EMI Suppression in Voltage Source Converters by Utilizing dc-link Decoupling Capacitors

Direct current (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 electromagnetic interference (EMI) noise as well as on device voltage stress. The design and selection of decoupling capacitors considering both voltage stress and EMI suppression 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 modules. 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.