scholarly journals Exploration of NDE Properties of AMB Supported Rotors for Structural Damage Detection

2011 ◽  
Vol 133 (10) ◽  
Author(s):  
Jerzy T. Sawicki ◽  
Dmitry L. Storozhev ◽  
John D. Lekki
Keyword(s):  
Structural Damage ◽  
Transverse Crack ◽  
Magnetic Bearing ◽  
Active Magnetic Bearing ◽  
Control Loop ◽  
Structural Damage Detection ◽  
Cracked Rotor ◽  
Rotating Shaft ◽  
Simulation Results ◽  
Combination Frequencies

This paper addresses self-diagnostic properties of active magnetic bearing (AMB) supported rotors for online detection of the transverse crack on a rotating shaft. In addition to pure levitation, the rotor supporting bearing also serves as an actuator that transforms current signals additionally injected into the control loop into the superimposed specially selected excitation forces into the suspended rotor. These additional excitations induce combination frequencies in the rotor response, providing unique signatures for the presence of crack. The background of theoretical modeling, experimental, and computer simulation results for the AMB supported cracked rotor with self-diagnostic excitation forces are presented and discussed.

scholarly journals Exploration of NDE Properties of AMB Supported Rotors for Structural Damage Detection

2010 ◽  
Author(s):  
Jerzy T. Sawicki ◽  
Dmitry L. Storozhev ◽  
John D. Lekki
Keyword(s):  
Structural Damage ◽  
Magnetic Bearing ◽  
Active Magnetic Bearing ◽  
Line Detection ◽  
Control Loop ◽  
Structural Damage Detection ◽  
Cracked Rotor ◽  
Rotating Shaft ◽  
On Line ◽  
Combination Frequencies

This paper addresses self-diagnostic properties of AMB (active magnetic bearing) supported rotors for on-line detection of the transverse crack on a rotating shaft. In addition to pure levitation, the rotor supporting bearing also serves as an actuator that transforms current signals additionally injected into the control loop into the superimposed specially selected excitation forces into the suspended rotor. These additional excitations induce combination frequencies in the rotor response, providing unique signatures for the presence of crack. The background of theoretical modeling, experimental and computer simulation results for the AMB supported cracked rotor with self-diagnostic excitation forces are presented and discussed.

Experimental Investigation of Active Control of Cracked Rotor-Bearing System Equipped With Magnetic Bearing

2019 ◽  
Author(s):  
Nilakshi Sarmah ◽  
Rajiv Tiwari
Keyword(s):  
Dynamic Behavior ◽  
Active Control ◽  
Transverse Crack ◽  
Vibration Suppression ◽  
Radial Force ◽  
Magnetic Bearing ◽  
Active Magnetic Bearing ◽  
Cracked Rotor ◽  
Rotor Bearing ◽  
Bearing System

Abstract The present work investigates the online vibration control of a cracked rotor-bearing system incorporated with AMB. A fatigue crack, which exhibits the opening and closure behavior of cracked faces while rotation, is introduced artificially in the shaft to understand the dynamic behavior of a cracked rotor system. For this, three-point bending tests were performed to obtain edge transverse crack in the shaft. An eight-pole electromagnetic actuator was used to apply control forces directly on to the shaft in the radial direction. The radial force was used to assist vibration suppression in the rotor. In order to achieve active control to mechanical vibration and other disturbances, a simple PID control strategy is used. Closed loop tests are conducted on the d-SPACE DS1202 platform using the differential driving mode of the PID controller to suppress the vibration of a shaft containing a transverse crack integrated with an AMB supported on two conventional bearings. The comparison of the dynamic behavior of the laboratory test rig with and without active magnetic bearing (AMB) with the numerically simulated data is analyzed. The vibration suppression is found to be achieved satisfactorily in the presence of the unbalance force, bow force, crack force, and with other forces on the rotor-bearing system.

Development of Experimental Active Magnetic Bearing Device for Measurement of Mechanical Seal Reaction Force Acting on Rotor

2018 ◽  
Author(s):  
Hiroki Manabe ◽  
Shota Yabui ◽  
Hideyuki Inoue ◽  
Tsuyoshi Inoue
Keyword(s):  
Force Measurement ◽  
Reaction Force ◽  
Magnetic Bearing ◽  
Active Magnetic Bearing ◽  
Mechanical Seal ◽  
Rotating Shaft ◽  
Fluid Force ◽  
Fluid Forces ◽  
Whirling Motion ◽  
Measurement And Evaluation

In turbomachinery, seals are used to prevent fluid leakage. At seal part, rotordynamic fluid force (RD fluid force), which causes whirling motion of rotor, is generated. Under certain conditions, the RD fluid force may contribute to instability of the machine. There are several cases that the whirling is accompanied by eccentricity due to the influence of gravity, or the whirling orbit becomes elliptical due to the influence of the bearing support anisotropy. In these cases, mathematical modeling of the RD fluid forces becomes increasingly complex. As a result, the RD fluid force measurement is more preferable. To improve the measurement and evaluation technology of the RD fluid force, a method to arbitrarily control whirling of the orbit is required. In this paper, RD fluid force measurement by controlling the shape of the orbit using an active magnetic bearing (AMB) is proposed. A contact type mechanical seal is used as a test specimen. When the rotating shaft is whirling, the RD fluid force due to hydrodynamics lubrication and the frictional force due to contact occur on the sliding surface. The resultant force of these forces is taken as the reaction force of mechanical seal and the measurement is performed. The measured reaction force of the mechanical seal is compared with simulation results and the validity of the proposed measurement method is confirmed.

Track-Following Controller Design Using an Active Magnetic Bearing for Measurement of the Rotor Dynamics Coefficient of the Annular Seal

2021 ◽  
Vol 143 (6) ◽  
Author(s):  
Shota Yabui ◽  
Hideyuki Inoue ◽  
Tsuyoshi Inoue
Keyword(s):  
Control System ◽  
Controller Design ◽  
Rotor Dynamics ◽  
Magnetic Bearing ◽  
Operating Conditions ◽  
Active Magnetic Bearing ◽  
Rotating Shaft ◽  
Operating Condition ◽  
Rotating Machine ◽  
Annular Seal

Abstract This study introduces a track-following controller design to measure the rotor dynamics (RD) coefficient of the annular seal using active magnetic bearings. The annular seal is implemented contiguously to prevent leakage of fluid between the rotating shaft and stationary area of a rotating machine. The force caused by the seal at the contact point can cause vibrations, which should be identified for designing rotating machinery. The RD force is coupled with mechanical and fluid dynamics. Moreover, the dynamics depend on the operating conditions of the rotating machine, namely, the rotating speed and orbit of the rotating shaft. This study proposes a control system for the active magnetic bearing to measure the RD force directly at the arbitrary operating condition. The main controller is designed to satisfy a criterion of the frequency characteristics of the rotating system. In addition, the control system employs adaptive feed-forward cancellation (AFC). This can estimate and compensate for the RD force in the control system simultaneously. The experimental results indicate that the control system can achieve an arbitrary operating condition and measure the RD coefficient of the annular seal in real-time. As a result, the RD coefficient is identified based on the equation of motion.

Development of a Measurement System for Analyzing Periodic External Forces Acting on Rotating Machineries

2019 ◽  
Vol 141 (10) ◽  
Author(s):  
Shota Yabui ◽  
Tsuyoshi Inoue
Keyword(s):  
Measurement System ◽  
Adaptive Algorithm ◽  
Journal Bearing ◽  
Magnetic Bearing ◽  
Contact Forces ◽  
Active Magnetic Bearing ◽  
Rotating Shaft ◽  
Rotating System ◽  
External Forces ◽  
Rotating Machineries

In this study, a measurement system is developed to analyze periodic external forces acting on a rotating machinery. The dynamics of a rotating machineries are influenced by various periodic external forces such as unbalanced forces, oil film forces at a journal bearing, and seal contact forces. The characteristics of periodic external forces are dependent on the rotating conditions, rotational speed, and rotating orbit of the rotating shaft. The proposed system employs an active magnetic bearing (AMB), which is implemented using an adaptive feed-forward cancellation (AFC). The use of AFC ensures that the proposed system can realize the desired harmonic orbit assuming actual operations under the periodic external forces. Moreover, AFC can measure the periodic external forces in real-time using an adaptive algorithm. The effectiveness of the proposed system is verified experimentally. Experimental results show that the control system can control the rotating shaft to an accuracy of micrometer order using the implemented AFC. The measurement error of the periodic external forces acting on the rotating system is less than 2%.

A New Approach for Health Monitoring and Detection of Shaft Crack Using an Active Magnetic Actuator During Steady-State Rotor Operation

2007 ◽  
Author(s):  
M. Kasarda ◽  
T. Bash ◽  
D. Quinn ◽  
G. Mani ◽  
D. Inman ◽  
...  
Keyword(s):  
Steady State ◽  
Natural Frequency ◽  
Health Monitoring ◽  
Magnetic Bearing ◽  
Active Magnetic Bearing ◽  
Vibration Monitoring ◽  
Rotating Shaft ◽  
Rotating System ◽  
Rotating Machine ◽  
Input Signals

This work demonstrates the capability of an Active Magnetic Bearing (AMB) to be used as an actuator for interrogating a system by applying multiple forces to a rotating shaft in order to monitor and evaluate the associated responses to these inputs. Similar to modal analysis techniques which apply input signals to static structures in order to monitor responses to those inputs, this approach allows for the measurement of both input and output response in a rotating system for evaluation. However, unlike these techniques, the procedure developed here allows for multiple forms of force inputs to be applied to a rotating structure. This procedure facilitates the development of new improved techniques for diagnosing subtle changes in machinery health or for identifying faults that would potentially go undetected by conventional methods before failure. Although it is expected that this approach can be used in rotors supported in AMBs, the technique developed here uses an AMB on the rotor in conjunction with conventional support bearings. Therefore, this approach has the potential to be used on any rotating machine that can be designed or retrofitted with a single AMB actuator. To demonstrate this approach experimentally, a notched shaft was chosen to represent a shaft crack for identification purposes. Three cases were examined, including a healthy (unnotched) shaft, and three cases of a shaft with a mid-span notch extending to a depth of 10%, 25%, and 40% of shaft diameter, respectively. During testing, excitations up to 1000 Hz were applied via one axis of the AMB actuator to the four rotor cases while the rotor was operating at a steady-state speed of 2400 rpm, and corresponding responses were recorded at the proximity probes. No changes in the 1st or 2nd natural frequencies were detected, but distinct shifts in the 3rd natural frequency were detected from the Frequency Response Function (FRF) data. Since the vast majority of rotating machinery are designed to operate below the 3rd natural frequency, the effect of the notch on the 3rd natural frequency would not have been identified without the application of excitation forces through the AMB actuator. This paper represents an introduction to the new health monitoring approach and results presented here demonstrate the viability of the technique for detecting shaft cracks that might otherwise go undetected in typical steady-state vibration monitoring approaches.

scholarly journals Disturbance and uncertainty estimator-based cascaded position-current controller for active magnetic bearing system

2019 ◽  
Vol 11 (3) ◽  
pp. 168781401983535 ◽  
Author(s):  
Yao-Nan Wang ◽  
Tran Minh Hai
Keyword(s):  
Control Method ◽  
Sliding Mode ◽  
Magnetic Bearing ◽  
Active Magnetic Bearing ◽  
System State ◽  
Control Loop ◽  
Current Controller ◽  
Highly Nonlinear ◽  
Uncertainty Estimator ◽  
Bearing System

This article presents a robust control method; all of the unknown disturbances and uncertainty values will be rejected. Suspension of active magnetic bearing system is aimed to figure out that the proposed control method is implementable for highly nonlinear unstable system. First, system state is described by dynamic model, with unknown lump of uncertainty value. Subsequently, the cascade control with inner and outer loops is defined by sliding mode control based on disturbance and uncertainty estimator. The outer control loop is used to force the system state converge on the predefined surface, while inner control loop is used to control the current of electrical part of the system. Finally, the simulation results show that the proposed control method is good at tracking trajectory.

Research on Inverse Control of Active Magnetic Bearing Based on Fuzzy Inverse Model

2014 ◽  
Vol 575 ◽  
pp. 744-748
Author(s):  
Wen Jiang ◽  
Yi Xin Su ◽  
Dan Hong Zhang
Keyword(s):  
Pid Controller ◽  
Closed Loop ◽  
Magnetic Bearing ◽  
Inverse Model ◽  
Active Magnetic Bearing ◽  
Inverse Control ◽  
Linear Plant ◽  
In Series ◽  
Simulation Results ◽  
Bearing System

For magnetic bearing system with characteristics of zero damping, negative stiffness and nonlinearity, this paper put forward a method of inverse control based on the fuzzy inverse model. The fuzzy system with fuzzifier and defuzzifier was used as an interpolator to approximate the inverse model of magnetic bearing. Then we connected the fuzzy inverse model in series with the magnetic bearing system to form a generalized pseudo linear plant, and selected a PID controller to control the pseudo linear plant. The fuzzy inverse model and the PID controller together formed an inverse controller to implement the closed-loop inverse control of the system. The simulation results demonstrate that the inverse control can reduce the overshoot, shorten the settling time, and make the rotor levitate in a larger range.

Permanent Magnet Biased Bearing of Suspension System

2011 ◽  
Vol 383-390 ◽  
pp. 5529-5535
Author(s):  
Ming Zong ◽  
Xiao Kang Wang ◽  
Yang Cao
Keyword(s):  
Magnetic Field ◽  
Mathematical Model ◽  
Permanent Magnet ◽  
Power Amplifier ◽  
Model Simulation ◽  
Simulation Method ◽  
Magnetic Bearing ◽  
Magnetic Bearings ◽  
Active Magnetic Bearing ◽  
Simulation Results

PM (Permanent Magnet) biased magnetic bearing with PM to replace the magnetic field produced by electromagnet an Active Magnetic Bearing generated static bias magnetic field, it can reduce the power consumption of power amplifier to reduce the number of turns of magnet safety, reduce the volume of magnetic bearings, reducing electromagnetic coil operating current, thereby reducing the power amplifier power control system and heat sink size, magnetic bearings significantly reduce power loss, and fundamentally reduce the cost of bearing. In this paper, a kind of PM biased magnetic bearings, describes its structure and working principle, derived a mathematical model of magnetic bearing and magnetic circuit of PM biased magnetic bearings are calculated, given the specific PM biased magnetic bearing size and accordingly calculate the parameters of magnetic bearings. A magnetic model constructed using Simulink simulation method, and constructed using this method, magnetic bearing specific mathematical model simulation results show that the rotor position in the balance, X and Y decoupling between the control winding, while the deviation from equilibrium position time, X and Y control coupling between the windings, the simulation results and the calculation results.

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