Investigation and Comparison of SiC Freewheeling Diode for Switching Characteristics and Losses

The traditional half-bridge circuit needs the inverse parallel diode for freewheeling. In recent years, some SiC applications have canceled the intrinsic body diode. To compare the advantages and disadvantages of canceling intrinsic body diode, this paper studies the influence of inverse parallel diode from the perspective of switching loss. In this paper, SBD, MOSFET, and MOSFET+SBD are used as freewheeling diodes to compare the circuit’s switching characteristics and switching loss. The three circuits were tested by simulation and building a double-pulse test prototype. The method of calculating the switching loss based on the drain current and the channel current is adopted respectively to better evaluate the switching loss of the three. The results show that the dynamic characteristics of the circuit become worse when MOSFET+SBD is used, in which total loss is larger than that of SBD and MOSFET, while turn-off loss is smaller.