Reducing magnetic flux leakage of linear induction motor by chamfering method

Linear Induction Motor (LIM) which is also known as non-adhesion drive system has been chosen as propulsion system for most of mass transit railway all over the world. This is due to several advantages such as quiet and smooth running, no mechanical coupling, capable of climbing steep gradients, excellent acceleration and deceleration, and less susceptibility to weather condition. However, the disadvantages of LIM is it has finite length of the primary or secondary parts thus causes end effects also called discontinuous airgap flux phenomenon. Assymmetric airgap magnetic flux density at end parts of LIM produces unbalanced normal force which is airgap tends to increase at the entry and decrease at the exit part. This unbalanced normal force adversely affect the performance of the LIM propulsion system. Main objective of this research is to reduce magnetic flux leakage that leads to end effect phenomenon thus proves effectiveness method of chamfering in weakening end effect phenomenon. In this research, there will be 3 models of LIM. First is known as reference LIM which is LIM with no chamfered angle. Two others are LIM with chamfered angle 30° and 45°. Software used in this research is JMAG-Designer. Reference and chamfered LIM 2D models consists of mover (primary), coil, aluminium sheet, and stator (secondary) are created using Geometry Editor included in JMAG-Designer. After running analysis 3 different models of LIM following parameters given, results were displayed in the form of tables that indicates value of magnetic flux for 3 phase current (U, V, W). Graph is being drawn to make views of these results more clearly and precisely. X-axis in the graph indicates times whereas Y-axis in the graph indicates value of magnetic flux for 3 different model of LIM. After that, figure of distribution of magnetic flux density for 3 models of LIM is shown. From the results, chamfering is proven to reduce end effect at the LIM. At the end, chamfered angle 45° LIM has highest number of magnetic flux, least leakage flux, least end effect thus has highest thrust value for LIM propulsion system