A Measurement of the Power Dissipated due to the Mutual Flux Linking Two Loosely Coupled Coils

This paper describes the adaptation of the capac-itive cancellation method for measuring loss in the magnetic materials in an inductive power transfer (IPT) link. The work focuses on determining the power dissipated in the magnetic materials due to the mutual flux linking the coils and the magnetic material (e.g. a shield). Data were gathered from simulation and experiments. A test circuit comprising a high frequency inductive link, powered by a Class E inverter, with different test-resistors in parallel with the primary coil, was set up. Experiments were performed using five resistors and an open circuit. By estimating the value of resistance which appears in series with the mutual inductance of the link (parallel to series transformation of the test-resistances on the T-model) it is shown that the proposed method is a viable approach for characterising power loss due to the mutual flux linking a loosely coupled excitation coil and the sense coil, which corresponds to the loss in the magnetic material. From the experiments, the method was able to produce above 90% accuracy for every test value of equivalent resistance larger than 2.5
$\mathrm{m}\Omega$
in series with the mutual inductance of the sense link.