Introduction of a Current Waveform, Waveshaping Technique to Limit Conduction Loss in High-Frequency DC-DC Converters Suitable for Space Power
NAVAL POSTGRADUATE SCHOOL MONTEREY CA
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Space power supply manufacturers have tried to increase power density and construct smaller, highly efficient power supplies by increasing switching frequency. Incorporation of a power MOSFET as a switching element alleviates switching loss. However, values of R sub DSon drain-to-source resistance in the on-state for mOSFETs are of such magnitude to produce greater on-state losses than an equivalent BJT operated in saturation. This research serves to introduce a design concept, pertinent to low-voltage relatively-high-current applications, that minimizes the peak current through the switching element in order to reduce average power loss. Basic waveforms produced by different PWM and resonant mode topologies were examined. Theoretical analysis reveals that a ramp-sine current waveform could cut conduction power loss by at least 18 over a conventional Buck switching converter. A 14V, 14W combination quasi-resonant BuckZCS, Quasi-Resonant Buck dc-dc converter with an unregulated input voltage of 28 V was built for simplicity to demonstrate one particular waveshaping technique. This converter represents a useful example of an actual circuit which is capable of producing the desired ramp-sine switch-current waveform. Final results confirm improvement in conduction loss enhancing existing power MOSFET technology for use in dc-dc power conversion.
- Electrical and Electronic Equipment
- Electric Power Production and Distribution