Reduction of the High-Speed Magnetically Suspended Centrifugal Compressor Harmonic Vibration Using Cascaded Phase-Shifted Notch Filters

In the active magnetic bearing (AMB)-rotor control system, rotor mass unbalance and displacement sensors runout will bring about harmonic current, which would further result in vibration force transmitted to machine housing. The undesired machine vibration would pose a potential threat to system stability and performance degradation. In order to attenuate harmonic current, this work has proposed a scheme of control system with cascaded mode phase-shift notch filters, and the system stability has been analysed. The harmonic current reduction performances of the system with cascaded mode notch filters are compared with that with parallel mode notch filters. Theoretical analysis has demonstrated that the proposed cascaded mode control system could achieve the same suppression performance as the commonly used parallel mode control system, which is also verified by simulation results. Experiments carried out on a high-speed magnetically suspended centrifugal compressor have validated that the proposed method is effective for harmonic current reduction.