| Traction system has the advantages of flexible control,fast response,high efficiency and energy saving,which has been widely used in industrial fields such as rail transit and intelligent manufacturing.With the rapid development of motor drive technology,voltage jump and current jump generated during the switching of power devices will cause serious electromagnetic interference(EMI)problems.Therefore,in order to ensure the safe and stable operation of Metro traction system(MTS),it has important theoretical value and practical significance to improve the efficiency of motor operation and carry out research on conducted EMI of MTS.This paper takes a 420 k W MTS as research object.The main research results and innovations are as follows.A high-pass filter circuit design method based on time domain analysis is developed.Because high-frequency noise floor of oscilloscope is too large,the highfrequency components of terminal noise cannot be effectively obtained.According to the corresponding relationship between the vertical accuracy of oscilloscope and the high-frequency noise floor,the time-domain target limit is determined,and a digital filter is designed to analyze the amplitude of time-domain noise in each frequency band.A high-pass filter circuit is designed and connected to DC side of MTS to suppress the low-frequency noise amplitude and improve the vertical resolution of oscilloscope,thereby high-frequency component of conducted EMI is obtained.An equivalent model of terminal conducted EMI with separation of common mode(CM)/ differential mode(DM)noise is established.Based on the test of power supply noise and inverter noise,the main conducted EMI source of port is determined.For the modeling of power supply port,the equivalent circuit model is used to fit CM / DM impedance curve of power supply port,and the parameters of equivalent circuit model are extracted.For the modeling of inverter input port,terminal CM / DM characteristics are changed through multiple sets of external impedances,and equivalent interference source and internal impedance in CM / DM model of inverter input port are obtained by using an optimized algorithm.Y capacitor and EMI filter based on terminal model is designed.For the highvoltage power circuit,equivalent interference source,internal impedance and load impedance are obtained according to the terminal model,and Y capacitor is designed to solve the problem of excessive conducted EMI.For the low-voltage control circuit,the design method of filter is proposed according to the characteristics of interference source and the topology of filter is determined.Combined with optimization algorithm,the parameters of filter are designed,and actual performance of filter is finally verified through experiments. |
PDF Full Text Request