A three-phase single-switch fly-back single-stage rectifier with lossless isolated snubber

A novel three-phase flyback rectifier with loss recovery snubber was presented. A discontinuous current mode (DCM) operation with constant duty ratio allows achieving unity power factor. ZCS at the turn on can be obtained by operating under the DCM, and ZVS at the turn off can be achieved by lossless snubber. The principal characteristics are the very simple topology with only one switch, low complexity of control method without current feedback loop and galvanic isolation between the input and output using high frequency transformers. The efficiency can be improved by a better design on the transformer and using auxiliary snubber. And the snubber can also protect the switch against over-voltage caused by leakage of transformers. Simulation and experiment results confirmed the validity of circuit, showing sinusoidal and balanced input currents and a ripple-less output voltage.