Analysis of EMI in Motor System Driven by PWM Inverter

With the wide application of PWM converter in motor drive system, the motor control performance is significantly improved, but the problems caused by electromagnetic interference (EMI) is becoming more and more serious. This paper conducts the research about EMI in typical PWM motor system. The parasitic parameters in motor system are analyzed, and the main EMI sources, common mode current (CMC) and electromagnetic radiation, are detailed studied, which includes their mathematical models, flowing path and time/frequency domain characteristics. Finally, the characteristics of CMC and EMR are experimentally verified under different distributed capacitances, and the experimental results are consisted with the theoretical analysis.