Highly Efficient Quasi-Single-Stage AC-DC Converter Employing Bidirectional Switch

This article proposes a highly efficient quasi-single-stage ac–dc converter that incorporates a bidirectional switch at the secondary side of the circuit. Its attractiveness is that the proposed ac–dc converter achieves almost ZVS turn-off at high instantaneous power and low-voltage turn-off at low instantaneous power. Moreover, the secondary-side switching reduces the loss at the main switch, and thereby more than offsets the losses that occur at the main switch and the clamp switch in a conventional ac–dc converter. An additional benefit of this converter is that the voltages across the primary-side capacitors and secondary-side capacitors are well balanced because the duty cycle at the primary-side switch is fixed at 0.5. Experimental results show that the proposed ac–dc converter is effective and more efficient than a conventional solution.