Unified magnetic field model of regular polygonal coils for electromagnetic assessment in WPT systems

Electromagnetic environment assessment plays an indispensable part in the practical application of wireless power transfer (WPT) technology. It can ensure that the WPT system meets the electromagnetic radiation limit requirements of the corresponding frequency. To improve the flexibility and universality of the electromagnetic environment assessment of WPT systems, a general magnetic field model suitable for regular polygonal coil wireless power transmission systems is proposed based on electromagnetic theory. First, using Biot-Savart law and by considering the correlation effect of the coil structure and parameters, a unified magnetic field model suitable for regular polygonal coils is established. On this basis, the model is used to compare and analyze the influence of different coil structures and parameters on magnetic flux density, and the evolution law of the electromagnetic radiation of the WPT system is obtained. Finally, the influences of transmission distance and misalignment on the electromagnetic environment of the WPT system are studied. The validity and accuracy of the model are verified by finite element simulation (FEM) and experimental results, which lays a theoretical foundation for the evaluation of the electromagnetic environment of WPT systems and the pre-design of coils.