Coils Design and Parallel Resonant H-bridge Inverter for Inductive Power Transfer of Low-power Portable Devices

The capability of the inductive power transfer (IPT) for wireless charging mainly depends on both coil structure and inverter topology. The paper presents the resonant inverter based on the concept of energy injection and free oscillation which are applied to increase the resonant frequency without raising the switching frequency. The implemented inverter utilizes the variable frequency zero current switching (ZCS) control strategy for parallel configuration that ensure the high operating frequency at multiplies of the inverter switching frequency. Consequently, it will result in decreasing the inverter switching loss and also reducing the coil size that operates at resonant frequency. The coil design methodology is introduced in details while studying the different factors affecting the coil behavior. The performance of the overall designed system is evaluated via simulation tests carried out using ANSYS Maxwell and MATLAB SIMULINK.