Inductive Charging of Electrical Vehicles - System Study

Abstract: A prerequisite of a fast increasing market of the electrical vehicles is the access to charging and reliability/accessibility of the charging systems. Wireless charging i.e. charging without a cord, is an interesting alternative that has been put forward during recent years. In this work a system study of topologies for inductively coupled power transfer over an air gap oftens of centimetres has been investigated. In order to obtain an effective power transfer compensation capacitors are used to achieve resonance circuits. In the thesis four different compensation topologies for inductively coupled power transfer are examined. Expressions for the compensation capacitances and the output voltage or current are derived. An example design for each of the four topologies capable of handling a transfer of 3 kW of power over an air gap of 20 cm with an efficiency of at least 96% is examined. These designs use an outer radius for both coils of 30 cm, and an operating frequency of 20 kHz. The efficiency only encompasses the windings, and does not take into account the efficiency of any power electronics before or after the coils. Prototype housing for the primary coil has been designed and built using basalt fibre reinforced high performance concrete, and magnetic measurements on the materials used are included in the report.