High performance control in ultra-low speed range of inverter-fed linear induction motor using vector control scheme

A LIM (linear induction motor) driven rotationally by setting three-phase stator windings at the periphery of the disc is considered. The disc is a composite of aluminum and iron and is operated as the secondary conductor of an induction motor. Vector control was applied to the LIM, and experimental results were obtained. The LIM realized a stable ultralow constant speed control without speed ripple under a thrust load of 35 kgf at the ultralow speed of 0.3 m/min. by vector control. Vector control has enabled a soft and shockless start and stop, and also an accurate positioning control with a precision of ±1.0 mm for the speed command. These results demonstrate that the LIM which is constructed as a rotational motor can be used as a direct drive motor