Resonant DC/DC converters with a transformer regulated synchronous rectifier

A transformer regulated synchronous high-frequency rectifier is described, analysed and experimentally tested. The rectifier can be applied to high power resonant DC/DC power converters with Class D or Class E DC/AC inverters operating at a constant frequency. In the rectifier, a HF power transformer is utilised to separate the regulating and rectifying elements of the circuit. This approach allows reducing conduction losses in the regulating transistors and achieving good efficiency. Design examples and experimental results for 240 W/V/sub 0/=12 V Class D and 50 W/V/sub 0/=5 V Class E DC/DC power converters are also presented. The power converters operated at a constant frequency (approx. 1 MHz) in a wide range of loads (from no load to short circuit) and achieved good efficiency 89% and 82% at a full load, respectively. Possible modifications of the circuits are also discussed. DC/DC resonant power converters with the proposed rectifier are suitable for noise sensitive applications where a high constant frequency of operation and a high output current and/or voltage are required (e.g. telecommunications, aircraft and satellite equipment). The power converters can also be built as multiple output circuits with independent regulation of each output voltage.