Tìm thấy 17+ kết quả cho từ khóa "Electrical Machines"
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Some authors believe that the magnetostriction affects the vibrations of rotating electrical machines [1,2]. others claim that the magnetostriction can be ignored [3]. Uncoupled dynamic models for the vibrations of rotating electrical machines also have been presented [6–8]. The goal of this study is to establish the effect of magnetostriction and magnetoelastic coupling on the vibrations and noise of rotating electrical machines.
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Landrath, “New Permanent Magnet Excited Synchronous Machine with High Efficiency at Low Speeds”, Proceedings of the International Electrical Machines Conference, Pisa, Italy, September 1988, pp. Jack, “A New High Torque Density Permanent Magnet Machine Config- uration”, Proceedings of the International Electrical Machines Conference, Cambridge, MA, USA, September 1990..
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The goal of these simulations is to establish the effect of the magnetostriction on the vibrations of rotating electrical machines. It is shown that the magnetostriction affects the vibrations of rotating electrical machines by increasing or decreasing the amplitudes of velocities measured at the outer surface of the stator core of the machine. Furthermore, the stress-dependency of the magnetostriction adds to the increase of the above amplitudes..
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Four methods are performed to determine the natural frequencies and the associated mode number. electrical quantities and the identification of mechanical parameters allows to transform the mechanical problem into an electrical circuit study. To Determine Natural Frequencies of Electrical Machines 227 Numerical determination with a FE software. where [H ] and [M] are, respectively, the stiffness and the mass matrixes.
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The same letter but capitalized denotes the rms value of the variable, assuming it is periodic.. ω r angular frequency of the rotor currents and voltages (in electrical de- grees). where i(t) is the instantaneous value of current through the load and v(t) is the instantaneous value of the voltage across it.. ˆ i sin(ωt + φ i ) (1.3) In this case the rms values of the voltage and current are:. The loads of the system as shown in figure 1.9 are said to be in Y or star.
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The goal of these simulations is to establish the effect of the magne- tostriction on the vibrations of rotating electrical machines. It is shown that the magnetostriction affects the vibrations of rotating electrical machines by increasing or decreasing the amplitudes of velocities measured at the outer surface of the stator core of the machine. Furthermore, The stress dependency of the magnetostriction adds to the increase of the above amplitudes..
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Liese, “Calculation of Eddy Current Losses and Temperature Rises at the Stator End Portion of Hydro Generators”, Proceedings on the 15th International Conference on Electrical Machines, ICEM, Brugge, Belgium, August, 2002.
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The same letter but capitalized denotes the rms value of the variable, assuming it is periodic.. ω r angular frequency of the rotor currents and voltages (in electrical de- grees). where i(t) is the instantaneous value of current through the load and v(t) is the instantaneous value of the voltage across it.. ˆ i sin(ωt + φ i ) (1.3) In this case the rms values of the voltage and current are:. The loads of the system as shown in figure 1.9 are said to be in Y or star.
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Mueller, “Comparison of Different Numerical Approaches for the Calculation of Eddy Current Losses in Large Synchronous Generators”, Proceedings of the Seventh International Conference on Modeling and Simulation of Electrical Machines, Converters and Systems, ELECTRIMACS, Montreal, Canada, 2002..
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One of the major thermal problems in electrical machines is the steady-state hot spot temperatures in the windings, which are responsible for its thermal aging and degrada- tion. So it is important to correctly determine those hot spots in the thermal design of the machine.. In the thermal finite element (FE) modeling of electrical machines, all the different ma- terials to be crossed by the heat flux should be considered, namely the windings insulations..
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Gmyrek, “The Calculation of Power Losses Under Rotational Magnetization Excess Losses Including”, International Conference Electrical Machines 2002 (ICEM 2002), Brugge, Belgium, August . Reprinted under the title “A Steinmetz contribution to the AC power revolution” introduced by J.E
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With these induction waves it is possible to calculate the mechanical forced vibrations due to the electromagnetic excitation of electrical machines regarding to structural vibration. This excitation wave force is produced by the fundamental induction harmonic wave p p = 6 of 60 Hz frequency, generated by the main winding and the fundamental induction harmonic wave p a.
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Coimbra, “Influence of the Thermal Dependency of the Windings Resistivity in the Solution of Heat Transfer Problem Using the Finite Element Approach”, Proc.. of the International Conference on Electrical Machines (ICEM94), Paris, France, September 1994, pp. This paper focuses on iron loss measurements and simulations in perspective to evaluate a loss model that can be used for SMC materials in FEA..
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Kladas, “Modeling and Control of a Variable-Speed Wind Turbine Equipped with Permanent Magnet Synchronous Generator”, International Conference on Electrical Machines, Helsinki, Finland, 2000, pp. Jahns, Motion control with permanent magnet AC machines, IEEE Proc., Vol. Razek, “Torque Optimization of a Buried Permanent Magnet Syn- chronous Machine by Geometric Modification using FEM”, Proc. THREE-PHASE TRANSFORMER ANALYSIS BASED ON NONLINEAR B-H.
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Fleming’s rules relate to the direction of the magnetic field, motion and current in electrical machines. For any closed loop path, the sum of the length elements times the magnetic field in the direction
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Hoeijmakers, “The (In)Stability of a Synchronous Machine with Diode Rectifier”, Proceedings of the International Electrical Machines Conference, UK, September 1992, pp. PERFORMANCE OF LARGE PM SYNCHRONOUS WIND GENERATOR. The paper presents a comparison between sinusoidal and trapezoidal waveforms in order to reduce the torque ripple and the power to grid fluctuation for large direct-drive PM wind generator..
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Reactive power is the capacity of specific metabolic intensity of electromagnetic energy, it creates a magnetic field fluctuations on the grid, helping stabilize the electricity, it also creates magnetic field to work for electrical machines so reactive power is consumed in most electric machines, especially transformers and asynchronous motors.
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Such machines, known as synchronous condensers, may be more economical in the large sizes than static capacitors.. If the stator excitation of a permanent magnet motor is controlled by its rotor position such that the stator field is always 90 o (electrical) ahead of the rotor, the motor performance can be very close to the conventional brushed dc motors, which is very much favored for variable speed drives.
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The value of the voltage is for machines of low power rating above one third of the rated voltage, while for machines of high power rating it is in between one sixth and one third of the rated voltage.. Due to significantly reduced value of the voltage, reactive power absorbed by the machine is significantly reduced as well, because the flux density that has to be established in the core is very low. 13 can be used in discussion of starting of the motor with rated voltage.
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RECENT DEVELOPMENTS OF ELECTRICAL DRIVES. Recent Developments of Electrical Drives. Coupled Model for the Interior Type Permanent Magnet Synchronous Motors at Different Speeds. A General Description of High-Frequency Position Estimators for Interior Permanent-Magnet Synchronous Motors. Wide-Speed Operation of Direct Torque-Controlled Interior Permanent-Magnet Synchronous Motors. Electrical Drives Applications. Kladas and J.A.Tegopoulos. r Permanent Magnet Machines