| Due to full electricity,the electric drive system of hybrid vehicles has many advantages over the traditional mechanical drive device,such as stepless speed regulation,steering at any radius,impact vibration without mechanical transmission shift,high acceleration flexibility,flexible component arrangement,low module construction noise,low oil consumption,low infrared radiation intensity and the like,and can meet the requirements of armored vehicles such as power improvement,silent driving,high-power on-board information equipment,weapon power supply,infrared stealth and the like.However,with the continuous improvement of vehicle informatization and intelligence,the number of on-board electronic equipment is increasing,the degree of precision is getting higher and higher,and the functions of the equipment are becoming more and more complex,which puts forward higher requirements for the electromagnetic compatibility of the whole vehicle system.Compared with the traditional mechanical transmission device,the electric drive system adds high-power electronic and electrical equipment such as a high-voltage and high-current power battery system and a motor drive system.These high-power devices usually contain high-power switching devices and have high operating voltage levels.dv/dt generated by switching devices will cause serious electromagnetic interference in a wide frequency range,affecting other driving performance,driving safety control systems and the normal operation of mounted devices,such as acceleration limitation,etc.To a large extent,it has become a key factor restricting the development and application of electric drive systems.In this paper,the high-voltage electric drive system of a vehicle is taken as the research object,and the circuit simulation and numerical simulation methods are taken as the analysis means.Firstly,the electromagnetic interference generation mechanism of the high-voltage electric drive system of the electric vehicle is studied.From the simplification and establishment of the electromagnetic interference simulation model of the electric drive system to the analysis of the electromagnetic interference coupling path of the high-voltage electric drive system of the electric vehicle,finally,the corresponding electromagnetic interference suppression technology is studied according to the electromagnetic interference characteristics and coupling path of the electric drive system.The main research contents are as follows:(1)Analysis of the mechanism of electromagnetic interference in high voltage electric vehicle drive system.Starting from the working principle of the high-voltage electric drive system,various components in the system are simplified and the electromagnetic interference simulation model at the vehicle system level is established.The generation mechanism of electromagnetic interference is analyzed from the system perspective.Through the analysis,it is obtained that the rapid turn-on and turn-off of IGBT during the operation of the electric drive system causes the rapid rise and fall of the voltage difference between the bridge arm midpoint and the reference ground(vehicle shell),thus forming huge dv/ dt and di/ dt which are the main reasons for the generation of electromagnetic interference in the electric drive system,and the relationship between the power supply voltage magnitude,voltage change time and electromagnetic interference spectrum is explained.(2)Analysis of electromagnetic interference coupling approach of high voltage electric vehicle drive system.According to the electromagnetic interference simulation model of electric drive system,the coupling approach of electromagnetic interference is analyzed.Determine the main propagation path and interference magnitude of common mode electromagnetic interference,differential mode electromagnetic interference and radiated electromagnetic interference.It provides data basis for electromagnetic interference suppression technology.(3)Electromagnetic Interference Suppression Technology for High Voltage Electric Vehicle Drive System.The electromagnetic interference suppression measures are designed according to the electromagnetic interference coupling approach and interference magnitude.Common mode choke coil,multilevel modulation algorithm and random space vector modulation algorithm are studied respectively to suppress electromagnetic interference from propagation path and source.Contribution and innovation are as follows:(1)A method to establish a simulation model of electromagnetic interference driven by high voltage is proposed.This method is based on the normal working process of the high voltage drive system.The simulation models of circuits and components including high voltage power battery,LISN,inverter main circuit,motor and parasitic parameters are simplified and established.The simulation results show that the model can accurately describe the normal working process(mainly the description of IGBT on and off)and electromagnetic interference generation mechanism and propagation path of the high voltage drive system by building the inverter main circuit and actual working peripheral circuit.Other modeling methods are lumped parameter models.Or is a simple behavior model without considering the problems of voltage overshoot and the like in the working process.The modeling method adopts the combination of IGBT and peripheral circuit behavior model modeling and parasitic parameter lumped parameter modeling,and has the advantages that the electromagnetic interference change rule in the simulation simulation period is mainly reflected,high-precision simulation is completed,conductive interference and radiation interference rules are obtained through the simulation method,and the test cost is effectively reduced.(2)Effective electromagnetic interference suppression technology for electric drive systems with high voltage above 600 V at present.According to the timefrequency characteristics of electromagnetic interference,this paper puts forward a comprehensive electromagnetic interference suppression technology based on common-mode choke coil,multilevel modulation algorithm and random space vector modulation algorithm to suppress electromagnetic interference from its propagation path and source respectively.The simulation results of common mode choke coil show that it has a suppression effect of more than 20 dB up to 40dB;in the range of 10kHz~30MHz.In the frequency band range of 30 MHz to 110 MHz,it has a suppression effect of more than 10 dB,which is consistent with the insertion loss of common mode choke coil.A multi-level space vector modulation algorithm model and a three-level electromagnetic interference simulation model are built.The joint simulation results show that both the time domain waveform and the frequency domain spectrum three-level algorithm are significantly lower than the two-level algorithm,and the whole frequency band has about 10 dB attenuation.A random space vector modulation algorithm model and a random electromagnetic interference simulation model are built.The simulation results show that the interference voltage amplitude has an unequal suppression effect of 5~30dB at the switching frequency. |
PDF Full Text Request