An Active Voltage Controller of SiC MOSFET for Reduced EMI Generation

SiC (Silicon carbide) MOSFETs have significant performance improvements over Si devices. However, the high switching speeds caused sudden changes in current or voltage will generate high-frequency electromagnetic interference (EMI), which is considered to be a major source of interference for power converters. By shaping the switching transient into a Gaussian “S-shape”, EMI generation can be greatly suppressed. The active voltage control (AVC) has proved to be particularly effective in controlling high power IGBT's switching transient. However, a gate driver suitable for SiC MOSFET to force its switching transient to follow a pre-defined S-shape reference has not yet been proposed. In this paper, the AVC system for SiC MOSFETs are successfully designed, and the switching dynamic characteristics of SiC MOSFETs are defined with a smooth Gaussian waveform. Finally, the effectiveness of the proposed control system and the suppression effect of EMI are verified through simulations.