kQ-product analysis of multiple-receiver inductive power transfer with cross-coupling

Abstract

This paper investigates maximum achievable efficiency of inductive power transfer (IPT) system with arbitrary number of receivers. We derive the formulas of optimal loads and maximum efficiency based on N-port network model. Via analysis and computer simulations, we show that the cross-coupling among receivers does not affect system efficiency if load resistances and reactances are jointly optimized. We also prove that the maximum efficiency is dominated by a so-called system kQ-product, whose square is interestingly, equal to the sum of squares of kQ-products of individual transmitter-receiver links.