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Dianhai Zhang,Chang Seop Koh IEEE 2012 IEEE transactions on magnetics Vol.48 No.1
<P>A semianalytic formula for calculating the magnetic field produced by a circular coil with rectangular cross section in air is proposed. In the formula, the coil is approximated as a series of circular rings with small cross sectional area, of which the current density can be considered as constant. In order to simplify the calculation of the magnetic field, the translation transformation and scaling transformation are introduced. Furthermore, all the possible singular cases, in the expressions, are treated properly. Therefore, with the help of one-dimensional Gauss-Legendre quadrature, the magnetic field at any points in space produced by current-carrying circular coil, especially inside the coil, can be calculated very easily.</P>
Dianhai Zhang,Hyo-Jun Kim,Wei Li,Chang-Seop Koh IEEE 2013 IEEE transactions on magnetics Vol.49 No.5
<P>This paper proposes an algorithm to analyze the magnetizing process of a new anisotropic bonded NdFeB permanent magnet (PM) which is magnetized by a capacitor discharge impulse magnetizing fixture. In the algorithm, the magnetic field analysis and the prediction of the residual magnetic flux density are achieved by using the transient finite element method (FEM) incorporating the scalar Jiles-Atherton (J-A) hysteresis model. The validity of the suggested method is demonstrated by applying to a 4-pole ring-type anisotropic bonded NdFeB PM and comparing the numerical results with the experiment ones.</P>
Dianhai Zhang,Chang Soon Park,Chang Seop Koh IEEE 2012 IEEE transactions on magnetics Vol.48 No.2
<P>This paper presents a systematic optimal design algorithm to design the shape of rotor slot to get a specific speed-torque characteristic in three-phase squirrel cage induction motor for the application to motor operated valve (MOV) actuator. The developed method consists of three steps: design based on equivalent circuit method (ECM) utilizing multi-objective formulation, selection of the strongly influential geometric parameters of rotor slot, and precise design based on finite element method (FEM). The validity of the suggested design method is demonstrated through applications to rotor slot design of three-phase induction motor to achieve a NEMA class D speed-torque characteristic.</P>
Dianhai Zhang,Yu Han,Ziyan Ren,Yanli Zhang,Chang-Seop Koh 대한전기학회 2016 Journal of Electrical Engineering & Technology Vol.11 No.5
This paper presents a calculation method of residual magnetic flux density distribution for a four-pole anisotropic bonded NdFeB permanent magnet (PM) considering the effect of aligning magnetic field during the forming process. To manufacture the anisotropic bonded NdFeB magnet, the magnet powder needs to be aligned with a proper aligning field before magnetizing. Therefore, it is necessary to analyze the magnetizing process based on the aligning field analysis to determine accurate distribution of residual magnetic flux density (Br) for the anisotropic bonded NdFeB PM. In order to estimate the Br distribution of the anisotropic bonded NdFeB magnet, an analysis method by combining the external electric circuit equation coupled with the transient finite element method and the scalar Jiles-Atherton hysteresis model is proposed.
Dianhai Zhang,Ziyan Ren,Chang-Seop Koh 대한전기학회 2014 Journal of Electrical Engineering & Technology Vol.9 No.1
This paper presents a multi-objective optimization approach to design rotor slot geometry of three-phase squirrel cage induction machine to achieve NEMA design D torque-speed (T-S) characteristics with high efficiency. The multi-objective Particle Swarm Optimization (MOPSO) algorithm combined with the adaptive response surface method and Latin hypercube sampling strategy is applied to obtain the Pareto optimal designs. In order to demonstrate the validity of the suggested optimal algorithm, an application to rotor slot design of three-phase induction motor is presented.
The Analysis of Anisotropic Bonded NdFeB Permanent Magnet Using an Improved JA Hysteresis Model
Dianhai Zhang,Ziyan Ren,Chang Seop Koh 대한전기학회 2012 대한전기학회 학술대회 논문집 Vol.2012 No.4
An improved Jiles-Atherton hysteresis model for anisotropic bonded NdFeB permanent magnet which is based on the theory of ferromagnetic hysteresis is proposed. The proposed algorithm is used to simulate both major and minor loops for the PM and the result is good agree with measured ones.
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.