Temperature-Dependent Characteristics of SiC Devices: Performance Evaluation and Loss Calculation

Silicon Carbide (SiC) devices have obvious advantages compared with conventional Si devices, and especially so at high temperatures. This paper aims at developing a method for the characterization of SiC JFET conduction and switching losses at high temperatures as well as the calculation of semiconductor losses in SiC JFET-based converters. To this end, the steady-state performance of SiC JFET and Schottky diodes at different temperatures is studied, and an improved conduction loss evaluation is proposed considering the bidirectional conduction paths of the JFET. Specifically, a SiC JFET bridge test bed is built to measure the switching losses at different temperatures with and without antiparallel diodes, where experimental results show that using SiC Schottky diodes in antiparallel eliminates the reverse recovery of the JFET body diode, improving the switching behavior and reducing the losses of the devices. Further, these test results are used to estimate the losses of a 10-kW ac-dc-ac converter, which shows that the use of Schottky diodes as freewheeling devices helps reduce both conduction and switching losses, presenting an even greater reduction at higher operating temperatures.