Design a high-frequency-fed unity power-factor AC-DC power converter for wireless power transfer application

This paper presents the design procedures of an unity-power-factor AC-DC power converter for wireless power transfer application. This newly proposed AC-DC converter consists of two stages: the PFC front stage uses LC series resonant circuit to perform power factor conditioning and the second stage uses a DC-DC converter to regulate the output voltage. New equations to describe the input impedance and power transfer characteristics of the converter have been developed. These new equations are used to formulated the design procedures of the converter. To verify, a proof-of-concept prototype is built and incorporated into a two coils wireless power transfer system. The system operates at 100 kHz to deliver 20 W to a remote load with a separation distance of 7.5 cm between the transmitter and receiver. The measured results are well agreed with the design specifications and theoretical anticipation.