Analysis and design of a single-stage single-switch bi-flyback ac/dc converter

Abstract

An analysis and design of single-stage, single-switch bi-flyback ac/dc converter is presented. The main flyback stage controls the output power from the link capacitor voltage with Discontinuous Conduction Mode (DCM) or Continuous Conduction Mode (CCM) operation, while an auxiliary flyback stage supplies the power to the output directly from ac line input with DCM operation. This scheme can effectively reduce the voltage stress on the link capacitor and can achieve the power factor correction (PFC) without a dead band at line zero-crossings, which reduces the harmonic distortion in ac line current. Theoretical analysis of the converter is presented and design guidelines to select circuit components are given. The experimental results on a 60 W (15 V, 4 A), 100 kHz ac/dc converter show that maximum link voltage and maximum efficiency are around 415 V and 82%, respectively. The power factor is above 0.96 under universal line input and load conditions.