Suppression of Multi-Harmonic Currents in the High-Speed Magnetically Suspended Motor Based on Adaptive Cascaded Notch Filters with Variable Phase Angle

Abstract

Rotor imbalance is identified as one of the predominant vibration sources in high-speed magnetically suspended motors. Due to factors such as rotor machining accuracy errors and uneven material distribution, synchronous vibration interference is caused. Moreover, sensor runout generates harmonic currents, which are attributed to material irregularities and inhomogeneity in the roundness of the sensor detection surface. Harmonic currents can generate harmonic vibrational forces that are transmitted to the motor housing, jeopardizing control accuracy and the device’s operational lifespan. In order to achieve real-time reduction of harmonic currents at specified frequencies and improve the accuracy of harmonic suppression, this paper proposes an algorithm for variable phase angle filtering of an adaptive cascaded mode notch filter. This paper performed dynamic modeling and analysis of the magnetically suspended rotor system with rotor imbalance and verified the correctness of the dynamic model. Subsequently, the structure of an adaptive notch filter with variable phase angle is introduced, highlighting the capability to maintain stability by adjusting the compensatory phase of the system. By comparing the harmonic current suppression performance of cascaded and parallel mode notch filters, the cascaded method can better enhance the overall frequency selectivity, emphasizing its ability to adjust the compensation phase based on the phase angle of the input signal at different frequencies to maintain system stability. Simulation and experimental results show that harmonic currents can be successfully suppressed in the cascade mode, and the amplitude of the synchronous frequency current is reduced by 94.4%.