Design of a Two-Switch Flyback Power Supply Using 1.7 kV SiC Devices for Ultra-Wide Input-Voltage Range Applications
The two-switch flyback topology provides the best trade-off in terms of performance and complexity among other topologies like LLC or full-bridge. With reference to Fig. 1, the benefit of this topology is that the over-voltages on the power switches are clamped to the dc bus by diodes D1 and D2, thus allowing the use of power switches with a breakdown voltage of 1.5 kV. Since this circuit topology is basically hard-switching, SiC MOSFETs (CREE C2M-1000170D 1.7 kV/5 A) have been chosen to reduce the losses of Q1 and Q2. Another feature of the two-switch flyback converter is that during the clamping period the leakage energy of the transformer is returned back to the source, effectively eliminating the need for dissipative snubber circuits.