Optimum Design of Single-Sided Linear Induction Motors for Improved Motor Performance

Linear induction motors (LIMs) are the best solution to the problem of producing linear motion directly, but the low efficiency, low power factor, and longitudinal end effect (LEE) are their major problems. These problems become more baneful in high-power and high-speed applications. For example, in the transport industry, they lead to high energy consumption, high input current that occupies transmission line capacity, and phase unbalance. Thus, it is necessary to overcome these problems; furthermore, the decrease in motor weight results in lower cost and better performance of linear induction motors. In this paper, first we present an accurate equivalent circuit model (ECM). Then, we introduce a new factor, K_lee, which can illustrate the end effect intensity in the LIM. At the next stage, we investigate the influence of motor design parameters on the efficiency, power factor, and end effect intensity. Then we develop several different muliobjective functions, which will be used to improve efficiency, power factor, end effect intensity, and motor weight. This procedure will be done by analytic method and by using the particle swarm optimization technique. Results will show the accuracy of the equivalent circuit model and the improvement of objective functions at the end of the optimization procedure. Two-dimensional finite-element analysis evaluates the results from the ECM.