• 전력전자학회:학술대회논문집
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• 전력전자학회 2004년도 전력전자학술대회 논문집(2)
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• pp.985-987
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• 2004

Switched Reluctance Motor(SRM) drive system is known to provide good torque characteristics and high efficiency drive. However, speed variation caused by higher torque ripple is one of main drawback. The Phase-Locked Loop (PLL) technique in conjunction with dynamic dwell angle control has good speed regulation characteristics. In this paper, appropriate advance angle control for high efficiency drive and PLL technique for accurate speed control is proposed. A TMS320F240 DSP is used to realize this drive system. Test results show that the system has good dynamic and precise speed control ability as well as high efficiency.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 학술대회 논문집 정보 및 제어부문
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• pp.563-565
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• 2005

This paper is proposed an efficiency optimization control algorithm for a synchronous reluctance motor(SynRM) which minimizes the copper and iron losses. ALso, this paper presents a sensorless control scheme of SynRM using artificial neural network(ANN). The proposed algorithm allows the electromagnetic losses in variable speed and torque drives to be reduced while keeping good torque control dynamics. The control performance of ANN is evaluated by analysis for various operating conditions. Analysis results are presented to show the validity of the proposed algorithm

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.768-769
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• 2008

This paper examines an design of double-barrier rotor structure for improving the efficiency performance in a single-phase line-start permanent magnet(LSPM) motor. By utilizing the advantages of double-barrier rotor design that by increasing reluctance torque generation to compensate magnet torque production, the copper loss reduction is achieved. The optimal approach of response surface methodogy(RSM) is performed for determining a optimum double-barrier rotor structure. The improving of efficiency performance is confirmed by finite element method(FEM) and test.

• Journal of Biosystems Engineering
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• 제22권4호
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• pp.497-502
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• 1997

Automation facilities of greenhouses have been continuously developed. However, the conventional two-stage worm gear reducer reveals some problems, including low transmission efficiency. The worm gear reducer also have some difficulties in manufacturing and short life. Therefore, this study was performed to develop a planetary gear reducer, having a high Sear reduction ratio and high torque transmission efficiency. The planetary gear system consisted of a fixed ring gear and a 2-teeth differential ring gear turning slow, as the planetary pinion orbits fast around the fixed ring gear. The developed gear system can achieve a high speed reduction rate at one stage. The reducing system was employed to the greenhouse ventilation system. The reducer has the transmission efficiency of 70.5%, 2∼3 times longer life time, and twofold roll-up torque at an affordable price, comparing with conventional reducers. This reducer can be also applied to many industrial equipments, such as industrial crane, hoist, elevator and gondola etc.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2001년도 춘계학술대회 논문집
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• pp.170-177
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• 2001

Since plug type passenger door has two motion modes, power transmission unit must be capable of plug-in or plug-out, and sliding mode. Complex planetary gear train is proposed, which is composed of two 2K-H, I type planetary gear units. For the proposed complex planetary gear train, ranges of addendum modification coefficients which would not lead to interferences is analyzed, and optimal addendum modification coefficients among these ranges which generate the maximum efficiency are presented. Based on the interference, efficiency and torque ratio analysis results, complex planetary new train is designed and manufactured.

• 제어로봇시스템학회논문지
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• 제17권3호
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• pp.241-247
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• 2011

This paper is intended to improve efficiency of two-phase BLDC motor using analytical and statistical methods, and then the stability of the starting for the designed model is investigated. The characteristics of the motor according to magnetization directions of permanent magnet are analyzed through the analytical method, and design variables that affect the efficiency are selected. Preliminary optimal design is performed using the analytical method with the design variable. The RSM (Response Surface Method) based on the FEA (Finite Element Analysis) is applied to complement errors of the analytical method. As a result, the optimal design is determined. Finally, the stability of the starting for the optimal designed model is evaluated by analyzing cogging torque, and it is verified through the FEA.

• International Journal of Advanced Culture Technology
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• 제3권2호
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• pp.67-76
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• 2015

This paper aims to study and design of Organic Rankine Cycle (ORC) Machine using Isopentane as working fluid expanding through Tesla turbine. The study on ORC machine expanding through Tesla turbine has result on the efficiency of Tesla turbine. In addition, Thermodynamics theory on isentropic efficiency proved to be a successful method for overcoming the difficulties associated with the determination of very low torque at very high angular speed. By using an inexpensive experiment device and a simple method, the angular acceleration method, for measuring output torque and power in a Tesla turbine is able to predict a tendency of output work. The experiments using two Tesla turbine sizes, the first size is 1.6 bigger than the second one. In comparison with the first size, the tesla turbine can produce power output more than 62% of the second size. Further study on the machine can be developed throughout the county due to its low cost and efficiency.

• 한국정밀공학회지
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• 제12권11호
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• pp.27-35
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• 1995

The fluid coupling combined with a pump and a turbine have many merits compared with other couplings, their uses are increesing rapidly in various industrial fields at home and abroad in pursuit of high-speed more efficiency durability of various mechanic devices. The authorities concerned have recognized the improtance of the fluid coupling and supported its developement and now some trial products began to show up. As the structrue and characteristics of the fluid coupling have little similarity to other kinds of couplings and its fluid behavior is unique, so its characteristic analysis is expected to be difficult. Until now no satisfactory study on the characteristics of the fluid coupling seems to have been conducted at home, so a study on this field needs to be done urgently. The purpose of this research is to construct the experimental test set-ups and establish a series of performance test program for the domestically developed fluid couplings and to provide a software to store and utilize these experimental data which can be used to improve the performance of the fluid coupling and solve on the job problems confronted in operation. The performance test consists of taking measurment of torque, rpm and efficiency of the fluid coupling for three different amount of working fluid inside with various loads to the output shaft and finally infestigating the torque, rpm and efficiency characteristics of the fluid coupling with respect to these parameters. The results of this study can contribute valuable references to the development of variable speed fluid coupling and torque converter currently pursued by the domestic industry.

• Tribology and Lubricants
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• 제33권6호
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• pp.269-274
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• 2017

Currently, fuel efficiency becomes one of critical issues for automotive industries as concerns about environmental and energy problems grow. In an automatic transmission of an automobile, a drag torque due to a viscous drag of a fluid between friction and clutch plates is one of factors that degrade fuel economy. In this work, the drag torque characteristics of a wet clutch was experimentally investigated with respect to rotational speed, temperature of automatic transmission fluid (ATF), and gap between friction and clutch plates. The experimental results showed that drag torque increases to a certain level, and then decrease to the steady state value with increasing rotational speed. This behavior may be associated with two-phase flow of air and ATF at gap between friction and clutch plates. Also, it was found that the maximum drag torque value decreased as ATF viscosity decreases with increasing temperature. However, it was shown that the point at which the maximum drag torque occurs was not significantly affected by the ATF temperature. In addition, maximum drag torque was found to decrease as the gap between friction and clutch plates increased from 0.1 mm to 0.2 mm. Furthermore, it was observed that the generation of maximum drag torque was delayed as the gap increased. The outcomes of this work are expected to be helpful to gain a better understanding of drag torque characteristic of a wet clutch, and may therefore be useful in the design of wet clutch systems with improved performance.

• Tribology and Lubricants
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• 제30권6호
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• pp.337-342
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• 2014

The reduction of drag torque is an important research issue in terms of improving transmission efficiency. Drag torque in a wet clutch occurs because of the viscous drag generated by the transmission fluid in a narrow gap (clearance) between the friction plate and a separate plate. The objective of this paper is to observe the effects of the friction plate area and the clearance on the drag torque using finite element simulation. The two-phase flow of air and oil fluid is considered and modeled for the simulation. The simulation analysis reveals that as the rotational speed increases, the drag torque generally increases to a critical point and then decreases sharply at a high speed regime. The clearance between the two plates plays an important role in controlling drag torque peak. An increase in the clearance causes a decrease in shear stress; thus, the drag torque also decreases according to Newton's law of viscosity. An observation of the effect of the area of contact between transmission fluid and friction plate shows that the drag torque increases with the contact area. The flow vectors inside the flow channel present clear evidence that the velocity of the fluid flows is faster with a larger friction plate, that is, in the case of a larger contact area. Therefore, the optimum size of the friction plate should be determined carefully, considering both the clutch performance and drag reduction. It is expected that the results from this study can be very useful as a database for clutch design and to predict the drag torque for the initial design with respect to various clutch parameters.