Overvoltage Mitigation Techniques for SiC-MOSFET based High-Speed Drives: Comparison of Active Gate Driver and Output dv/dt Filter

Abstract

The high-speed drives can be supplied by the wideband-gap (WBG) power devices such as SiC-MOSFETs, as they offer the possibility to increase efficiency and reduce the size of passive components. Nontheless, HF operation of the SiC devices emphasizes the effect of parasitics generating reflected waves phoenomena across the interconnection cables and transient overvoltage on motor terminals, reducing the life time and the reliability of electric drives. In this paper, the two solutions for the overvoltage mitigation of SiC-MOSFET based 2L inverter have been compared: the solution with an active gate driver based on digital control and the solution with an output dv/dt filter. The filter has been designed in order to meet the NEMA standard on voltage stress. The complete parasitic model of SiC-MOSFET based inverter has been developed in the LTspice simulation tool, as resulting from the experimental prototype pcb board and tested with the high frequency models of the motor in order to determine the overvoltages on the motor terminals. The two solutions have been compared in terms of efficiency, cost and volume, in order to have the clearest picture possible when comes to the judicious choice that practitioners in the motor drive industry have to make. These comparisons were carried out by realistic dynamic models of power devices obtained from the manufacturer’s experimental tests and verified both in the LTspice and PLECS simulation tools.