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Estimation of Acoustic Noise and Vibration in an Induction Machine Considering Rotor Eccentricity
Kim, Do-Jin,Kim, Hae-Joong,Hong, Jung-Pyo,Park, Chul-Jun Published by the Institute of Electrical and Elect 2014 IEEE transactions on magnetics Vol.50 No.2
In this paper, a static rotor eccentricity analysis method is proposed. Electromagnetic noise by static eccentricity occurs in the course of manufacturing. The increase in errors is attributed to manufacturing errors of the components: the assembly and the torsional errors caused by shrink fitting. For these reasons, the rotor is displaced from the center of the stator bore, but it still turns on its own axis. Accordingly, in this paper, the acoustic noise using the electromagnetic excitation force was analyzed according to the rotor eccentricity. Finite-element analysis was used to analyze the rotor eccentricity considering the electrical and mechanical characteristics. To verify the proposed method, an induction machine was fabricated and an experiment was conducted.
Kim, Dong-Wook,Choi, Nak-Sun,Choi, K. K.,Kim, Dong-Hun Published by the Institute of Electrical and Elect 2014 IEEE transactions on magnetics Vol.50 No.2
This paper proposes an efficient optimization method that can deal with electromagnetic design problems with high-dimensional design variables. To achieve this, the universal Kriging method is combined with a new-type local window, called the hypersphere, and the truncated Gaussian sampling. At the center of a nominal design point, accurate surrogate models for performance functions of interest are generated in a relatively small hyperspherical local window. The first-order design sensitivity values are extracted from Jacobian matrices of the locally approximated models. Such optimization scheme considerably reduces sampling points and iterative designs, and also facilitates deriving the design sensitivity with high precision. The proposed method is tested with two design models having more than 10 design variables. Its efficiency and accuracy is thoroughly investigated by comparing it with existing methods.
Design of a Vernier Machine With PM on Both Sides of Rotor and Stator
Jang, Dae Kyu,Chang, Jung Hwan Published by the Institute of Electrical and Elect 2014 IEEE transactions on magnetics Vol.50 No.2
This paper proposes a new type of vernier machine with permanent magnets (PMs) on both sides of rotor and stator. The rotor is of the flux concentrating structure and the stator has also PMs between the flux modulation poles. Compared with the other types of vernier machine, the proposed model has a huge increase in the induced voltage and developed torque at the same size. This shows the possibility of the new suggested machine to the direct-drive applications such as wind-power generators and in-wheel motors.
Soo-Cheol Lim,Young-Pil Park,No-Cheol Park Published by the Institute of Electrical and Elect 2007 IEEE transactions on magnetics Vol.43 No.5
<P>We propose a new load/unload (L/UL) suspension featuring shape memory alloy (SMA) thin film and demonstrate its effectiveness through the L/UL simulation. We estimated the mechanical properties of the SMA with respect to the material phases by experiment and designed the proposed suspension by considering the vibration modes related to the L/UL performance. In order to effectively verify the effectiveness of the proposed suspension, we designed the suspension to have similar L/UL performance to that obtained from the conventional suspension when the SMA film is not activated. After analyzing the L/UL design parameters of the proposed suspension when the SMA is activated, we examine the relative performance of the conventional and proposed suspensions by L/UL simulation by comparing the vibration motions of the slider and the minimum gap size between the disk and slider</P>
Lee, Sun-Kwon,Kang, Gyu-Hong,Hur, Jin,Kim, Byoung-Woo Published by the Institute of Electrical and Elect 2014 IEEE transactions on magnetics Vol.50 No.2
This paper deals with the reduction of torque pulsation including torque ripple and cogging torque in surface PM brushless ac motors. The fractional combination and air-gap shape design by shaping the PM and stator core are studied to reduce torque pulsation. Torque ripple reduction is achieved by adjusting the magnetic flux density in air-gap contour by cutting magnet outer shape. Quasi-zero torque pulsation in this paper means the ripple ratio to average torque <0.5%. The magnetic field and torque characteristics are analyzed by 2-D finite element analysis and prototype to validate is manufactured and measured.
Zhang, Dianhai,Ren, Ziyan,Koh, Chang-Seop Published by the Institute of Electrical and Elect 2014 IEEE transactions on magnetics Vol.50 No.2
This paper presents a systematical optimal design method for powder aligning fixture during forming process and magnetizing fixture during magnetizing process for an anisotropic-bonded NdFeB magnet. Before the forming process, the mixture ratio of magnet powder and resin, molding tool temperature, and filling density are selected to improve the magnetic performance. During the forming process, a newly multiobjective optimization model is proposed to obtain the required orientation and maximum aligning field. Thus, in the magnetizing process, an anisotropic-bonded NdFeB magnet with required orientation and high residual magnetic flux density is obtained by applying a single-objective optimization process. To accurately predict the residual magnetic flux density, the transient finite element method combined with the Jiles-Atherton hysteresis model, taking the aligning field into account.
A Study on the Estimation of the Shapes of Axially Oriented Cracks in CMFL Type NDT System
Kim, Hui Min,Park, Gwan Soo Published by the Institute of Electrical and Elect 2014 IEEE transactions on magnetics Vol.50 No.2
Axially oriented small crack, which is the most dangerous defect in the underground pipeline, is hard to detect by conventional system. In this paper, a circumferential magnetic flux leakage-type non-destructive testing is adopted to detect axial cracks. Because the measured signal contains the size and shape information simultaneously, it is necessary to decompose the size and shapes of cracks for the maintenance of underground pipelines. This paper focused on the decomposing method of the sizing and shaping of the axial cracks using measured defect signals. Estimated shapes in this paper agreed well with measuring ones.
Kim, Dong-Wook,Choi, Nak-Sun,Lee, Chang-Uk,Kim, Dong-Hun Published by the Institute of Electrical and Elect 2014 IEEE transactions on magnetics Vol.50 No.2
This paper proposes a composite first-order reliability analysis method to effectively perform the reliability-based optimization of electromagnetic (EM) design problems. The proposed method utilizes both of two different ways, reliability index approach (RIA) and performance measure approach (PMA), for reliability analysis of probabilistic constraints. However, each performs a distinct function: the first merely checks the feasibility status of probabilistic constrains, and the second evaluates the failure probability of only active constraints selected from the feasibility identification. Such a unique scheme can substantially enhance computational efficiency during optimization process. The proposed method is applied to two EM design problems, and its numerical efficiency and accuracy are examined by comparison with existing methods.
Lee, Ho-Young,Jung, Jae-Seung,Kim, Hong-Kyu,Park, Il-Han,Lee, Se-Hee Published by the Institute of Electrical and Elect 2014 IEEE transactions on magnetics Vol.50 No.2
The discharge currents were evaluated and validated using the generalized energy method and the integral Ohm's law combined with the recently developed discharge analysis technique for dielectric liquid media, such as transformer oil. The terminal current in voltage-driven systems was found to play an essential role in characterizing the pattern of electric discharge, such as corona, breakdown, etc. Until now, the generalized energy method and integral Ohm's law were normally adopted to evaluate this terminal current, but no experimental validation was reported and no test was performed in a dielectric liquid media. The generalized energy method can be derived directly using Poynting's theorem and is well suited for the finite element method. As an alternative approach, the integral Ohm's law can be applied to multiport systems. To confirm the numerical results, an experimental setup was proposed with a multiport system composed of a tip and separated conducting ring shells. The numerical results were compared with those from experiments, which would be the first trial in a dielectric liquid with a multiport system. The calculated current profile was similar to that from the experimental result, but the breakdown voltage from the calculated results was relatively high.
Published by the Institute of Electrical and Elect 2014 IEEE transactions on magnetics Vol.50 No.2
This paper proposes a method to minimize the cogging torque and torque ripple of an interior permanent magnet synchronous motor by adopting asymmetric barrier design and inverting lamination method. The analysis method for cogging torque and torque ripple is suggested using finite-element method. An asymmetric barrier in a permanent magnet rotor is optimally designed without permanent magnet skew. This proposed design for low cogging torque and torque ripple has an advantage over skew design from a manufacturing point of view. The proposed model is compared with the skew model and nonskew model by calculating torque characteristics to determine the more effective method to reduce torque distortion.