Adaptive Load Impedance Compensation Theory for Inductive Power Transfer Systems

An analysis of load compensation in inductive power transfer (IPT) systems is described by modelling coupled resonators using impedance inverters. The theory shows that any spatial variation that modifies coupling between resonators can be compensated by adjusting the load impedance. For a transmission link under misalignment, the impedance inverter model can be used to analytically derive the optimal resistances that lead to a constant input impedance. Experimental results are shown for a second order IPT system at 27.12 MHz where load compensation is used to provide matched power transfer over a change in gap size from 4.4 cm to 9.4 cm. Simulation results are also shown for higher order systems.