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.