Improved field oriented control of an LIM having joints in its secondary conductors

This paper presents a primary-flux-control algorithm suitable for applications in short-primary long-secondary linear induction motor-drive systems. The advantage of the proposed control algorithm is that it is more robust than the conventional vector control algorithm to the variation of the secondary resistance caused by the effect of a joint in the secondary conductors, which can be made of several pieces of aluminum plates or rails joined together. The algorithm was tested by simulation on a sample of linear motor disk-drive system. The simulation results were compared to those obtained by a conventional vector control algorithm. Simulations and experiments have shown that the fluctuations of the thrust and attraction forces obtained with the proposed primary-flux control algorithm were significantly less than those obtained with the conventional vector control algorithm.