Design and application of wireless power transfer using Class-E inverter based on Adaptive Impedance-Matching Network

Class-E inverter, which is assumed as an ideal exciter for wireless power transfer system due to their low power losses and suitability for high-frequency operation, can operate under the proper switching conditions when the distance between the transmitter and the receiver and the load is constant. The change in the distance between the coils or the load value removes the optimum switching conditions and causes high switching losses. This paper describes all design procedures and the inductive coupling wireless power transfer system based on a Class-E inverter used as a coil driver. In case the distance between the coils changes, the optimum switching condition of the Class-E inverter and the impedance matching between the transmitter and receiver have been dynamically sustained with an adaptive capacity array on the transmitter side. The best combination of the array involving a serial/parallel capacitor network is configured using a novel searching algorithm for different coil distances. In addition, this study investigates both coupling efficiency and the efficiency of Class-E inverter that is remarked by a few studies in the existing literature. The developed simulation studies and the laboratory prototype with power of 1 kW demonstrate the providing of the zero voltage-switching requirement for Class-E inverter and the impedance matching of the wireless power transfer system in case of variable coupling coefficient. Therefore, the efficiency of power transfer achieved as 91.13% for the implementation circuit.