Improving Quality Factor of Ferrite-Core Inductors Applied in Inductive Power Transfer

Structural designs of the ferrite core and copper winding to improve the Q value of inductors for IPT (inductive power transfer) applications are studied via simulations and experiments. Magnetic circuit analysis and loss decomposition analysis are conducted to qualitatively assess the inductor performance. Improving Q is realized from two aspects: core shape design and winding pattern design. Geometry of the ferrite core resembles that of a pot core. Multiple small air gaps with optimized parameters are inserted into the magnetic circuit to reduce the flux density inside the core and the resultant core loss. A solenoidal winding is adopted and the impacts of winding parameters are studied. Part of the optimization measures are verified via experiments and effectiveness of the proposed measures is validated. Meanwhile, simulations show that conductive plates can be adopted for magnetic shield and the impact on Q value is acceptable.