Optimization of Efficiency and Receiver-Coil Mass in an Autonomous 700-W S-S IPT System for UAV Applications

Wireless Power Transfer (WPT) is an attractive solution to sustain complete autonomy in drone charging. This paper proposes a Series-Series (S-S) compensated IPT system with a primary that maintains a constant transmitter coil current by means of phase-shift modulation. A dual-objective design optimization problem was defined considering the receiver coil mass and the DC-DC efficiency of the IPT system. Using Bayesian Optimization, the algorithm converged to a 91%-efficient IPT system with a 138-g receiver coil. The optimized design was prototyped and tested while charging 7-Ah and 14-Ah drone batteries in CC and CV modes. The measured peak DC-DC efficiency is 91.6% at 600 W, validating the design and optimization procedure. Further, A 2-D motorized coil alignment mechanism that uses a search algorithm is experimentally validated to overcome lateral misalignment caused by the inaccurate landing of drones and ensure autonomy.