Suppression of harmonic current in magnetically suspended rotor system based on frequency adaptive fractional compensation RC

Due to the existence of mass unbalance and sensor runout, magnetically suspended rotor (MSR) system will generate harmonic current. The ratio of sampling frequency to fundamental frequency of the harmonic current is not always an integer. However, the existing repetitive controller (RC) for harmonic current suppression of MSR can only compensate for the cases where the ratio is an integer, so the accuracy will be degraded. To address this issue, a frequency adaptive fractional compensation repetitive controller (FCRC) that combines integer delay link and fractional delay link is proposed in this paper. Meanwhile, the low-pass filter in the feedback loop is moved to the outside of the loop. To verify the feasibility and superiority of the proposed method, experiments are carried out.