Journal articles on the topic 'Variable rotor parameter'
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1
Cui, Peiling, Jingxian He, Jiancheng Fang, Xiangbo Xu, Jian Cui, and Shan Yang. "Research on method for adaptive imbalance vibration control for rotor of variable-speed mscmg with active-passive magnetic bearings." Journal of Vibration and Control 23, no. 2 (August 8, 2016): 167–80. http://dx.doi.org/10.1177/1077546315576430.
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Imbalance vibration control for rotor is the main factor affecting attitude control performance for satellite using magnetically suspended control moment gyro (MSCMG). The method for adaptive imbalance vibration control for the rotor of variable-speed MSCMG with active-passive magnetic bearings is investigated in this paper. Firstly, on the basis of feedforward compensation, a rotor model for the imbalance vibration of variable-speed MSCMG with active-passive magnetic bearings is built, and the main factor affecting imbalance vibration compensation is also analyzed. Then, power amplifier parameter modifier with control switches is designed to eliminate the effects of time-varying parameters on the imbalance vibration compensation precision. The adaptive imbalance vibration control based on this modifier not only has high compensation precision, but also can control the frequency of parameter adjustment according to the compensation precision. Besides, since the passive magnetic bearing displacement stiffness of the rotor of variable-speed MSCMG with active-passive magnetic bearings cannot be obtained accurately, displacement stiffness modifier is employed. Finally, stability analysis is made on the imbalance vibration control system, and the range of rotation speed to ensure system stability is derived. Simulation results show that, imbalance vibration control method proposed in this paper can suppress the imbalance vibration of the rotor of variable-speed MSCMG with active-passive magnetic bearings effectively and has high precision.
2
Bian, Yu Chuan, Han Chen Gong, Jing Wei Yang, and Jian Feng Liu. "Variable Structure Control of Suspension Rotor System in the Mement Gyro." Advanced Materials Research 1030-1032 (September 2014): 1578–83. http://dx.doi.org/10.4028/www.scientific.net/amr.1030-1032.1578.
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According to the magnetic suspension character of the rotor in moment Gyro, the control mathematic model for the Gyro’s rotor magnetic suspension system is founded. The system is characterized by its instability,nonlinearity. In this paper, a Variable Structure Controller is designed. Based on the general Variable Structure Controller theory, the design of switch function using the method of self-adapting configuring pole and the design of Variable Structure Controller using trending law are discussed. At the same time, the switch surface of Variable Structure Controller is designed by the method of self-adoptive configuring pole, so the performance quality of sliding mode is ensured. Accordingly, the Variable Structure Controller, self –adaptive control and fuzzy control are organic combined. The simulating results show that the controller is characterized by fast dynamic respond, strong robust, according to the application in the rotor magnetic suspension system. The result show that the controller can guarantee every state parameter in the rotor magnetic suspension system to trend the designed value.
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Fan, Bo, Zhixin Yang, Wei Xu, and Xianbo Wang. "Rotor Resistance Online Identification of Vector Controlled Induction Motor Based on Neural Network." Mathematical Problems in Engineering 2014 (2014): 1–10. http://dx.doi.org/10.1155/2014/831839.
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Rotor resistance identification has been well recognized as one of the most critical factors affecting the theoretical study and applications of AC motor’s control for high performance variable frequency speed adjustment. This paper proposes a novel model for rotor resistance parameters identification based on Elman neural networks. Elman recurrent neural network is capable of performing nonlinear function approximation and possesses the ability of time-variable characteristic adaptation. Those influencing factors of specified parameter are analyzed, respectively, and various work states are covered to ensure the completeness of the training samples. Through signal preprocessing on samples and training dataset, different input parameters identifications with one network are compared and analyzed. The trained Elman neural network, applied in the identification model, is able to efficiently predict the rotor resistance in high accuracy. The simulation and experimental results show that the proposed method owns extensive adaptability and performs very well in its application to vector controlled induction motor. This identification method is able to enhance the performance of induction motor’s variable-frequency speed regulation.
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Millsaps, K. T., and G. L. Reed. "Reducing Lateral Vibrations of a Rotor Passing Through Critical Speeds by Acceleration Scheduling." Journal of Engineering for Gas Turbines and Power 120, no. 3 (July 1, 1998): 615–20. http://dx.doi.org/10.1115/1.2818190.
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A method is presented for reducing the lateral response of an imbalanced rotor accelerating or decelerating through its first lateral bending critical speed by using a variable acceleration rate. A lumped parameter model along with a numerical integration scheme is used to simulate the response of a simply supported, single disk rotor during fast acceleration and deceleration through critical speed. The results indicate that the maximum response and/or the total vibrational energy of a rotor passing through the critical speed can be reduced significantly by using a variable acceleration schedule. That is, reducing the acceleration rate after the nominal critical speed is passed. These predictions were verified experimentally for a single disk rotor.
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Gao, Yong, Zhao Qing Song, and Xiao Liu. "A Robust Adaptive Sliding Mode Control Method for Attitude Control of the Quad-Rotor." Advanced Materials Research 852 (January 2014): 391–95. http://dx.doi.org/10.4028/www.scientific.net/amr.852.391.
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Quad-rotor is a multi-variable and strong coupling system which has nonlinear and uncertainties. According to the quad-rotor, a dynamic model of attitude which included uncertainty parameters and unknown disturbances was established. The tracking error state was used to design a slide mode surface, and a Lyapunov function which includes slide mode surface and unknown parameter was built. Further more, a robust adaptive control law was designed. At last, the designed control law was simulated, and the results justify the feasibility of the proposed control law.
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Syed Shah, Khalid, and Liang Zhang. "Comprehensive Study on Variable Pitch Vertical Axis Tidal Turbine." Applied Mechanics and Materials 229-231 (November 2012): 778–82. http://dx.doi.org/10.4028/www.scientific.net/amm.229-231.778.
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To overcome the stalled effect and poor starting torque of fixed pitch Darrieus turbine, researchers invent variable pitch vertical axis tidal turbine (VATT). For tidal stream designers main challenge is that the design can sustain in hostile marine environment. Due to lift base design VATT is very critical for cavitation, so appropriate parameter selection can improve the hydrodynamic performance and life of the turbine. An attempt is made to optimize the design parameters of VATT for variable pitch using ANSYS CFX, hereafter CFX, which is based on a Reynolds-Averaged Navier-Stokes (RANS) model. A transient simulation is done for variable pitch VATT using Shear Stress Transport turbulence (SST) scheme. Main hydrodynamic parameters like torque T, combined moment CM, coefficients of performance CP and coefficient of torque CT, etc. are investigated. The modeling and meshing of turbine rotor is performed in ICEM-CFD. Mesh motion option is employed to achieve variable pitch phenomenon. This article is the one part of the ongoing research on turbine design and developments. The numerical simulation results are validated with analytical Matlab results performed by Edinburgh Design Ltd. The article concludes that CFX simulation is done accurately and major parameter selections for turbine development are feasible.
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Cui, Chun Yan, Kui Li, Bing Li, Chao Fu, and Jia Guo. "Based on Sliding Mode Variable Structure Current Controller for Induction Motor Vector Control Technology." Advanced Materials Research 711 (June 2013): 426–31. http://dx.doi.org/10.4028/www.scientific.net/amr.711.426.
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In this paper, according to the induction motor in rotating coordinate system mathematical model, established based on rotor flux oriented vector control model and realized flux linkage and torque decoupling. In order to solve the current high coupling, designed the sliding mode variable structure control algorithm of current controller. Based on the sliding mode variable structure control algorithm achievable conditions and Lyapunov stability theorem, proved that the sliding mode of accessibility and stability, determined the sliding model parameters. The simulation results show that the sliding mode variable structure control of induction motor vector control system, can reduce the torque ripple and the speed overshoot and improve the system parameter perturbation and external disturbance signal robustness.
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Chaieb, Ismahane, Toufik Boufendi, and Xavier Nicolas. "Taylor-Couette flow with mixed convection heat transfer and variable properties in a horizontal annular pipe." Thermal Science, no. 00 (2021): 271. http://dx.doi.org/10.2298/tsci210218271c.
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Taylor-Couette flows in a horizontal annular gap between finite coaxial cylinders in rotor-stator configuration are numerically investigated. The inner cylinder (rotor) rotates at a constant angular velocity while the outer cylinder (stator) is at rest. They are limited at their extremities by two fixed walls that prevent axial fluid flow. In addition, a heat transfer is generated by an imposed temperature difference, with the rotor hotter than the stator while the end-walls are adiabatic. The fluid physical properties are temperature dependent. This non-linear physics problem, with a strong coupling of the conservation equations and boundary conditions, is solved by a finite volume method with numerical schemes of second order space and time accuracies. The radius and aspect ratios and the Taylor, Grashof and Prandt numbers are the control parameters. The developed numerical code has been tested for different meshes and perfectly validated. Extensive calculations have been made in large ranges of the Taylor and Grashof numbers to analyze the Taylor-Couette flow in convection modes. The results highlight the dynamic and thermal instabilities generated in the Taylor Couette flow from the appearance of Ekman cells to the Taylor vortex propagation in the entire annulus. The combined effect of these vortices with the secondary flow improves the heat transfer. Furthermore, the influence of the physical properties in the radial direction is more marked in the vicinity of the walls. Finally, we propose an empirical correlation of the Nusselt number in the studied parameter ranges.
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Muazzam, Hassam, Mohamad Khairi Ishak, and Athar Hanif. "Compensating the performance of permanent magnet synchronous machines for fully electric vehicle using LPV control." Bulletin of Electrical Engineering and Informatics 10, no. 4 (August 1, 2021): 1923–29. http://dx.doi.org/10.11591/eei.v10i4.2946.
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The state-of-the-art robust H∞ linear parameter-varying controller is designed for wide speed operating range for non-linear mathematical model of permanent magnet synchronous machines (PMSM) in d-q reference frame for fully electric vehicle. This study propose polytopic approach using rotor speed as scheduling variable to reformulate mathematical model of PMSM into linear parameter varying (LPV) form. The weights were optimized for sensitivity and complementary sensitivity function. The simulation results illustrate fast tracking and enhanced performance of the proposed control technique over wide range of rotor speed. Moreover, as part of this work, the results of H∞ linear parameter varying controller is validated by comparing it with linear quadratic integrator and proportional integral derivative (PID) control techniques to show the effectiveness of the proposed control technique.
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Wang, Wei Na, Ru Mei Li, Yong Duan Song, Yong Sheng Hu, and Xub Kui Zhang. "Adaptive Variable Speed Control of Wind Turbines." Advanced Materials Research 311-313 (August 2011): 2393–96. http://dx.doi.org/10.4028/www.scientific.net/amr.311-313.2393.
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The uncertain and random characteristics of wind energy make the problem of wind turbine control interesting and challenging. This work investigates an adaptive method for variable speed control of wind turbines under varying operation conditions. For fixed-speed operation of wind turbines, maximum power conversion can be achieved only at a particular wind speed, thus variable speed control of wind turbines is of practical interest in enhancing wind turbine operating efficiency over wide wind speeds. Based on the nonlinear dynamic model of wind turbine, adaptive algorithms are developed in accommodating unknown system parameter uncertainties. This method is shown to be able to achieve smooth and effective tracking of rotor angular speed to capture maximum wind energy. The effectiveness and adaptation of the proposed approach is validated via numerical simulation.
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Johnson, Kathryn E., Lee J. Fingersh, Mark J. Balas, and Lucy Y. Pao. "Methods for Increasing Region 2 Power Capture on a Variable-Speed Wind Turbine." Journal of Solar Energy Engineering 126, no. 4 (November 1, 2004): 1092–100. http://dx.doi.org/10.1115/1.1792653.
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The standard region 2 control scheme for a variable-speed wind turbine, τc=Kω2, has several shortcomings that can result in significant power loss. The first of these is that there is no accurate way to determine the gain K; modeling programs are not accurate enough to represent all of the complex aerodynamics, and these aerodynamics change over time. Furthermore, it is not certain whether the value of K used in the standard control even provides for the maximum energy capture under real-world turbulent conditions. We introduce new control methods to address these issues. First, we show in simulation that using smaller values of K than the standard can result in increased energy capture. Second, we give simulation results showing that an optimally tracking rotor control scheme can improve upon the standard scheme by assisting the rotor speed in tracking wind-speed fluctuations more rapidly. Finally, we propose an adaptive control scheme that allows for maximum power capture despite parameter uncertainty.
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Wei, Liejiang, Zengguang Liu, Yuyang Zhao, Gang Wang, and Yanhua Tao. "Modeling and Control of a 600 kW Closed Hydraulic Wind Turbine with an Energy Storage System." Applied Sciences 8, no. 8 (August 7, 2018): 1314. http://dx.doi.org/10.3390/app8081314.
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In this paper, an innovative closed hydraulic wind turbine with an energy storage system is proposed. The hydraulic wind turbine consists of the wind rotor, the variable pump, the hydraulic bladder accumulator, the variable motor, and the synchronous generator. The wind energy captured by the wind rotor is converted into hydraulic energy by the variable pump, and then the hydraulic energy is transformed into electrical energy by the variable motor and generator. In order to overcome the fluctuation and intermittence shortcomings of wind power, the hydraulic bladder accumulator is used as an energy storage system in this system to store and release hydraulic energy. A double-loop speed control scheme is presented to allow the wind rotor to operate at optimal aerodynamic performance for different wind speeds and hold the motor speed at the synchronous speed to product constant frequency electrical power regardless of the changes of wind speed and load power. The parameter design and modeling of 600 kW hydraulic wind turbine are accomplished according to the Micon 600 kW wind turbine. Ultimately, time-domain simulations are completed to analyze the dynamic response of the hydraulic wind turbine under the step change conditions of wind speed, rotor speed input, and load power. The simulation results validate the efficiency of the hydraulic wind turbine and speed control scheme presented, moreover, they also show that the systems can achieve the automatic matching among turbine energy, accumulator energy, and generator output energy.
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Khvatov, Oleg Stanislavovich, Ilya Aleksandrovich Tarpanov, and Dmitry Sergeevich Kobyakov. "Variable diesel-generator power plant based on double-fed machine." Vestnik of Astrakhan State Technical University. Series: Marine engineering and technologies 2020, no. 3 (August 19, 2020): 82–90. http://dx.doi.org/10.24143/2073-1574-2020-3-82-90.
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The article considers the problem of improving power efficiency of the diesel generator power plants as one of the priority objectives for development of low power generation in Russia. Improving energy efficiency for autonomous facilities is directly related to the optimization of hydrocarbon fuel consumption by marine diesel engines. It is possible to optimize the fuel consumption of internal combustion engines by creating variable-speed diesel generators (VSDG), which are diesel-generator units with semiconductor converters, i.e. systems with valved generators. Optimization of specific fuel consumption by VSDG is provided by the forced regulation of the rotational speed of the shaft of the internal combustion engine in accordance with its multi-parameter characteristic in the shared load conditions of the power plant. The synchronous electric machine is used as a generator as part of a ship power station. Its use in the classic constant-speed diesel generators is more preferable than an asynchronous electric machine. In the development of VSDG - valved power plant - the use of an electric machine with a phase rotor as a generator is technically justified, because the installed capacity of the frequency converter in the rotor circuit of an asynchronous generator with a phase rotor is determined by the sliding power and, with a limited range of speed control, SDGV significantly reduces the installed capacity of the electrical equipment. Such power topology of a ship’s power plant is called VSDG based on a dual-power machine. There has been proposed to consider a variant of a ship power plant based on VSDG with a dual-power machine. Its functional diagram and mathematical model are developed. A structural diagram is presented and dynamic modes of the amplitude and frequency of the generated voltage are modeled during electrical load switching.
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Xiao, Fei, Lei Yuan, and Ming Liang Chen. "Adaptive Sliding-Mode Observer Scheme for Sensorless Control of Low-Speed IPMSM Drive." Applied Mechanics and Materials 380-384 (August 2013): 536–40. http://dx.doi.org/10.4028/www.scientific.net/amm.380-384.536.
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This paper proposes an adaptive sliding-mode observer (SMO) for a low-speed interior permanent magnet synchronous motor (IPMSM) drive. In this paper, an adaptive SMO is employed to estimate the rotor speed and extended EMF, a soft phase locked loop (PLL) technology is used to estimate rotor position due to its strong robustness since under voltage phase unbalance or polluted and variable-frequency environment. The global asymptotic stability of the proposed adaptive SMO is verified using Lyapunov stability analysis with considering motor parameter variations. Simulation results are presented to verify the principles and to demonstrate the effectiveness of the proposed method.
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Eryilmaz, I., L. Pawsey, and V. Pachidis. "Multidisciplinary methodology for turbine overspeed analysis." Aeronautical Journal 122, no. 1257 (November 2018): 1711–33. http://dx.doi.org/10.1017/aer.2018.100.
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ABSTRACTIn this paper, an integrated approach to turbine overspeed analysis is presented, taking into account the secondary air system dynamics and mechanical friction in a turbine assembly following an unlocated high-pressure shaft failure. The axial load acting on the rotating turbine assembly is a governing parameter in terms of overspeed protection since it governs the level of mechanical friction which acts against the turbine acceleration due to gas torque. The axial load is dependent on both the force coming from secondary air system cavities surrounding the disc and the force on the rotor blades. It is highly affected by secondary air system dynamics because rotor movement modifies the geometry of seals and flow paths within the network. As a result, the primary parameters of interest in this study are the axial load on the turbine rotor, the friction torque between rotating and static structures and the axial position of the rotor.Following an initial review of potential damage scenarios, several cases are run to establish the effect of each damage scenario and variable parameter within the model, with comparisons being made to a baseline case in which no interactions are modelled. This allows important aspects of the secondary air system to be identified in terms of overspeed prevention, as well as guidelines on design changes in current and future networks that will be beneficial for overspeed prevention.
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Li, Qihang, Weimin Wang, Lifang Chen, and Dan Sun. "Rotor-System Log-Decrement Identification Using Short-Time Fourier-Transform Filter." International Journal of Rotating Machinery 2015 (2015): 1–12. http://dx.doi.org/10.1155/2015/809785.
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With the increase of the centrifugal compressor capability, such as large scale LNG and CO2reinjection, the stability margin evaluation is crucial to assure the compressor work in the designed operating conditions in field. Improving the precision of parameter identification of stability is essential and necessary as well. Based on the time-varying characteristics of response vibration during the sine-swept process, a short-time Fourier transform (STFT) filter was introduced to increase the signal-noise ratio and improve the accuracy of the estimated stability parameters. A finite element model was established to simulate the sine-swept process, and the simulated vibration signals were used to study the filtering effect and demonstrate the feasibility to identify the stability parameters by using Multiple-Input and Multiple-Output system identification method that combines the prediction error method and instrumental variable method. Simulation results show that the identification method with STFT filter improves the estimated accuracy much well and makes the curves of frequency response function clearer. Experiment was carried out on a test rig as well, which indicates the identification method is feasible in stability identification, and the results of experiment indicate that STFT filter works very well.
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Nataraj, C., and H. Ashrafiuon. "Optimal Design of Centered Squeeze Film Dampers." Journal of Vibration and Acoustics 115, no. 2 (April 1, 1993): 210–15. http://dx.doi.org/10.1115/1.2930332.
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A two degree-of-freedom model, consisting of a rigid rotor supported on rigid bearings which are in turn supported on squeeze film dampers, is considered. Isotropic centering springs are assumed resulting in a steady synchronous centered circular response for the rotor. The resulting nonlinear system is modeled in nondimensional form. The transmissibility ratio of the system as well as the power dissipated are minimized for various values of unbalance and at several speeds, with the squeeze film bearing parameter as the primary design variable. Expressions are derived for linear variational stability of the circular orbit, and are imposed as constraints in the optimization process. The dependence of the optimal configuration on speed and unbalance is discussed.
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Rosa, Fabiano C., and Edson Bim. "A Constrained Non-Linear Model Predictive Controller for the Rotor Flux-Oriented Control of an Induction Motor Drive." Energies 13, no. 15 (July 31, 2020): 3899. http://dx.doi.org/10.3390/en13153899.
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Predictive controllers have been extensively studied and applied to electrical drives, mainly because they provide fast dynamic responses and are suitable for multi-variable control and non-linear systems. Many approaches perform the prediction and optimization process on-line, which requires a high computational capacity for fast dynamics, such as, for example, the control of AC electric motors. Due to the complexity of embedding constraints in controller design, which demands a high computational capacity to solve the optimization problem, off-line approaches are one of the choices to overcome this problem. However, these strategies do not deal with the inherent constraints of the drive system, which significantly simplifies the design of the controller. This paper proposes a non-linear and multi-variable predictive controller to control the speed and rotor flux of an induction motor, where the constraints are treated after the controller design. Besides dealing with the constraints of the electric drive system, our proposal allows increasing the stability of the system when the model does not incorporate disturbances and when parameter incompatibilities occur. Several computer simulations and experimental tests were performed to evaluate the behavior of the proposed controller, showing good performance to track the controlled variables under normal operating conditions, under load disturbances, parametric incompatibility, and at a very low rotor speed.
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Jagadish, H. P., and L. Ravikumar. "Effect of Temperature and Electric Field on the Damping and Stiffness Characteristics of ER Fluid Short Squeeze Film Dampers." Advances in Tribology 2013 (2013): 1–10. http://dx.doi.org/10.1155/2013/526428.
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Squeeze film dampers are novel rotor dynamic devices used to alleviate small amplitude, large force vibrations and are used in conjunction with antifriction bearings in aircraft jet engine bearings to provide external damping as these possess very little inherent damping. Electrorheological (ER) fluids are controllable fluids in which the rheological properties of the fluid, particularly viscosity, can be controlled in accordance with the requirements of the rotor dynamic system by controlling the intensity of the applied electric field and this property can be utilized in squeeze film dampers, to provide variable stiffness and damping at a particular excitation frequency. The paper investigates the effect of temperature and electric field on the apparent viscosity and dynamic (stiffness and damping characteristics) of ER fluid (suspension of diatomite in transformer oil) using the available literature. These characteristics increase with the field as the viscosity increases with the field. However, these characteristics decrease with increase in temperature and shear strain rate as the viscosity of the fluid decreases with temperature and shear strain rate. The temperature is an important parameter as the aircraft jet engine rotors are located in a zone of high temperature gradients and the damper fluid is susceptible to large variations in temperature.
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Saihi, Lakhdar, Brahim Berbaoui, Hachemi Glaoui, Larbi Djilali, and Slimani Abdeldjalil. "Robust Sliding Mode H∞ Controller of DFIG Based on Variable Speed Wind Energy Conversion System." Periodica Polytechnica Electrical Engineering and Computer Science 64, no. 1 (October 24, 2019): 53–63. http://dx.doi.org/10.3311/ppee.14490.
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In this study, a Sliding Mode (SM) methodology combined with a robust H∞ control scheme (SM-H∞) was proposed to control the stator active and reactive power generated by the Doubly Fed Induction Generator (DFIG). The purpose of the proposed controller is to improve the DFIG stator active and reactive power tracking performances by reducing chattering phenomena under variable wind speed, which provides major drawbacks of conventional SM controllers. The H∞ technique was used to define the SM attractive control part, which helps to reduce chattering phenomena and improves robustness in the presence of parameter variations and wind speed changing. The DFIG stator was directly connected to the grid and, its rotor was linked to the grid through a back-to-back converter. The proposed approach was tested using Matlab/Simulink and a comparison with the conventional SM and the SM fuzzy logic controllers was carried out. The results of simulation illustrated an effectiveness of the proposed SM-H∞ controller even in the presence of the DFIG parameter variations and speed changing compared with the other techniques.
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Sun, Xing Wei, He Wang, Ke Wang, and Xin Feng. "Finite Element Analysis of the Helical Surface Cutting Tool." Applied Mechanics and Materials 141 (November 2011): 289–92. http://dx.doi.org/10.4028/www.scientific.net/amm.141.289.
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The screw motor is one kind of volume type power generator, the stator and the rotor is screw motor's core part. In this paper, cutting tool's internal stress and the distortion under the condition of milling inner helical curved surface was dissected with finite element method. Variable rule of feed engagement with changing of the processing parameter was discussed. The modal analysis of the special-purpose cutting tool was carried. To reduce the abnormal wear of special-purpose cutting tool in processing process and increase the special-purpose cutting life, the optimizing scheme was given. This research provides the theory reference for the optimized processing technological parameter.
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Ram, Paras, Vimal Kumar Joshi, Kushal Sharma, Mittu Walia, and Nisha Yadav. "Variable Viscosity Effects on Time Dependent Magnetic Nanofluid Flow past a Stretchable Rotating Plate." Open Physics 14, no. 1 (January 1, 2016): 651–58. http://dx.doi.org/10.1515/phys-2016-0072.
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AbstractAn attempt has been made to describe the effects of geothermal viscosity with viscous dissipation on the three dimensional time dependent boundary layer flow of magnetic nanofluids due to a stretchable rotating plate in the presence of a porous medium. The modelled governing time dependent equations are transformed a from boundary value problem to an initial value problem, and thereafter solved by a fourth order Runge-Kutta method in MATLAB with a shooting technique for the initial guess. The influences of mixed temperature, depth dependent viscosity, and the rotation strength parameter on the flow field and temperature field generated on the plate surface are investigated. The derived results show direct impact in the problems of heat transfer in high speed computer disks (Herrero et al. [1]) and turbine rotor systems (Owen and Rogers [2]).
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Le, V. T., M. M. Korotina, A. A. Bobtsov, S. V. Aranovskiy, and Q. D. Vo. "Identification of Linear Time-Varying Parameters of Nonstationary Systems." Mekhatronika, Avtomatizatsiya, Upravlenie 20, no. 5 (May 25, 2019): 269–65. http://dx.doi.org/10.17587/mau.20.259-265.
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The paper considers the identification algorithm for unknown parameters of linear non-stationary control objects. It is assumed that only the object output variable and the control signal are measured (but not their derivatives or state variables) and unknown parameters are linear functions or their derivatives are piecewise constant signals. The derivatives of non-stationary parameters are supposed to be unknown constant numbers on some time interval. This assumption for unknown parameters is not mathematical abstraction because in most electromechanical systems parameters are changing during the operation. For example, the resistance of the rotor is linearly changing, because the resistance of the rotor depends on the temperature changes of the electric motor in operation mode. This paper proposes an iterative algorithm for parameterization of the linear non-stationary control object using stable LTI filters. The algorithm leads to a linear regression model, which includes time-varying and constant (at a certain time interval) unknown parameters. For this model, the dynamic regressor extension and mixing (DREM) procedure is applied. If the persistent excitation condition holds, then, in the case the derivative of each parameter is constant on the whole time interval, DREM provides the convergence of the estimates of configurable parameters to their true values. In the case of a finite time interval, the estimates convergence in a certain region. Unlike well-known gradient approaches, using the method of dynamic regressor extension and mixing allows to improve the convergence speed and accuracy of the estimates to their true values by increasing the coefficients of the algorithm. Additionally, the method of dynamic regressor extension and mixing ensures the monotony of the processes, and this can be useful for many technical problems.
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Ha, Yunseok, Tae-Woong Ha, Jaeseung Byun, and Yongbok Lee. "Estimation of the rotordynamic characteristics of a single brush seal using least-squares and instrumental variable methods under super-heated steam environment." Advances in Mechanical Engineering 12, no. 3 (March 2020): 168781402091367. http://dx.doi.org/10.1177/1687814020913676.
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The exact understanding of the dynamic characteristic of the seal is a crucial parameter for designing the system. This article presents an experiment that estimates the dynamic characteristics of a brush seal under a super-heated steam environment for a steam turbine. The super-heated steam facility makes super-heated steam (523.15 K) to replicate the real steam turbine environment. Two brush seal units are utilized with a housing connected by springs to measure the modal parameters of the system. To extract the brush seal characteristics, the modal parameters of the pure housing were subtracted from the overall dynamic system. Moreover, to predict modal parameters more accurately, the least-squares method and the instrumental variable method were used to reduce the noise caused by the steam. Two major effects were experimentally investigated by varying the operating speed (0–16,900 r/min) of the rotor and the injection flow of super-heated steam. The results showed that the direct stiffness and damping of the brush seal increased significantly when the steam was injected. Under steam exposure, obtaining the modal parameters using instrumental variable method was confirmed to reduce more noise than obtaining the parameters via least-squares method.
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Noshadi, Amin, Juan Shi, Wee Sit Lee, Peng Shi, and Akhtar Kalam. "Robust control of an active magnetic bearing system using H∞ and disturbance observer-based control." Journal of Vibration and Control 23, no. 11 (September 3, 2015): 1857–70. http://dx.doi.org/10.1177/1077546315602421.
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Active magnetic bearing systems (AMBs) have many potential industrial applications where extremely fast and accurate operations are required. However, AMBs are often subject to disturbances in the form of synchronous vibrations due to unmodeled dynamics such as the rotor mass-imbalance and centrifugal forces while the rotor is in rotation. Several methods such as variable notch filters, gain scheduling controllers, and linear parameter varying controllers have been proposed recently to reject the disturbances while the system is operating at high rotational speeds. These methods are practical only if the frequencies of these sinusoidal-like disturbances are directly measurable or accurately known in advance. In this paper, a hybrid control scheme comprised of a feedback H∞ controller and an inner-loop disturbance observer-based control is proposed. The effectiveness of this control scheme is verified by simulation and real-time experiments on an AMB system. Both constant and sinusoidal disturbances are taken into consideration while the rotor is stationary as well as while it is rotating at different speeds. The results demonstrate that the proposed hybrid control scheme exhibits significantly improved performance in comparison to single-loop controllers in the presence of unknown but bounded disturbances.
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Travieso-Torres, Juan Carlos, Miriam Vilaragut-Llanes, Ángel Costa-Montiel, Manuel A. Duarte-Mermoud, Norelys Aguila-Camacho, Camilo Contreras-Jara, and Alejandro Álvarez-Gracia. "New Adaptive High Starting Torque Scalar Control Scheme for Induction Motors Based on Passivity." Energies 13, no. 5 (March 10, 2020): 1276. http://dx.doi.org/10.3390/en13051276.
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A novel adaptive high starting torque (HST) scalar control scheme (SCS) for induction motors (IM) is proposed in this paper. It uses a new adaptive-passivity-based controller (APBC) proposed herein for a class of nonlinear systems, with linear explicit parametric dependence and linear stable internal dynamics, which encompasses the IM dynamical model. The main advantage of the HST-SCS includes the ability to move loads with starting-torque over the nominal torque with a simple and cost-effective implementation without needing a rotor speed sensor, variable observers, or parameter estimators. The proposed APBC is based on a direct control scheme using a normalized fixed gain (FG) to fine-tune the adaptive controller parameters. The basic SCS for induction motors (IM) and the HST-SCS were applied to an IM of 200 HP and tested using a real-time simulator controller OPAL-RT showing the achievement of the proposal goal.
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Zhou, Zhen Xiong, Yong Yin Qu, and De Jun Liu. "Study on Magnetic Materials with Suspension Altitude Control of 6DOF Precision Magnetic Suspension Platform." Advanced Materials Research 771 (September 2013): 187–91. http://dx.doi.org/10.4028/www.scientific.net/amr.771.187.
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A novel magnetic suspension platform is studied in this paper. Three sets of suspension apparatus is adopted to produce suspension force, each of which consists of the permanent magnet, the U shape yoke and suspension coils. Material of yoke is laminated transformer silicon steel (30ZH100).Material of Permanent magnet is Nd2Fe14B. The mathematical model of suspension was established by analyzing the force exerting on rotor. In view of the levitation system with multi-variable, nonlinear, strong coupling characteristics, ADRC is applied to realize decoupling and disturbance rejection. The rule of ADRC parameter setting was obtained through lots of simulations. The simulation and experimental results indicate this suspension altitude control system has better dynamic characteristics and robust.
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Dybkowski, Mateusz, and Szymon Antoni Bednarz. "Modified Rotor Flux Estimators for Stator-Fault-Tolerant Vector Controlled Induction Motor Drives." Energies 12, no. 17 (August 22, 2019): 3232. http://dx.doi.org/10.3390/en12173232.
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This paper deals with fault-tolerant control (FTC) of an induction motor (IM) drive. An inter-turn short circuit (ITSC) of the stator windings was taken into consideration, which is one of the most common internal faults of induction machines. The sensitivity of the classic, well-known voltage and current models to the stator winding faults was analyzed. It has been shown that these classical state variable estimators are sensitive to induction motor parameter changes during stator winding failure, which results in unstable operation of the direct field-oriented control (DFOC) drive. From a safety-critical applications point of view, it is vital to guarantee stable operation of the drive even during faults of the machine. Therefore, a new FTC system has been proposed, which consists of new modified rotor flux estimators, robust to stator winding faults. A detailed description of the proposed system is presented herein, as well as the results of simulation and experimental tests. Simulation analyses were performed using MATLAB/Simulink software. Experimental tests were carried out on the experimental test bench with a dSpace DS1103 card. The proposed solution could be applied as an alternative rotor flux estimation technique for the modern FTC drive.
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Yan, Di, Qian Tang, Ahmed Kovacevic, Yuanxun Zhang, Wei Liu, Pinghua Liang, and Huijun Zhang. "Designing nano-aluminum laden fuel pump for aviation applications." Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering 234, no. 6 (June 25, 2020): 634–43. http://dx.doi.org/10.1177/0954408920935315.
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In view of the fact that traditional liquid propellants cannot meet the design requirements of large-thrust flight vehicle, it has become a new trend to add nano-metal powder to liquid propellants to greatly increase density and specific impulse. In order to achieve the variable flow-rate and variable-proportion transportation of aviation fuel with nano-aluminum, a new type of solid-liquid mixing pumping system is designed, including powder conveying device, stirring device, pump and corresponding drive and transmission system. For the purpose of avoiding the frictional contact between the rotors, which will bring potential hazard to nano-aluminum powder, a non-contact twin-screw pump with synchronous gears is designed. Among them, based on the considerations of flow pulsation, volumetric efficiency and manufacturing difficulty, cycloid profile is adopted for screw rotors. After completing the functional design, geometric parameter design, structural design, 3D modeling, prototype manufacturing and preliminary performance estimation of the mixing pumping system, the performance of the screw feeder, agitator, screw pump was tested through experiments to meet the expected design requirements. The designed agitator can achieve sufficient mixing at 500 rpm in less than 10 s. Even though 50-micron clearances are designed with a relatively small rotor diameter, the volumetric efficiency of screw pump can reach above 50% when the discharge pressure is below 450 kPa and the flow rate is set as 10 L/min, the power of the screw pump is less than 700 W. This design facilitates the rapid real-time preparation of metallized propellants and provides a reference for further improving the design and control methods of nanoparticle two-phase flow pumping.
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Youcef, Mihoub, Toumi Djilali, Sandrine Moreau, Hassaine Said, and Daoud Bachir. "DSP improvement of a vector speed induction motor control with a RST and adaptive fuzzy controller." Bulletin of Electrical Engineering and Informatics 10, no. 3 (June 1, 2021): 1232–44. http://dx.doi.org/10.11591/eei.v10i3.1798.
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The aim of this work is to improve the dynamics and to overcome the limitation of conventional fixed parameters PI controller used in induction motor (IM) field-oriented control (FOC). This study presents and implements a RST and an adaptive fuzzy controller (AFC) to enhance variable speed control. Theoretical background of theses controllers is outlined and then experimental results are presented. Practical implementation has been realized on a board with a 1.1 KW IM supplied by 10 KHz space vector pulse width modulation current regulated inverter used as power amplifier consisted of 300V, 10A IGBT and Matlab/Simulink environment. Test benches have been established under different operating conditions in order to evaluate and compare the performances of the PI, IP, and polynomial RST and adaptive fuzzy controllers. Parameter variations for the rotor and the inertia moment variation were done in order to compare and verify the robustness of each controller. High dynamic performances and robustness against parameters variation were obtained with the use of both RST and AFC.
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Zhou, Shihua, Zhaohui Ren, Guiqiu Song, and Bangchun Wen. "Dynamic Characteristics Analysis of the Coupled Lateral-Torsional Vibration with Spur Gear System." International Journal of Rotating Machinery 2015 (2015): 1–14. http://dx.doi.org/10.1155/2015/371408.
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A sixteen-degree-of-freedom (16-DOF) lumped parameter dynamic model taking into account the gravity, eccentricity, bearing clearance, transmission error, and coupled lateral-torsional vibration is established. Based on the dynamical equation, the dynamic behaviors of the spur gear rotor bearing system are investigated by using Runge-Kutta method. The research focuses on the effect of rotational speed, eccentricity, and bearing clearance and nonlinear response of the coupled multibody dynamics is presented by vibration waveform, spectrum, and 3D frequency spectrum. The results show that the rotational frequency of the driven gear appears in the driving gear, and the dynamic characteristics of gears have obvious differences due to the effects of the gear assembly and the coupled lateral-torsional vibration. The bearing has its own resonance frequency, and the effect of the variable stiffness frequency of the bearings should be avoided during the system design. The results presented in this paper show an analysis of the coupled lateral-torsional vibration of the spur gear system. The study may contribute to a further understanding of the dynamic characteristics of such a spur gear rotor bearing system.
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Turaga, R., A. S. Sekhar, and B. C. Majumdar. "Stability analysis of a rigid rotor supported on hydrodynamic journal bearings with rough surfaces using the stochastic finite element method." Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology 212, no. 2 (February 1, 1998): 121–30. http://dx.doi.org/10.1243/1350650981541949.
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The effect of surface roughness on the stability characteristics of hydrodynamic journal bearings has been studied. Roughness has been considered to be a stochastic variable, which is stationary, ergodic with mean zero. Both one-dimensional roughness (longitudinal and transverse) and two-dimensional roughness (isotropic) have been studied using the stochastic finite element method. Journal bearings with different width-diameter ratios have also been considered. It is seen that the transverse roughness tends to increase the stability (non-dimensional mass parameter) whereas in the case of isotropic roughness there is a decrease when compared with the smooth bearing. Longitudinal roughness has a marginal effect of decreasing the stability of hydrodynamic journal bearings with rough surfaces.
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Yoon, Keun-Young, and Soo-Whang Baek. "Robust Design Optimization with Penalty Function for Electric Oil Pumps with BLDC Motors." Energies 12, no. 1 (January 2, 2019): 153. http://dx.doi.org/10.3390/en12010153.
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In this paper, we propose and evaluate a robust design optimization (RDO) algorithm for the shape of a brushless DC (BLDC) motor used in an electric oil pump (EOP). The components of the EOP system and the control block diagram for driving the BLDC motor are described. Although the conventional deterministic design optimization (DDO) method derives an appropriate combination of design goals and target performance, DDO does not allow free searching of the entire design space because it is confined to preset experimental combinations of parameter levels. To solve this problem, we propose an efficient RDO method that improves the torque characteristics of BLDC motors by considering design variable uncertainties. The dimensions of the stator and the rotor were selected as the design variables for the optimal design and a penalty function was applied to address the disadvantages of the conventional Taguchi method. The optimal design results obtained through the proposed RDO algorithm were confirmed by finite element analysis, and the improvement in torque and output performance was confirmed through experimental dynamometer tests of a BLDC motor fabricated according to the optimization results.
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Al-barbarawi, Omar, and Ghazi M. Qaryouti. "Implementation simulink modeling to analysis the transient cases and torque speed characteristic in a three phase induction motors." Indonesian Journal of Electrical Engineering and Computer Science 16, no. 3 (December 1, 2019): 1077. http://dx.doi.org/10.11591/ijeecs.v16.i3.pp1077-1087.
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In this research, has been a developed modular approach for investigation of the dynamic behavior and analysis the steady -state and transient cases for a three-phase induction motor when it is fed with a balanced and unbalanced voltage , and analysis the behavior of the Torque-Speed characteristics at various conditions. This analysis is done systematically by development two mathematically models. Where the first model is proposed to simulate the dynamic behavior of the motor when supplying it at balanced and unbalanced voltage in Matlab/Simulink by using d-q axis theory in the reference frame. This model can investigate and described in details the behavior of the induction motor parameters, and enables the researcher to calculate or investigate any variable for an induction machine parameter ; (e.g. The voltage, current, flux, speed and torque as a function of time) in both cases transient and steady state , when the motor in operation state [11-16]. The other model is proposed to simulate in the Microsoft Excel program, by using the ratio between the conventions of the electromagnetic torque equation(Tem) and maximum torque equation (Tmax) . To study and analysis the behavior of the Torque-Speed characteristics for a 3-phase induction motor. Where this models study's by using Excel program's and Matlab / Simulink to simulation the effect of the various parameters on the dynamic behavior of the motor such as inserting variable external resistance in series with rotor circuit , and when supplying the stator by variable voltage. These Mathematical models could be used for a wide range of motors which has a various horse powers , which needing it in a scientific research and practical applications.
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Magzoub, Muawia A., Nordin B. Saad, and Rosdiazli B. Ibrahim. "The Impacts of the Disturbances for the Hybrid Fuzzy-Fuzzy Controller Applied to Induction Motor Drive." Applied Mechanics and Materials 785 (August 2015): 116–21. http://dx.doi.org/10.4028/www.scientific.net/amm.785.116.
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The study of the effects of an internally and externally caused disturbances for the advanced hybrid fuzzy-fuzzy controller (HFFC) scheme in order to gain control over the speed of an induction motor’s (IM) variable speed drive (VSD) is the main objective of this research paper The HFFC works on the principle of gaining control over the rotor speed during steady-state stage using fuzzy stator current magnitude controller whereas, during an accelerate-decelerate stage by utilising a fuzzy frequency controller, to overcome the disadvantage of field oriented control (FOC) method. The design of a scalar controller involves two aspects of FOC i.e current and frequency. Hence, the performance of a controller has been observed with a series of tests which yielded a controller which is more effective, consistent and insensitive to the parameter variation for the motor and system strength to noise and load disturbances.
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Kandoussi, Zineb, Zakaria Boulghasoul, Abdelhadi Elbacha, and Abdelouahed Tajer. "Real time implementation of a new fuzzy-sliding-mode-observer for sensorless IM drive." COMPEL - The international journal for computation and mathematics in electrical and electronic engineering 36, no. 4 (July 3, 2017): 938–58. http://dx.doi.org/10.1108/compel-07-2016-0330.
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Purpose The purpose of this paper is to improve the performance of sensorless vector control of induction motor drives by developing a new sliding mode observer for rotor speed and fluxes estimation from measured stator currents and voltages and estimated stator currents. Design/methodology/approach In the present paper, the discontinuity in the sliding mode observer is smoothed inside a thin boundary layer using fuzzy logic techniques instead of sign function to reduce efficiently the chattering phenomenon that affects the rotor speed. Findings The feasibility of the proposed fuzzy sliding mode observer has been verified by experimentation. The experimental results are obtained with a 1 kW induction motor using a dSPACE system with DS1104 controller board showing clearly the effectiveness of the proposed approach in terms of dynamic performance compared to the classical sliding mode observer. Practical implications The experimental results of the whole control structure highlights that this kind of sensorless induction motor drive can be used for variable speed drive in industrial applications such as oil drilling, electric vehicles, high speed trains (HSTs) and conveyers. Such drives may work properly at zero and low speed in both directions of rotation. Originality/value Both the proposed speed observer and the classical sliding mode observer have been developed and implemented experimentally with other adaptive observers for detailed comparison under different operating conditions, such as parameter variation, no-load/load disturbances and speed variations in different speed operation regions.
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R, Ashok kumar, and Balaji K. "Sensor less control of PMSM fed from three phase four switch inverter based on back EMF observer and sliding mode controller with fast reaching law." International Journal of Engineering & Technology 7, no. 2 (May 12, 2018): 725. http://dx.doi.org/10.14419/ijet.v7i2.10847.
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Closed Loop control of PMSM drives require rotor position and angular velocity information, the use of position sensor increases cost of the drive and increases complexity in motor construction. A position sensor less vector control technique is proposed where a back EMF observer is used to estimate motors speed and position signal. Back EMF observer method is simple and has high accuracy in estimating speed of PMSM motor. Permanent magnet synchronous motor is fed from a three-phase four-switch inverter and sliding mode controller is used as a speed regulator. Fast reaching law is added to sliding mode speed controller, which replaces constant switching gain function by variable switching function based on sliding surface. Variable switching function for SMC eliminates the chattering problem that occurs due to high value of constant switching gain. The proposed reaching law for sliding mode controller reduces the time taken for the controller to reach convergence and also increases robustness of the drive during parameter variation and full load conditions. Use of sensor less control technique and four-switch inverter reduced the overall cost of the drive whilst maintaining the performance of the system. Merits of pro-posed sensor less control technique and sliding mode controller with fast reaching law is verified by simulations using MATLAB/Simulink software.
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Eggers, Torben, Hye Rim Kim, Simon Bittner, Jens Friedrichs, and Joerg R. Seume. "Aerodynamic and Aeroelastic Effects of Design-Based Geometry Variations on a Low-Pressure Compressor." International Journal of Turbomachinery, Propulsion and Power 5, no. 4 (September 24, 2020): 26. http://dx.doi.org/10.3390/ijtpp5040026.
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In modern aircraft engines, the low-pressure compressor (LPC) is subjected to a flow characterized by strong wakes and secondary flows from the upstream fan. This concerns ultra-high bypass ratio (UHBR) turbofan engines, in particular. This paper presents the aerodynamic and aeroelastic sensitivities of parametric variations on the LPC, driven by the design considerations in the upstream fan. The goal of this investigation was to determine the influence of design-based geometry parameter variations on the LPC performance under realistic inlet flow distributions and the presence of an s-duct. Aerodynamic simulations are conducted at the design and off-design operating points with the fan outflow as the inlet boundary conditions. Based on the aerodynamic results, time-linearized unsteady simulations are conducted to evaluate the vibration amplitude at the resonance operating points. First, the bypass ratio is varied by reducing the channel height of the LPC. The LPC efficiency decreases by up to 1.7% due to the increase in blockage of the core flow. The forced response amplitude of the rotor decreases with increasing bypass ratio due to increased aerodynamic damping. Secondly, the fan cavity leakage flow is considered as it directly affects the near hub fan flow and thus the inflow of the LPC. This results in an increased total-pressure loss for the s-duct due to mixing losses. The additional mixing redistributes the flow at the s-duct exit leading to a total-pressure loss reduction of 4.3% in the first rotor at design point. This effect is altered at off-design conditions. The vibration amplitude at low speed resonance points is increased by 19% for the first torsion and 26% for second bending. Thirdly, sweep and lean are applied to the inlet guide vane (IGV) upstream of the LPC. Despite the s-duct and the variable inlet guide vane (VIGV) affecting the flow, the three-dimensional blade design achieves aerodynamic and aeroelastic improvements of rotor 1 at off-design. The total-pressure loss reduces by up to 18% and the resonance amplitude more than 10%. Only negligible improvements for rotor 1 are present at the design point. In a fourth step, the influence of axial gap size between the stator and the rotor rows in the LPC is examined in the range of small variations which shows no distinct aerodynamic and aeroelastic sensitivities. This finding not only supports previous studies, but it also suggests a correlation between mode shapes and locally increased excitaion with increasing axial gap size. As a result, potential design improvements in future fan-compressor design are suggested.
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Laghridat, Hammadi, Ahmed Essadki, Maha Annoukoubi, and Tamou Nasser. "A Novel Adaptive Active Disturbance Rejection Control Strategy to Improve the Stability and Robustness for a Wind Turbine Using a Doubly Fed Induction Generator." Journal of Electrical and Computer Engineering 2020 (March 30, 2020): 1–14. http://dx.doi.org/10.1155/2020/9847628.
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A novel and robust active disturbance rejection control (ADRC) strategy for variable speed wind turbine systems using a doubly fed induction generator (DFIG) is presented in this paper. The DFIG is directly connected to the main utility grid by stator, and its rotor is connected through a back-to-back three phase power converter (AC/DC/AC). Due to the acoustic nature of wind and to ensure capturing maximum energy, a control strategy to extract the available maximum power from the wind turbine by using a maximum power point tracking (MPPT) algorithm is presented. Moreover, a pitch actuator system is used to control the blades’ pitch angle of the wind turbine in order to not exceed the wind turbine rated power value in case of strong wind speeds. Furthermore, the rotor-side converter is used to control the active and reactive powers generated by the DFIG. However, the grid-side converter is used to control the currents injected into the utility grid as well as to regulate the DC-link voltage. This paper aims to study and develop two control strategies for wind turbine system control: classical control by proportional integral (PI) and the proposed linear active disturbance rejection control (LADRC). The main purpose here is to compare and evaluate the dynamical performances and sensitivity of these controllers to the DFIG parameter variation. Therefore, a series of simulations were carried out in the MATLAB/Simulink environment, and the obtained results have shown the effectiveness of the proposed strategy in terms of efficiency, rapidity, and robustness to internal and external disturbances.
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Hong, Chih-Ming, Cong-Hui Huang, and Fu-Sheng Cheng. "Design of an adaptive intelligent control scheme for switched reluctance wind generator." Engineering Computations 34, no. 1 (March 6, 2017): 105–22. http://dx.doi.org/10.1108/ec-10-2015-0314.
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Purpose This paper aims to present the analysis, design and implementation of functional link-based recurrent fuzzy neural network (FLRFNN) for the control of variable-speed switched reluctance generator (SRG). Design/methodology/approach The node connecting weights of the FLRFNN are trained online by back-propagation (BP) algorithms. The proposed estimator requires less processing time than traditional methods and can be fully implemented using a low-cost digital signal processor (DSP) with MATLAB toolboxes. The DSP-based hybrid sensor presented in this paper can be applied to a wind energy-conversion system where the SRG is used as a variable-speed generator. The current transducer is used to monitor the energized current and proximity sensors for rotor salient. Findings The authors have found that optimal based on FLRFNN with Grey controller can resolve the regulation of the system with uncertainty model and unknown disturbances. This technique can maintain the system stability and reach the desired performance even with parameter uncertainties. Originality/value This design will improve the performance of SRG to operate more smoothly. This application is currently being studied because the SRG has well-known advantages such as robustness, low manufacturing cost and good size-to-power ratio. Performance of the proposed controller can offer better stability characteristics. Finally, the SRG has a very good efficiency in the whole operating range.
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Lahmar, M. "Elastohydrodynamic analysis of double-layered journal bearings lubricated with couple-stress fluids." Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology 219, no. 2 (February 1, 2005): 145–65. http://dx.doi.org/10.1243/135065005x9835.
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Elastohydrodynamic (EHD) analysis of a journal bearing with a realistic model for the bearing made of two distinct layers is extended to include couple-stress effects in lubricants blended with polymer additives. Based on the Stokes microcontinuum theory, a transient pressure differential equation (modified Reynolds' equation) is derived from the fluid motion equations and solved numerically. The elegant and powerful semi-analytical approach based on the complex variable theory developed in an earlier work is extended to solve linear elastostatics problems for a double-layered journal bearing. The EHD solution in isothermal conditions is obtained numerically by means of an iterative procedure. By the finite perturbation technique, the eight fluid-film stiffness and damping coefficients are determined. At the threshold of instability, the dynamic coefficients are used as input data for studying the linear stability of the rotor-bearing system. According to the results obtained, the influence of couple-stress parameter on the static and dynamic performance characteristics of the compliant journal-bearing system is physically apparent and not negligible. Compared with the Newtonian lubricants case, lubricants with couple-stresses provide an increase in the load-carrying capacity and stability, a reduction in the attitude angle and the friction factor. It is also found that the fluid-solid interaction effect on the performance characteristics is more important, especially for high values of couple-stress parameter and relative rigidity of liner-bush assembly.
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Liu, Jun, and Jing Ru Chen. "Simulation Studies for Doubly-Fed Wind Generator Based on Neural Network Internal Model Control." Advanced Materials Research 383-390 (November 2011): 3571–77. http://dx.doi.org/10.4028/www.scientific.net/amr.383-390.3571.
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Wind power is a clean and renewable energy, and its exploitation is developing rapidly across the world. The Variable Speed Constant Frequency (VSCF) wind power generation system requires the doubly-fed wind generator (DFIG) to have high response as well as good robustness. DFIG will be affected both by internal disturbance of parametic variations and external disturbance of the load torque oscillation. The dynamics of the current response of the present PI controlled rotor may be in bad condition. In addition, the above disturbances reduce efficiency and stability of the wind turbine. Internal model control (IMC) is a kind of control strategy based on mathematical model to design the controller, it has advantages such as simply to design, robustness, convenient to research. Compared with PI control, IMC has a faster response, and is insensitive to the parameter variation and disturbances, but the IMC highly depends on accurate model of the controlled object. To solve this problem, combine the neural networ and IMC to design the neural network internal model controller .The simulation indicates that the dynamic performance and the anti-interference ability of DFIG are improved.
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LI, ZHEN, SIU-CHUNG WONG, CHI K. TSE, and GRACE CHU. "BIFURCATION IN WIND ENERGY GENERATION SYSTEMS." International Journal of Bifurcation and Chaos 20, no. 11 (November 2010): 3795–800. http://dx.doi.org/10.1142/s0218127410028070.
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This letter reveals the possibility of Hopf bifurcation in a grid-connected wind energy generation system which handles an unbalanced loading. The wind energy generation system consists of a typical doubly fed induction generator (DFIG) which allows variable speed operation by using partially rated back-to-back quadruple active and reactive power PWM converters. Many control schemes reported in the literature are designed to solve some specific control problems associated with DFIG and have rarely been tested for general stability. Specifically, bifurcation analysis of the system has not been reported so far. We study the system stability in terms of the magnitude of some unwanted oscillation of the voltage link capacitor under a practical scenario where the system interacts indirectly with unbalanced single-phase constant power loads through the power grid. In this letter, the rotor speed of the DFIG is used as a variation parameter for bifurcation analysis. Bifurcation diagram of the voltage link capacitor indicates a Hopf-like bifurcation of the system in super-synchronous operation. This clearly explains the instability phenomenon of the practical DFIG system when unbalanced single-phase constant power loads are connected to the connecting grid.
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Cao, Wenping, Ning Xing, Yan Wen, Xiangping Chen, and Dong Wang. "New Adaptive Control Strategy for a Wind Turbine Permanent Magnet Synchronous Generator (PMSG)." Inventions 6, no. 1 (December 28, 2020): 3. http://dx.doi.org/10.3390/inventions6010003.
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Wind energy conversion systems have become a key technology to harvest wind energy worldwide. In permanent magnet synchronous generator-based wind turbine systems, the rotor position is needed for variable speed control and it uses an encoder or a speed sensor. However, these sensors lead to some obstacles, such as additional weight and cost, increased noise, complexity and reliability issues. For these reasons, the development of new sensorless control methods has become critically important for wind turbine generators. This paper aims to develop a new sensorless and adaptive control method for a surface-mounted permanent magnet synchronous generator. The proposed method includes a new model reference adaptive system, which is used to estimate the rotor position and speed as an observer. Adaptive control is implemented in the pulse-width modulated current source converter. In the conventional model reference adaptive system, the proportional-integral controller is used in the adaptation mechanism. Moreover, the proportional-integral controller is generally tuned by the trial and error method, which is tedious and inaccurate. In contrast, the proposed method is based on model predictive control which eliminates the use of speed and position sensors and also improves the performance of model reference adaptive control systems. In this paper, the proposed predictive controller is modelled in MATLAB/SIMULINK and validated experimentally on a 6-kW wind turbine generator. Test results prove the effectiveness of the control strategy in terms of energy efficiency and dynamical adaptation to the wind turbine operational conditions. The experimental results also show that the control method has good dynamic response to parameter variations and external disturbances. Therefore, the developed technique will help increase the uptake of permanent magnet synchronous generators and model predictive control methods in the wind power industry.
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Seidel, Cory, and David A. Peters. "How Big Is a Lock Number?" Journal of the American Helicopter Society 66, no. 1 (January 1, 2021): 1–3. http://dx.doi.org/10.4050/jahs.66.012001.
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The traditional Lock number for lifting rotors is recast in terms of a different set of parameters. This new formulation, while not changing the basic definition of the Lock number, gives additional physical insight into the design variables that influence this number. The new formulation enables one to better understand why Lock numbers fall into the range they do. The fundamental basis of the Lock number is studied for 33 rotors, ranging in size from the main rotor of the CH-53E (with seven blades and a diameter of 79 ft) down to the tail rotor of the Robinson R22 Beta (with two blades and a diameter of 3.5 ft).
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Geng, Guoqing, Qingyuan Shen, and Haobin Jiang. "ANFTS Mode Control for an Electronically Controlled Hydraulic Power Steering System on a Permanent Magnet Slip Clutch." Energies 12, no. 9 (May 8, 2019): 1739. http://dx.doi.org/10.3390/en12091739.
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There are various uncertain factors such as parameter perturbation and external disturbance during the steering process of a permanent magnet slip clutch electronically controlled hydraulic power steering system (P-ECHPS) of medium and heavy duty vehicles, which is an electronically controlled hydraulic power steering system based on a permanent magnetic slip clutch (PMSC). In order to avoid the immutable single assistance characteristic of a hydraulic power steering system, a PMSC speed-controlled model and P-ECHPS of each subsystem model were studied. Combined with non-singular terminal sliding mode and fast terminal sliding mode, an Adaptive Non-singular Fast Terminal Sliding (ANFTS) mode control strategy was proposed to control precisely the rotor speed of the PMSC in P-ECHPS, thus achieving better power control for the entire P-ECHPS system. The simulation results show that adaptive nonsingular fast terminal sliding mode control enables PMSC output speed to track the target speed. Compared with the non-singular terminal sliding mode control and the ordinary sliding mode control, the convergence speed has been improved by 66.7% and 84.2%, respectively. The rapid control prototype test of PMSC based on dSPACE (dSPACE is a development and verification platform based on MATLAB/Simulink software.) was carried out. The validity of the adaptive NFTSM algorithm and the correctness of the offline simulation results are validated. The adaptive NFTSM algorithm have better robustness and can realize variable assist characteristics and save energy.
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Kaleta, Jiří, Jin Wen, Thomas F. Magnera, Paul I. Dron, Chenhui Zhu, and Josef Michl. "Structure of a monolayer of molecular rotors on aqueous subphase from grazing-incidence X-ray diffraction." Proceedings of the National Academy of Sciences 115, no. 38 (March 23, 2018): 9373–78. http://dx.doi.org/10.1073/pnas.1712789115.
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In situ grazing-incidence X-ray scattering shows that a monolayer of artificial rod-shaped dipolar molecular rotors produced on the surface of an aqueous subphase in a Langmuir trough has a structure conducive to a 2D ferroelectric phase. The axes of the rotors stand an average of 0.83 nm apart in a triangular grid, perpendicular to the surface within experimental error. They carry 2,3-dichlorophenylene rotators near rod centers, between two decks of interlocked triptycenes installed axially on the rotor axle. The analysis is based first on simultaneous fitting of observed Bragg rods and second on fitting the reflectivity curve with only three adjustable parameters and the calculated rotor electron density, which also revealed the presence of about seven molecules of water near each rotator. Dependent on preparation conditions, a minor and variable amount of a different crystal phase may also be present in the monolayer.
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Topp, D. A., and S. Fleeter. "Splitter Blades as an Aeroelastic Detuning Mechanism for Unstalled Supersonic Flutter of Turbomachine Rotors." Journal of Turbomachinery 108, no. 2 (October 1, 1986): 244–52. http://dx.doi.org/10.1115/1.3262044.
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A mathematical model is developed to demonstrate the application of splitter blades as an aeroelastic detuning mechanism for unstalled supersonic flutter of turbomachine rotors. The splitters introduce both aerodynamic and structural detuning, thereby leading to enhanced aeroelastic stability. The aerodynamic detuning is due to the variable circumferentially spaced splitters between each pair of full chord airfoils, with aerodynamic detuning due to alternate circumferential spacing of the full chord airfoils also considered. The structural detuning arises from the lower natural frequencies of the splitters as compared to that of the full chord airfoils. The enhanced torsion mode flutter stability due to the incorporation of splitters into a rotor design is demonstrated by applying this model to two unstable baseline twelve-bladed rotors which are based on Verdon’s Cascade A and Cascade B configurations. In each case, the unstable baseline rotor is stabilized by the introduction of appropriate splitters. The critical parameters for this stability enhancement are the chord length and the circumferential and axial locations of the splitters.
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Ilten, Erdem, and Metin Demirtas. "Fractional order super-twisting sliding mode observer for sensorless control of induction motor." COMPEL - The international journal for computation and mathematics in electrical and electronic engineering 38, no. 2 (March 4, 2019): 878–92. http://dx.doi.org/10.1108/compel-08-2018-0306.
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Purpose To meet the need of reducing the cost of industrial systems, sensorless control applications on electrical machines are increasing day by day. This paper aims to improve the performance of the sensorless induction motor control system. To do this, the speed observer is designed based on the combination of the sliding mode and the fractional order integral. Design/methodology/approach Super-twisting sliding mode (STSM) and Grünwald–Letnikov approach are used on the proposed observer. The stability of the proposed observer is verified by using Lyapunov method. Then, the observer coefficients are optimized for minimizing the steady-state error and chattering amplitude. The optimum coefficients (c1, c2, ki and λ) are obtained by using response surface method. To verify the effectiveness of proposed observer, a large number of experiments are performed for different operation conditions, such as different speeds (500, 1,000 and 1,500 rpm) and loads (100 and 50 per cent loads). Parameter uncertainties (rotor inertia J and friction factor F) are tested to prove the robustness of the proposed method. All these operation conditions are applied for both proportional integral (PI) and fractional order STSM (FOSTSM) observers and their performances are compared. Findings The observer model is tested with optimum coefficients to validate the proposed observer effectiveness. At the beginning, the motor is started without load. When it reaches reference speed, the motor is loaded. Estimated speed and actual speed trends are compared. The results are presented in tables and figures. As a result, the FOSTSM observer has less steady-state error than the PI observer for all operation conditions. However, chattering amplitudes are lower in some operation conditions. In addition, the proposed observer shows more robustness against the parameter changes than the PI observer. Practical implications The proposed FOSTSM observer can be applied easily for industrial variable speed drive systems which are using induction motor to improve the performance and stability. Originality/value The robustness of the STSM and the memory-intensive structure of the fractional order integral are combined to form a robust and flexible observer. This paper grants the lower steady-state error and chattering amplitude for sensorless speed control of the induction motor in different speed and load operation conditions. In addition, the proposed observer shows high robustness against the parameter uncertainties.
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Ghanmi, Hanen, Adel Ghith, and Tarek Benameur. "Open-End Yarn Properties Prediction Using HVI Fibre Properties and Process Parameters." Autex Research Journal 17, no. 1 (March 1, 2017): 6–11. http://dx.doi.org/10.1515/aut-2015-0026.
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AbstractThis article provides three models to predict rotor spun yarn characteristics which are breaking strength, breaking elongation and unevenness. These models used noncorrelated raw material characteristics and some processing parameters. For this purpose, five different cotton blends were processed into rotor spun yarns having different metric numbers (Nm10, Nm15, Nm18, Nm22, Nm30 and Nm37). Each count was spun at different twist levels. Response surface method was used to estimate yarn quality characteristics and to study variable effects on these characteristics. In this study, predicting models are given by the analysis of response surface after many iterations in which nonsignificant terms are excluded for more accuracy and precision. It was shown that yarn count, twist and sliver properties had considerable effects on the open-end rotor spun yarn properties. This study can help industrial application since it allows a quality management-prediction based on input variables such as fibre characteristics and process parameters.