Autonomous Inductive Power Transfer System With Quasi Constant Power Output Against Coupling and Load Variations

The output power of an inductive power transfer (IPT) system may fluctuate with magnetic coupling and load variations. Traditional methods of achieving constant output power require dedicated power regulation by complex feedback control based on communication between the power transmitter (Tx) and receiver (Rx). This article presents a communication free autonomous voltage-fed inverter (AVFI) for a series-series compensated IPT system to achieve a constant wireless power output against magnetic coupling and load variations. A synchronized gate control method is proposed by following the zero crossings of the induced voltage of the Tx current. A thorough theoretical study is conducted to analyze the steady-state operation of the system. A 65 W prototype is built, and the experimental results show that the proposed AVFI system can deliver quasi constant power with a maximum 10% fluctuation when the coupling coefficient and the load are varied from 0.2 to 0.6 and 14 to 26 ohm, respectively.