• Transactions of Materials Processing
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• v.8 no.6
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• pp.583-590
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• 1999

New forward slip model has been developed for the precise prediction of rolling speed in the hot strip finishing mill. Besides those influential factors such as neutral point, work roll diameter, friction coefficient, bite angle and the thickness at each side of entry and delivery of the rolls, roll torque was specifically taken into account in this study. To consider the effect of width change on forward slip, calibration factors obtained from rolling torque has been added to new prediction model and refining method has also been developed to reduce the speed unbalance between adjacent stands. The application of the new model showed a good agreement in rolling speeds between the predictions and the actual measurements, and the standard deviation of prediction error has also been significantly reduced.

• Journal of Magnetics
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• v.16 no.4
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• pp.417-422
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• 2011

This paper presents the characteristics of PM eddy current loss and harmonic iron loss for PM step-skewed Interior Permanent Magnet Synchronous Motor (IPMSM) with concentrated windings and multi-layered PM under the running condition of maximum torque per ampere (MTPA) and flux-weakening control. In particular, PM eddy current loss and harmonic iron loss in IPMSM have been numerically computed with three-dimensional Finite Element Analysis (3D FEA), whereby IPMSM with concentrated windings and multi-layered PM has been designed to identify the optimized skew angle contributing to the reduced PM eddy current loss and torque ripples, while maintaining the required average torque. Furthermore, numerical investigation on PM eddy current loss and iron loss at MTPA and flux-weakening control has been carried-out in terms of PM step-skew.

• Proceedings of the KIEE Conference
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• 1997.07a
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• pp.159-161
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• 1997

This paper presents a method of reducing cogging torque and improving average torque by changing the dead zone angle of trapezoidal magnetization distribution of rotor magnet in ring type. Because brushless d.c. motor has 3D shape of overhang, 3D analysis should be used for computation of its magnet field. In this paper, Three Dimensional Equivalent Magnetic Circuit Network method (3DEMCN) which can calculate an accurate 3D magnetic field has been introduced. The method has an advantage that nonlinear magnetic phenomena can be considered and the cogging torque analyses requesting the rotation of the rotor can be performed by the variation of magnetization distribution without remesh.

• Proceedings of the KIPE Conference
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• 2005.07a
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• pp.562-564
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• 2005

This paper presents the reasonable design parameters of a SRM for hybrid electric vehicle driving. For the design of SRM, the initial model is designed using the equivalent magnetic circuit method. In order to optimize the SRM for HEV. The initial model is redesigned by FEM with the variation of the stock length and turns of winding. This paper shows that a flat-topped current of a phase can be made from a change of the stack length and the number of turns for high efficiency, high average torque and a lower torque ripple. The change of current falling time as a variation of turn-off angle was shown by FEA. The iron loss and copper loss were described. The torque of the redesigned motor is suitable for low and high speed ranges to drive a HEV that was verified by the speed-torque curve.

• The Transactions of the Korean Institute of Power Electronics
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• v.14 no.3
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• pp.204-210
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• 2009

This paper proposes a novel current-sensorless maximum torque per ampere control for a surface mounted permanent magnet synchronous motor with low-resolution position sensor. A direct axis current is estimated from the mathematical model of the permanent magnet synchronous motor and the phase angle between direct and quadrature axis voltage commands is controlled to adjust the estimated direct axis current to zero, thus a maximum torque per ampere control can be achieved. The proposed method is suitable for low cost applications with slow dynamic response characteristics.

• Proceedings of the KIEE Conference
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• 1998.07a
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• pp.25-27
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• 1998

The switched reluctance motor(SRM) drive system provides a good adjustable speed and torque characteristics. However, it also has some drawbacks such as relatively high torque ripple and acoustic noise which are caused by the torque production mechanism. To reduce torque ripple and to have precise speed control, PLL technique is adopted. The PLL system in conjunction with dynamic dwell angle control scheme has good speed regulation characteristics. Digital control system with a 80c196kc micro-controller is used to be realized this drive system. Test results show that the suggested control system has the ability of dynamic and precise speed control.

• Journal of international Conference on Electrical Machines and Systems
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• v.2 no.2
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• pp.134-140
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• 2013

This paper proposes a new design of rotor shape of Interior Permanent Magnet Synchronous Motor (IPMSM) used for agricultural electric vehicle (AEV). The distribution of the residual magnetic flux density at the air gap is modified by rotor surface shape and V-type magnet angle. As a result, cogging torque and physical characteristic have been improved, and back electromotive force (back-EMF) of the suggested model has been improved to be closest to sine wave form compared to initial model. The validity of the proposed rotor shape optimization is confirmed by the manufactured IPM rotor core and measured the performance of the cogging torque.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.54 no.8
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• pp.358-363
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• 2005

This paper presents the reasonable design parameters of a switched reluctance motor to drive a hybrid electric vehicle by using the equivalent magnetic circuit method. The designed motor can be redesigned by using finite element analysis as a variation of the parameter for the purpose of improving performance. This paper shows that a flat-topped current of a phase can be made from a change of the lamination stack length for high average torque and a lower torque ripple. The change of current falling time as a variation of turn-off angle was shown by finite element analysis. The core loss and copper loss were described. The torque of the redesigned motor is suitable for low and high speed ranges to drive a HEV. which is verified by the speed-torque curve.

• Journal of Electrical Engineering and Technology
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• v.4 no.1
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• pp.66-78
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• 2009

This paper introduces the design of a fuzzy logic controller in conjunction with direct torque control strategy for a Permanent Magnet synchronous machine. A stator flux angle mapping technique is proposed to reduce significantly the size of the rule base to a great extent so that the fuzzy reasoning speed increases. Also, a fuzzy resistance estimator is developed to estimate the change in the stator resistance. The change in the steady state value of stator current for a constant torque and flux reference is used to change the value of stator resistance used by the controller to match the machine resistance.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.11
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• pp.17-22
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• 2010

This paper presents a unique method for simulating permanent magnet motors without time-consuming numerical methods used in the conventional magnetic circuit method. The conventional method gives us average values like torque and power over specified periods of time, but it is usually very difficult and time-consuming to obtain instantaneous characteristics like cogging torques and torque ripples. The convolution operations method we present, however, considers relative angle variations of stator magnetic circuits and rotor magnetic circuits. As a result, it makes uses of instantaneous values possible. The authors compare the new method with the coventional method and verify that calculating cogging torque values and back-emf values is possible with the proposed new convolution method.