Jinlei Li

For the influence of residual unbalance and sensor error on the micro-vibration control accuracy of magnetically suspended rotor system, a high-precision harmonic vibration force suppression method using finite dimension adaptive filter is proposed. The double-input finite dimension adaptive filter is constructed by using the orthogonal characteristic of the output signals of the rotor radial X and Y displacement sensors. On the basis of harmonic current suppression, the power amplifier is taken as a controlled object, and a displacement stiffness force feedforward compensation loop is constructed. The influence of the low-pass characteristic of the power amplifier is fully considered, and the error free tracking characteristic of the adaptive filter is used to make the deviation of the synchronous input signal zero, and then the high-precision compensation of the synchronous displacement stiffness force is realized. In addition, by changing the gain factors of different sub-filters, the suppression effect at each harmonic frequency can be guaranteed, and finally the micro-vibration control of the magnetically suspended rotor system can be further realized. The feasibility and effectiveness of this method are verified by experimental research.

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The AMB-rotor system is complex and has strong coupling characteristics, which allows multi-harmonic disturbances to enter the system through different ways to produce vibrations with rich spectrum components, which has a great influence on the improvement of micro-vibration accuracy of the rotor system. To further achieve active control of the micro-vibration in the AMB-rotor system, firstly, the mechanism of multi-source disturbance is analyzed according to the working principle of the AMB-rotor system, and the mathematical and physical relationship between the mechanism of disturbance generation and the inducement is deeply studied. Then, the structure of a novel adaptive notch filter, the method of adaptive frequency estimation and analysis of harmonic current suppression in the AMB system are presented. Finally, simulation and experimental research using an MSCMG system demonstrate the feasibility of the proposed method regarding the elimination of harmonic control current.

The machining accuracy error makes the rotor inevitably have residual unbalance, which generates unbalanced vibration force through the magnetic bearing closed-loop control system. For magnetically suspended rotor system, the suppression accuracy of unbalanced vibration force largely depends on the accuracy of modeling of magnetic bearing closed-loop control system. Aiming at the problem of high-precision suppression of unbalanced vibration of magnetically suspended rotor system, this paper carries out dynamic modeling of magnetically suspended rotor, combined with controller model and power amplifier model, and analyzes the motion characteristics of rotor system under the action of residual unbalance, so as to reveal the action law of rotor self -centering effect and unbalanced vibration force. Finally, the dynamic model and self-centering effect of the magnetically suspended rotor system built in this paper are simulated and experimentally studied, which also lays a theoretical and model foundation for the subsequent realization of high-precision suppression of unbalanced vibration force.

A field dynamic balancer is crucial to the applications of magnetically suspended turbomolecular pumps. Therefore, this paper presents a novel field dynamic balancing method based on autocentering control mode without any additional instrumentation. Firstly, the dynamics of the active magnetic bearing rotor system with unbalance are modeled. Through model analysis, it was found that making the rotor rotate around the geometric axis can improve the accuracy of dynamic balancing. Secondly, the relationship between the correcting masses and the synchronous currents based on the influence coefficient method is established. Then, an autocentering controller is designed to make the rotor rotate around the geometric axis. The synchronous currents can be detected and extracted by the current transducers to calculate the unbalance correction mass. Finally, the experimental results show that this novel field dynamic balancing method can effectively eliminate the majority of rotor unbalance. Compared with the original unbalance of a rotor, the synchronous current in the A-end has been reduced by 71.4% and the synchronous current in the B-end, by 90.8% with the proposed method.

The harmonic vibration force generated by multisource disturbances through the magnetic bearing closed-loop control system seriously affects the improvement of the performance of the magnetically suspended control moment gyroscope (MSCMG). The harmonic noise introduced by the displacement sensor generates harmonic components through a closed-loop control system, and the compensation accuracy of synchronous displacement stiffness force is reduced by the low-pass characteristics of the power amplifier. In this letter, the rotor displacement signal and current signal are used as inputs to the repetitive controller and notch filter, and the power amplifier and repetitive controller are constructed into three closed-loop systems to achieve high-precision suppression of harmonic vibration forces. Finally, the effectiveness of the method is demonstrated by using a 200-N $\cdot$ m $\cdot$ s MSCMG and a microvibration test system.

The mass imbalance of the rotor will produce the synchronous vibration force that is transmitted to the magnetically suspended control moment gyroscope (MSCMG) through the magnetic levitation stator, which affects the imaging performance of the satellite. The suppression of the synchronous vibration force needs the speed signal. In order to solve the synchronous vibration force of the MSCMG when the speed measurement sensor fails, this article proposed an modified double second-order generalized integral frequency-locked loop (SOGI-FLL) method, which uses the frequency of the disturbance signal generated through the mass imbalance of the rotor to adaptively estimate the rotor speed and suppress the synchronous vibration force generated by the active magnetic bearing system. The phase compensation is introduced to ensure the stability of the system in full frequency band. The electromagnetic force is directly used as the input signal of the control algorithm to achieve zero magnetic force control. Simulation and experiment are carried out, and the results are given to prove that the algorithm proposed in this article can accurately estimate the rotation speed and achieve the vibration force suppression in the full rotation speed range. It is of great significance for the high-precision control of the active magnetic bearing (AMB) rotor system.

The controller contains harmonic components due to the detection error of the displacement sensor. The harmonic component acts on the magnetic bearing coil in the form of harmonic current, resulting in undesirable harmonic vibration force, which is not conducive to the microvibration control of active magnetic bearing (AMB) rotor system. In order to solve the problems of slow response speed and limited harmonic frequency range in series mode, an improved resonant controller in parallel mode is proposed in this article, which greatly improves the response speed of the system and the suppression effect at harmonic frequency. In addition, the gain and phase angle at each harmonic frequency can be adjusted, so the robustness of each harmonic frequency can be independently controlled, and the system stability can be guaranteed in a wide range of operating speeds. Finally, the effectiveness of the proposed algorithm is verified by simulation and experiment, which has important significance and application value for harmonic current suppression of AMB-rotor system.

In rotating machinery, the rotor mass unbalance will cause synchronous vibration, in which static unbalance will produce synchronous vibration force, and dynamic unbalance will produce synchronous vibration moment. In order to suppress the vibration moment of the magnetically suspended control moment gyro, a modified dual-channel notch filter (DNF) is proposed in this article. First, the modeling of the rotor system with mass unbalance is performed. Then, the design of modified DNF is carried out. This notch filter uses the equivalent vibration moment calculated by the current and displacement signals as input, and uses the orthogonal characteristics of the moment signals in the X and Y directions to enter the controller at the same time. The stability of the rotor system with a DNF is proven. Finally, the experimental results are given to show that this method can effectively eliminate the synchronous vibration moment in the rotor system.

The active magnetic bearing rotor in magnetically suspended control moment gyro (MSCMG) will produce unbalance vibration due to the mass unbalance, and the frequency equal to the rotation speed. In order to suppress the unbalance vibration of MSCMG, the working principle of the active magnetic bearing (AMB) is introduced and the unbalance vibration model is established. And then, a high-precision closed-loop detection method of the synchronous signal based on synchronous rotating frame transformation (SRFT) is proposed. This method can detected synchronous signals in two directions at the same time, with less calculations. The synchronous current is suppressed by detecting and compensating the synchronous component in the output signal of the displacement sensor, which can reduce most of unbalance vibration. The phase modulation angle is introduced to make the algorithm have a wider stable range. In order to simplify the analysis method, the orthogonal characteristic of the output signal of the displacement sensor is used to equalize the dual output system to a complex-coefficients single-input system, and the dual frequency Bode diagram is used to analyze and evaluate the stability of the system. Finally, experimental results are given to verify that this method can effectively suppress synchronous current.