Self-Tuning Variable Frequency Controller for Inductive Electric Vehicle Charging With Multiple Power Levels

A self-tuning controller for contactless electric vehicle (EV) charging systems based on inductive power transfer (IPT) with multiple power levels is proposed. The multiple charging levels (consisting of ten charging levels) are achieved by controlling the energy injection frequency of the transmitter coil of the IPT system. The proposed controller is capable of self-tuning the switching operations to the natural resonance frequency of the IPT system, and it benefits from soft-switching operations (zero-current switching), which ensures the maximum performance of the IPT system. The proposed controller has such a simple design, which can be implemented based on a simplified control circuit. The simulation of the proposed controller for an inductive charging system at different charging levels is carried out in MATLAB/Simulink. Also the proposed controller with an ac/dc/ac converter is implemented experimentally on an IPT charging system to verify the effectiveness of the controller at different charging levels. The experimental test results conform with the simulation results and verify that the proposed controller effectively enables self-tuning capability and soft-switching operations at different charging levels for IPT-based contactless EV charging systems.