A Novel Unsymmetrical Coupling Structure Based on Concentrated Magnetic Flux for High-Misalignment IPT Applications

The capability of misalignment tolerance is vital for an inductive power transfer system. This paper proposes a novel unsymmetrical coupling structure that can remarkably enhance the output voltage stability with respect to the horizontal, vertical, and angular displacements. The core of this structure is concentrated magnetic field. The optimization method to derive the optimal loosely coupled transformer providing the strongest tolerance to misalignment and fulfilling the requirement of the minimum coupling coefficient is presented. The proposed structure is compared with planar circular and square coils and double-D (DD) coupler from the perspectives of magnetic coupling and anti-misalignment capability. A 200-W prototype is finally fabricated, where the primary series, secondary series-parallel compensation topology is employed to further improve the system's tolerance to misalignment. A maximum output voltage ripple factor of 2.83% and a minimum system efficiency of 91.9% are achieved when the horizontal displacement is as high as one-third of the coupling coil.