Resonance converter for wireless power transfer

Abstract Wireless Power Transmission (WPT) is a modern technology that represents a new epoch for electricity without the need for a bunch of wires, it is an emerging technology and has arisen as a result of significant advancements in the field of power electronics. With this technology, the electric vehicles´ (EV) battery can be charged while being parked over a certain charging spot (stationary charging) or when in motion (dynamic charging). The possible applications of this technology are vast including the potential to transform and change the way that we use today’s application. Findings from a review of the literature on WPT systems show that significant progress have been recorded by researchers although a number of issues including design challenges still need to be addressed. Low power efficiencies and limited transfer range are the two major issues for WPT, therefore, the identified impediments have to be solved in order for these systems to reach full functionality and compete with existing wired solutions. In order to address the major impediments faced by conventional WPT system, a detailed evaluation of compensation circuit models was carried out and a one sided series capacitor on the primary side was considered while an active rectifier which work as an active resonant circuit for reactive power compensation was considered for the pickup side. In this thesis a detailed evaluation of mathematical analysis has been performed on the electric circuit model of the resonance converter for wireless power transfer. This gives a better understanding on how power can be transferred from primary side to the pickup side by deploying a phase shift angle between the terminal voltage of the inverter Vp and the terminal voltage Vs of the active rectifier. Equivalent circuit representations were presented in order to simplify the design process of WPT systems. Various scenarios related to the real power delivered as a function of phase shift angles to various resistive loads ranging from 10 to 500 ohms were evaluated alongside with their corresponding power efficiency versus different phase shift angles. The maximum power was obtained with a given load resistance of 80 ohms, this maximum output power was achieved when active rectifier terminal voltage Vs led the inverter terminal voltage Vp by 60 degree. Therefore, maximum output power versus phase shift angle obtained is 484.6W with an output voltage of 196.9V. Furthermore, maximum power transmission efficiency was obtained with a given load of 80 ohms, when the active rectifier terminal voltage Vs leads Vp by 15 degree, therefore 92% of transmission efficiency was reached. Additionally, the low power transmission efficiency, which is caused by the compensation capacitor malfunction and the resonance tank detuning, could be mitigated.