Analysis of the novel soft-switching buck-boost type AC-DC converter using magnetic coupling

This paper presents the design-oriented analysis of the novel soft-switching buck-boost type AC-DC converter with high power efficiency and high power factor. In this AC-DC converter, the power factor and input current harmonic distortion are improved by using the third winding of the energy-storage reactor, and the high power efficiency is achieved by the soft-switching operation of the main power switch and output rectifier diode. The circuit operation of the AC-DC converter is defined by using the equivalent circuit model and its performance characteristics are analyzed theoretically. The theoretical results are confirmed by the experimental ones. As a result, it is revealed that the proposed AC-DC converter satisfies the maximum limits of the input current harmonic distortion in IEC 61000-3-2 Class D and that its power efficiency is 95% at the rated load current.