Suspension Characteristics of Magnetic Suspension System by Linear Induction Motor

Abstract

To protect products from the dust in the factory automation system, various conveyance systems, which make use of magnetic suspension, have been considered and investigated. We have been investigated an alternative magnetic suspension system by linear induction motor (LIM) and obtained the stable suspension characteristics.
This system has linear induction motor as the primary guide way, and an U-shaped iron core is fixed on the center top of the vehicle. The vehicle is kept near the directed position by changing the repulsed motion and the attracted motion by switching the short-circuit and open circuit of the coil wound on the U-shaped core. To simplify the system structure, the driving magnetic field of linear induction motor, which is excited by three phase voltage, is used for both the suspended force and the driving force. To obtain the stability of the suspended motion of this system, the gap displacement and the calculated velocity of the displacement are used for the switching control. In this paper, we report the details of the stable suspension characteristics of the system and the transient chracteristics.