Powerless Fractional-Order Tuning Wireless Power Transfer System With Zero Phase Angle Input

Zero phase angle (ZPA) input is an effective way to improve the power transfer capability and minimize the volt-ampere (VA) rating, thus, it can effectively reduce the cost of devices. Affected by magnetic fields, control strategies and compensation networks, parameters detuning inevitably lead to the loss of ZPA input. Fractional-order circuits are concerned in wireless power transfer (WPT) system due to a higher degree of freedom. In this paper, a powerless fractional-order capacitor (P-FOC) construction method is proposed to achieve ZPA input in an arbitrary frequency-fixed WPT system, which can realize adaptive capacitance with order 1 or
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1. No external high-voltage power supply is required compared with the conventional FOC. No feedback or communication circuit is employed, while it has a full range of impedance matching. The proposed P-FOC can be applied to adaptively offset the reactive power without considering the topology and parameters of the system. Then, the working mechanism and application scenarios are analyzed. To verify the feasibility, the P-FOC is introduced in the semi-active rectification (SAR) WPT system and ZPA input is realized. The experimental results verify the effectiveness of the proposed structure.