Reconfigurable Bidirectional Stacked Half-Bridge Resonant DC-DC Converter for Extended Voltage Conversion Range

Abstract

This article proposes a reconfigurable bidirectional stacked half-bridge resonant DC/DC converter that can operate under wide ranges of forward voltage conversion-ratio M<inf>f</inf> and backward voltage conversion-ratio M<inf>b</inf>. In the forward direction, the proposed converter operates as a full-wave resonant buck converter (when M<inf>f</inf><1), as a half-wave resonant boost converter with three-level voltage v<inf>cd</inf> (when 1≤M<inf>f</inf><2), and as a half-wave resonant boost converter with two-level v<inf>cd</inf> (when M<inf>f</inf>≥2). In the backward direction, the proposed converter operates as a full-wave resonant boost converter (when M<inf>b</inf>≥1), as a half-wave resonant buck converter with three-level v<inf>cd</inf> (when 0.5≤M<inf>b</inf><1), and as a half-wave resonant buck converter with two-level v<inf>cd</inf> (when M<inf>b</inf><0.5). When it operates with three-level voltage v<inf>cd</inf>, alternative asymmetric pulse-width modulation alternately charges and discharges the secondary-side half-bridge capacitors, thus inherently balancing their voltages. We obtain the accurate voltage conversion ratio of the proposed converter operating with three-level voltage v<inf>cd</inf>, which is continuous at the operating boundaries. We provide detailed design guidelines for the proposed converter, considering three operating modes in each power-flow direction. The proposed bidirectional converter and its modulation scheme are experimentally validated using a 200−1000 V, 1-kW hardware prototype powered from a 125-V input. © 2015 IEEE.