scholarly journals Vibration Torque Suppression for Magnetically Suspended Flywheel Using Improved Synchronous Rotating Frame Transformation

2019 ◽  
Vol 2019 ◽  
pp. 1-13 ◽  
Author(s):  
Cong Peng ◽  
Kaiwen Cai ◽  
Zhiquan Deng ◽  
Kexiang Li
Keyword(s):  
Control Method ◽  
Magnetic Bearing ◽  
Active Magnetic Bearing ◽  
Rotating Frame ◽  
Overall Stability ◽  
High Power Consumption ◽  
Frame Transformation ◽  
The Stability ◽  
Amb System ◽  
Gyroscopic Effects

Synchronous vibration, a common issue in active magnetic bearing (AMB) system, is mainly caused by mass imbalance of the rotor. It comes with high-power consumption and serious impact on the housing base, dramatically degrading the performance of AMB. Magnetically suspended flywheel (MSFW), which owns a flat rotor and consequently shows strong gyroscopic effects even at low operating speed, requires additional attention not only for suppressing the synchronous vibration but also for maintaining the overall stability faced with the coupled dynamics. In this work, in order to suppress the vibration torques in MSFW with significant gyroscopic effects, an improved synchronous rotating frame- (SRF-) based control method is proposed. The proposed method introduces the compensation phase for stability adjustment and aims at simultaneously suppressing the synchronous components in the coupled axes. Firstly, the vibration torque model of MSFW is established, and the baseline control strategy for suspension and gyroscopic effects restrain is derived. Then, the principle and implementation of the improved SRF-based vibration torque method are analyzed, which aims at suppressing the synchronous vibration torques through attenuating synchronous components in coil currents. Moreover, the stability of the overall closed-loop system is analyzed. Finally, the effectiveness of the proposed method is verified through simulation and experimental results.

Nonlinear Oscillation of a Rotor-AMB System With Time Varying Stiffness and Multi-External Excitations

2009 ◽  
Vol 131 (3) ◽  
Author(s):  
M. Kamel ◽  
H. S. Bauomy
Keyword(s):  
Steady State ◽  
Order Approximation ◽  
Nonlinear Differential Equations ◽  
Steady State Solution ◽  
Magnetic Bearing ◽  
Active Magnetic Bearing ◽  
Multiple Time ◽  
Time Varying ◽  
The Stability ◽  
Amb System

The rotor-active magnetic bearing system subjected to a periodically time-varying stiffness having quadratic and cubic nonlinearities is studied and solved. The multiple time scale technique is applied to solve the nonlinear differential equations governing the system up to the second order approximation. All possible resonance cases are deduced at this approximation and some of them are confirmed by applying the Rung–Kutta method. The main attention is focused on the stability of the steady-state solution near the simultaneous principal resonance and the effects of different parameters on the steady-state response. A comparison is made with the available published work.

A new control method of rotor re-suspension after short failure of active magnetic bearing system

2018 ◽  
Vol 32 (34n36) ◽  
pp. 1840077
Author(s):  
Yi-Li Zhu ◽  
Yan-Hong Zhang ◽  
Yi-Lin Liu
Keyword(s):  
Control Algorithm ◽  
Position Control ◽  
Control Method ◽  
Speed Control ◽  
Magnetic Bearing ◽  
Active Magnetic Bearing ◽  
Dynamic Responses ◽  
Control Mode ◽  
Collision Force ◽  
Amb System

As it is difficult for traditional control method to realize rotor resuspension after short failure of Active Magnetic Bearing (AMB) system, a new control method containing rotor collision force evaluation algorithm module, rotor position control algorithm module and rotor vibration speed control algorithm module was proposed. Through the evaluation of rotor collision force, the controller automatically selects rotor positon control mode or rotor speed control mode. Based on rigid rotor theory, rotor dynamic model was established to analyze the dynamic responses after short failure of AMB system utilizing different control method. The results proved that the proposed control method can successfully realize rotor re-suspension.

Cancelling Gyroscopic Effects in AMB Systems With Flexible Rotors via Modal Feedback

2019 ◽  
Author(s):  
Alican Sahinkaya ◽  
Jerzy T. Sawicki
Keyword(s):  
Feedback Control ◽  
Controller Design ◽  
Sensory Information ◽  
Magnetic Bearing ◽  
Open Loop ◽  
State Feedback Control ◽  
Active Magnetic Bearing ◽  
Flexible Rotors ◽  
Amb System ◽  
Gyroscopic Effects

Abstract For active magnetic bearing (AMB) systems with rotors having significant polar to transverse moments of inertia ratio, the influence of gyroscopic effects needs to be considered in controller design procedures to prevent excessive vibrations and potential instability during operation. This consideration leads to conservative controllers due to large uncertainties caused by the rotational speed range of the rotor, or gain-scheduled controllers that require larger computational power, both of which are not desirable. A cross-feedback control has been applied in the literature to compensate for the gyroscopic effects of AMB systems with rigid rotors. However, the method is not applicable to AMB systems with flexible rotors due to lack of full-state sensory information and under actuation. This paper proposes a novel modal state feedback control as an addon controller for AMB systems with flexible rotors to compensate for the gyroscopic effects of selected modes. The aim of the add-on controller is to alter the open loop AMB system such that the open loop dynamics presents reduced gyroscopic effects of the selected modes from a controller point of view, reducing the uncertainties in the model for robust controller design. The proposed approach is demonstrated on an AMB rotor test rig with a rotor configuration featuring noticeable gyroscopic effects. The comparison of the frequency response data of the open loop AMB system with and without the proposed add-on controller shows the feasibility of the approach.

The Dynamics of a Cracked Rotor With an Active Magnetic Bearing

2001 ◽  
Author(s):  
Changsheng Zhu ◽  
David A. Robb ◽  
David J. Ewins
Keyword(s):  
Dynamic Characteristics ◽  
Critical Speed ◽  
Magnetic Bearing ◽  
Rotor System ◽  
Active Magnetic Bearing ◽  
Cracked Rotor ◽  
Harmonic Components ◽  
The Stability ◽  
Amb System ◽  
Cracked Rotor System

The dynamic characteristics of a cracked rotor with an active magnetic bearing (AMB) are theoretically analyzed in this paper. The effects of using optimal controller parameters on the dynamic characteristics of the cracked rotor and the effect of the crack on the stability of the active control system are discussed. It is shown that the dynamic characteristics of the cracked rotor with AMBs are clearly more complex than that of the traditional cracked rotor system. Adaptive control with AMBs may hide the fault characteristics of the cracked rotor, rather than helping to diagnose a crack; this will depend on the controller strategy used. It is very difficult to detect a crack in the AMB-rotor system when the vibration of the rotor system is fully controlled. Only the super-harmonic components of 2X and 3X revolution in the sub-critical speed region can be used as a index to detect a crack in the rotor–AMB system. If the effect of the crack is not considered in designing the controller, then the AMB-rotor system will lose its stability in some cases when cracks appear.

Pseudospectral method-based optimal control for a nonlinear five degree of freedom active magnetic bearing system

2021 ◽  
pp. 014233122098653
Author(s):  
Sudipta Saha ◽  
Arunava Banerjee ◽  
Syed Muhammad Amrr ◽  
Mashuq un Nabi
Keyword(s):  
Optimal Control ◽  
Control Method ◽  
Pseudospectral Method ◽  
Magnetic Bearing ◽  
Degree Of Freedom ◽  
Active Magnetic Bearing ◽  
Physical Contact ◽  
Computational Time ◽  
Optimal Control Strategy ◽  
Amb System

Active magnetic bearings (AMB) are used to suspend the rotor freely inside the stator to avoid any physical contact between them. Thus, it helps in significantly reducing the wear and tear that may cause a system breakdown. With the advancement of power electronics and the implementation of advanced control techniques, the use of AMB in industrial applications has increased. This paper proposes an optimal control strategy for the five degree of freedom (DOF) AMB system. The time-energy consumption of input is minimized by the application of a relatively new optimal control method called the pseudospectral method (PSM). Since the AMB is a nonlinear system, therefore the implementation of classical optimal control strategies becomes challenging. Thus, the PSM first transforms the optimal control problem at non-uniform nodes and converts it into a nonlinear programming problem, which is relatively easier to tackle. The PSM, as demonstrated in this paper, is able to find optimal solutions using relatively fewer grid points which in turn reduces the computational time and converges to the solution faster. The simulation analysis for the AMB system using two different types of PSM, that is, Legendre PSM and the Chebyshev PSM illustrates the optimal performance of the proposed strategy.

Some Nonlinear Effects of Magnetic Bearings

1999 ◽  
Author(s):  
Norbert Steinschaden ◽  
Helmut Springer
Keyword(s):  
Equations Of Motion ◽  
Period Doubling ◽  
Path Following ◽  
Nonlinear Effects ◽  
Magnetic Bearing ◽  
Operating Conditions ◽  
Active Magnetic Bearing ◽  
Nonlinear Phenomena ◽  
Amb System ◽  
Large Rotor

Abstract In order to get a better understanding of the dynamics of active magnetic bearing (AMB) systems under extreme operating conditions a simple, nonlinear model for a radial AMB system is investigated. Instead of the common way of linearizing the magnetic forces at the center position of the rotor with respect to rotor displacement and coil current, the fully nonlinear force to displacement and the force to current characteristics are used. The AMB system is excited by unbalance forces of the rotor. Especially for the case of large rotor eccentricities, causing large rotor displacements, the behaviour of the system is discussed. A path-following analysis of the equations of motion shows that for some combinations of parameters well-known nonlinear phenomena may occur, as, for example, symmetry breaking, period doubling and even regions of global instability can be observed.

An Evaluation of Stability Indices Using Sensitivity Functions for Active Magnetic Bearing Supported High-Speed Rotor

2006 ◽  
Vol 129 (2) ◽  
pp. 230-238 ◽  
Author(s):  
Naohiko Takahashi ◽  
Hiroyuki Fujiwara ◽  
Osami Matsushita ◽  
Makoto Ito ◽  
Yasuo Fukushima
Keyword(s):  
High Speed ◽  
Transfer Functions ◽  
Mimo System ◽  
Magnetic Bearing ◽  
Singular Value ◽  
Active Magnetic Bearing ◽  
Sensitivity Functions ◽  
Phase Lags ◽  
The Stability ◽  
Stability Indices

In active magnetic bearing (AMB) systems, stability is the most important factor for reliable operation. Rotor positions in radial direction are regulated by four-axis control in AMB, i.e., a radial system is to be treated as a multi-input multioutput (MIMO) system. One of the general indices representing the stability of a MIMO system is “maximum singular value” of a sensitivity function matrix, which needs full matrix elements for calculation. On the other hand, ISO 14839-3 employs “maximum gain” of the diagonal elements. In this concept, each control axis is considered as an independent single-input single-output (SISO) system and thus the stability indices can be determined with just four sensitivity functions. This paper discusses the stability indices using sensitivity functions as SISO systems with parallel/conical mode treatment and/or side-by-side treatment, and as a MIMO system with using maximum singular value; the paper also highlights the differences among these approaches. In addition, a conversion from usual x∕y axis form to forward/backward form is proposed, and the stability is evaluated in its converted form. For experimental demonstration, a test rig diverted from a high-speed compressor was used. The transfer functions were measured by exciting the control circuits with swept signals at rotor standstill and at its 30,000 revolutions/min rotational speed. For stability limit evaluation, the control loop gains were increased in one case, and in another case phase lags were inserted in the controller to lead the system close to unstable intentionally. In this experiment, the side-by-side assessment, which conforms to the ISO standard, indicates the least sensitive results, but the difference from the other assessments are not so great as to lead to inadequate evaluations. Converting the transfer functions to the forward/backward form decouples the mixed peaks due to gyroscopic effect in bode plot at rotation and gives much closer assessment to maximum singular value assessment. If large phase lags are inserted into the controller, the second bending mode is destabilized, but the sensitivity functions do not catch this instability. The ISO standard can be used practically in determining the stability of the AMB system, nevertheless it must be borne in mind that the sensitivity functions do not always highlight the instability in bending modes.

Dynamic Modeling and Analysis of Active Magnetic Bearings

2014 ◽  
Vol 494-495 ◽  
pp. 685-688
Author(s):  
Rong Gao ◽  
Gang Luo ◽  
Cong Xun Yan
Keyword(s):  
Dynamic Characteristic ◽  
Dynamic Modeling ◽  
Magnetic Bearing ◽  
Integrated System ◽  
Magnetic Bearings ◽  
Active Magnetic Bearing ◽  
Active Magnetic Bearings ◽  
Modeling And Analysis ◽  
Amb System ◽  
Mathematics Method

Active magnetic bearing (AMB) system is a complex integrated system including mechanics, electronic and magnetism. In order to research for the basic dynamic characteristic of rotor supported by AMB, it is necessary to present mathematics method. The dynamics formula of AMB is established using theory means of dynamics of rotator and mechanics of vibrations. At the same tine, the running stability of rotor is analyzed and the example is presented in detail.

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