Design Of Permanent Magnet Bias Magnetic Bearing And Its Controller

Magnetic bearing is a new type of high performance bearing that can make its rotor suspended in space by the magnetic force, there is no mechanical contact between its rotor and stator. It’s often used to implement high-speed motor rotor’s suspension in the modern industry. The magnetic bearing has fundamentally changed the traditional form of bearing’s support for the advantages of no pollution, no lubrication, no friction, no wear, high speed, high precision, low power consumption etc. And it overcomes the disadvantages of the liquid and air bearings that demand the independence of hydraulic and pneumatic system, complex structure, large volume and low efficiency. This is the reason of especially suitable for high speed, vacuum, ultra clean and other special applications. It is a typical electromechanical integration product with high technology and high-added value. The performance of Magnetic bearing is determined by its control system. With the development of the computer technology, automatic control technology and microelectronics technology, its application is becoming more and more extensive.First of all, this paper introduces the magnetic bearing’s fundamental theory and the classification, and discusses the research status at home and abroad, puts forward the Permanent Magnetic Biased Magnetic Bearing (Hybrid Magnetic Bearing) with excellent characteristics. Then, the Permanent Magnet Biased Magnetic Bearing is analyzed and studied, and its working principle and mathematical model are discussed. The structure parameters based on the bearing capacity of 2-degree freedom radial Permanent Magnet Biased Magnetic Bearing are designed through the magnetic circuit analysis, as well as the protect bearing and loss of the bearing are described briefly.Secondly, the finite element method based on the variation theory is applied for the values analysis of the magnetic bearing’s electromagnetic field.The entity model of the magnetic bearing for this paper is constructed by the finite element analytical software Ansoft mawell. And this paper uses 3D nonlinear finite element method to calculate the electromagnetic field distribution of magnetic bearing in balance and deviation state. Then the magnetic flux density and magnetic field strength are calculated, and the correctness of the structure design is verified.Finally, the control system which is the other important part of the Permanent Magnet Biased Magnetic Bearing is elaborated in this paper. The control system includes displacement sensor, power amplifier and the controller who is the core part of the control system, the parameters of PID controller are set and the controller is simulated with MATLAB.It has tested and verified the PID controller can make the rotor restore to the balance position after disturbed by the external force.