• Journal of the Korean Society for Precision Engineering
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• v.31 no.8
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• pp.705-713
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• 2014

In this paper, we propose a novel velocity ripple controller using phase compensation feedforward control. Velocity ripples result in many kinds of performance degradations in manufacturing machines, especially such as ultra-precision roll lathes. The generation of velocity ripple in constant velocity control comes from various causes, such as electrical torque ripples, mechanical worn out, inconsistent mass center, etc. Conventional researches about ripple is mainly for reducing torque ripple in actuator level, which is only one of reasons for velocity ripples, so in this study, we focus on eliminating velocity ripples in upper level controller using phase compensation feedforward controller. The proposed algorithm is composed of several modules, such as ripple extractor, phase adjuster and phase follower etc. The suggested algorithm can be easily extended, and it shows a superior performance in the experiments of ultra-precision roll lathes.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.6
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• pp.92-99
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• 2005

We are interaction refrigeration warehouse cold water pump system and photovoltaic generation system. At this time, a target pressure is able to control in spite of change of the pressure according to pump head and rate of flow of pump. Also, we carry out the vector control of BLDC motor with the maximum torque operation and a high reliability from territory of each operation speed. Therefore, in this paper, we conclude energy saving technique of refrigeration warehouse cold water pump system.

• Proceedings of the KIEE Conference
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• 2003.04a
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• pp.170-172
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• 2003

Among low power servo applications, classical DC motors are very popular because they are reasonably cheap and easy to control. The main disadvantage is the mechanical collector which has only a limited life period. Also, brush sparking can destroy the rotor coil, generate EMC problems. So permanent magnet brushless do motors and drives are being used increasingly in a wide range of applications. This has been made possible with the advantages of high performance permanent magnets with high coercively and residual magnetic, which make it possible for the PM to have superior power density, torque to inertia ratio and efficiency, when compared to an induction or conventional dc machine. This paper presents the design of a PM brushless dc motor drive simplistically operates as a classical dc motor. The BLDC motor drive system for this paper composes to the power integrated circuits, the one chip device. And several simple semiconductors add to drive system for a motor drive system simplistically operates as a conventional dc motor. Test results confirmed the feasibility of the proposed motor drive system design.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.3
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• pp.114-119
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• 2004

An oxyge generator, which is applied to a particular space such as automobile, must consider compactness and lightweight as well as problems caused by noise, vibration and heat dissipation. For these matters, a BLDC motor was adopted to reduce heat while a bed using synthetic zeolite NaX made it possible to generate high-density oxygen with relatively small size. Moreover, owing to the characteristic of synthetic zeolite Nax, a two-head vacuum pump was designed to desorb nitrogen without additional pump unit.

• 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.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.9
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• pp.3161-3167
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• 2010

Hall sensors of BLDC(brushless DC) motor are used to detect a position information for a control mechanism, which implements an algorithm for velocity and position control. Actual azimuth and altitude were measured to evaluate a control precision. The measurement revealed comparatively good accuracy that the measured values were $2.02^{\circ}$ and $1.01^{\circ}$ respectively, and the maximum error falls within $1.86^{\circ}$. The developed monitoring system of photovoltaic generation plants is a LCU(Local Control Unit) based on an integrated monitoring system which supports 1:N method for multiple simultaneous connections, remote control and real-time system state monitoring.

• The Transactions of the Korean Institute of Power Electronics
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• v.12 no.1
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• pp.9-18
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• 2007

This paper proposes the modeling of sensorless drive system using 120 degree conduction method for IPM (Interior Permanent Magnet) BLDC motors and analyzes characteristics of the terminal voltage that is used to detect the rotor position. This paper shows that the ZCP (Zero-Crossing Point) of the measured terminal voltage used In sensorless control is ahead of that of the back EMF of IPM motors because they have a saliency. This research also analyzes that the amount of position detection error is related to saliency, rotor speed, and load condition. In addition, this paper shows that motors have bigger advance angles than we have expected because the ZCP of terminal voltage precedes the actual ZCP, and under operation conditions such as heavy load and high speed it may generate abnormal currents that flow toward opposite direction after phase current becomes zero.

• Journal of Power System Engineering
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• v.18 no.4
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• pp.43-51
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• 2014

In this paper, transient temperature and vibration characteristics of a brushless DC (BLD(c) motor are studied for external load (165W~495W) and rotational speed (2000 rpm~4000 rpm). For experiment, a simple measurement system is developed to allow a change in load and speed for measuring transient temperature and vibration simultaneously. Temperature and vibration were also measured under the conditions of natural convection and forced convection. Vibrations in the directions of x-axis (#Ch1), y -axis (#Ch2) and z -axis (#Ch3) were obtained by three accelerometers and temperature was obtained by a thermo-couple with respect to time until the motor is steady. Experimental results show that the amplitude of vibration is higher in the order of z-axis (#Ch3), x -axis (#Ch1) and y-axis (#Ch2) and the amplitude of vibration at the forced convection conditions is 10.6% to 17.8% lower than that of vibration at the natural convection. However, the ratio of the vibration value is similar on average regardless of external convection condition.

• Journal of the Korean Society of Industry Convergence
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• v.21 no.3
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• pp.141-147
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• 2018

In a time when product development cycles are getting shorter and shorter, many companies are making efforts to develop products with high reliability in a short period of time, accelerated life test is widely used as a method to quickly evaluate reliability. Accelerated life test reduces the test life or the life of the product from the observed data by shortening the lifetime of the product or abruptly lowering the performance under the worse condition than the actual condition in order to shorten the test cost or the test time. In this paper, BL3640A-06P+RB35, DC12V model, which is used in the support device of an automatic rotation type digital signage, which display various information such as textures and images on a display screen in a public place or a commercial space, BLDC motors were subjected to a constant stress test and at the rotational speed of 1rpm, $180^{\circ}$ rotation and reverse rotation under actual use conditions, the stress was imposed on the rotating speed of 2rpm and the weight of the actual installed product from 22.2kgf to 10kgf were installed. The lifetime of the actual use environment condition is 23,545 hours and the rotation speed is accelerated. The life time of the acceleration condition with the additional weight is 1,380 hours. The acceleration factor is calculated as 17.06, the one year guarantee test day is 235 days to 14 days, of the period from 470 days to 28 days, and the third year from 704 days to 42 days. The test date of the BLDC motor was tested on the shortened test date, and the rotational speed and the current value were measured. It is found that there is no defect even if it operates as the test date corresponding to the specified one year warranty period and the 3 year accelerated life test which is experimented. Using the statistical technique of the regression analysis the expected time for the motor to defect to #4 samples was 20 years.

• The Transactions of the Korean Institute of Power Electronics
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• v.10 no.6
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• pp.569-577
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• 2005

In this paper, a new control scheme to use 6-switch IGBI module for 3-phase switched reluctance motors(SRM) is proposed. Compared with the conventional asymmetric bridge converter topology, it can minimize the entire system size and cost. Therefore, it may have a new topology lot SRM to compare the other ac motors, such as induction motors, brushless dc motors, and so on. The validity of the proposed method is verified by simulation, and experimental results.