Study Of EMI And It's Suppression For DC/AC Converters For Hybrid Electric Vehicle

Compared with traditional automobiles,a large number of electrical and electronic equipments are used in hybrid vehicles,making the electromagnetic compatibility of hybrid vehicles increasingly prominent.The DC/AC inverter is one of the most important electronic devices in hybrid vehicles.The interference it generates may affect the normal operation of the electronic components in the car and the self-safe driving of the car.Therefore,we must attach great importance to the electromagnetic compatibility of hybrid DC/AC inverters.The research object of this dissertation is hybrid electric vehicle DC/AC inverter,and conducts relevant research on the characteristics of conducted electromagnetic interference.The main content is as follows:(1)Determine the EMI source and propagation path of the DC/AC inverter.After grasping the overall structure and working principle of DC/AC inverters for hybrid vehicles,the main reasons for the EMI generation in DC/AC inverters are analyzed.At the same time,the coupling path of the inverter to electromagnetic interference is analyzed.(2)Establish a conductive EMI model for hybrid vehicle inverters.In the conducted EMI frequency range,establish the interference source model of the inverter,the motor model and the LISN equivalent circuit,and based on the multi-conductor transmission line theory,the establishment of the cable equivalent circuit model to study the common-mode interference and differential mode of the inverter Interference laid the foundation.(3)The common mode interference suppression method of DC/AC inverter is analyzed.The conduction EMI of hybrid electric vehicle DC/ AC inverter is studied,and several common mode interference suppression methods of the DC/AC inverter are discussed,from which two suppression methods are selected:1)An improved SVPWM control strategy is designed.In the design of the improved control strategy,only the cooperation of six non-zero vectors is considered,and two zero-vector suppression common mode voltages with high common-mode voltage are omitted.2)An improved second-order RLC low-pass filter is designed.The structure of the filter can reduce the electromagnetic interference at the output side of the inverter symmetrically in each switch.(4)Connect the designed improved SVPWM control circuit and filter circuit to the DC/AC inverter,build a simulation circuit in MATLAB/SIMULINK for simulation analysis,verify the improved SVPWM control strategy and the improved filter to common mode interference The correctness and effectiveness of the suppression.