Abstract

Due to the rising energy (and electricity) cost it is essential that an active magnetic bearing (AMB) system is operated as efficiently as possible. Frequency switching caused by an external source can cause an AMB system to operate at a higher than expected energy level and lower than expected efficiency. The purpose of this paper is therefore to investigate the impact of frequency switching (caused by an external source) on the efficiency of a fully suspended AMB system. The shaft of the fully suspended AMB system for this project is mechanically connected and driven by an induction motor and the vertical and horizontal displacements of the driven unit are controlled by means of PID controllers. The model of the fully suspended AMB system with the external fault and the process diagram used for frequency extraction during the fault condition is presented. It is shown that the efficiency of the fully suspended AMB system can be improved by optimizing the controller performance during the external fault condition.

Key words: Active magnetic bearings, efficiency and vibration analysis, induction motor, external faults.