A resonant DC-DC transformer

The characteristics of a push-pull parallel resonant converter (PPRC) when operated as a DC-DC transformer were investigated theoretically and experimentally. In the DC-DC transformer region, the voltage transfer ratio was found to be practically constant and independent of the input voltage and load. In this mode, all the switching elements operate in the zero voltage switching (ZVS) conditions. This helps to achieve high efficiency at high switching frequencies Another important feature of the proposed DC-DC transformer is the ability to be driven by an arbitrary switching frequency, provided that it is lower than the self-oscillating frequency. This permits the synchronization of the converter to a master clock to obtain a stable signal spectrum of a desired base frequency. The analytical expressions for the peak voltages and currents derived are applied to the converter. The proposed topology was tested experimentally on a 100 W unit which was run in the 200 kHz frequency region