Analysis of Leakage Magnetic Field and Reducing Method in Bi-Directional Wireless Charging System of Electric Vehicle

This paper analyzes the leakage magnetic field generated by the Bi-Directional wireless charging system of Electric Vehicle(EV) and confirms the effect of the shielding coil in the Bi-Directional wireless charging system. In particular, in EV using the Inductive Power Transfer(IPT) method, the effective shielding coil position is proposed by analyzing the contribution of the leakage magnetic field of the Ground Assembly(GA) coil and the Vehicle Assembly(VA) coil according to the power transfer direction. Simulations were conducted using the WPT3/Z2 model of the standard SAE J2954, and it was confirmed that the GA coil contributed more to the leakage magnetic field due to the relatively large size compared to the VA coil regardless of power transfer direction. The same tendency was confirmed not only in alignment condition but also in misalignment condition, and it was also confirmed that the same tendency appeared in the situation where a larger current flows in the VA coil by inversely transferring power. As a result, it was concluded that the shielding coil should be located near the GA coil, which contributes greatly to the leakage magnetic field, and the simulation confirmed the effect of reducing the leakage magnetic field by about 66%.