A Novel High Efficiency Quasi-Resonant Converter

Abstract

In this paper, a new constant-frequency quasi-resonant converter is proposed. Compared with the traditional LLC converter, the proposed converter can effectively reduce the range of the operating frequency. The output voltage is changed to adjust the reactance of the resonant cavity. The proposed converter has a better loss factor. To verify the theoretical analysis and soft-switching condition, a 250 W, 100 V output prototype was built and compared with the full-bridge LLC converter. Analysis and experimental results verify that a smaller operating frequency range and volume of the transformers, a soft-switching condition, and a higher overall efficiency are achieved with the proposed converter.

Keywords

• constant frequency
• quasi-resonant
• switch-control-capacitor (SCC)
• zero voltage switching (ZVS)
• zero current switching (ZCS)
• smaller volume
• higher overall efficiency