Phase Detection Method Using Decoupled Auxiliary Coil for Active Rectification of Mega-Hertz WPT

This paper proposes a phase detection method for active rectification of mega-hertz wireless power transfer systems. By using a decoupled auxiliary coil integrated on the receiving coil, the switching phase of active rectifiers can be detected indirectly. The auxiliary coil has much higher available frequency compared with conventional methods using current transformers. Analytical modeling and implementation of decoupling coil structures are investigated. The interference from the receiving coil current can be well suppressed due to the decoupling feature, thus the auxiliary coil acts as a mapped transmitting coil, which realizes high-stability phase detection and position sensing for the receiver. A 6.78-MHz receiver with active class E rectification is built to verify the proposed methodology, which achieves phase detection and misalignment measurement with high stability, low cost, and compact size. The proposed method is preferable for wireless power transfer applications with mega-hertz active rectifiers.