A Reliable Magnetic Suspension System using a Single Level Discrete Controller

J.N. Santoso, S.K. Mukherjee, and A.M. Abdelrahman (Malaysia)


Magnetic suspension, PD controller, nonlinear system, discrete control


This study presents a discrete magnetic suspension system using a simple control strategy, which relies on a single decision plane. The proposed system deploys an infrared (IR) emitter detector pair with a beam width of 2mm to detect the suspended iron ball. Whenever the ball intercepts the IR beam the uncompensated proportional derivative (PD) controller switches on the current flow to the electromagnet (EM) which pulls up the iron ball. After a while the PD controller becomes unstable and pushes the ball above the IR beam, meanwhile the controller switches off the EM current flow and consequently drops the ball as the suspension force becomes less than the gravitational force. And again, while intersecting the IR beam, the pulling process will be started. The experiments have proved that the suspension is possible for a wide air gap, ranges from 3mm to 10mm. The simulation results corroborate the experimental ones. It has been found that the low current consumption is one of the major advantages of the proposed system.

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