Study and implementation of a single-phase isolated AC-DC converter

A single-phase isolated AC-DC converter is presented in this paper. The front semi-stage, which is a modified buck-boost converter, is used for power factor correction and is operated in discontinuous conduction mode (DCM) to achieve high power factor and low total harmonic distortion of input current. The rear semi-stage, which is a forward converter, is operated in DCM for step-down voltage conversion. The proposed converter is suitable for universal input voltage (90~264 V_rms) and wide output-power range. This converter has the merits of low voltage stress on the DC-link capacitor and electrical isolation. Also, the operating principle and steady-state analysis is discussed. Finally, a prototype circuit is implemented to verify the feasibility of the proposed converter.