Dual-Mode Resonant Flyback Single Power-Conversion Inverter

This article presents a dual-mode resonant flyback single power-conversion inverter with reduced number of power components. Unlike conventional flyback converters, it transfers power in a resonant manner during the first half of the switching period and in a linear way during the remaining half of the switching period. It operates in above resonance mode below the computed instantaneous power level, and in below resonance mode above this instantaneous power level. The secondary diodes of the resonant flyback converter are merged into two of the secondary-side switches in the proposed inverter configuration, which reduces the number of active-power components. The operation principle of the inverter is presented and analyzed. By using the dual-mode control strategy, the proposed converter achieves maximum efficiency of <inline-formula><tex-math notation="LaTeX">$94.3\%$</tex-math></inline-formula> with total harmonic distortion of <inline-formula><tex-math notation="LaTeX">$3.8\,\%$</tex-math></inline-formula>. Experimental results with a prototype 240-W inverter verify the performance.