Suppression of Harmonic Current in Active–Passive Magnetically Suspended CMG Using Improved Repetitive Controller

Active-passive magnetically suspended control moment gyro is a novel attitude control actuator for superquiet satellite. Harmonic current in its active magnetic bearing will be caused by mass unbalance of the rotor and sensor runout. It can generate multifrequency vibration and then degrade the pointing accuracy of the superquiet satellite. In this paper, an improved repetitive controller (RC) is proposed to suppress harmonic current validly. The low-pass filter in improved RC is put from internal loop to outside for reducing the tracking error of harmonic current. Phase compensators are designed to compensate the phase lag in high, middle, and low frequencies for enhancing the stability of magnetically suspended rotor system, respectively. Simulation and experimental results are given to show the validity and superiority of improved RC in harmonic current suppression.