University of Hertfordshire

This paper presents a novel isolated resonant zero-voltage switching converter with a self-driven synchronous rectifier for low-voltage high-current applications. The active resonant tank comprises of a transformer leakage inductance, a capacitor and a diode-connected MOSFET which provides zero-voltage switching conditions for all switches. Due to the use of leakage inductance of the transformer in both the primary and secondary sides, the resonant tank and the output section require no external inductor, resulting in a major size reduction of the circuit. The proposed converter has the advantages of high efficiency; low switching, conducting, and thermal losses; high switching frequency range and isolation; and small size. To verify the proposed converter, a laboratory prototype was manufactured with satisfactory performance. The practical results show that the power efficiencies of the converter including self-driven synchronous rectifier for the light load and the full load are 91.9% and 94.95% at output power P out = 20 W and P out = 100 W, respectively.