Design and Optimization of a Three‐Dimensional Offset‐Resistant Wireless Power Transfer System Based on a Cross‐shaped Four‐way Compensation Coil Structure

To address significant fluctuations in system output caused by drastic mutual inductance variations under multi‐directional displacement conditions in dynamic wireless power transfer systems for electric vehicles, a cross‐shaped four‐way compensation coil structure (CSFCC) is proposed to achieve tridirectional displacement resistance. First, a structural model of the CSFCC is established to analyze its mutual inductance variation characteristics under triaxial displacement conditions. Second, a mutual inductance calculation method for the CSFCC based on Biot‐Savart law is proposed. Third, using this calculation method, the structural parameters of the CSFCC are optimized to minimize mutual inductance fluctuations. Additionally, a magnetic core structure that matches the coil's characteristics is designed and optimized to enhance mutual inductance and system displacement resistance. Finally, a experimental prototype is constructed, with simulation and experimental validation confirming the correctness of coil design and optimization. Experimental results demonstrate that when the coil is offset by up to of the transmission coil's outer dimension along the or axis () or up to of the diagonal outer dimension of the transmission coil along the diagonal direction (), the peak fluctuation ratio of mutual inductance is merely , with a system transmission efficiency as high as and an output current fluctuation rate below .