An Isolated Soft-Switched High-Power-Factor Rectifier Based on the Asymmetrical Half-Bridge Flyback Converter

This article presents the analysis and design of a high-power-factor rectifier that integrates a discontinuous conduction mode operated Boost input cell with an asymmetrical half-bridge flyback converter (AHBFC). The particular connection of the dc–dc stage with the boost cell makes the dc link voltage decrease at light load, thus naturally limiting the switches’ voltage stress. A suitable design procedure is described that accounts for the resonant nature of the AHBFC, and allows to calculate all converter parameters to meet the design specifications and to achieve zero-voltage turn-on for the switches in any operating condition, considering both input voltage and load variations. The theoretical analysis is validated by experimental results taken on a $\mathbf {160\,}$W rated prototype, working at the nominal switching frequency $\mathbf {f_{s}= 400\,}$kHz, with a line voltage rms value ranging from $\mathbf {85\,}$ to $\mathbf {135\;{\mathrm V}}$.