Motion control for short primary linear drive using induction or synchronous operation in different sections for material handling aplications

The moderate thrust force and high accuracy make the short primary linear motor a good selection for material handling application with very long track and closed paths. This paper deals with the motion control of a linear drive which operates at some sections of the track as synchronous machine and for other sections as induction machine. Unlike applications with long primary linear motors, the costs can be considerably reduced by using an active vehicle on a passive track. In sections where no fast speed changes are necessary, a sensorless speed control method is used. A suitable vehicle motion control strategy is necessary especially during the transition between synchronous to induction motor operation and between sensor based to sensorless region operations. The classic MRAS (Model Reference Adaptive System) speed and flux estimators are activated in the sensorless induction motor operation mode. The transition control strategies are experimentally verified, discussed and presented.