Coil Design of Electric Vehicle Inductive Chargers with Homogeneous Low Magnetic Flux Density

摘要

Wireless inductive power transfer for electric vehicles is getting highly investigated in the scientific field, since the electrification of personal cars is focused on. One of the major challenges of this technology is to realize high efficiency at different working conditions, especially with varying relative positions of the vehicle to the primary charging pad. These displacements lead to higher demands in reactive power, which has to be compensated. This means more effort is required and additional power losses at the primary and secondary power components occur. On the other hand the magnetic flux density must be kept as low as possible to avoid metallic object heating on the surface of the stationary transmitter unit. These two constraints lead to a specific coil design aiming a homogeneous low magnetic flux density on the primary pad. A way to design such a coil is presented in this work. An algorithm is introduced to figure out which parameters should be varied to optimize the coupling of the magnetic circuit in the required intervals.