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Sensors 2013, 13(12), 16000-16022; doi:10.3390/s131216000

Field Balancing of Magnetically Levitated Rotors without Trial Weights

1,2,3,* , 1,2,3
1 Key Laboratory of Fundamental Science for National Defense, Beihang University, Beijing 100191, China 2 Science and Technology on Inertial Laboratory, Beihang University, Beijing 100191, China 3 School of Instrument Science and Opto-Electronics Engineering, Beihang University, Beijing 100191, China
* Author to whom correspondence should be addressed.
Received: 20 August 2013 / Revised: 11 November 2013 / Accepted: 11 November 2013 / Published: 25 November 2013
(This article belongs to the Section Physical Sensors)


Unbalance in magnetically levitated rotor (MLR) can cause undesirable synchronous vibrations and lead to the saturation of the magnetic actuator. Dynamic balancing is an important way to solve these problems. However, the traditional balancing methods, using rotor displacement to estimate a rotor’s unbalance, requiring several trial-runs, are neither precise nor efficient. This paper presents a new balancing method for an MLR without trial weights. In this method, the rotor is forced to rotate around its geometric axis. The coil currents of magnetic bearing, rather than rotor displacement, are employed to calculate the correction masses. This method provides two benefits when the MLR’s rotation axis coincides with the geometric axis: one is that unbalanced centrifugal force/torque equals the synchronous magnetic force/torque, and the other is that the magnetic force is proportional to the control current. These make calculation of the correction masses by measuring coil current with only a single start-up precise. An unbalance compensation control (UCC) method, using a general band-pass filter (GPF) to make the MLR spin around its geometric axis is also discussed. Experimental results show that the novel balancing method can remove more than 92.7% of the rotor unbalance and a balancing accuracy of 0.024 g mm kg−1 is achieved.
Keywords: field balancing; magnetically levitated rotor; no trial weights; unbalance compensation control field balancing; magnetically levitated rotor; no trial weights; unbalance compensation control
This is an open access article distributed under the Creative Commons Attribution License (CC BY 3.0).

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Fang, J.; Wang, Y.; Han, B.; Zheng, S. Field Balancing of Magnetically Levitated Rotors without Trial Weights. Sensors 2013, 13, 16000-16022.

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