Predicting Wireless Charging Coils Performance with Permanent Magnets

Wireless charging is widely used in consumer electronics, and the inductance values of the transmitter and receiver coils are of great importance to charging power and efficiency. However, the inclusion of permanent magnets, that are used for alignment, generate strong magnetic fields. These fields may saturate parts of the nonlinear ferrite used for magnetic shielding and magnetic flux concentration, causing inaccurate inductance calculations. If this localized magnetic saturation is not taken into account, these simulation inaccuracies may result in incorrect power and efficiency predictions. To address this problem, a permeability link method is proposed to include the localized saturation effects due to the magnets and produce an accurate model. Coil structures are geometrically modeled and magnetic finite element analysis is conducted to successfully realize the proposed method.