Showing papers by "Yan-Fei Liu published in 1998"
17 May 1998
TL;DR: In this article, a modified asymmetrical pulsewidth-modulated resonant dc/dc converter employing an auxiliary circuit consists of a network of two capacitors and an inductor.
Abstract: A modified asymmetrical pulse-width-modulated resonant dc/dc converter employing an auxiliary circuit will be proposed in this paper. The auxiliary circuit consists of a network of two capacitors and an inductor. The aim of this network is to produce zero-voltage-switching (ZVS) over a wide input voltage range, while reducing the voltage stress on the resonant component. A detailed analysis and performance characteristics are presented. Experimental results for a 5 V, 35 W converter show an efficiency of 83% at a constant operating frequency of 500 kHz. Using metal oxide semiconductor field effect transistors (MOSFETs) as synchronous rectifiers can further reduce power losses and improve the efficiency to be greater than 90%.
46 citations
Patent•
16 Oct 1998TL;DR: In this article, a flyback converter has a main switch coupling a primary winding of a transformer between supply terminals, a duty cycle of the main switch controlling an output of the converter derived from a secondary winding of the transformer.
Abstract: A flyback converter has a main switch coupling a primary winding of a transformer between supply terminals, a duty cycle of the main switch controlling an output of the converter derived from a secondary winding of the transformer. Soft (zero voltage) switching of the main switch is facilitated by a snubber capacitor in parallel with the main switch. An auxiliary circuit coupled in parallel with the snubber capacitor and main switch includes a series-connected auxiliary switch, capacitor, and inductor coupled via another inductor to a full wave rectifier arrangement for recovering energy from the snubber capacitor. Resonant circuits provided by the auxiliary circuit facilitate soft switching of the auxiliary switch for low power loss and high frequency operation. The switches can be MOSFETs with reverse-poled diodes in parallel with their drain-source paths.
25 citations
17 May 1998
TL;DR: An improved zero voltage switching flyback converter topology is presented and experiments show an improvement of about 2% in the overall efficiency as compared to the previous ZVSFlyback converter.
Abstract: An improved zero voltage switching flyback converter topology is presented in this paper. This converter employs an auxiliary circuit that provides ZVS for both the main and auxiliary and it permits the operation of the converter at very high frequencies. Operating principle, steady state analysis, and design procedure for the auxiliary circuit of the proposed converter, are given. A 50 W, 260 kHz prototype converter is built to verify the performance. Experiments of the proposed converter show an improvement of about 2% in the overall efficiency as compared to the previous ZVS flyback converter.
22 citations