Misalignment Parameterization of a 13.56 MHz Inductive Power Transfer System for in-situ Soil Sensing

This paper discusses the measurement and characterization of the coil-to-coil misalignment in a 13.56 MHz inductive power transfer (IPT) system using variables that are either measurable on the wireless power transmitter alone (inverter current) or in conjunction with the receiver’s Bluetooth module (rectifier voltage). A two- axis gantry transported the receiver on a plane 22 cm below the transmitter to perform these tests. The results from these tests demonstrate that the lateral coil-to-coil misalignment of this IPT system can be parameterized over the range of 0 to 30 cm with an average error of less than 2 cm. At peak alignment, this error decreases power transmission efficiency by less than 0.2%.