Accurate transient calorimetric measurement of soft-switching losses of 10kV SiC MOSFETs

The characterization of soft-switching losses of modern high-voltage SiC MOSFETs is a difficult but necessary task in order to accurately model converter systems such as medium-voltage-connected Solid-State Transformers (SSTs), where soft-switching techniques are employed for an increased efficiency. Usually, switching losses in general are measured with the well-known double pulse method. However, in case of soft-switching loss measurements, this method is very sensitive to several effects such as probe skew and limited measurement accuracy, among others, and thus unsuitable for the characterization of fast switching high-voltage MOSFETs. This paper presents an accurate and reliable calorimetric method for the measurement of soft-switching losses using the example of 10 kV SiC MOSFETs. Finally, measured soft-switching loss curves of these 10 kV SiC MOSFETs are presented for different DC-link voltages, currents and gate resistors.