Analysis of Volt-Second Error for Medium Voltage SiC MOSFET Power Modules

This article presents an analytical derivation of the volt-second error caused by converter nonlinearities such as dead time and the finite switching speeds of the emerging medium voltage silicon-carbide MOSFETs. The analytical model considers the transient behavior of the MOSFETs, the gate-driving circuitry, and the intrinsic parasitic capacitances of the MOSFETs and the power module. The importance of compensating converter nonlinearities has been revived with the utilization of wide bandgap semiconductor devices as the increased switching frequency penalizes the relative impact of dead time squared in motor drive applications. The first-order analytical model is validated with experimental and simulated results of switching events of a 10 kV silicon-carbide MOSFET power module. In addition, the analytical model is utilized to map out the individual contributions from each time period of the switching event.