Core Structure Optimization in Double-D Coil With Enhanced Performance for Inductive Wireless Power Transfer System

In the domain of wireless charging for electric vehicles (EVs), Inductive Wireless Power Transfer (IWPT) is meritorious in terms of durability and low maintenance. In IWPT systems designed for EVs, ferromagnetic structures are used for the transmitter (Tx) and receiver (Rx) coils to amplify magnetic coupling while restricting flux leakage. To optimize IWPT, parameters like the shape and size of ferrite cores and coils and the weight of cores are supposed to be prioritized. Researched data depicts that Double-D (DD) coils excel in misalignment tolerance, low flux leakage, and high coupling with respect to circular and rectangular coils. Therefore, this article examines the four different shapes and sizes of ferrite cores for DD coils at the Tx and Rx sides. This work considers the Rectangular-type, S-type, D-type and I-type ferrite-bars. Further, the ANSYS Maxwell 3D is used to analytically observe the coupling coefficient, losses and energy transfer for each structurally different core. The study indicates that the structure, dimensions, and sizes of ferrite bars substantially impact the energy delivered in the wireless power system. For an unshielded arrangement of I-type ferrite core, the optimal coupling coefficient value is achieved as 0.2358, accounting for 17.3346 Watts of core loss when the core volume is 2376000 Cubic mm. However, considering safety parameters, shielding is unavoidable. Hence, as per observations, the shielded I-type ferrite core is optimally better by 6.446% in terms of coupling coefficient while taxing on overall volume.