An Optimal Multivariable Control Strategy for Inductive Power Transfer Systems to Improve Efficiency

Efficiency of wireless power transfer systems, based on inductive power transfer (IPT) technology, suffers significantly due to coil misalignment and load variations. Although numerous control strategies have been proposed in the past to improve the efficiency under these conditions, a technique that utilizes all freedoms of control simultaneously to maximize efficiency is yet to be reported. This article therefore proposes a multivariable control strategy that uses the optimal combination of all control variables to maximize the efficiency of IPT systems when regulating power and even under large coil misalignments and load variations. The article presents a comprehensive mathematical model, describing the underlying theory of the proposed optimal control philosophy, and investigates the performance and limitations of the proposed technique under wide range of operating conditions. To demonstrate the improvement in performance, theoretical results are presented in comparison to those obtained from a 1-kW prototype bidirectional IPT system, and also benchmarking against conventional control techniques. Results convincingly indicate that the proposed optimal control strategy regulates power at maximum efficiency despite large coil misalignments and load variations.