Efficient high power factor single-stage AC/DC converter

A near flat-top input current waveform and direct energy transferring AC/DC converter which features high efficiency and high power factor is described. In the proposed converter, energy transfers in hybrid mode which means that when the instant line voltage exceeds the preset value, energy is transferred directly to the output side from the input line; otherwise the energy storage capacitor powers the output load. The performance of the proposed concept was evaluated on a 200 W (48 V@4.17A) experimental prototype. It is shown that the efficiency is increased significantly over the case without the direct energy concept. Proof of the concept was verified theoretically and experimentally.