Receive Power Control in Multiuser Inductive Power Transfer System Using Single-Frequency Coil Array

Abstract

This paper investigates receive power control for multiuser inductive power transfer (IPT) systems with a single-frequency coil array. The primary task is to optimize the transmit coil currents to minimize the total input power, subject to the minimum receive powers required by individual users. Due to the complicated coupling mechanism among all transmit coils and user pickups, the optimization problem is a non-convex quadratically constrained quadratic program (QCQP), which is analytically intractable. This paper solves the problem by applying the semidefinite relaxation (SDR) technique and evaluates the performance by full-wave electromagnetic simulations. Our results show that a single-frequency coil array is capable of power control for various multiuser scenarios, assuming that the number of transmit coils is greater than or equal to the number of users and the transmission conditions for individual users are uncorrelated. key words: inductive power transfer, multiuser, single-frequency coil array, receive power control Recently, researchers are paying more attention to multiuser IPT system, where a charging platform-consisting of one or more coils-simultaneously delivers power to multiple users [10]-[12]. Users typically require different power levels for their operations, calling for efficient power control for individual users. The receive power control problem is challenging because in multiuser IPT system, the power flows are influenced by a mash-up of: (1) coupling between charging-platform and users, (2) crosscoupling among users, and (3) cross-coupling among coils in the charging-platform. A straightforward solution is to completely decouple the users by exploiting the frequencydivision technique [10]; but this approach has a drawback in Manuscript