• Journal of Electrical Engineering and Technology
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• 제1권1호
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• pp.73-79
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• 2006

Conceptually, mechanical port of an electric machine can be doubled and the concept of dual-mechanical-port (DMP) will then give birth to a new breed of electric machines. In this paper, the various possible structures of DMP electric machine are discussed. Basic modeling and analysis issues related to the DMP electric machine are presented. An exemplary design of DMP machine is given and verified by FEM results. Potential applications and future research work are given to conclude the paper.

• Journal of Power Electronics
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• 제13권2호
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• pp.250-255
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• 2013

This paper proposes an optimal current distribution method of dual-rotor brushless DC machines (DR-BLDCMs) which have inner and outer surface-mounted permanent-magnet rotors. The DR-BLDCM has high power density and high torque density compare to the conventional single rotor BLDCM. To drive the DR-BLDCM, dual 3-phase PWM inverters are required to excite the currents of a dual stator of the DR-BLDCM and an optimal current distribution algorithm is also needed to enhance the system efficiency. In this paper, the copper loss and the switching loss of a DR-BLDCM drive system are analyzed according to the motor parameters and the switching frequency. Moreover, the optimal current distribution method is proposed to minimize the total electrical loss. The validity of the proposed method was verified through several experiments.

• 대한기계학회논문집B
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• 제27권9호
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• pp.1256-1261
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• 2003

Since the viscous effect increases as the size of device decreases, viscous-driven micropump is a promising mechanism in microscale applications. In the present study, a dual-rotor type pump which contains two counter-rotating cylinders for improving performance characteristics is proposed. First, for flows in the single-rotor type pump, the present unstructured grid simulation method is validated by comparing its results to the previous results. Next, the performance of the dual-rotor type pump is evaluated by the parametric studies and is compared to that of the previous single-rotor type pump. The flow characteristics are qualitatively similar to those of single-rotor type pump. However, the performance of the micropump with tandem rotors is still better than that of previous pumping type, e.g. much larger flow rate, smaller driving region, higher efficiency, and wider operation range.

• Journal of Magnetics
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• 제21권4호
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• pp.561-569
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• 2016

Although pretty methods have been proposed to reduce torque ripple, they generally suffer from the decreased torque density. This paper will investigate the spoke-type interior permanent magnet (IPM) machine with shaping methods, including the sinusoidal (SIN), the inverse cosine (ICS), the sinusoidal with third harmonic (SIN+3rd), and the inverse cosine with third harmonic (ICS+3rd). In order to obtain low torque ripple and high torque density, the shaping method applied in rotor and stator at the same time, termed as the dual-shaping method, is proposed. This method is analytically derived and further confirmed by finite element method (FEM). It turns out that the ICS and ICS+3rd shaping methods are more suitable for outer rotors, while the SIN and the SIN+3rd shaping method should be used in inner stators. The original machine, the singular shaped machines and the dual-shaped machines on electromagnetic performances are compared for evaluation. The results verify that the dual-shaping method can improve torque density, whilst reducing torque ripple.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• 제5B권3호
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• pp.248-252
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• 2005

This paper deals with a new design method for a small-size rotating machine with high power. In order to achieve high performance, secondary excitation by Nd-Fe-B magnets and the grain oriented electrical steel sheets were selected and a new design using dual rotors is proposed. The outline of the high-performance rotating machine will be presented and the results of the finite element analysis by using this method combined with the E&SS modeling will be shown in the paper.

• Tribology and Lubricants
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• 제40권1호
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• pp.8-16
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• 2024

This study conducts numerical modeling and eigen-analysis of a rod-fastened rotor, which is mainly used in aircraft gas turbine engines in which multiple disks are in contact through curvic coupling. Nayak's theory is adopted to calculate surface parameters measured from the tooth profile of the curvic coupling gear. Surface parameters are important design parameters for predicting the stiffness between contact surfaces. Based on the calculated surface parameters, elastoplastic contact analysis is performed according to the interference between two surfaces based on the Greenwood-Williamson model. The equivalent bending stiffness is predicted based on the shape and elastoplastic contact stiffness of the curvic coupling. An equation of motion of the rod-fastened rotor, including the bending stiffness of the curvic coupling, is developed. Methods for applying the bending stiffness of a curvic coupling to the equation of motion and for modeling the equation of motion of a rotor that includes both inner and outer rotors are introduced. Rotordynamic analysis is performed through one-dimensional finite element analysis, and each element is modeled based on Timoshenko beam theory. Changes in bending stiffness and the resultant critical speed change in accordance with the rod fastening force are predicted, and the corresponding mode shapes are analyzed.