Design and performance evaluation of a high power density EMI filter for PWM inverter-fed induction motor drives

This paper presents the design of an electromagnetic interference (EMI) filter for a low voltage high current induction motor drives supplied by DC power grids, such as those used in several vehicle applications. In order to effectively design the EMI filter a suitable Common Mode/Differential Mode (CM/DM) separation technique has been used. In consideration of the high operating currents, a software based separation technique using time domain measurements has been applied. The proposed technique allows the CM and DM sections of the EMI filter to be properly selected in a more economical way, i.e. without the need of dedicated hardware or costly radio frequency (RF) instrumentation. The design has been done according to a power density criterion. The effectiveness of the proposed CM/DM separation technique and the EMI filter features/performance have been assessed by experimental tests, carried out with a 1.1 kW PWM inverter-fed induction motor drive, supplied by a 48V DC power grid.