Research On Passive Filter Of PWM Inverter

As the core device of inverter,PWM inverter is widely used in industrial production,and the suppression method of electromagnetic interference is always the focus of scholars.The electromagnetic interference produced by inverter affects not only its own stable operation,but also the stability of other equipment.The differential mode interference and common mode interference generated by high frequency switching devices will not only pollute the power grid,but also damage the load.The use of long cables also aggravates the degree of over-voltage at the load end,further endangering the load.At present,the way to solve these problems is to use some filter circuits to reduce or eliminate these hazards.It is a trend to develop a kind of filtering device which can solve many problems at the same time.This paper describes the modulation principle of PWM inverter,and analyzes the mechanism of electromagnetic interference from the input side and the output side respectively,as well as the reason why PWM inverter produces overvoltage at the load side,which provides a theoretical basis for the design of this paper.According to different sensitive devices,this paper studies the input side and output side passive filters of PWM inverter.On input side,adding EMI filter is the most effective way to attenuate EMI from the transmission path,and planar passive integration is the research trend of EMI filter.Therefore,this paper studies the performance index and design method of integrated EMI filter.An integrated EMI filter is designed,and the design method and steps are given.The prototype meets the design requirements and passes the insertion loss test and temperature test.On this basis,a single core second-order EMI filter structure is proposed.Prototype experiments verify the superiority of this structure.On the output side,the traditional RLC filter can effectively suppress the differential mode interference and the over-voltage phenomenon at the load side,and the common mode transformer has better suppression effect than the common mode choke.According to these characteristics,a new type of CRLC filter is proposed in this paper,which can suppress differential mode interference and common mode interference at the same time,and has a certain suppression effect on the overvoltage at the load end.The parameters of the filter are designed by using MATLAB;The winding modes of common mode transformer are simulated and compared by ANSYS;The circuit model is built by saber simulation software,and the suppression effect of CRLC filter on EMI and overvoltage is tested.Based on the simulation results,an experimental platform is built to prove the effectiveness and superiority of CRLC.The paper has 85 figures,8 tables,and 59 references.