A Fixed-Pulse-Width Frequency Modulation Strategy for Lightweight Wireless Charging of Drones With Single-Stage Voltage Regulation

Wireless power transfer is a promising technology for charging drones, although many drones impose strict requirements on the weight and size of the on-board equipment. This article proposes a lightweight wireless charging circuit based on S-S resonance compensation network, along with a new fixed-pulse-width frequency modulation and voltage regulation (FFMVR) control strategy. The system is maintained in resonance through frequency modulation via zero-crossing detection of the inverter bridge's voltage and primary current, enabling self-tuning is realized to ensure high efficiency when system parameters deviate from the rated values. Single-stage output voltage regulation is achieved by inserting zero states during which all inverter switches are turned off and the current resonating are paused, thereby eliminating the need for an additional secondary DC/DC stage and improving the power density of the on-board equipment. The voltage stress on devices and overall efficiency are also discussed. A 200W wireless charging experimental platform was built, and experimental results demonstrate that the proposed method achieves single stage voltage regulation with system tuning capability.