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Wei Xu,,
Yaohua Li,, Guangsheng Sun,,
Jinqi Ren,,
Longcheng Tan,,
Ke Wang,,
Junfei Han,
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ABSTRACT: This paper, on the base of the two-dimensional magnetic equations of linear induction motor (LIM), achieves the phase current and excited voltage expressions by dummy electric potential method. Then it deduces the air-gap flux linkage expression by connecting Maxwell electromagnetic field equations, complex power method with conformal transformation method fully considering half-filled slots, york magnetic saturation, back iron resistance. This article, by the equal complex power relationship between magnetic and circuit, obtains some expressions involving excited reactance x<sub>m0</sub>, secondary resistance r<sub>2</sub>', secondary leakage reactance x<sub>2</sub>, longitudinal end effect coefficients K<sub>r</sub>(s) and K<sub>x</sub>(s), transverse end edge effect coefficients C<sub>r</sub>(s) and C<sub>x</sub>(s), skin effect coefficient K<sub>f</sub>. Depending on the T-model of rotary induction motor (RIM), this paper presents a new revised T-model equivalent circuit for LIM by superposition theorem. This new model makes calculation for Japanese 12000-LIM in detail. Many curves attained by new model including thrust force, phase current, power factor and efficiency are compared with those of space harmonic method and experience. The contrastive curves and error analysis indicate that this model is credible and accords with engineering application requirement. Therefore, it is so useful that establishes foundation for design and optimization of high-power LIM in transportation.
Electrical Machines and Systems, 2007. ICEMS. International Conference on; 11/2007
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ABSTRACT: Nanosecond-pulse breakdown indicates special characteristics depending on the pulse rise-time and duration. Based on a repetitive nanosecond-pulse generator, breakdown phenomena of parallel-plane gaps in nitrogen were investigated with single pulse and repetitive bursts under different gap conditions. The relationships between applied voltage, pulse repetition frequency, breakdown time lag, repetitive pulse stress time and the number of applied pulses are presented. The curves regarding E-field strength, breakdown time lag and gas pressure are also obtained. The experimental results show that breakdown characteristics with repetitive nanosecond-pulses are different from that with single pulse. Repetitive nanosecond-pulse breakdown is concerned with the accumulation effect that is attributed to residual ions and metastable species survived from previous pulses. In addition, a modified empirical formula about E-field strength, breakdown time lag and gas density is given for the breakdown data.
IEEE Transactions on Dielectrics and Electrical Insulation 09/2007; · 1.09 Impact Factor
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ABSTRACT: Based on a Marx generator and a coaxial pulse forming line, an experimental investigation of surface flashover characteristics in vacuum is conducted by using nanosecond pulses of 10 ns rise time and 30 ns full width at half maximum (FWHM). Insulator dielectrics chosen for this investigation are Teflon, PMMA and Nylon. The tested factors include gas pressure, cone angle of conical frustum, diameter and length of cylindrical insulator, material and shape of electrode, and contact style between insulator and electrodes. The effects of these parameters on the surface flashover characteristics are described and analyzed in this paper. In addition, the character of flashover time lag in the nanosecond range, and surface flashover theory in vacuum charged by nanosecond pulses are also discussed.
IEEE Transactions on Dielectrics and Electrical Insulation 07/2007; · 1.09 Impact Factor
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ABSTRACT: This paper, basing on the rotary motor model, develops a new equivalent circuit to analyze the single-sided linear induction motor. This method, in a novel viewpoint, takes the end effects, half-filled slots, skin-effect and back-iron resistance into accounts. These predictions and calculations agree with experiment data very well, which is helpful for the linear induction motor design and control.
Industrial Electronics and Applications, 2007. ICIEA 2007. 2nd IEEE Conference on; 06/2007
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ABSTRACT: An equivalent-circuit model of a single-sided linear induction motor is developed. This model sets out a novel method to analyze motor performance considering end effects, half-filled slots, gap leakage flux density. These predictions and emulational conclusions agree with test results of a practical single-sided linear induction motor very well, which validates the proposed means.
Power Conversion Conference - Nagoya, 2007. PCC '07; 05/2007
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ABSTRACT: The SLIM has been widely applied in transportation for its simple-firm structure and its directly forward electromagnetic thrust. The motor has transverse and longitudinal end-effects because of its discontinuous magnetic circuit. There are eddy currents, which become greater as motor speed increases, occurring in both entrance and exit of its secondary sheet. End effects and eddy currents bring ill impact to air gap magnetic flux, which reduce its available magnetic flux and pull coefficient. This paper works out the d-q axis equivalent circuits of SLIM considering end effects. The changes of mutual inductance and resistance in d-axis indicate both the second longitudinal end effect and the eddy current influences. Then the article establishes SLIM math equations connected with the rotor-flux oriented (RFO) vector control theory. This paper brings forward u<sub>ds</sub>, u<sub>qs</sub>, i<sub>qs</sub> online decouple compensation basing on the rotor magnetic flux, speed, current regulators, which adjust and accommodate tractive force, d-q axis voltages, d-q magnetic fluxes, d-axis mutual inductance. The simulation and experimental results indicate that this method is reasonable, which provides theory guidance to the SLIM application analysis and achieves some active effects.
Industrial Technology, 2006. ICIT 2006. IEEE International Conference on; 01/2007
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ABSTRACT: Electrical trees are greatly influenced by the morphological
structure in semi-crystalline polymers. In this paper, samples of
polyethylene (PE) films have been annealed. The electrical tree
initiation voltages of these samples also have been measured. It was
found that the thickness of lamellae is the important parameter that
affects the tree initiation. It was also found that the thermal
stability could be related to the thickness of lamellae. It was
considered that the larger the thickness of lamellae, the higher the
thermal stability, which results in the more difficult tree initiation
Electrical Insulating Materials, 2001. (ISEIM 2001). Proceedings of 2001 International Symposium on; 02/2001
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ABSTRACT: Recently, single linear induction motor(SLIM), which comes from rotary induction motor(RIM), has been widely applied in transportation systems, especially in intermediate speed arrange, because of its merits, such as ability to exert thrust on the secondary without mechanical contacts, high acceleration or deceleration, less wear of the wheels, smaller turn circle radius and more flexible road line etc. However, for cut-open magnetic circuit, inherent characteristics of SLIM such as longitudinal end-effect, transverse edge-effect and half filled slots etc are the main subjects by researchers all along. In this paper, T model equivalent circuit, achieved on the base of the one-dimensional magnetic equations of air gap is proposed first. The end effect and edge effect which affect excited reactance and secondary resistance can be rectified by coefficients K'r (s), K'x (s), Cr(s) and Cx(s). The half slots are considered by correcting poles number. From this T model equivalent circuit, two-axis equivalent circuits(dq or αβ) according flux linkage conservation, which unifies with those of RIM, are deduced. The four coefficients of equivalent circuits above are analyzed and the simulation curves are compared with experiments. The results indicate that this T model and new two-axis circuits are very reasonable to describe SLIM performance and control process.
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ABSTRACT: Based on the platform of laser-triggered surface flashover in pulsed voltage, experiment of laser-triggered surface flashover is carried out in air and vacuum condition with pulsed voltage. A single/double harmonic, with wavelength l of 1064/532 nm, Q-switched Nd: YAG laser is applied to trigger the surface flashover. The test system consists of flat electrodes and columned insulator. The material of electrode is copper and the material of insulator is polycarbonate. Laser pulse's wavelengths are 532nm and 1064nm, and laser is focused with rectangle. The results of experiment show that flashover delay time and jitter time decrease with increase of pulsed voltage or laser energy density, the delay time of 1064nm laser trigger is larger than that of 532nm laser trigger, and the delay time and jitter time in vacuum condition are less than the delay time and jitter time in air condition.
Electrical and Control Engineering, International Conference on.
