Comparison of the power losses in 1700V Si IGBT and SiC MOSFET modules including reverse conduction

The paper presents a study of the power losses in 1700V rated half-bridge power modules applied in a 250kVA three-phase converter. Two types of the modules with comparable parameters (1700V/300A) are analyzed: the first one is based on Si IGBT and the second is built with SiC MOSFETs and Schottky diodes. A special focus of this paper is a reverse conduction of SiC MOSFETs. This phenomenon is analyzed by means of Saber simulations and new, corrected equations describing conduction power losses of the diodes and transistors are provided. Then, combined electro-thermal calculations are conducted using datasheet parameters of the compared modules. The collected data suggest that the Si IGBT module show lower conduction power losses while SiC MOSFETs provides much better switching performance. Thus, both modules are comparable at low switching frequencies but an advantage of the SiC MOSFET module is more visible with the switching frequency increase. When the three-phase converter is operating in an active rectifier mode the conduction power losses are strongly reduced due to the reverse conduction of SiC transistors. In consequence, the SiC MOSFET module shows lower conduction losses and total power losses than Si IGBT.