• Journal of Power Electronics
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• v.5 no.3
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• pp.173-179
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• 2005

In this paper, a very low cost and robust sensing method for the rotor position of a TSRM(Toroidal Switched Reluctance Motors) is described. Position information of the rotor is essential for SRM drives. The rotor position sensor such as an opto-interrupter or high performance encoder is generally used for the estimation of rotor position. However, these discrete position sensors not only add complexity and cost to the system but also tend to reduce the reliability of the drive system. In order to solve these problems, in the proposed method, rotor position detection is achieved using voltage waveforms induced by the time varying flux linkage in the search coils, and then the appropriate phases are excited to drive the SRM. But the search coil's EMF is generated only when the motor rotates. Therefore the rotor position sensing method using squared Euclidean distance at a standstill is also examined. The simulation and experimental results are presented to verify the performance of the proposed method in this paper.

• International Commerce and Information Review
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• v.19 no.2
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• pp.85-107
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• 2017

The aim of this study is to empirically examine fundamental factors that drive FDI to a particular location. This study further explores operating conditions of Korean firms in Myanmar. A survey methodology and then a regression analysis are employed. The study finds that the factors such as transportation, production factor, market, and cost play an important role for the location of FDI. However, the Korean investment in Myanmar decreases from 2013. The decrease of Korean investment implies that investing in Myanmar has not been profitable. The empirical study finds a complicated pattern of FDI. Large Korean firms are located far from the consumer market, thus, bear an increased transport cost to reach the consumer market. They are rather located in a place where they can access to a transport means and raw materials with low cost to export final products. They place FDI into a host country to serve as a production platform for exports to neighboring countries.

• Proceedings of the KIPE Conference
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• 2005.07a
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• pp.248-250
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• 2005

This paper suggests a new type of 4-switch inverter for switched reluctance motor drives. 4-switch Inverter topology is studied to provide possibility for the realization of cost of 3-phase SRM drive system. We used Y-connection and two-phase exciting method. For effective utilization of the developed system, a direct current controlled PWM scheme is designed and implemented to produce the desired dynamic. We solve to balance the neutral point of Y-connection by the direct current controlled PWM and examine the performance of proposed system. With the algorithm and developed control scheme, is expected that the proposed system can be widely used in commercial applications with a reduced system cost.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.4B no.3
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• pp.114-121
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• 2004

Switched reluctance motors have received much attention as a driving means for various industrial applications because they have simple construction, low cost and high efficiency. Nevertheless, the requirements of drive converters make it difficult to lower the overall system cost as compared with the DC motor application. Single phase switched reluctance motors (SPSRMs) provide a solution to the high cost problem since the number of switching power devices can be reduced and consequently the trials for application are increased. However, research involving SPSRMs, especially in the area of design work, is insufficient. This paper introduces a novel design methodology of single phase SRM. The design work for SPSRM comprises the determination of many variables such as stator and rotor pole arc as well as on, off and so on. Managing all variable combinations leads to lengthy computation time and a fault in the design process. For that reason, a reliable technique and brief procedure term are required in SPSRM design.

• The Transactions of the Korean Institute of Power Electronics
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• v.11 no.4
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• pp.328-339
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• 2006

In this paper the characteristic analysis of a single-phase switched reluctance motor (SRM) drive system with power factor correction (PFC) circuit is presented. The SRM is a low cost, simple and has a good high speed performance. The SRM drive with diode rectifier and filter capacitor has a low power factor because of short switch on time of capacitor. A novel switching topologic is presented to improve power factor and reduce torque ripple based on analysis of PFC circuit. Accordingly the SRM drive system with PFC circuit is also presented. Through the numerical analysis of the system, the toque ripple, power factor and efficiency with the change of rotary speed, load torque and capacity of the capacitor are achieved and compared with actual measured value.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.49 no.8
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• pp.451-458
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• 2000

The precise speed and position control technique for Brushless DC Motor demands accurate position and speed feedback information. Generally, resolver or absolute encoders are used as speed and positiion sensor. But they increase cost and more problem happens at low speed than high speed specially. Therefore, in this paper, optimal speed observer is proposed for decreasing size and cost of whole system. And also, we consider the error problem about the system modeling and measurement at low speed range as well as high speed. The overall system consists of two parts, a drive and a speed observer. We make use of Least square curve fitting algorithm as speed observer and can overcome low resolution by proposed observer. Also, because of using the signal of hall sensor, robust control is possible in low speed as well as high speed for the change of the parameters of the system and disturbance. To construct observer using the signal of hall sensor, we design the pulse multiplier circuit and the software of microprocessor, AT89CC2051. Finally, the performance of the proposed observer is exemplified by some simulations and experiments.

• Transactions of the Society of Information Storage Systems
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• v.3 no.3
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• pp.139-143
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• 2007

In recent years new recording media and materials for head-disk interface (HDI) have been developed in order to increase the recording density of storage devices and decrease the cost of production. It is well known that HDI in hard disk drive (HDD) needs high durability and stability. The tribological characteristic of commercialized HDI systems is an important indicator of the HDD reliability. In this study, experimental investigation on the wear coefficient of commercialized hard disk slider pads was performed. The slider was placed on top of a hard disk and allowed to slide for a set distance. The wear of the pads was measured after the sliding tests. The result showed that the micro-bumps in commercialized HDD have extremely low wear coefficient of $10^{-11}$. The results of this work may be used for further development of the HDI technology for HDD.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10a
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• pp.315-318
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• 1996

In this paper a new positioning method for cylindrical work pieces on rotating supports is studied. A work piece on a rotating axis is positioned by an impact drive mechanism (IDM) whose driving parameters are steadily updated by observing the object movement. The application of this actuator and the use of a multi-functional PC board for all necessary input and output operations such as e.g. data acquisition or wave form generation allow an alignment with a precision of less than 1.mu.m in a relatively short time and at low cost compared to conventional methods.

• Proceedings of the KIEE Conference
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• 2007.04c
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• pp.100-102
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• 2007

In this paper, a modified multi-level convert for low cost high speed switched reluctance (SR) drive is proposed The proposed multi-level converter has reduced number of power switches and diodes than that of a conventional asymmetric converter for SRM, and lower voltage rating of the dump capacitor comparing with energy efficient c-dump converter. It can supply five operating modes that is boosted, DC-link, zero, negative bias and negative boosted voltage. The proposed multi-level converter has fast excitation and demagnetization modes of phase current, so dynamic response can be achieved. The proposed multi-level converter is verified by computer simulation and experimental results.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.12B no.1
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• pp.31-36
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• 2002

In a switched reluctance motor drive, it is important to synchronize the stator phase excitation with the rotor position; therefore, the position of rotor is an essential information. Although optical encoders or resolvers are used to provide the position information, these sensors are expensive. Moreover, in the high-speed region, switching angles are fluctuated back and forth out of the preset value, which is caused by the sampling period of the microprocessor. In this paper, a low cost analog encoder suitable for practical applications is proposed. And the control algorithm to generate switching signals using a simple digital logic is presented. The validity of the proposed analog encoder with a proper logic controller is verified from the experiments.