A ZVS dual resonant converter for battery charging applications

A load side resonant, high power density, DC-to-DC converter is discussed. The proposed converter features a constant current source output characteristic while utilizing all component parasitics. The converter is based on a half-bridge topology with zero voltage switching (ZVS) characteristics, feeding an isolation transformer and output rectifiers. The converter's resonant action is based on the leakage inductance of the isolation transformer and the output rectifier capacitance. This output side resonance resets the energy normally dissipated in the Schottky capacitance and also enables a buck-boost condition for the output voltage. The converter demonstrates current source output characteristics which are applied to a battery charging application. Coaxial winding techniques for the isolation transformer are also investigated. These winding characteristics are shown to be unique and favorable when applied to DC-to-DC converters and especially the dual resonant converter topology.>