SPREKER

Funda Sahin, Competence Leader Electromechanics, Philips Innovation Services

TITEL

Linear induction motor for magnetic levitation

ABSTRACT

Magnetic levitation and bearing systems implementing permanent magnets (PM) are widely accepted for various high-speed industrial applications. Both at Philips Applied Technologies and at the EPE-group of the TU Eindhoven years of research and development have been conducted on Lorentz force based actuators. Lorentz actuators and levitation systems have significant advantages in terms of overall motor volume, linearity and their relatively simple decoupling algorithms (force/current) for control. The mover or the levitating unit can both be composed of coils or permanent magnets. However, in either case the mover has a significant weight.

Funda Sahin will present a feasibility study of the novel concept of magnetic levitation with a linear induction motor topology (non-PM). It is well known that induction or asynchronous motors have lower force per overall motor volume and are more difficult to control due to the asynchronous speed and it is more challenging to decouple forces and current. On the other hand the mover or forcer can be made of a very thin aluminium or copper sheet. Therefore, the main advantage clearly is that, although the stationary part is relatively heavier than Lorentz based motors, this topology can be used for very high accelerations of the mover because of the extreme low-weight of the mover. Further advantages of this topology are lower material costs and ease of assembly due to the absence of magnetic attraction forces and sustainability due to the avoidance of rare-earth materials.

The presented work is based on analytical modelling, FEM modelling, and measurements conducted on a single-sided linear induction motor, capable of 300 N thrust force. The mover is only composed of a 1 mm aluminium sheet, glued on a 3 mm thick steel plate. The steel plate is not compulsory, but just used to strengthen the magnetic field in the experimental set-up. The future outlook is to apply thrust and normal forces on a thin aluminium sheet.

This concept is advantageous for all industrial applications which require very high accelerations and consequently benefit from a lower weight of the mover.