Research And Design Of Electromagnetic Bearing And Its Control System

Magnetic bearing and the support of high-speed motor are the current hot research fields.For high-speed motor with a speed of more than ten thousand revolutions per minute,the supporting device using magnetic bearing is a king of ideal solution,not only between the bearing and rotor without the possibility of mechanical wear,but also has extraordinary advantages of active control through the running state of the rotor bearing.According to the different sources of bias magnetic field in magnetic bearings,there are many types of magnetic bearings.In this paper,studying active electromagnetic bearings which the bias magnetic field is derived from the control system,and mainly according to the following several aspects to study and design its mechanical structure and control system:Aiming at the defects of the existing magnetic bearings and high-speed motor structure is fixed,an eight pole active electromagnetic bearing which is separated from the high-speed motor is designed,it can increase flexibility in magnetic bearing applications.With the help of3 D printing technology,the coil frame of the electromagnetic bearing and the micro probe of eddy current sensor are produced,providing a shortcut for realization.The mathematical model of the electromagnetic bearing control system is established by using a differential winding drive linearization method and its model formula is derived.Based on the finite element analysis software Ansoft Maxwell,the three dimensional electromagnetic field finite element optimization design of the designed electromagnetic bearing is carried out,which provides an accurate carrier for the research and design of the control system.Achieving a differential amplitude modulated eddy current sensor which can eliminate the error due to the component manufacturing process dispersion,and the two probe differential demodulation method is used to measure the rotor bearing in the single degree of freedom,which can improve the control precision of rotor position.The PWM power amplifier hardware circuit of the electromagnetic bearing control system is researched and realized by using the analog control method.The simulation results show that the three level drive strategy can reduce the amplitude of current ripple on the coil.Study on the electromagnetic bearing displacement/current double closed-loop control system.Based on Simulink,the current inner loop and displacement outer loop model of the electromagnetic bearing control system are established,and the PI and PID parameters are adjusted.For the current inner loop,studying a modeling method of power electronics.The simulation results show that the method is feasible and can be used as the reference for the modeling of the current inner loop and regulator parameters setting.