Nearly Constant Power Tuning Network for Wireless Inductive Power Transfer Systems

Wireless inductive power transfer (IPT) is being widely used for applications ranging from phone charging, implantable medical devices to electric vehicle charging. One challenge associated with IPT systems is misalignment between the primary coil and secondary coil. This paper proposes a parallel resonant series-series (PRSS) tuning which is a new design methodology for tuning IPT systems to maintain constant power for range of coupling coefficients. With PRSS tuning, power variations with misalignment in wireless charging systems are reduced while maintaining high efficiencies and also achieving zero voltage switching (ZVS) for the primary switches. A detailed design procedure for PRSS tuning method for IPT systems is shown in this paper. Design methodology has been verified using analysis and simulation results for dynamic wireless power transfer system (DWPT) for electric vehicle charging. Comparison of the PRSS tuning method with series-series and double-sided LCC tuning in terms of constant power transfer has been presented in this paper.