• Proceedings of the KIEE Conference
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• 2008.10c
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• pp.132-135
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• 2008

This paper presents a PLL(Phase Lock Loop) control method for speed control of high speed miniature BLDCM(Brushless DC Motor) using hall sensor. The Proposed PLL based speed control method uses a only phase shift between reference pulse signal according to speed reference and actual pulse signal from hall sensor. It doesn't use any speed calculation, and calculates a direct current reference from phase shift. The current reference is changed to reduce the phase shift between reference and actual pulse. So the actual speed can keep the reference speed. The proposed control scheme is very simple but effective speed control is possible.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.869-873
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• 2008

Optimization method for the open loop commutation time intervals in HDD spindle start-up control is presented in this paper. A hard disk drive(HDD) uses a sensorless brushless DC motor(BLDC) for the platter rotation. Because there is no direct sensor for the rotor position, open loop commutations after sensing the rotor position at a standstill using inductive sensing method are performed to speed up the rotor up to a certain speed where the zero crossings of the back electromotive force(EMF) are measurable. Therefore successful open loop commutations are necessary for the stable start-up control of the spindle motors. Random neighborhood search(RNS) algorithm is introduced as a optimization technic in this paper. Rotor speed and its standard deviation are used as a cost function and commutation intervals obtained from the spindle motion equation are used as initial parameter values for the RNS. With the help of the proposed method optimized open loop commutation time intervals for the very low start-up current are acquired and tested. The experimental results shows that the proposed method can decrease the start-up failure rate of a HDD spindle motor.

• Journal of Advanced Navigation Technology
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• v.15 no.5
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• pp.833-838
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• 2011

X-ray device used in the diagnosis has made possible to have more effective and accurate diagnosis, powered by the development of various devices. Based on this, X-ray device has become the most basic and essential diagnostic equipment in clinical medicine. At present, in the image acquisition field using X-ray, the use of Digital radiography which is useful in the acquisition time reduction and transfer of images and is possible to have the dose reduction has expanded. With the structure using one detector, this DR device has disadvantages in that it needs structural changes unlike existing X-ray and the detector should be moved to the desired position depending on the shooting location. Therefore, in this study, using BLDC(Brushless direct current) motor and PID(Proportional integral differential) control method, the automatic control system of 3-axis which is upward and downward, left and right and rotation of detector where having the most movement in DR was designed and produced and its performance was evaluated.

• Journal of IKEEE
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• v.20 no.2
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• pp.163-166
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• 2016

It is important to operate the driving circuit under the optimal condition through precisely sensing the power consumption causing the temperature made mainly by the MOSFET (metal-oxide semiconductor field-effect transistor) when a BLDC (Brushless Direct Current) motor operates. In this letter, a Super-junction (SJ) power TMOSFET (trench metal-oxide semiconductor field-effect transistor) with an ultra-low specific on-resistance of $0.96m{\Omega}{\cdot}cm^2$ under the same break down voltage of 100 V is designed by using of the SILVACO TCAD 2D device simulator, Atlas, while the specific on-resistance of the traditional power MOSFET has tens of $m{\Omega}{\cdot}cm^2$, which makes the higher power consumption. The SPICE simulation for measuring the power distribution of 25 cells for a chip is carried out, in which a unit cell is a SJ Power TMOSFET with resistor arrays. In addition, the power consumption for each unit cell of SJ Power TMOSFET, considering the number, pattern and position of bonding, is computed and the power distribution for an ANSYS model is obtained, and the SJ Power TMOSFET is designed to make the power of the chip distributed uniformly to guarantee it's reliability.

• Journal of Power System Engineering
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• v.21 no.5
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• pp.5-12
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• 2017

With the difficulties in increasing the efficiency of conventional crank-driven compressors due to mechanical loss, compressor manufacturers have investigated new kinds of compressor such as a free piston compressor mechanism. This study investigates the energy efficiency of two different types of compressor for a household refrigerator. One is the conventional crank-driven compressor, and the other one is a linear compressor. The energy efficiencies of these compressors are evaluated. Experimental results show that the linear compressor has 10% lower power consumption than the brushless direct-current (BLDC) reciprocating compressor. The linear compressor demonstrates excellent energy efficiency by reducing the friction loss. Furthermore, a motor efficiency exceeding 90% is achieved by using a linear oscillating mechanism with a moving magnet. Additionally, the compressor stroke to piston diameter ratio of the oscillating piston in the linear compressor can be adjusted in order to modulate the cooling capacity of the compressor for improved system efficiency.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.05a
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• pp.540-545
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• 2001

In case of small motors, coil bundle occupies a large portion of stator in view of mass and volume as well as dynamics. It is observed through modal test on the stator of an IPM BLDC (interior permanent magnet brushless direct current) motor that coil bundle wound on the stator core causes the first and second natural frequencies to decrease by about 20-30% compared with those of bare stator. Especially the third natural frequency is newly observed below 3 KHz, which is not observed on the bare stator. It is found that at the third mode the end-coil and the core vibrate out of phase in radial direction. In this paper, the stator is dynamically modeled in terms of the core and the coil bundle consisting of the end-coil and the slot coil based on the above observations for the prediction of dynamic properties. The core can easily be modeled using finite element method with its actual material properties and geometric shape. The concept of equivalent bending stiffness is used for modeling of the end-coil so that predictions may match with the measured natural frequencies for the end-coil cut out of the stator. Although the same concept can be applied to the slot coil, separation of the slot coil from the stator is impractical. Therefore, equivalent bending stiffness of the slot coil is determined through iterative comparisons with the measurements of natural frequencies of the stator with the slot coil in it.

• Transactions of the Korean hydrogen and new energy society
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• v.34 no.6
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• pp.758-766
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• 2023

Multi-copter of unmanned aerial vehicle (UAV) was initially developed as strategic technology in the only military field, but it is developing into an industrial field with a wide range of applications in the civil sector based on the development and convergence of aviation technology and information and communication technology. Currently, the degree of utilization of multi-copter is increasing in various industries for the purpose of performing classic tactical missions, logistics transportation, farm management, internet supply, video filming, weather management, life-saving, etc, and active technology development responding to market demand. Existing commercial multi-copter mainly use an electric energy propulsion system consisting of an electric battery and a brushless direct current (BLDC) motor. It is the limitations for usage in the flying time (up to 20 minutes) and payload (less than 20 kg). this study aims to overcome these limitations and expand the commercialization of engine-powered multi-copter of UAV in various industries in the futures.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.7
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• pp.109-114
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• 2013

Power MOSFET (metal-oxide semiconductor field-effect transistor) are widely used in power electronics applications, such as BLDC (Brushless Direct Current) motor and power module, etc. For the conventional power MOSFET device structure, there exists a tradeoff relationship between specific on-state resistance and breakdown voltage. In order to overcome the tradeoff relationship, a non-uniform super-junction (SJ) trench MOSFET (TMOSFET) structure for an optimal design is proposed in this paper. It is required that the specific on-resistance of non-uniform SJ TMOSFET is less than that of uniform SJ TMOSFET under the same breakdown voltage. The idea with a linearly graded doping profile is proposed to achieve a much better electric field distribution in the drift region. The structure modelling of a unit cell, the characteristic analyses for doping density, and potential distribution are simulated by using of the SILVACO TCAD 2D device simulator, Atlas. As a result, the non-uniform SJ TMOSFET shows the better performance than the uniform SJ TMOSFET in the specific on-resistance at the class of 100V.