An AC-AC energy injection resonant converter for wireless power transfer applications

This paper proposes a direct ac-ac converter to generate a high-frequency AC current for inductive power-transfer (IPT) applications. The proposed converter adopts a bidirectional fly-back converter to inject the energy into a resonant tank discretely. It achieves the direct ac-ac energy conversion by using only three switches and can produce the required high frequency current with significantly lower switching frequency. Thus, the DC bus capacitor is eliminated and low speed high power semiconductor switches can be used in high frequency IPT system. The circuit topology, basic operating principle and control methods of the new converter are explained and analyzed in detail. Theoretical analysis and simulation results show that the output current is fully controllable with good waveforms for wireless power transfer applications.