Abstract
In recent years, as the consumer electronics devices have become popular, quick and convenient electric charging technology is the development highlight in mobile devices; hence, wireless charging technology has gradually become perceptive in the world. Up to date, electromagnetic induction and electromagnetic resonance are the dominant wireless charging techniques whereas electromagnetic induction may exhibit limited power transfer distance, but it is theoretically easier in design so that most wireless charging products are based upon the electromagnetic induction technique. The objectives of this thesis are to establish a non-contact power system based upon electromagnetic induction, and to analyze the resonance circuits so that the energy transfer efficiency is improved. In this thesis, we started with the analysis of the primary components of an induction cooker with analysis of induction coils and power ferrites by magnetic models for simulation of dynamic electromagnetic responses. First, we redesigned and optimized the power ferrites to improve the magnetic coupling coefficient. Then, we simulated the driving circuits and compared with experimental results. In addition, we designed a sinusoidal driving circuit for further analysis of the energy transfer efficiency. Finally, a commercial class-D power amplifier was used as a sinusoidal driving source in order to conduct both open-circuit and short-circuit tests to extract the parameters of equivalent circuit. With consideration in impedance matching via parallel capacitor compensation, the power factor and total power transfer efficiency is improved significantly.