Study On Active Magnetic Bearings And The Control Method

Magnetic bearing is a bearing that to use the magnetic force to let the bearing without mechanical contact suspended in space. It is a new high-performance bearings, which has many good quality such as no mechanical loss, high-speed, no lubrication and bearing kinetic parameters adjustable. Its main application is currently concentrated in the fields of conventional bearings can not be qualified. Most developed product is still in the laboratory stage, and there is a gap from the large-scale application in bearing aspect of stiffness and load capacity. In order to make magnetic bearings can be widely applied in more fields, this paper will systematically study on the entire magnetic bearing system design process, specific tasks include:First, establish the basic magnetic bearing linear model. Describes the calculation method of the magnetic flux density of magnetic bearing electromagnet, by the magnetic bearing electromagnet magnetic circuit analysis. Derived formula of magnetic bearing electromagnetic force. Make a linearization of the relationship between the electromagnetic force with the control current and the air gap, and then proposed the mathematical expression of magnetic bearing closed-loop control system.Secondly, the general model of 8-pole differential active magnetic bearings will be derived. Study on the design basis of magnetic bearing electromagnet geometry in engineering application. Select the models of stator electromagnet silicon, and select the work area and the bias flux. Design the geometry of magnetic bearing stator and rotor, and verify the results of the design.Third, to simulate the designed magnetic bearing stator electromagnet electromagnetic by the finite element analysis software Ansoft. Verify the magnetic bearing electromagnets have the ability to provide electromagnetic force that could make it back to equilibrium position when the rotor is generated disturbance offset. The designing magnetic bearing structure will be processed, to complete the assembly of the magnetic bearing stator core, sensor loading ring and rotor assembly.Finally, introduce the principle of eddy current sensor, design of differential eddy current sensor circuit, and use simulation software Proteus to study on the designed circuit. Describes the basic theory and characteristics of PID control, and do simulation research with the PID control.