Robust Digital Algorithm for Rapid Phase Angle Tracking in Wireless Power Transfer

Within wireless power transfer (WPT) systems, proper selection of the operating frequency is imperative in order to achieve high efficiency and power transfer. In the vast majority of WPT systems, disturbances to both the secondary side load and coupling condition alter the system dynamics, shifting the frequency corresponding to the optimum phase angle and necessitating closed-loop frequency control. In this paper, a fully digital phase angle tracking algorithm is presented. The proposed algorithm provides accurate phase tracking through a computationally efficient implementation robust to switching noise, allowing for high frequency and high power operation. Moreover, the phase measurement is fast converging, facilitating high-performance regulation under disturbances. By employing a fully digital approach, the system cost and complexity are reduced, as additional hardware required by competing analog methods is entirely eliminated. These qualities are concretely demonstrated through completed analysis and are further verified through collected experimental results.