Search

A novel zero-voltage-transition high-efficiency bridgeless power-factor-correction (PFC) circuit with a zero-current-switching auxiliary switch was proposed, analyzed, and experimentally verified. An assist circuit, consisting of a resonant inductor, two blocking diodes, a clamping circuit, an autotransformer, and an auxiliary MOSFET switch, was used to reduce the turn-on switching loss of the two main switches of the bridgeless PFC circuit and the turn-off switching loss of the auxiliary switch. The soft commutation of the main switches is achieved without imposing an additional voltage stress on the main switches. Feedback gate-drive signals can be obtained by using an existing converter IC controller modified to fit the purpose. In this paper, a detailed description of the circuit operation will be given. Based on the analysis, the guidelines for the component selection are presented. A prototype of 100-kHz 600-W universal-line PFC bridgeless circuit was built to verify the proposed scheme. In addition, based on the same concept, a family of bridgeless PFC configuration was proposed. [ABSTRACT FROM AUTHOR]

In this paper, an interleaved soft-switching dc-to-dc converter configuration is proposed. It consists of two parts: the primary side is a constant-frequency asymmetrical converter with active-clamp feature and the secondary side is a series-resonant tank circuit. The active-clamp circuit recycles the energy stored in the magnetizing inductance of transformer to allow main/auxiliary switches turn-ON at zero-voltage switching and clamps the voltage stress of the main switches. Series-resonant tank circuit employs the transformer leakage inductance and secondary resonant capacitance to achieve zero-current switching of the output diodes. The circuit features constant-frequency operation and soft switching for both the transistors and the diodes. Interleaving operation of this configuration combines the aforementioned benefits and small output capacitor. Theoretical analysis and computer simulation of the converter were given. An 80-KHz 500-W experimental circuit of the proposed converter was demonstrated. [ABSTRACT FROM PUBLISHER]