A soft-switched constant-frequency square-wave half-bridge DC-DC converter

Abstract

A constant-frequency zero-voltage-switched square-wave DC-DC converter is introduced, and results from experimental half-bridge implementations are presented. A saturable magnetic element produces the advantageous square waveforms and provides isolated terminals from which the output voltage can be controlled. Semiconductor stresses and losses are minimized both by the square waveforms and by low switching losses. The active switches and the output rectifiers both exhibit zero-voltage switching. The active switches (MOSFETs) are operated at a fixed frequency with 50% duty cycle, which allows the use of a simple self-oscillating gate drive. An experimental implementation achieves over 80% efficiency at approximately 70 W/in/sup 3/.<>