Energy injection and free resonance converter for AC–AC inductive power transfer

To address the intricate issues of power control and the short-time margin of the switches in inductive power transfer (IPT) systems, a converter based on an energy injection mode and a free resonance mode for AC–AC IPT is proposed. The power source is completely decoupled from the resonant network, allowing power control by adjusting the energy injection time. Additionally, the converter introduces a unique switching control mechanism, ensuring that the soft switching is not restricted to the current zero-crossing point. In addition, the proposed system eliminates the requirement for bulky filtering capacitors on the AC bus, enabling a high output power factor without the need for power factor correction. To validate the characteristics of the proposed converter, an experimental prototype is constructed. By varying the transmission distance of the system from 11 to 14 cm and the load resistance from 20 to 50 Ω, the transfer power can be precisely adjusted throughout the duration of energy injection, and the system achieves a transmission efficiency of over 88%.