Highly Efficient Wireless Power Transfer System With Single-Switch Step-Up Resonant Inverter

In this article, a highly efficient wireless power transfer (WPT) system is realized by employing the proposed single-switch step-up resonant inverter with a series-series-compensated network. This resonant inverter has the merits of a simplified circuit structure, low component count, inherent voltage boosting, zero-voltage switching (ZVS), and high efficiency. Based on the equivalent circuit model, the two-coil WPT system is analyzed in the frequency domain, which shows that a quasi-constant current (CC) in the primary side and a corresponding quasi-constant voltage (CV) in the secondary side can theoretically be achieved. A systematic top-down design methodology of the entire WPT system is also provided, which serves as a practical design guideline. The proposed solution benefits real WPT applications by generating a clean and stable dc voltage for the built-in dc-dc battery management system of the receiving device. The experimental results show that the maximum efficiency of the WPT system at the rated output power of 11 W is around 86.4%.