Magnetic Alignment Detection Using Existing Charging Facility in Wireless EV Chargers

Wireless charging is a promising outlet to promote the electric vehicle (EV) industry due to its safe and noncontactmanner. Wireless EV chargers require the secondary receiver coil to be well aligned with the primary station for efficient charging, which could require more of the driver's time and attention when parking a vehicle. Therefore, this paper presents a magnetic alignment system to assist the EV driver during parking. The magnetic alignment approach uses the existing coil and frequency tracking control electronics of wireless chargers to detect the distance between the two coils while using 4 small auxiliary coils for direction and fine adjustment, leading to a cost effective detection method for coil alignment in electric vehicle wireless charging (EVWC). The testing results of a prototype show acceptable measurement correctness and the mean error for ten trials in range detection is within 0.25 cm at three different misalignment conditions (10.5, 15, and 20 cm). The positioning accuracy of coil alignment is within 1.2 cm for three different start positions with the auxiliary coils.