Extending the horizontal transmission range of an inductive wireless power transfer system using passive elliptical resonators

Abstract

This paper investigates the development of a passive elliptical planar coil for extending the horizontal transmission distance in an inductive transmitter-receiver wireless-power transfer system (WPT). The passive base coil partially overlaps the transmitter coil and extends the horizontal wireless link between the transmitter and receiver. The base coil models investigated are divided into three categories based on their length. Moreover, for each length category, the optimum number of turns is determined. All proposed models are analysed through the electromagnetic simulation (EMF) software Ansys–Maxwell and Simplorer as well as validated experimentally. For the entire analysis, the maximum efficiency principle is followed in this system. Therefore, impedance matching networks are used across all three terminals in order to tune the system to the operating frequency of 200 kHz to achieve maximum efficiency. The maximum achievable efficiency is determined for each coil prototype (in both simulation and experiment) and the results are compared. The extent to which the EMF software is a valuable tool in developing a planar passive base for an inductive WPT system is discussed. Overall, the proposed concept behind the passive base coil is proved to be successful in extending the horizontal distance between the transmitter and receiver.