• Proceedings of the KIEE Conference
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• 2003.10b
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• pp.161-165
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• 2003

In this paper, A new controller for power factor and harmonics compensation of a single-phase PWM converter is described. The proposed controller requires only the dc voltage sensor and the at current sensor to compensate the power factor and harmonics. Detail simulation model with EMTBC (Electro-Magnetic Transient program for DC transmission) including power circuit and controller was developed to verify the operation of proposed controller. The application feasibility of the proposed controller was verified through experimental works with a prototype. The proposed controller has a simple structure in the point of hardware implementation, and shows excellent performance in normal operation as well as in sudden load change.

• Journal of international Conference on Electrical Machines and Systems
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• v.1 no.3
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• pp.384-390
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• 2012

This paper proposes a fault diagnosis method of the line-to-line voltage sensors in 3-phase AC/DC pulse width modulation (PWM) converters. The line-to-line voltage sensors are an essential device to obtain the information of the grid voltages for controlling the 3-phase AC/DC PWM converters. If the line-to-line voltage sensors are mismeasured by various faults, the voltage sensors can obtain wrong information of the grid voltage. It has an adverse effect on the control of the converter. Therefore, the converter causes the unbalance input AC current and the DC-link voltage ripple in the 3-phase AC/DC PWM converter. Hence, fast fault detection and fault tolerant control are needed. In this paper, the fault diagnosis method is proposed and verified through simulations and experiments.

• Journal of Advanced Marine Engineering and Technology
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• v.23 no.3
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• pp.292-299
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• 1999

DC motors are widely used in many industrial fields as the actuator of the robot and the driving power motors of the electrical vehicle, Usually in the sensors of DC motors such as the encoder the tachogenerator and the potentiometer etc. are applied, But usage of these sensors results in the increased price and operating cost such that the application of the motors are limitted. To solve this problem another method to construct low cost control system is investigates. In this paper a new speed control method for DC motor is proposed. This method uses motor parameters instead of using speed or position sensors. In this way the angular velocity is estimated by the measure-ment values of the armature voltage and current instead of measuring the sensor signal. This paper presents an alorithm for estimating the angular velocity of DC motor The effectiveness of the proposed method is verified by experimental results. Also the applicability of the proposed method is presented by applying to the velocity contol of a wheeled mobile robot.

• Journal of Power Electronics
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• v.13 no.5
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• pp.829-840
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• 2013

The modified sinusoidal pulse-width modulation (SPWM) is one of the PWM techniques used in three-phase AC-DC buck converters. The modified SPWM works without the current sensor (the converter is current sensorless), improves production of sinusoidal AC current, enables obtainment of near-unity power factor, and controls output voltage through modulation gain (ranging from 0 to 1). The main problem of the modified SPWM is the huge starting current and voltage (during transient) that results from a large step change from the reference voltage. When the load changes, the output voltage significantly drops (through switching losses and non-ideal converter elements). The single-input single-output (SISO) approach with minor-loop voltage feedback controller presented here overcomes this problem. This approach is created on a theoretical linear model and verified by discrete-model simulation on MATLAB/Simulink. The capability and effectiveness of the SISO approach in compensating start-up current/voltage and in achieving zero steady-state error were tested for transient cases with step-changed load and step-changed reference voltage for linear and non-linear loads. Tests were done to analyze the transient performance against various controller gains. An experiment prototype was also developed for verification.

• Proceedings of the KIPE Conference
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• 2012.11a
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• pp.211-212
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• 2012

This paper proposes a single current sensor control technique for controlling motors that use only a single DC-Link current sensing resistor to obtain the information of three line currents. However, the measurement is distorted due to the too narrow current pulse width in the shunt resistor. To solve this problem, the existing phase current reconstruction methods are voltage split methods. They have a disadvantage which makes noise. A new dedicated observer is applied to decrease noise problem. Experimental results showed the effectiveness of the proposed method.

• Proceedings of the KIEE Conference
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• 2002.06a
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• pp.12-15
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• 2002

This propose a simple DC voltage sensor less single phase PFC(Power Factor Correction Circuit) converter by detecting a AC current sensors are not required to construct the control system. The DC voltage is directly controlled by the command input signal Kd($V_o/V_a$)for the boost chopper circuit. The DC voltage regulation is small because of the feed forward control for the AC line voltage VS and no dependence of the circuit parameters. The sinusoidal current waveform in phase with the AC input voltage can be obtained. These characteristics are confirmed by some experiment results.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.11
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• pp.1894-1899
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• 2016

In this paper, because the position sensor represents the important factor in BLDC (Brushless DC) motor drives, BLDC motor is necessary that the three Hall-sensors evenly be distributed around the stator circumference in case of the 3 phase motor. The Hall-sensor is set up in this motor to detect the main flux from the rotor. So the output signal from Hall-sensor is used to drive IGBT to control the stator winding current. However, in case of breakdown Hall sensor, we research that the estimation algorithm of Hall sensor signal to detect rotor position and for the speed feedback signals with BLDC motor whose six stator and two rotor designed. In addition, this paper presents a sensorless speed control of BLDC Motor using terminal voltage of the one phase. Rotor position information is extracted by indirectly sensing the back EMF from only one of the three terminal voltages for a three-phase BLDC motor.

• Journal of Sensor Science and Technology
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• v.23 no.1
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• pp.42-45
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• 2014

Recently, tremendous application utilizing electrospun nanofibers have been actively reported due to its several advantages, such as high surface to volume ratio, simple fabrication and high-throughput manufacturing. In this paper, we developed highly sensitive and consistent nanofiber humidity sensor by electrospinning. The humidity sensor was fabricated by rapid electrospinning (~2 sec) $TiO_2$/PVP/LiCl mixed solution on the micro-interdigitated electrode. In order to evaluate the humidity sensing performances, we measured current response using DC bias voltage under various relative humidity levels. The results show fast response / recovery time and marginal hysteresis as well as long-term stability. In addition, with the aid of micro-interdigitated electrode, we can reduce a total resistance of the sensor and increase the total reaction area of nanofibers across the electrodes resulting in high sensitivity and enhanced current level. Therefore, we expect that the electrospun nanofiber array for humidity sensor can be feasible and promising for diverse humidity sensing application.

• Journal of the Korean Magnetics Society
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• v.23 no.2
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• pp.49-53
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• 2013

A current sensor is one of important component which is used for the electrical current measurement during charge and discharge of the battery, and monitoring system of the motor controller in the electric and hybrid vehicle. In this study, we have developed an open loop type current sensor using GaAs Hall sensor and magnetic core has an air gap. The Hall sensor detect magnetic field produced by the current to be measured. The 3 mm air gap core was made by HGO electrical steel sheets after slitting, winding, annealing, molding, and cutting. Developed current sensor shows 0.03 % linearity within DC current range from -400 A to +400 A. Operating temperature range was extended to the range of $-40{\sim}105^{\circ}C$ using temperature compensating electronic circuit. To Improve frequency bandwidth limit due to the air flux of PCB (Printed Circuit Board) and Hall sensor, We employed an air flux compensating loop near Hall sensor or on PCB. Frequency bandwidth of the sensor was 100 kHz when we applied sine wave current of $40A{\cdot}turn$ in the frequency range from 100 Hz to 100 kHz. For the dynamic response time measurement, 5 kHz square wave current of $40A{\cdot}turn$ was applied to the sensor. Response time was calculated time reach to 90 % of saturation value and smaller than $2{\mu}s$.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.27-28
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• 2011

본 논문에서는 싱글전류센서를 이용하여 브러시리스 직류 전동기의 속도제어시스템 시뮬레이션 방법 및 그 결과을 제시한다. BLDC 전동기 제어에 매우 중요한 역할을 가지고 있는 피드백 센서 방식으로 싱글 전류검출센서를 이용한 속도제어 방법은 모터 설계의 비용을 낮추고, 심플한 제어기 설계를 가능하게 한다. 또한, 전동기에 손상을 줄 수 있는 오류조건을 감지함으로서 신뢰성을 향상시켜 줄 수 있다. 시뮬레이션에 사용하는 BLDC 전동기는 3상 Y결선 전동기를 모델로 하며 MATLAB/SIMULINK를 사용한 시뮬레이션을 수행하여 그 성능을 분석하였다.