| Inverter is widely used in modern industry,agriculture,transportation,navigation,aviation and other fields.With the continuous development of power electronic technology,the inverter power system is becoming high frequency and high power,thus the conducted electromagnetic interference(EMI)caused by the high frequency action of the switching devices become an important factor that restrict the application of the inverter power.In this paper,the inverter power system is modeled,and the EMI filter is designed and improved to suppress the conducted EMI.Firstly,the mechanism of conducted EMI in the inverter power system is analyzed,finding that the dv/dt and di/dt are the main sources of EMI of the system.At the same time,the main common mode(CM)and differential mode(DM)propagation path of the system are analyzed and the main devices in the system are modeled and parameterized.Then,the CM and DM model are established according to the system interference source and propagation path respectively.Secondly,the common mode and differential mode filter are designed according to the equivalent model and the measured CM and DM interference.The high frequency model of EMI filter is established and the corresponding model parameters are extracted.The simulation results show that the insertion loss of the designed EMI filter meets the requirements.The comparison of experimental results verify that the design of the EMI filter basically meets the design requirements.Finally,the influence of source impedance on the performance of EMI filter is analyzed.It is concluded that the source impedance resonance is the main reason for the deterioration of the high frequency performance of the filter.Meanwhile,an RL damping circuit is proposed to suppress the noise source impedance resonance to optimize the EMI filter design.The simulation and experiment verify that the improved filter can suppress the high frequency conducted EMI very well. |
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