Analysis of the Magnetic Field Distribution in Inductive Power Transfer Systems under the Influence of Aluminum Shielding

The knowledge about the field distribution of the alternating magnetic field in an inductive power transfer system is of considerable relevance for the use in an electric vehicle. On the one hand, the reference values of the International Commission on Non-Ionizing Radiation Protection (ICNIRP) must be respected in the area of the sill and in the interior of the passenger cabin which can be achieved by the use of shielding. On the other hand, a strong stray field in the essential shielding components causes additional losses and thus reduces the efficiency of the system. Therefore, in this paper an inductive power transfer system based on the proposals for standardization of automotive WPT systems is being analyzed. Using simulation models in ANSYS Maxwell, the field distribution of both a circular and a Double-D coil topology on the vehicle side is being considered and the influence of primary-side shielding is further investigated. To validate the simulation results a field measurement during power transfer is performed on the test bench.