Performance Study of Eight-Figure Coils in Wireless Power Transfer System

In wireless power transfer (WPT) system, the structure of coils can affect the power and efficiency performance of WPT system. In this paper, transmission coils with different structures is designed and analyzed in magnetically coupled resonant WPT system. An eight-Figure coil structure is designed. Moreover, an array is built by two eight-Figure coils. The system is simulated under the same magnetic excitation. Finite element method is used to simulate transmitting coils to obtain the distribution of magnetic fields. The current and voltage of eight-Figure coil WPT system are analyzed in the case that receiver shifts from middle axis. The current and voltage of from 50 mm and 200 mm above transmitting coil under the same excitation are compared. The results show that eight-Figure coil is able to relieve coil misalignment issue in WPT system. Moreover, coil array can reduce the influence of the radial offset to entire WPT system.