagnetic interference simulation system to enter a stable working state. The voltage simulation initial value of the multi-port bus capacitor at the DC input end is set to the DC power supply voltage value of 400V. According to the current working condition of the system, the power is 20kW, and the inverter DC input current simulation initial value I is 50A according to the formula P=U·I. By simulating the voltage and current waveforms of each port, the common mode current time domain waveform is converted into a spectrum with the help of fast Fourier transform, and compared with the measured results, as shown in the figure. Figure 8 As shown in the figure, it can be seen that the common-mode electromagnetic interference simulation model of the electric vehicle all-in-one drive module established in this example can better reflect the actual system conduction electromagnetic characteristics and is suitable for electromagnetic compatibility simulation analysis.

[0063] By changing the circuit parameter values ​​in the simulation circuit by doubling the step size or the actual optional parameter value, variable parameter simulation analysis is performed to obtain the simulation results of the system conducted electromagnetic interference level under different circuit parameters. The changing rules are summarized to provide a basis for the electromagnetic compatibility forward design of the electric vehicle all-in-one drive module.

[0064] (7) Complete the simulation of conducted electromagnetic interference of the electric vehicle all-in-one drive module on the circuit simulation platform, analyze the resonant path and mechanism of the common-mode interference of the electric vehicle all-in-one drive module, and simplify the full circuit model of the common-mode interference of the electric vehicle all-in-one drive module; perform sensitivity analysis on the electrical parameters in the simplified circuit, judge the main electrical parameters affecting the resonant frequency, and determine the resonant path; based on the resonant path, obtain the common-mode interference resonance mechanism.

[0065] (8) A quantitative electromagnetic compatibility design method for suppressing common-mode interference in electric vehicle all-in-one drive modules is presented. Based on the filter insertion loss principle, the filter is designed. Based on the common-mode interference resonance mechanism, the electromagnetic interference insertion loss formula is obtained. Based on the minimum insertion loss requirement, the topology and parameter selection of the suppression method are determined.

[0066] In this example, the electric vehicle all-in-one drive module adds Y capacitors at the connection between the fast charging cable and the multi-port bus capacitor to suppress common-mode conducted interference. In order to study the influence of the Y capacitor parameters on the common-mode conducted interference of the system, based on the full circuit simulation circuit model of the common-mode electromagnetic interference of the electric vehicle all-in-one drive module mentioned above, Y capacitors are added at the corresponding ports. Taking into account the influence of leakage current and based on the results of insertion loss calculation, the actual value of the Y capacitor is selected to be 4.7nF, and variable parameter simulation analysis is performed. Figure 9 As shown in the figure, the Y capacitor primarily affects the magnitude of common-mode conducted interference voltage in the mid- to high-frequency band of 10MHz to 30MHz. In theory, the larger the Y capacitor value, the more pronounced the suppression effect. However, in actual design, considering the leakage current, the Y capacitor value cannot exceed the capacitance value determined by the leakage current limit. In actual design, if other communication equipment or electrical equipment in the system has low electromagnetic interference immunity in this frequency band, the addition of a Y capacitor to the DC negative bus should be used with caution to avoid causing malfunctions in other equipment.

[0067] The above description of the embodiments is intended to facilitate understanding and application of the present invention by those skilled in the art. It will be apparent that those skilled in the art can readily make various modifications to the above embodiments and apply the general principles described herein to other embodiments without requiring inventive effort. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention should fall within the scope of protection of the present invention.

Claims

1. A method for modeling and suppressing common-mode interference of an all-in-one drive module for an electric vehicle, wherein the all-in-one drive module for an electric vehicle is composed of a DC power supply, an artificial power network, a DC cable, an electromagnetic interference filter, a fast-charging cable, a multi-port bus capacitor, an inverter, a DC busbar, and a motor connected in sequence. The method comprises the following steps: (1) Establish an electromagnetic interference source model for common-mode interference of the drive module; (2) Establish a high-frequency circuit model of the cable that drives the common-mode interference of the module; (3) Establish a filter for common-mode interference of the drive module and a high-frequency equivalent circuit model of the motor; (4) Establish a high-frequency impedance model of the DC busbar for common-mode interference of the drive module. First, build a dual-pulse test platform. Use the oscillation frequency information in the IGBT module turn-on and turn-off current waveform in the platform as the resonant frequency f0 of the DC busbar high-frequency impedance model. Then calculate and extract the stray inductance of the DC busbar. Specifically: The double pulse test platform is composed of the stray inductance L of the DC busbar. busbar , DC support capacitor C, resonant circuit resistance R S , power device module inductor L S And two IGBT modules T1 and T2 with anti-parallel diodes are connected in series, and an equivalent capacitor C is connected in parallel at both ends of T1. j , T2 has an air-core inductor L in parallel at both ends, and the DC support capacitor C is an RLC series high-frequency equivalent circuit, which consists of the equivalent inductor L C , equivalent capacitance C C , equivalent resistance R C The air-core inductor L is composed of an RLC parallel high-frequency equivalent circuit, which consists of an equivalent resistor R L , equivalent inductance L L , equivalent capacitance C L In parallel, there is a lead inductance L between the positive electrode of the air-core inductor L and the collector of T2. lead , the collector of T1 and the negative electrode of the air-core inductor L are provided with current measurement ports for testing the current spectrum; the DC bus high-frequency impedance model is composed of a step voltage source V step , the total distributed resistance R of the test circuit sum , additional distributed inductance L sum , additional distributed capacitance C sum , the equivalent capacitance C of the air-core inductor L And the stray inductance L of the DC busbar busbar Finally, the measured f0, C L and L sum Substitute the following expression into the calculated DC busbar stray inductance L busbar ; in: Additional distributed inductance L sum The parasitic inductance of DC support capacitors, air-core inductor leads and IGBT modules; (5) Establish a multi-port busbar capacitor high-frequency circuit model for common-mode interference of the driving module; (6) Connecting the models established in the above steps to obtain a full-circuit simulation model of the common-mode interference of the electric vehicle all-in-one drive module, adding voltage and current measurement devices to the DC and AC side ports of the inverter, and analyzing the resonant path and mechanism of the full-circuit simulation model; (7) Based on the analysis results of step (6), the common mode interference of the electric vehicle all-in-one drive module is suppressed through electromagnetic compatibility quantitative design.

2. The modeling and suppression method according to claim 1, characterized in that: The specific implementation method of step (1) is as follows: first, the voltage change rate and current change rate generated by the switching action of the IGBT module in the inverter are used as interference sources, and the waveform characteristics under different output voltage and current conditions are extracted; then, the model dynamic parameters of the IGBT module are extracted according to the turn-on and turn-off characteristic parameters in the device data manual, and the device parameterized feature modeling tool is used to interpolate and fit the output change waveform of the IGBT module under different voltages and currents to obtain the model static parameters of the IGBT module, thereby generating an IGBT module device-level behavior model that can be imported into a circuit simulation platform, and finally, combining it with the SVPWM modulation adopted by the drive module to obtain the electromagnetic interference source model of the drive module.

3. The modeling and suppression method according to claim 1, characterized in that: The specific implementation method of the step (2) is as follows: first, a three-dimensional structural dimension model of the cable is established in the three-dimensional mechanical design software, and the model is imported into the high-frequency parasitic parameter simulation software; then, a finite element frequency sweep simulation analysis is performed in a wide frequency band to obtain a high-frequency circuit model of the structural component within the frequency range of the conducted electromagnetic interference, wherein the frequency sweep range is 150kHz to 30MHz, covering the entire common-mode conducted electromagnetic interference frequency range, and the frequency sweep step is 10kHz, ensuring that high-frequency parasitic parameter data at sufficient frequency points are used for model fitting; and then, high-frequency parasitic parameters that can reflect the high-frequency characteristics of the cable are extracted through the finite element frequency sweep simulation, thereby obtaining a high-frequency circuit model of the cable per unit length; finally, a high-frequency circuit model of the actual length of the cable is established by cascading multiple high-frequency circuit models of cables per unit length.

4. The modeling and suppression method according to claim 1, characterized in that: The specific implementation method of step (3) is as follows: first, an impedance analyzer is used to test the common-mode and differential-mode impedance frequency characteristic curves of the electromagnetic interference filter and the motor, and then a vector matching method is used in combination with an equivalent circuit of a network function to convert the partial fractions in the approximate rational function expression Z(s) of the impedance frequency characteristic curve into circuit models for series connection, and a high-frequency equivalent circuit model of the electromagnetic interference filter and the motor is constructed according to the number and type of resonant points in the impedance frequency characteristic curve; Among them: the extreme point p n The number N is greater than or equal to the number of resonant points in the impedance frequency characteristic curve. The constant term d and the first-order term h correspond to the equivalent circuits of resistors in series and inductors in series, respectively. The residue r n is a real number or a conjugate complex number, and s is the Laplace operator.

5. The modeling and suppression method according to claim 1, characterized in that: The specific implementation method of step (5) is as follows: first, a three-dimensional structural dimension model of the copper busbar of the multi-port busbar capacitor is established in three-dimensional mechanical design software, and the model is imported into high-frequency parasitic parameter simulation software, and the conductor and the insulator are given corresponding electrical properties. Then, a finite element simulation analysis is performed within a wide frequency band to obtain a high-frequency circuit model of the copper busbar; then, a genetic algorithm is used to fit the input end impedance test results to obtain a high-frequency equivalent model of the embedded capacitor; finally, the high-frequency circuit model of the multi-port busbar capacitor is obtained by connecting the high-frequency circuit model of the copper busbar in parallel with the high-frequency equivalent model of the embedded capacitor.

6. The modeling and suppression method according to claim 1, characterized in that: In the step (6), after measuring and obtaining the voltage and current time domain waveforms, the voltage and current time domain waveforms are converted into frequency spectra by fast Fourier transform, so as to realize rapid simulation analysis of the common mode interference of the driving module; then, in view of the influence of circuit parameters on the common mode interference level of the system, variable parameter simulation analysis is performed by doubling the step size in the full circuit simulation model or changing the model parameter value according to the actual optional parameter value, so as to obtain the simulation results of the system conducted electromagnetic common mode interference level under different model parameters, summarize the change rules, and provide a basis for the electromagnetic compatibility forward design of the electric vehicle all-in-one driving module; finally, the full circuit simulation model is simplified, and the electrical parameters in the simplified circuit are subjected to sensitivity analysis to judge the main electrical parameters affecting the resonant frequency, determine the resonant path, and obtain the common mode interference resonance mechanism based on the resonant path.

7. The modeling and suppression method according to claim 1, characterized in that: In the step (7), a filter is designed for the system based on the insertion loss principle, that is, the electromagnetic interference insertion loss expression is obtained according to the common-mode interference resonance mechanism, and the topology and parameter selection of the filter are determined according to the minimum limit requirement of the insertion loss, and then a filter is added at the connection between the fast charging cable and the multi-port bus capacitor to suppress the electromagnetic interference resonance of the system.

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