Study On Dynamic Decoupling And Unbalance Vibration Control System Of Bearingless Induction Motor

Bearingless induction motor is a combination of magnetic bearing and normal induction motor, with both advantages and functions of them, so it has wide application prospect in many fields. But the operation mechanism of bearingless induction motor also determines that it is a complex nonlinear controlled object with strong coupling characteristics, realizing the dynamic decoupling between each controlled variable is the premise for its high performance operation. Moreover, the inevitable rotor mass eccentricity problem can also lead to the unbalance vibration of rotor, which will influence the control precious of suspension system. Therefore, it is important to study on the dynamic decoupling and unbalance vibration compensation control of bearingless induction motor.In this paper, starting from the operation mechanism of bearing induction motor, the mathematical model of the motor is derived, and also the dynamic decoupling control strategy based on inverse system method and the unbalance vibration compensation method based on minimum rotor vibration displacement principle is studied. The main research work includes:1. In the rotor field oriented reference frame, considering the influence of the dynamic characteristic of stator winding current, the state equation of bearingless induction motor is established, and the inverse system decoupling control strategy based on voltage control is studied. The theoretical analysis and simulation results have shown that: the control strategy does not only effectively realize the dynamic decoupling between the speed, flux linkage and radial displacement, but also simplify the structure of the control system to some extent.2. To further simplify the inverse model of suspension system, the inverse decoupling control strategy of suspension system based on torque system’s synthetic air gap flux is studied. The theoretical analysis and simulation results have shown that: the control strategy can achieve good decoupling performance, and the decoupling operation of suspension system can be effectively simplified.3. The cause of rotor’s unbalance vibration is analyzed, and two extraction method of rotor’s unbalance vibration displacement based on rotating transform filtering and LMS adaptive filter are proposed according to the characteristics of unbalance vibration displacement signal, simulation results have verified the effectiveness of these two methods.4. Feedback plus feedforward compensation controller and adaptive feedforward compensation controller are designed to compensate rotor’s unbalance vibration. The simulation results have shown that: the two kinds of compensation control strategy can effectively suppress the unbalance vibration of rotor, thus improving the suspension control precision.The dynamic decoupling and unbalance vibration compensation control strategy proposed in this paper can provide theory and technique foundation for the research and development of high performance controller of bearingless induction motor.