A 13.56 MHz inductive power transfer system operating with corroded coils

Abstract

This paper describes experiments which investigate the effects resulting from corrosion of air-core coils for high frequency inductive power transfer (HF-IPT). A group of coils were treated by exposing them to corrosive conditions for thirty days. Afterwards, the coils were measured with an impedance analyser and the coil with the lowest Q-factor was selected for further experiments. The treated coil was tested at the transmit side of a HF-IPT system, where the system DC-to-DC efficiency was measured and compared against an equivalent system using an untreated transmit coil. The total losses measured increased when the system was operating with the treated coil across a broad loading range, and thermal images were used to establish the additional losses on the treated coil. Analysis of the treated coil identified widespread damage to the surface of the coil. However, it was specific aggressive corrosion only found locally which was able to significantly reduce the Q-factor of the treated coil by 20%.