Modelling and Analysis of Coupled Coil Topologies for Dynamic Wireless Charging

This dissertation analyses and characterises different coil topologies for dynamic inductive charging of a moving electrical load. Dynamic inductive charging refers to energy transfer through inductively coupled coils during motion, such as with an electric vehicle. The theoretical part covers the fundamentals of inductive energy transfer, introducing the necessary system components. Maxwell’s equations are simplified for low frequencies, relevant to inductively coupled systems. A review of the state of the art presents global research efforts and current prototypes. The SAE coil geometries, described in standard J 2954 for static charging, serve as a basis for identifying typical coil topologies, which are then analysed for their magnetic properties. For selected topologies, equations for calculating magnetic flux density and inductance are derived. Methods for determining the coupling factor, which significantly influences system behaviour, are presented. Based on criteria such as performance and safety, the rectangular and double-D topologies are chosen for further investigation. The experimental part describes the operation of a test bench used to evaluate coil prototypes. The measured magnetic flux density shows qualitative agreement with the calculations, and deviations in inductance are within an acceptable range. It is demonstrated that the double-D topology exhibits less variation in the coupling factor when multiple coils are connected in series compared to the rectangular topology, making it more suitable for dynamic charging, provided certain positioning conditions are met.