• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
• /
• 2004.05a
• /
• pp.63-68
• /
• 2004

Since rotor position information is necessary to drive the SRM, absolute-encoder, resolver and incremental-encoder is used to detect a poor position. But, it is not desirable to use a high priced encoder and high efficient microprocessor under the condition of the simple driving system when precision control is not demanded. In this paper, Only using the reflective type 2 photosensors replace the conventional opto interrupter and slotted disk, which not only remove a slotted disk section but drive 3-phase 6/4 SRM bidirectionally. Moreover, as control circuit only is composed of common analog device economy is maximized.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.20 no.1
• /
• pp.48-56
• /
• 2006

This paper studies particularly applicable method for sensorless PM BLDC motor drive system. The waveform of the motor internal voltages(or back emf) contains a fundamental and higher order frequency harmonics. Therefore the third harmonic component is extracted from the stator phase voltage. The resulting third harmonic signal keeps a constant phase relationship with the rotor flux for any motor speed and load condition. Also because of low resolution of estimated signal obtained by the proposed sensorless algorithm, to improve the wide range of speed response characteristic more exactly, we propose the rotor position signal synthesizer using PLL circuit based on estimated signals. Some experimental results are provided to demonstrate the validity of the proposed control method.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.13 no.6
• /
• pp.403-410
• /
• 2008

This paper suggests a standstill estimator to accurately identify induction motor (IM) parameters necessary for the vector control. A mathematical model that faithfully represents the general skin effect is introduced. Then, two exciting signals with a different frequency are sequentially injected to track the parameters based on the skin effect of the rotor bar. Little knowledge of the unknown motor allows the proposed methodology to employ a closed-loop control of an injected current, rather than open-loop voltage injection approaches. Subsequently, this control scheme proactively prevents electrical accidents resulting from an inadequate open-loop voltage injection. We develop a specialized offline commissioning test to compensate the phase delay resulting from the drive, which significantly affects the precision of the IM parameters. The effectiveness of the identification technique is validated by means of experiments performed on the three different IMs.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.11 no.1
• /
• pp.49-54
• /
• 2010

Rotor pole for AC(alternating current) generator is manufactured through transfer warm forging die. As soon as the material is heated at the warm manufacturing process, it is transferred to the first stage for upsetting work and then to the second stage for lateral extrusion work. The processes at the lateral extrusion work such as die block, die bushing, center punch, and side punch make severe condition and abrasion which leads to shorten the die life. This causes production decrease, long maintenance time, and low level of precision. Research on the die material selection, heat process cycle improvement, electric discharge machining trouble solution, and re-construction of main parts is expected to find a method to lengthen the die life up to 40 - 50%.

• Journal of the Korean Society for Precision Engineering
• /
• v.27 no.9
• /
• pp.67-77
• /
• 2010

An internal lobe pump is suitable for oil hydraulics of machine tools, automotive engines, compressors, constructions and other various applications. In particular, the pump is an essential machine element of an automotive engine to feed lubricant oil. The subject of this paper is the theoretical analysis of internal lobe pump whose the main components are the rotors: usually the outer one is characterized by lobe with elliptical and involute shapes, while the inner rotor profile is determined as conjugate to the other. And the integrated design system which is composed of three main modules has been developed through AutoLISP under AutoCAD circumstance plus CFD-ACE+. It generates new lobe profile and calculates automatically the flow rate and flow rate irregularity according to the lobe profile generated. CFD simulation results show trends similar to those carried out in experiments, and a quantitative comparison is presented. Results obtained from the automotive integrated design system enable the designer and manufacturer of oil pump to be more efficient in this field.

• Journal of the Korean Society for Precision Engineering
• /
• v.22 no.10 s.175
• /
• pp.174-185
• /
• 2005

This paper presents the design, fabrication, and testing results of a dual stage actuator system for a fine positioning of magnetic heads in magnetic disk drives. A novel rotary microactuator which is electrostatically driven and utilized as a secondary actuator was designed. The stator and rotor electrodes in the microactuator was revised to have the optimal shapes and hence produces much higher rotational torque compared with the conventional comb-shape electrodes. The microactuators were successfully fabricated using SoG(silicon on glass) processing technology, which is known as being cost-effective. The fabricated microactuator has the structural thickness of $45{\mu}m$ with the gap width of approximately $3{\mu}m$. The dynamic characteristic of microactuator/slider assembly was investigated, and its natural frequency and DC gain were measured to be 3.4kHz and 32nm/V, respectively. The microactuator/slider assembly was integrated into a HDD model V10 of Samsung Electronics Co. and a dual servo algorithm was tested to explore the tracking performance of dual stage actuator system where the LDV signals instead of magnetic head signals were used. Experimental results indicate that this system achieves the tracking accuracy of 30nm. This value corresponds to a track density of 85,000 track per inch(TPI), which is about 3 times greater than that of current hard disk drives.

• Particle and aerosol research
• /
• v.4 no.2
• /
• pp.37-50
• /
• 2008

Concerns on centrifugal classifiers, of which have cut sizes are below few micrometers, have been increased and it is prospected to be used in extensive industries, such as manufacturing the fine minerals, cosmetics, advanced electric materials, and life science. This paper reviews the recent progress of research and development on the centrifugal classifiers. General categorization of classifiers for feeds was assessed and separation mechanism of the classifiers was followed. History of centrifugal classifiers was explored and some points to be improved were briefly indicated. Fundamental theory of the classification by centrifugal classifiers was pearly studied, and advanced and further understandings on factors affecting the separation or grading efficiency are described. Factors determining the classification precision and efficiency of centrifugal classifiers, such as geometry, rotational speed and inclined angle of rotating vanes, feed and air flow rates, and rotor dimensions are reviewed.

• Proceedings of the KIEE Conference
• /
• 2001.07e
• /
• pp.127-133
• /
• 2001

In SRM drive, the ON OFF angles of each phase switch should be accurately controlled in order to control the torque and speed stably. The accuracy of the switching angles is dependent upon the resolution of the encoder and the sampling period of the microprocessor, that are used to provide the information of the rotor position and to control the SRM power circuit, respectively. However, as the speed increases, the amount of the switching angle deviation from the preset values is also increased. Therefore, the low cost encoder suitable for the practical and stable SRM drive is proposed and the control algorithm to provide the switching signals using the simple digital logic circuit is also presented in this paper. As a result, a stable high speed SRM drive can be achieved by the high resolution switching angle control and it is verified from the experiments that the proposed encoder and logic controller can be a powerful candidate for the practical low cost SRM drive.

• Korean Journal of Agricultural Science
• /
• v.50 no.3
• /
• pp.427-435
• /
• 2023

This study was conducted to evaluate the spraying performance according to the flight conditions of agricultural drones for the development of a variable control system. The analyzed flight conditions comprised six factors: spraying direction, flight speed, altitude, wind speed, wind direction, and rotor rotational speed. The ratio of the area sprayed on the water-sensitive paper was used as the coverage, and the distribution and amount of the coverage were evaluated. The coverage distribution based on the distance from the drone was used to evaluate a spray pattern, and the distribution was expressed as a Gaussian function approximation. In addition, the probability distribution based on coverage was expressed as the cumulative probability via Gamma function approximation to analyze the spraying efficiency in the target area. The results showed that the averaged coverage decreased significantly as the flight speed and wind speed increased, and the wind direction changed the spray pattern without a coverage decrease. This study contributes to the development of a control technique for the precision control system of agricultural drones.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• v.9 no.1
• /
• pp.951-954
• /
• 2005

This paper presents a study on the accuracy position Controller design for the Composite Smoke Bomb Rotational driving system using a BLDC servo motor. Function of Smoke Bomb is blind in the enermy's sight so that need to high response. The BLDC servo motor controller was designed with DSP(TMS320VC33), IGBT(Insulated Gate Bipolar. Transistor), IGBT gate driver and CPLD(EPM7128). This paper implements those control with vector control and MIN-MAX PWM. Vector control requires information about rotor positions, a resolver should be used to achieve that. The main controller is implemented with a TMS320VC33 high performance floating-point DSP(Digital Signal Process) and PWM Generator is embodied using EPM7128.