SiC Pushes MFT Frequency Higher: Lessons From a 180 kHz-Class SST

MFT miniaturization, loss and insulation lessons from a 180 kHz-class SiC solid-state transformer.

Wide-bandgap devices enable medium-voltage converters to switch faster with lower switching loss. A DOE-supported modular SiC SST study demonstrated a 50 kVA system for above-6 kV AC input with a resonant DC/DC stage operating at about 180 kHz, providing a representative path toward smaller MFTs. Frequency increase is not simple scaling Core volume can fall, but material loss, skin and proximity effects, shield eddy currents, parasitic capacitance and insulation electric fields must all be recalculated. In medium-voltage MFTs, partial-discharge margin can become a constraint before magnetic size does. Engineering guidance Select core material from the actual waveform, temperature and flux swing. Prototype tests should capture efficiency, hot-spot temperature, leakage inductance, common-mode current and partial-discharge behavior together. Source: OSTI: Modular SiC High-Frequency SST