Single‐Stage Four‐Switch Buck–Boost AC–DC Wireless Power Transfer Converter With SS Compensation for UAV Charging Applications

Abstract

Unmanned aerial vehicles (UAVs) are increasingly used for transmission‐line inspection, where limited battery capacity and long‐range missions impose stringent requirements on compact, efficient, and reliable charging systems. Conventional AC‐DC wireless charging systems commonly employ a two‐stage architecture consisting of a front‐end power‐factor‐correction converter and a back‐end wireless power transfer stage, which increases component count, conversion loss, and system volume. To address these limitations, this paper proposes a single‐stage AC‐DC wireless power transfer converter that integrates a four‐switch buck–boost power‐factor‐correction stage with a series–series compensated resonant network. The proposed converter achieves wide input‐voltage operation, inherent grid‐side power‐factor correction, reduced DC‐link voltage stress, and high‐frequency resonant power transfer within a unified power‐processing stage. In addition, a coordinated constant‐current/constant‐voltage charging strategy is developed by regulating the switching frequency and duty ratio, enabling stable lithium‐ion battery charging without an additional DC‐DC conversion stage. The operating principles, power‐factor‐correction mechanism, resonant‐tank characteristics, and power‐balance design are analyzed in detail. A 150 W prototype with an 85–265 V AC input range and a 60 V/2.5 A output specification is built to validate the proposed approach. Experimental results demonstrate reliable charging performance, improved input power quality, and high conversion efficiency, confirming the suitability of the proposed converter for compact UAV wireless charging applications.