Synchronous Vibration Moment Suppression for AMBs Rotor System in Control Moment Gyros Considering Rotor Dynamic Unbalance

2021 ◽  
pp. 1-9
Author(s):  
Peiling Cui ◽  
Liang Du ◽  
Xinxiu Zhou ◽  
Jinlei Li ◽  
Yanbin Li ◽  
...  
Keyword(s):  
Rotor System ◽  
Control Moment ◽  
Rotor Dynamic ◽  
Dynamic Unbalance

scholarly journals Rotor dynamic experimental investigation of an ultra-high-speed permanent magnet synchronous motor supported on a three-pad bidirectional gas foil bearing

2019 ◽  
Vol 11 (9) ◽  
pp. 168781401987536
Author(s):  
Wenjie Cheng ◽  
Zhikai Deng ◽  
Ling Xiao ◽  
Bin Zhong ◽  
Wenbo Duan
Keyword(s):  
Permanent Magnet ◽  
High Speed ◽  
Permanent Magnet Synchronous Motor ◽  
Synchronous Motor ◽  
Rotor System ◽  
Permanent Magnet Motors ◽  
Foil Bearings ◽  
Foil Bearing ◽  
Ultra High Speed ◽  
Rotor Dynamic

With a 10-kW, 120,000-r/min, ultra-high-speed permanent magnet synchronous motor taken as a prototype, experimental research is conducted on the rotor dynamic behaviours of a three-pad bidirectional gas foil bearing high-speed motor rotor system. Load-carrying properties of the three-pad bidirectional gas foil bearing are analysed, and natural frequencies of conical and parallel whirling modes of the elastically supported rotor are calculated based on an appropriate simplification to the stiffness and damping coefficients of the gas foil bearings. The prototype passes through a 90,000-r/min coast-down experiment. Experiments show that there are violent subsynchronous whirling motions that are evoked by the gas foil bearing–rotor system itself. The cause of shaft orbit drift is analysed, and the corresponding solution is put forward. The theoretical analysis and experimental results can offer a useful reference to the bearing–rotor system design of ultra-high-speed permanent magnet motors and its subsequent dynamic analysis.

Improved Blade Fault Diagnosis Using Discrete Blade Passing Energy Packet and Rotor Dynamics Wavelet Analysis

2010 ◽  
Author(s):  
Meng Hee Lim ◽  
M. Salman Leong
Keyword(s):  
Fault Diagnosis ◽  
Gas Turbine ◽  
Vibration Analysis ◽  
Rotor System ◽  
Field Conditions ◽  
Spectra Analysis ◽  
Vibration Spectra ◽  
Time Frequency ◽  
Blade Tip ◽  
Rotor Dynamic

Blade fault represents one of the most frequent causes of gas turbine failures. Although various measurement methods (i.e. pressure, strain gauges, and blade tip measurements) have been found to be effective in diagnosing blade faults, it is often difficult to deploy these methods under field conditions due to the requirement of mounting sensors in the interior of a running gas turbine. Vibration spectra analysis is inevitably still represents the most widely used method for blade fault diagnosis under field conditions. However, this method is known to be only effective in detecting severe blade fault conditions (i.e. terminal rubbing); whilst, minor and transient blade faults (i.e. geometry alterations, reduction in blade tip clearance, and Foreign Object Damage (FOD) event) are often left undetected. This makes vibration spectra analysis an unreliable tool for total blade fault diagnosis in the field. This study was thus conducted to investigate methods that can improve the sensitivity and reliability of vibration analysis for blade faults diagnosis. Two novel vibration analysis methods were formulated, namely the Rotor Dynamic Wavelet Map (RDWM) and Blade Passing Energy Packet (BPEP). Experimental results showed that the time-frequency display of RDWM could provide a clearer picture of the rotor dynamic characteristics of a rotor system compared to vibration spectra. RDWM also provides a better visualization of the blade condition in the rotor and enables discrimination of various blade fault conditions (i.e. creep rub and eccentricity rub). Meanwhile, the BPEP method which breaks the overall Blade Passing Frequency (BPF) component into instantaneous and discrete energy packets of running blades in the rotor system, enables a more sensitive detection of rotor eccentricity conditions and provides early warning for impending blade rubbing which is often undetectable in the vibration spectra.

Active vibration control of rotor-bearing system by virtual dynamic absorber

2019 ◽  
Vol 86 (3) ◽  
pp. 30901
Author(s):  
Behnam Monjezi ◽  
Hamidreza Heidari
Keyword(s):  
Transient Response ◽  
Control Method ◽  
Active Vibration Control ◽  
Resonance State ◽  
Rotor System ◽  
Manufacturing Defects ◽  
Resonance Frequencies ◽  
Active Vibration ◽  
Dynamic Absorber ◽  
Rotor Dynamic

The main sources of the vibration in rotor dynamic systems are unbalanced masses and manufacturing defects of bearings used in the rotor system. In this study, magnetic absorber as a new method brings the rotor system out of resonance state by applying a dynamic absorber system force and creating two new natural frequencies. This study virtually reconstructed magnetic absorber controller software as a combined active and passive dynamic absorber to reduce vibration amplitude, efficiently. In this approach, combined routes are defined for the rotor frequency response, so that the optimal values of the parameters of dynamic absorber system are calculated using H∞ method and maximum damping for frequencies lower and higher than resonance frequencies, respectively. The results confirm that transient response overshoot is less, and transient response attenuation is more in maximum damping method. Hence, the controller system easily recognizes initial overshoots and determines the parameters of the dynamic absorber system in accordance with maximum damping state if it is struck at any rotor frequency and any rotation angle. It is also observed that for all rotor rotation frequencies, the system overshoot reduces in comparison with H∞ method by using this control method.

Multi-order repetitive controller for harmonic current suppression in magnetically suspended rotor system

2020 ◽  
pp. 107754632096431
Author(s):  
Peiling Cui ◽  
Wensi Li ◽  
Xinxiu Zhou ◽  
Jinlei Li ◽  
Fanjun Zheng
Keyword(s):  
Control Method ◽  
Rotation Frequency ◽  
Industrial Applications ◽  
Rotor System ◽  
Harmonic Current ◽  
Suppression Effect ◽  
Rotor Systems ◽  
Control Moment ◽  
Control Moment Gyro ◽  
Repetitive Controller

Repetitive controllers are widely used in rotor systems of magnetically suspended control moment gyro, which are responsible for suppressing harmonic current because of sensor runout and mass imbalance of the rotor. However, the rotation frequency of the rotor is not constant in industrial applications, and it is likely to fluctuate around the rotation frequency, which greatly affects the suppression effect of the repetitive controller on harmonic current. This article proposes a new repetitive control method with strong frequency robustness, which still has high suppression accuracy when the rotation frequency is fluctuant. This method is simulated and verified on the magnetically suspended rotor system, which has achieved better results than previous research.

Extended harmonic disturbance observer-based attitude control for flexible spacecraft with control moment gyroscopes

2019 ◽  
Vol 233 (14) ◽  
pp. 5331-5346
Author(s):  
Liya Huang ◽  
Zhong Wu
Keyword(s):  
Attitude Control ◽  
Disturbance Observer ◽  
Wide Frequency Range ◽  
Flexible Spacecraft ◽  
Space Environment ◽  
Harmonic Model ◽  
External Disturbances ◽  
Control Moment ◽  
Control Moment Gyroscopes ◽  
Rotor Dynamic

In the flexible spacecraft with control moment gyroscopes, there are multiple disturbances including not only internal disturbances from actuators and flexible appendages, but also external disturbances from space environment. These disturbances are characterized by a wide frequency range and may degrade attitude control performance to a great extent. In this paper, the lumped disturbance is modeled as a harmonic plus a polynomial model, and an extended harmonic disturbance observer (EHDO) is proposed to estimate the total disturbance. Since the rotor dynamic imbalance disturbance from control moment gyroscopes is described by an internal harmonic model, the lumped disturbance can be estimated precisely via EHDO even with a lower bandwidth. Afterwards, a backstepping-based composite controller is designed to compensate the disturbances by combining the output of EHDO and realize high-precision attitude control for flexible spacecraft with control moment gyroscopes. Simulation results are presented to demonstrate the effectiveness of the proposed method.

scholarly journals Numerical Investigation on Static and Rotor-Dynamic Characteristics of Convergent-Tapered and Divergent-Tapered Hole-Pattern Gas Damper Seals

Materials ◽  
2019 ◽  
Vol 12 (14) ◽  
pp. 2324
Author(s):  
Dan Sun ◽  
Sheng-Yuan Li ◽  
Huan Zhao ◽  
Cheng-Wei Fei
Keyword(s):  
Dynamic Characteristics ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Rotor System ◽  
Damping Coefficient ◽  
Single Frequency ◽  
Relative Variation ◽  
Gas Damper ◽  
Rotor Dynamic ◽  
Tapered Hole

To study the influence of taper seal clearance on the static and rotor-dynamic characteristics of hole-pattern damper seals, this paper develops three-dimensional transient computational fluid dynamic methods, which comprise single-frequency and multi-frequency elliptical orbit whirl model, by the transient solution combined with a mesh deformation technique. Through the investigations, it is illustrated that: (1) In the present paper, the leakage rates of convergent-tapered hole-pattern damper seals are less than divergent-tapered hole-pattern damper seals for the same average seal clearance, and the maximum relative variation reaches 16%; (2) Compared with a constant clearance hole-pattern damper seal, the maximum relative variation of the rotor-dynamic coefficients is 1,865% for nine taper degrees in this paper; (3) Convergent-tapered hole-pattern damper seals have smaller reaction forces and effective damping coefficient, larger cross-over frequency, and direct stiffness coefficient, while divergent-tapered damper seals have the opposite effects; (4) Divergent-tapered hole-pattern damper seals alleviate the rotor whirl because of a larger effective damping coefficient when the rotor system has large natural frequency and small eccentricity. Convergent-tapered damper seals provide both sealing and journal bearing capabilities at the same time, and are more advantageous to the stability of the rotor system when rotor eccentricity is the main cause of rotor instability.

Research on Dynamic Balance of Grinding Wheel Spindle

2011 ◽  
Vol 487 ◽  
pp. 482-485
Author(s):  
Qin Yuan Zhou ◽  
Zhi Xiong Zhou ◽  
Y. Li
Keyword(s):  
High Precision ◽  
Critical Speed ◽  
Dynamic Balance ◽  
New Method ◽  
Grinding Wheel ◽  
Speed Range ◽  
Rotor Dynamic ◽  
Dynamic Unbalance ◽  
Quality Surface

In this paper, grinding wheel spindle of high precision CNC is researched. Mathematics - mechanical mode of dynamic balance of grinding wheel is established on the principle of rotor dynamic balance. New method of critical speed of grinding wheel is proposed, and verified by testing the reasonableness. And, dynamic unbalance of grinding wheel spindle of high precision CNC is studied on quality surface. These studies provide theoretical direction for balance speed range and the accurate level.

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