Research On Control System Of Consequent-pole Bearingless Permanent Magnet Motor

As the special rotor structure of consequent-pole bearingless permanent magnet motor, the coupling of the motor between the levitation and torque system is greatly weakened. So the control system of the motor can be designed respectively. The reliability of the whole system is enhanced. Thus, it has extensive applied foreground in national defence, industry, agriculture, daily life, and so on.This paper takes a consequent-pole bearingless permanent magnet motor for control object and its control system for research object, and the following work has been accomplished.Firstly, a profound theoretical analysis on mechanism of levitation for a consequent-pole bearingless permanent magnet motor is presented and its mathematical model is also analyzed. This paper explains the reason in theory that the decoupling between levitation and torque system and how it can avoid the compromise between radial suspension force and drive torque. Based on above theoretical analysis and considering the interaction of the inner variable in the motor, a mathematical model of the motor in the form of state space has been established to convey various connections in the motor.Secondly, PID control algorithm is extensively used in control system of the bearingless motor, but its parameters tuning are always assured by trial and error and there is no regulation to abide by. This paper makes an intensive study of mathematical model and control system of the motor and simplifies the levitation system of the motor. Based on the simplified levitation system model and linear regulator design theory, a regulation about how to assure a PID controller and how to tune parameters has been introduced. The validity of the parameters tuning regulation has been tested through circuit loop and displacement loop simulation in the levitation system. PID control algorithm, which concentrates on input and output of a system, cannot convey various connections in the system. In order to introduce modern control into control system of the bearingless motor, a state feedback tracking controller, which is based on the mathematical model of the motor in the form of state space, is designed by linear system theory. The validity of the control algorithm has been tested through load and unload experiment of the torque system simulation and anti-disturbance capability, parameters variation experiment of the levitation system simulation.Finally, the control algorithm based on linear theory, which depends on the model of the control object, cannot apply to engineering practice. In order to achieve stable suspension of the motor, the active disturbance rejection control (ADRC) algorithm has been selected, which is practical nonlinear control strategy and can be applied to nonlinear and strong coupled control object. The validity of the ADRC algorithm has been tested through various working condition simulation such as constant disturbance, step disturbance, impulsive disturbance, white-noise disturbance, sinusoidal disturbance and parameters variation .In this paper, the active disturbance rejection control program of the levitation system has been written based on DSP F2812 and the levitation system close-loop experiment has been achieved. At last the torque system close-loop experiment has also been achieved base on the active disturbance rejection control of the levitation system.