Reduction of Input- and Output-Side Common-Mode Currents Based on a Coupled Common-Mode Inductor in DC-Fed Three-Phase Motor Drive Systems

This study proposes an input/output coupled passive electromagnetic interference filter (PEF) for motor drive systems. The proposed PEF is based on the conventional PEF and integrates common-mode inductors, which are connected to the input and output sides of the inverter, into a single magnetic component through magnetic coupling. First, a simplified common-mode (CM) equivalent circuit was constructed for the motor drive system. Simple analysis based on the CM equivalent circuit demonstrate that the attenuation of the conventional PEF on the input-side CM current is insignificant, and the proposed PEF can effectively reduce both the input- and output-side CM currents. Thereafter, the proposed PEF was implemented in the motor drive system, and the input- and output-side CM currents were measured to evaluate the effectiveness of the proposed PEF on the input- and output-side CM currents. The results demonstrate that the proposed PEF can effectively suppress the input- and output-side CM currents over a wide band frequency range without increasing the filter volume and number of magnetic components compared to the conventional PEF.