Electrolytic Capacitor-less Quasi-Single-Stage AC/DC Converter With Controllable Rectifier Circuits

A quasi-single-stage single-phase AC/DC converter includes fewer switches than a two-stage architecture. However, large dc-link electrolytic capacitors are usually needed in such quasi-single-stage topology to buffer the inherent double-line frequency ripple power. This paper introduces an approach to eliminating the large electrolytic capacitors by using a controllable rectifier circuit at secondary windings of the transformer in the DC/DC conversion stage. In the proposed AC/DC converter, the power delivered to the load over each switching cycle can be manipulated and decoupled from the dc-link voltage. This increases the allowed dc-link voltage ripple and hence reduces the capacitance requirement such that the electrolytic capacitors can be replaced by ceramic capacitors. The proposed method was verified by the experimental results.