Optinization of wireless energy transfer for mid-range distances

This thesis deals with the optimization of resonators for wireless power transfer by resonant magnetic coupling, where loosely coupled LC resonators are used for wireless power transmission. While systems that are currently available use discrete capacitors for frequency tuning, this work proposes self-resonating coils on a printed circuit board. For these coils, different three-dimensional (3D) Computer Aided Design (CAD) models are created and investigated using the method of finite elements. Finally, a set of inductively coupled and capacitively coupled self-resonant coils for the 6.78 MHz ISM band is found. Furthermore, the shielding of the coils with ferrite materials is discussed to maintain a high efficiency for any application. For both types, equivalent circuit models are derived and analyzed. Besides the coil optimization, a power amplifier is also proposed. During operation the optimal operational frequency is maintained by frequency tracking. The theoretical results are verified using a demonstrator circuit.