Gain-Scheduled Control of Asymmetric Thrust Magnetic Bearing

Abstract

The thrust position of the magnetic levitation rotor can be changed, bringing convenience to the practical application of cold compressors. This paper derives the mathematical model of asymmetric thrust magnetic bearings for a cold compressor and analyzes the changes in the system characteristics with the equilibrium position. By constructing PID controllers associated with the structural parameters of the magnetic bearing, the adaptive adjustment of the control parameters under different balanced position commands is realized. The simulation and experimental results prove that the gain-scheduled control method proposed in this paper can achieve a robust stability of the rotor in the range of 50 to 350 μm, and not at the cost of the response speed, adjustment time, and overshoot. The research results have reference significance for the structure design of asymmetric thrust magnetic bearings and play an important role in the commissioning and performance improvement of cold compressors.

Keywords

• asymmetric
• thrust magnetic bearings
• gain-scheduled control
• PID
• changing balanced position