Switching Performance Comparison of the SiC JFET and SiC JFET/Si MOSFET Cascode Configuration

Abstract

Silicon Carbide (SiC) devices are becoming increasingly available in the market due to the mature stage of development fact of their manufacturing process. Their numerous advantages compared to silicon (Si) devices, such as, for example, higher blocking capability, lower conduction voltage drop, and faster transitions make them more suitable for high-power and high-frequency converters. The aim of this paper is to study the switching behavior of the two most-widely studied configurations of SiC devices in the literature: the normally-on SiC JFET and the cascode using a normally-on SiC JFET and a low-voltage Si MOSFET. A detailed comparison of the turn-on and turn-off losses of both configurations is provided and the results are verified against the experimental efficiency results obtained in a boost converter operating in both continuous conduction mode (CCM) and discontinuous conduction mode (DCM). Furthermore, special attention will be paid to the switching behavior of the cascode configuration, analyzing the effect of its low-voltage Si MOSFET and comparing different devices. The study carried out will confirm that the overall switching losses of the JFET are lower, making it more suitable for operating in the CCM in terms of the overall converter efficiency. However, the lower turn-off losses of the cascode show this device to be more suitable for the DCM when ZVS is achieved at the turn-on of the main switch. Finally, all the theoretical results have been verified in an experimental 600-W boost converter.