Vibration control and experimental study of flexible rotor in magnetically suspended motor

In order to solve problems confronted when the magnetic suspended rotor pass through the first bending critical speed, an integrated vibration control method is presented. To ensure the accuracy of the controller design, the online sweeping technology is used to certify the model of every segment of the magnetic bearing system. Based on incomplete differential PID controller, a fixed central frequency notch filter is designed to suppress the second bending mode. According to damping characteristics of the equivalent control system, the phase compensator is used to suppress the first bending mode. Considering large second-order flexible unbalanced mass, a general notch filter is applied when the rotor has crossed over the first bending critical speed based on the minimum current control standard to make the power amplifier work in the smallest current state to avoid amplifier voltage saturation. Experimental results show that the integrated controller effectively suppress the first and second rotor bending mode, and the rotor successfully cross over the first bending critical speed. In additional, the maximum displacement amplitude in the first bending mode frequency of the rotor is 5% of the protection gap of the catched bearing, and finally the rotor stably operating above the rated speed 34 000 r/min.