Online control of thrust and flux in linear induction motors

A PC-based control of thrust and primary flux is presented for a single-sided linear induction motor (LIM). Online control is achieved by proposing a thrust-estimating algorithm which also leads to speed estimation. Good agreement is observed between the estimated and measured results for the primary speed, which can lead to the elimination of the control system from the speed-measuring equipment. Since the LIM has been built as a prototype for a larger system, a five-level GTO inverter is used to drive the motor. Space-vector modulation with hysteresis controllers provides a flexible control system. The experimental and simulation results verify the proposed system.