Analysis and Design of a T/S Compensated IPT System for AGV Maintaining Stable Output Current Versus Air Gap and Load Variations

Abstract

Inductive power transfer (IPT) technology for automatic guided vehicles wireless charging has widely drawn attention. The displacement of the air gap is inevitable due to tire pressure and spring deformation when vehicles are loaded with various weights. It can degrade the performance of the IPT system because the loosely coupled transformer parameters (self-inductances and mutual inductance) deviate from the designed values due to the position deviation of both sides’ ferrite cores. In this article, a parameter design method based on T-series (T/S) topology is proposed to maintain stable output current versus air gap and load variation. Then, the parameter design process of the T/S topology to improve air gap misalignment performance is elaborated. Finally, a 20 A/1 kW experimental setup was built to verify the validity. Experimental results show that the output current fluctuation is within 4.71% when the load varies from 1.2 to 2.4 Ω and the air gap decreases from 90 to 30 mm (primary self-inductance, secondary self-inductance, and mutual inductance increase by 4.71%, 30.22%, and 121.52%, respectively). Moreover, the overall output current fluctuation is less than 6% when the secondary side moves along the track with the air gap varying from 30 to 90 mm.