A control system of an electromagnetic bearing

Abstract

A three-loop control system for the radial electromagnetic bearing of powerful rotating machines is proposed, the working clearances in which between the stator and rotor amount to tenths of a millimeter with a rotor weight of about 1 t. In the open state, the system is unstable and has features that need to be taken into account when creating the controllers. The control system is designed in accordance with general principles typical for the systems of subordinate regulation. The problems of design of the pulse-control system and various variants of constructing the internal current loop were considered. For calculating the parameters of controllers, the method of transfer functions and z-transformation method were used. At the initial stage, the internal current loop was investigated and it was revealed that the construction of the current loop of an electromagnetic bearing with a relay controller operating in a sliding mode is the most appropriate. In accordance with the mathematical model of an electromagnetic bearing and corresponding structural diagrams, simulation models were designed in the MATLAB/Simulink software package. As a result of simulating the pulsed control system of an electromagnetic bearing, oscillograms of transient processes under control and disturbance effects were obtained. Analysis of transient processes during simulation revealed that electromagnetic bearings equipped with a three-loop control system have a high static rigidity and high operating speed. The obtained results were used in constructing a control system using the electromagnetic bearing of the gas pressurizer at the Pomarskaya compressor station.