Estimating switching losses for SiC MOSFETs with non-flat miller plateau region

Abstract

Power loss calculations are critical to a power converter design, helping with estimation of efficiency, switch selection and cooling system design. Moreover, power losses in a MOSFET may limit the maximum switching frequency in a power converter. Switching energy values aren't always available in MOSFET datasheets at all operating points, and calculation of voltage and current rise-time and fall-time is needed. This paper introduces a method to obtain an estimate of switching transition times and power losses, using datasheet parameters, for SiC MOSFETs with non-flat gate-plateau region. Three methods are discussed here, two existing and a proposed method. These methods are used to evaluate a certain MOSFET product, and calculated values are compared with results from PLECS simulation and double pulse test experiment. The proposed method is shown to yield improved accuracy.