Mechanical and Electrical Technology IV

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Authors: Bao Dong Bai, Jian Zhang, Guo Hui Yang, Jia Yin Wang
Abstract: DC bias would cause the half-wave saturation of transformer, distortion of the exaction current, generation of high harmonic and the vibration and noise increases rapidly, which harm the safe operation of the transformers. In this paper, simulation of magnetic vibration and noise of a 160KVA dry-type transformer with DC bias and modal analysis with the finite element software comsol multiphysics is obtained. The software conduct multi-physical field coupling analysis to electric field, magnetic field, structural stress field and acoustic field, calculate the distribution of the noise and the natural frequency of transformer and propose effective measures to reduce the noise and vibration of transformer with DC bias.
Authors: Bao Dong Bai, Ying Ying Gao, Jia Yin Wang
Abstract: This paper mainly researches the eddy current losses of transformer shielding coil by adopting for analytical method. This method calculates the conductor’s boundary conditions directly by using the analytical solution of the leakage magnetic field, which is generated into the conductor eddy current equation for the analytical formula, then compared the analytical method with the finite element method to fix the analytical formula, the relevant theories are applied to analyze the results of using two different shielding to reduce the losses and find the effectively measures.
Authors: Jun Guo Cui, Wen Sheng Xiao, Jian Bo Zhao, Jing Xi Lei, Xiao Dong Wu, Zhi Gang Wang
Abstract: To meet the demands of direct-drive petroleum equipment, developed a low-speed and high-torque permanent magnet synchronous motor. By analyzing and identifying the suitable key parameters such as permanent magnet structure parameters, air gap length, type and size of Stator Slot and so on, designed permanent magnet synchronous motor with the torque 10800 Nm, the rated speed 30 r/min and high efficiency and power factor. Obtained the flux density distribution situation and characteristic curves under no-load working condition through simulation and analysis. Manufactured the low-speed and high-torque permanent magnet synchronous motor and applied it to pumping unit. Test results show that this motor has many advantages such as wide range of speed regulation, small torque ripple, smooth operation and other characteristics. The Direct-drive Pumping Unit used this permanent magnet synchronous motor can save 20% energy than the beam pumping unit, so its social and economic benefits are significant.
Authors: Yue Jun An, Dong Xu Pei, Li Ping Xue, Yong Li
Abstract: In order to solve the existing permanent magnet synchronous motor starting from starting performance and energy target fight between rotor and limited space of conflict. The line-start permanent magnet synchronous motor with the special structure of the disk magnet polyed magnetic type has been proposed. Motor rotor punching trough, size, and cast aluminum material can give full consideration to the requirements of line-start function in the new type of permanent magnet synchronous motor. polymer magnets which is formed from alternating magnetic yokes and permanent magnetic ring is set between the hinge and the rotor part; Interval set on the outer circle of magnetic yoke take the magnetic flux to pole. Air-gap flux density can be achieved highly by utilized to set up the starting winding after the rest of the limited space in the poly magnet structure. By finite electromagnetic field analysis software Ansoft, Three-dimensional magnetic field can be analyzed in Poly-Magnet Line-start Permanent Magnet Synchronous Motor. The result show that poly magnet structure improves the air gap magnetic field strength; Under the premise of better starting capability, it can improve the power index of motor.
Authors: Lin Zhu, Xu Cheng Zhao, Heng Sheng Hu, Wei Xing Huang
Abstract: This paper researches on half-bridge rectifier of double salient Electro-magnetic motor. It analysis principles of two rectifier models and studies the armature reaction. Through the experiment of the output of 28.5V on the motor, we find the proper rectifier model for low voltage output of direct current.
Authors: De Zhi Chen, Bao Dong Bai, Bo Zhang, Wu Hao Jia, Bing Yin Qu
Abstract: Transformer is irreplaceable to make sure power system running stably. It's showed in research that magnetic resistance is relevant to capacity on restraining DC bias both in three-phase three-column transformer and three-phase five-column transformer. Magnetic resistance can be changed by changing the seam size of transformer. 3D field-circuit coupling models of single-phase four-column power transformer with two kinds of seam were created by FEA in this paper. Models were simulated with different DC bias current. The analysis result of influence of seam size on power transformer's capacity on restraining DC bias was obtained by DC bias current efficient extraction and comparison of models with different seam size, which is the theoretical basis of developing new transformer with more capacity on restraining DC bias.
Authors: Hui Zhong, Xiu He Wang, Cheng Zhang, Ming Yin
Abstract: The new type single-phase induction motors with three stator windings are brought forward for there high efficiency and low cost. However, the unbalance current density in the stator windings is still a problem to the design of this type motor. This paper presents the asymmetrical stator windings and slots structure in the motor design to get the currents density balance. A magnetic field analysis of the new type tri-winding induction motor is preformed using a two-dimensional finite element method. The Maxwell stress method is used to compute the air gap torque that is required for solving the equation of motion. The perfomance of the motor with different structure stator are compared and analysised.
Authors: Yue Jun An, Li Ping Xue, Zhao Jun Meng, Li Min Zhou
Abstract: This paper design an identical polarization embedding high-efficiency permanent magnet synchronous motor and analysis electromagnetic field distribution of the new structure permanent magnet synchronous motor, as well as optimize the design using modern chaos optimization algorithm based on the invention patent. Carried out analysis of energy-saving effect combination high-performance interior PMSM with the aid of identical polarization embedding in textiles with small batch production type test. The optimize design and experiment show that the new structure motor efficiency and power factor higher than the previous configuration of the asynchronous motor, and with high-efficiency and energy-saving advantages in a very broad power output range at the condition of same load.
Authors: Ji Lin
Abstract: This paper concerns the power transmissions between two flexible subsystems (i.e., with short-wavelength deformations) coupled by a stiff junction (i.e., with long-wavelength deformations). Typical examples of such built-up models are flexible plates connected via stiff beams, for instance. Research shows that, in general, the power flow exchanged between the two flexible subsystems decreases as the stiffness of their junction part increases. Conditions are then derived under which the power transmission between the two flexible subsystems can be neglected such that the statistical energy response of each individual subsystem can be predicted independently. It thus allows the mid-frequency vibration behavior of whole built-up model to be predicted in a very simple manner. A numerical example consisting of two short-wavelength plates connected via a long-wavelength beam is given to illustrate the validity of the present theory.
Authors: Bao Dong Bai, Guo Hui Yang, Bing Yin Qu, Jian Zhang
Abstract: In this paper, the modal analysis was carried out on the core and cavity of a 160KVA dry-type transformer based on the finite element analysis software of ANSYS. And the simulation results of the natural frequencies and modal shapes were obtained, which provided a theoretical guidance to the design of the transformer structure, and were meaningful to reduce the vibration and noise level of the transformer.

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