Robust odd repetitive controller for magnetically suspended rotor system

The magnetically suspended rotor (MSR) system has advantages of no lubrication, adjustable stiffness, and damping. However, harmonic current induced by mass unbalance and sensor runout will cause harmonic vibration. Wherein, odd-harmonic current occupies the main components of harmonic current in the MSR system and its fundamental frequency is fluctuant. Thus, it is very necessary to suppress odd-harmonic current in the MSR system. The conventional repetitive controller has been proven to be an effective control method to suppress periodic signals in MSR. With notable results on the area, this method appears a deteriorative performance when harmonic current fundamental frequency is fluctuant. To enhance the robustness of the control system, a novel robust odd repetitive control method is investigated in this paper. Experimental results are given to verify the effectiveness and superiority of the proposed method.