Coupling coefficient identification for maximum power transfer in WPT system via impedance matching

Maximum power transfer is a significant issue in wireless power transfer system, the common used method is impedance matching to track the optimal impedance point by using a power electronic converter. However, in a practical WPT system, the coupling coefficient will drift from the designed value due to the air gap, receiver structure and other environmental influence. As a result, the optimal impedance will drift from the designed value accordingly. This paper proposes a coupling coefficient identification and impedance matching method for maximum power transfer tracking. The method can identify the coupling coefficient and the load, and realize the impedance matching through changing the duty cycle of the Buck converter. The correctness of the proposed method has been proved by both the simulation and the experiment results.