Analysis and optimization of a solenoid coupler for wireless electric vehicle charging

In light of the increased interest in e-mobility, comfortable, and safe charging systems, such as inductive charging systems, are gaining importance. Several standardization bodies develop guidelines and specifications for inductive power transfer systems in order to ensure a good interoperability between different coil architectures from the various car manufacturers, wireless power transfer suppliers, and infrastructure companies. A combination of a bipolar magnetic coil design on the primary side with a secondary solenoidal coil promises a good magnetic coupling and a high-transmitted power with small dimensions at the same time. In order to get a profound knowledge of the influence and behavior of the main variables on the coil system, a detailed parameter study is conducted in this paper. Based on these findings, a solenoid was designed for a specific case of application. Further, this design is optimized. The dimensions of the system could be reduced by 50% with a constant coupling factor at the same time. Besides the reduction of the dimensions and subsequently the costs of the systems, the stray field could be reduced significantly.