Study On Electromagnetic Compatibility Modeling Methods For Electronic Components In Power Conversion Systems

Power conversion systems,due to the rapid switching of semiconductor switching devices,often give rise to significant electromagnetic interference.When conducting system electromagnetic interference analysis,it is essential to first establish the electromagnetic compatibility models of electronic components.The existing component models are mostly simulation models designed to achieve electrical functionality,failing to fully reflect the electromagnetic compatibility characteristics of the components.Therefore,this dissertation studies the method of establishing the electromagnetic compatibility model of electronic components in power conversion system.The aim is to create simulation models that not only achieve the functionalities of the components but also accurately reflect their electromagnetic compatibility characteristics,so as to simulate the functions and electromagnetic compatibility characteristics of power conversion system.Specifically,the main research contents are as follows:（1）Study on the method of establishing electromagnetic compatibility model of passive devices.As the rise time of switching devices decreases,the high-frequency components of electromagnetic interference signals increase,and passive devices exhibit characteristics with multiple resonance points within a wide frequency band.In this dissertation,the impedance characteristic curve of passive devices is first measured.Subsequently,high-frequency equivalent circuit topologies,suitable for capacitors,inductors,and resistors with both multi-resonance and single resonance frequencies,are proposed based on impedance characteristic analysis.Due to the increase in equivalent circuit components,the resulting optimized fitness function becomes more complex,leading to challenges in solving equivalent parameters.To fit the complicated impedance curve,the dissertation proposes an equivalent circuit parameter calculation method based on the least squares method and particle swarm optimization algorithm.This method exhibits strong solving capabilities and is not easy to fall into a local optimal solution.Finally,the accuracy of the models is verified through testing.（2）Study on the method of establishing electromagnetic compatibility model of semiconductor active devices.Semiconductor devices are usually important sources of electromagnetic interference because of their nonlinear input-output characteristics.This dissertation first studies the principles of existing modeling methods and proposes overall modeling methods for active devices;then,the electromagnetic compatibility characteristics of diodes,transistors,and MOSFETs are analyzed,and applicable circuit topologies and model parameter equations are proposed,respectively.In this process,a more comprehensive and accurate set of electromagnetic compatibility parameters is considered,and methods for parameter extraction and fitting are researched.Subsequently,the key parameters influencing the electromagnetic compatibility characteristics of various devices and their influence laws are analyzed.The global EMC joint simulation optimization of model parameters is conducted using the simplex method.Finally,the accuracy of the models is verified through testing.（3）Study on the method of establishing electromagnetic compatibility model of IC devices.Due to the complexity of the internal circuits of IC devices and the difficulty in obtaining their schematics,modeling them faces significant challenges.The dissertation first analyzes the principles and structures of SPICE models and IBIS models,and proposes a joint modeling method of SPICE model and IBIS model for IC devices,aiming to simultaneously achieve the electrical functionality and port electromagnetic compatibility characteristics of IC devices.Subsequently,for analog IC devices,a study on the method of establishing SPICE models based on parameter fitting is conducted,using the three-terminal voltage regulator as an example.For digital IC devices,a study on the method of establishing IBIS model based on behavioral characteristic data is conducted,using the ADC chip as an example.Finally,for complex IC devices,a study on the method of establishing SPICE models based on macro model construction is conducted,using the delay chip as an example.The tests show that the device models can accurately reflect the electromagnetic compatibility characteristics of the devices.（4）Modeling and analysis of electromagnetic compatibility characteristics in power conversion systems.The EMC models of the electronic components,established using the methods described in this dissertation,are applied to construct a simulation model of an actual power conversion system,and the electromagnetic compatibility characteristics of the system are analyzed.Firstly,the square wave electromagnetic interference characteristics of switching devices are analyzed,and the harmonic frequency spectrum law of switching actions is obtained.Then,a system-level modeling and simulation method from control signals to conducted and radiated interference is studied for a power conversion system-the inverter motor drive system.Finally,for a BLDC motor drive system,applying the component models established with the methods presented in this dissertation and combining the system-level modeling method,an electromagnetic compatibility simulation model for the drive system is established.The electromagnetic compatibility characteristics of the system are simulated,and testing validation is conducted,further confirming the accuracy of the component models.The main innovations of this dissertation are as follows:（1）Proposed an equivalent modeling method of passive components with multiple resonant frequencies.In response to the impedance characteristics of passive components with multiple resonance frequencies in a wide frequency band,this method proposes two high-frequency equivalent circuit topologies:one for capacitors and another for resistors（or inductors）,each suitable for multi-resonant frequency characteristics.The two topologies can reflect the impedance characteristics of multiple resonance frequencies by introducing multiple sets of parallel R-L-C branches.Considering the increase in topological circuit parameters,this dissertation proposes a method for calculating circuit parameters that combines the least squares method and the particle swarm optimization algorithm.The algorithm can globally optimize and is insensitive to initial values.The optimization evaluation parameter rs_lg,defined and proposed in this method,comprehensively considers errors at both maximum and minimum values.The impedance characteristic curves obtained through simulation and measurement are in good agreement.Compared to the vector fitting method,the model parameters in this method possess practical physical meanings,so this method can be advantageous for EMC optimization design of devices.（2）Proposed a bipolar junction transistor EMC modeling method based on physical characteristic measurement and simplex optimization.This modeling method proposes a parameter calculation approach for the BJT model based on the G-P model containing 40 model parameters,and suitable locally approximated physical equations.This calculation approach enables the BJT model to possess more accurate and more model parameters affecting EMC characteristics,and simplifies the parameter calculation process.This modeling method uses the simplex method to globally optimize all model parameters in EMC joint simulation,thereby reducing the approximation errors from local calculations in the preliminary model establishment phase,and enabling the final model to have higher electromagnetic compatibility simulation accuracy.（3）Proposed a MOSFET EMC modeling method based on the simplex method and particle swarm optimization.This modeling method proposes a MOSFET model parameter calculation approach based on Level 3 SPICE MOSFET model topology containing 24 model parameters and suitable physical equations.This calculation approach enables the MOSFET model to contain more accurate and more parameters affecting EMC characteristics,taking into account the electrical characteristics of the body diode and junction capacitance.To solve the more complex physical equations containing more model parameters in the calculation approach,a global optimization computation is conducted using the proposed curve-fitting method based on particle swarm optimization.This modeling method uses the simplex method to globally optimize all MOSFET model parameters in EMC joint simulation,thereby reducing the approximation errors from local calculations in the initial model establishment phase and enhancing the electromagnetic compatibility simulation accuracy of the final model.