Levitation Force Enhancement in Single-Sided Linear Induction Motors

Abstract

Traditional magnetic levitation trains (maglev) generally use two or three separate systems to perform propulsion, levitation, and guidance (PLG) functionalities. Linear electromagnetic motors (LEMs) may be used for propulsion, electromagnetic suspension (EMS), or electrodynamic suspension (EDS) for levitation and guidance. Although considerable effort has been made to integrate these functionalities in a single LEM, a maglev with combined PLG is not yet available. This article proposes a solution to increase the levitation force of a single-sided linear induction motor (SLIM) at medium-to-high speed by adding an appendix of ferromagnetic material to its rear section. The appendix’s role is to conserve the magnetic flux density at the SLIM rear, which would otherwise be unexploited, and use it to generate additional levitation. The impact of the tail size on the levitation force has been modeled and added to an analytical model developed in previous works. The accuracy of the proposed model has been numerically and experimentally validated through f.e.m. and measurements from a custom-made test bench. A sensitivity analysis on the appendix length for a realistic-size SLIM is finally carried out, proving the effectiveness of the proposed solution and demonstrating the potential of SLIMs for combined PLG for medium-to-high-speed magnetic levitation vehicles.