Sizing Selection Optimization of SiC/Si Hybrid Switch in DC/DC Buck Converters

The SiC/Si hybrid switch concept of paralleling a higher-current main Si IGBT and a lower-current auxiliary SiC MOSFET offers an improved cost/performance tradeoff in power converters. Most study of the hybrid switch focuses on the optimal gate control strategy to minimize its power loss, neglecting the optimization study of its sizing selection. To further improve the cost/performance tradeoff, this paper comprehensively investigates the limiting factors of sizing selection of the hybrid switch and proposes criteria of its sizing selection optimization in DC/DC buck converter. The influence of the auxiliary MOSFET, s sizing selection on its electrical performance is experimentally studied, including forward conduction characteristics, switching losses and short-circuit ruggedness. Then a DC/DC Buck converter based on SiC/Si hybrid switch is demonstrated to investigate the influence of the auxiliary MOSFET, s sizing selection on its thermal characteristics and the converter's efficiency. Finally, the device cost and converter's efficiency tradeoff is recommended as the key criteria for the sizing selection optimization of the SiC/Si hybrid switch.