Experimental Compensation of Runout and High Order Harmonic Effects in Lorentz Force Type Integrated Motor-Bearing System

Abstract

An integrated motor-bearing system integrates the functions of an active magnetic bearing and an electric motor into a single unit. Because this system requires the simultaneous generation of torque and radial control force, there will inevitably be undesired high order harmonic components in the rotating magnetic field, which will result in torque ripple and radial force distortion. Sensor target runout is a severe excitation source and, as such, causes a lot of vibration. In this paper, we propose an experimental compensation procedure for the oscillation and coupling of torque and radial force using a digital controller of the Lorentz force type integrated motor-bearing system in a dual disk rotor configuration. After the compensation of high order harmonics, the runout profile and rotor unbalance are identified by the extended influence coefficient method. The proposed scheme does not require complicated analysis or modeling of high order harmonic effects, and it can also compensate for manufacturing errors. The experimental results confirm that this compensation method effectively attenuates the rotor vibration throughout the operating range of rotational speeds.

Model development and harmonic current reduction in active magnetic bearing systems with rotor imbalance and sensor runout

“…However, it is complex to design the adaptive algorithm and to analyze its performances, and extensive computational effort is needed even in a onedegree-of-freedom AMB system. The experimental compensation procedure (Park and Lee, 2005), compact wavelets (Cole et al, 2006), adaptive notch filter (Mojiri and Bakhshai, 2007), and response matching (Jiang and Zhu, 2011) can also be used to identify or suppress the multi-frequency vibrations, but these systems have not been comprehensively modeled, hence it is difficult to analyze the controller performance. Moreover, large software resources will be inescapably needed to suppress multi-frequency vibrations, and this is inconvenient, even unavailable, particularly for space applications with central processing unit (CPU) chips of high reliability but low calculation capability (Ren and Fang, 2012).…”