A Novel Asymmetric Magnetic Coupler Applied to Multiple-Receiver Wireless Charging System for Automated Guided Vehicles

Conventional planar coils in an asymmetric structure cannot provide stable mutual inductance over a wide range. To address this issue, a novel asymmetric flat cross-shaped solenoid magnetic coupler (FCSMC) with high lateral misalignment tolerance for a multiple-receiver wireless power transfer system is proposed in this article, which can achieve freer charging positions for multiple automated guided vehicles at a single wireless charging station. Moreover, the analytical model of FCSMC is analyzed to simplify the design process based on the air-core mutual inductance equations. Then, a general design process is proposed for larger-scale FCSMC, which greatly reduces the workload of finite-element analysis (FEA) simulations. Finally, a 200/400 W prototype is built to verify the validity of the system within a±90-mm misalignment. In single-receiver cases with a 10-mm air gap, the comparisons with conventional planar square coils show that FCSMC's (planner square coils') output power fluctuates within 5% (27%) with maximum efficiency of 88.55% (92.01%), indicating that FCSMC sacrifices about 3% efficiency for 22% improvement in power stability. At the highest±90-mm misalignments, the output power fluctuates within 1% (19%), improving about 18%. In multiple-receiver cases for FCSMC, the charging positions are free with maximum efficiency of 87.96% when the shortest distance between ferrites of receivers is 20 mm or more.