Accurate Offset Angle Detection Strategy for Wireless Charging Coils Based on Electronic Compasses

In order to achieve high-efficiency transmission in the electric vehicles' wireless power transfer system, it is important to ensure that the transmitting and receiving coils are properly aligned. Only if the real-time offset position of the two coils is obtained can the driver align the two coils. This paper proposes a novel offset angle detection strategy for wireless charging coils based on electronic compasses, aiming at the angle offset between transmitting and receiving coils. An electronic compass is placed in the transmitting coil and the receiving coil, respectively. In this process, the exact angle positioning of the charging coil is realized with the aid of geomagnetic and the application of vector theory to determine the offset angle between the two coils. Finally, an experimental prototype has been constructed. The experimental results indicate that the positioning error of the coil angle is within 1 °. This method's measurement process is simple, and the deviation angle between the coils can be directly and conveniently calculated by examining the electronic compass output, which helps guide to align the transmitting coil with the receiving coil.