The biased transformer DC-to-DC converter

Abstract

A dc-to-dc converter design based on the constant-current flux-reset principle is presented. Such converters use a mulitude of separate individual half-wave switching sections. Each section consists of a power transistor and a transformer which is reset through an external bias current source. The transformer typically contains a square-loop core without an airgap. Center tap, SCR, and bridge-type configurations are presented attendant to single-phase full-wave, and polyphase operation. Transformer-core saturation dc ratcheting and cross conduction problems, which frequently plague dc/dc converters, are eliminated. As a result, considerable differences in conduction times between power transistors can be tolerated, as well as some overlap resulting from storage and recovery lags. Typical approaches, circuit variations, and tradeoffs are being presented. Detailed schematic diagrams of actual units for aerospace applications and for industrial uses are discussed in the Appendix.