A Fractional-Order Wireless Power Transfer System With Misalignment and Detuning Tolerance

For wireless power transfer (WPT) systems, parameter fluctuations and misalignment of coils will lead to frequency detuning, which will, in turn, affect system performance and output accuracy. In general, the conventional frequency-tuning strategies rely on adjustable capacitors or inductors, which increase the control complexity or require additional modules. Therefore, this article proposes a fractional-order WPT system with adjustable fractional order. The proposed system with misalignment and detuning tolerance can provide a constant current (CC) or constant voltage (CV) output. First, based on the coupled mode theory, the frequency and output characteristics are analyzed. Then, a frequency-tuning strategy based on the fractance element is proposed. Operation modes and equivalent impedance of the fractance element are analyzed. On this basis, control strategies of CC and CV are designed for the transmitter and receiver, respectively, Finally, an 864-W prototype is set up to validate the proposed frequency-tuning strategy and control strategy. The proposed system has robustness to misalignment and parameter fluctuations, which can improve efficiency and output accuracy.