SiC/GaN power semiconductor devices: a theoretical comparison and experimental evaluation under different switching conditions

Abstract

(This study is for special section ‘Design, modelling and control of electric drives for transportation applications’) The conduction and switching losses of silicon carbide (SIC) and gallium nitride (GaN) power transistors are compared in this study. Voltage rating of commercial GaN power transistors is <650 V, whereas that of SiC power transistors is <1200 V. This study begins with a theoretical analysis that examines how the characteristics of a 1200 V SiC metal–oxide–semiconductor field-effect transistor (MOSFET) change if device design is re-optimised for 600 V blocking voltage. Afterwards, a range of commercial devices [1200 V SIC junction gate FET, 1200 V SiC­MOSFET, 650 V SiC-MOSFET and 650 V GaN high-electron-mobility transistor (HEMT)] with the same current rating are characterised and their conduction losses, inter-electrode capacitances and switching energy E sw are compared, where it is shown that GaN-HEMT has smaller conduction and switching losses than SiC devices. Finally, a zero-voltage switching circuit is used to evaluate all the devices, where device only produces turn-OFF switching losses and it is shown that GaN-HEMT has less switching losses than SiC device in this soft switching mode. It is also shown in this study that 1200 V SiC-MOSFET has smaller conduction and switching losses than 650 V SiC-MOSFET.