Modeling of the DD planar coil with ferrite for the wireless power transfer system

The DD planar coil is widely used in the wireless power transfer system for electric vehicles. Modeling of the coil helps to optimize the structure and parameters of the coupler. In this paper, an analytical model is proposed for computing the self-inductance and the mutual inductance of the two mutually coupled DD planar coil with ferrite used in the wireless power transfer system. The contribution of each turn in the coil to the mutual inductance and self-inductance is analyzed separately. The mirror image method is used to eliminate the influence of the ferrite simplifying the analytical model. For verifying the correctness and accuracy of the proposed model, the calculated values obtained from the proposed model are compared with the results by finite-element analysis (FEA). Finally, the laboratory prototype is also built to verify the proposed model. The theoretical value is in good agreement with the experimental simulation value.