12 kW Flyback Converter with a Passive Quasi-resonant Snubber

The flyback DC/DC converter traditionally finds use in low power applications (up to about 300 W). This contribution presents a high-power flyback converter, utilizing a lossless quasi-resonant snubber circuit and silicon-carbide MOS-FETs and diodes. The experimental 12 kW converter reaches a maximum efficiency of 97 % while maintaining small dimensions and low weight. The maximum output parameters are 420 V, 30 A; the converter is fully controllable from zero voltage and current. In contrast to resonant converters, the presented converter keeps high efficiency even at decreased output voltages and currents, which makes it suitable for variable voltage/current applications.