Harmonic Current Suppression of AMB Rotor System Based on Improved Multiple SOGI-FLL

In active magnetic bearing (AMB) systems, harmonic currents induced by mass unbalance and sensor runout cause the system to generate harmonic vibrations. Conventional harmonic current suppression methods depend highly on accurate rotational speed information, which limits their application in scenarios without rotational speed sensors. To address this problem, this article first analyses the main sources of harmonic vibration and then proposes an improved multiple second-order generalized integral frequency-locked loop (IMSOGI-FLL) algorithm. The algorithm achieves adaptive estimation of the rotational frequency by using the frequency of the fundamental component in the disturbance signal and effectively suppresses the harmonic currents generated by the mass unbalance and sensor beating. In addition, in order to ensure the stability of the system in the operating range, this article designs a simple phase compensator without parameter switching, which can improve the stability range of the system in the low-frequency band. The experimental results show that the proposed algorithm can not only accurately estimate the rotational frequency but also significantly eliminate the harmonic currents caused by mass unbalance and sensor runout, which provides an effective solution for harmonic current suppression in the case of no speed sensor.