Misalignment-Tolerant Wireless Power Transfer System Based on Double-Layer Quadrature Double-D Coil With Magnetic Field Control

Aiming at the rapid decrease of coupling coefficient and transfer efficiency caused by misalignment during static wireless charging of electric vehicle, a high-misalignment-tolerance wireless power transfer (WPT) system based on magnetic field control of double-layer quadrature double-D (DQDD) coil is proposed. First, the excitation scheme of the two sets of DD coils on the primary side for a different magnetic field distribution is elaborated. Accordingly, the principle of high misalignment tolerance by matching the position of the secondary coils with the magnetic field distribution is explained. Second, the equivalent circuit model of the WPT system with dual-path LCC-series (LCC-S) compensation network is constructed, and the parameter configuration for constant excitation current of the primary coil and output voltage are deduced. Then, a magnetic field control strategy and the coil positioning method without additional auxiliary detection are proposed. Finally, a 1-kW experimental prototype was built to verify the feasibility, and the experimental results indicate that the power transfer efficiency, from dc input to dc output, of 87% is achieved with the longitudinal and lateral misalignments as high as 120 mm in the meantime.