Investigation of a Linear Induction Machine for a Railway Braking Application

Linear induction machines have been employed in the railways for several decades for traction and braking, using an additional “reaction” rail. Linear DC eddy current brakes have also been adopted to provide braking forces by inducing eddy currents in the existing running rails, but at the expense of considerable rail heating. This paper focuses on the concept design of an induction machine that operates at low slips to develop longitudinal braking forces as well as increased adhesion through vertical attractive forces with minimal rail losses. Several candidate topologies were compared using 2D finite element analysis (FEA), whilst 2D and 3D FEA as well as a static test rig were used to analyse and validate the static and dynamic performance of the final design. The simulation and physical test results showed reasonable agreement, and demonstrated that the concept is able to meet the vertical force target at a minimal rail loss.