A Novel Asymmetric Magnetic Coupler Applied to Multiple-Receiver Wireless Charging System for Automated Guided Vehicles
Chendawei Zhang, Wenzhou Lu, Jian Zhao, Xu Wu, Haiying Chen, Dezhi Xu
Abstract
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 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\pm$</tex-math></inline-formula> 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 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\pm$</tex-math></inline-formula> 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.