Suppression of High-Frequency DC- and AC-Side Common-Mode Currents in DC-Fed Motor Drive Systems

To reduce radiated electromagnetic interference (EMI) in a motor drive system with long power cables, it is necessary to suppress both high-frequency (HF) input- and output-side common-mode (CM) current. In a DC-fed motor drive system, due to stray capacitance between power devices and heat sink, it is difficult to suppress both HF DC- and AC-side CM current by using only the conventional AC-side passive EMI filter. In this paper, the authors investigate how to suppress both HF DC- and AC-side CM currents on a DC-fed motor drive system. To achieve the above purpose, the DC-fed motor drive system based on SiC-MOSFET is constructed and DC- and AC-side CM currents are measured and evaluated for each filter condition.