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) condition. 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 expression for the peak voltages and currents, derived in this paper, are applied to develop design guidelines for the proposed DC-DC converter. The proposed topology was tested experimentally on a 100 Watt unit which was run at the 200KHz frequency region. The basic characteristics of the proposed PPRC based DC-DC transformer which include: simplicity, robustness, isolation, ZVS, constant transfer ratio, relatively low current stress and the ability to be synchronized to an external frequency source make it a viable candidate for a master power processor in multiple output configurations.