EMI suppression in voltage source converters by utilizing DC-link decoupling capacitors

DC-link decoupling capacitors are normally used to control the voltage overshoot of switching devices in voltage source converters. This paper analyzes decoupling capacitors´ impacts on device EMI noise as well as on device voltage stress. The design and selection of decoupling capacitors considering both voltage stress and EMI suppressions are presented. A new high-frequency EMI filter by utilizing the decoupling capacitors is proposed. The filter is adopted as a local EMI filter for power module. The integratable characteristics of the proposed filter are discussed. Simulation and experimental results verify the design. This high-frequency filter shows good attenuation for high-frequency EMI noise and voltage overshoot suppression.