Framework and Topology for Active Tuning of Parallel Compensated Receivers in Power Transfer Systems

Wireless power transfer (WPT) based on magnetic coupling is becoming widely accepted as a means of transferring power over small to medium distances. An unresolved issue is the source and receiver resonance matching in multireceiver systems where the source operating frequency adjustment is not possible. This paper presents a framework to analyze the effect of parallel-compensated receiver detuning on the power transfer in WPT systems. Building on this analytical study, we present a new receiver design for WPT systems. The proposed design combines a parallel compensated resonant tank with a tristate boost converter. By synchronizing the tristate boost switching period with the half-period of the resonant tank voltage, we position the inherently discontinuous current pulse drawn by the tristate boost to control both active and reactive power flows from the resonant circuit. Controllable reactive current can be used effectively to emulate appropriate inductance or capacitance to tune the resonant tank and achieve optimal power transfer.