• Proceedings of the KIPE Conference
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• 2020.08a
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• pp.403-404
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• 2020

본 논문에서는 단일 2-level 3-leg 전압형 인버터를 사용하여 직렬 연결된 3상 및 단상 표면부착형 영구자석 동기전동기(SPMSM)를 가변속 운전하는 기법을 제안한다. 일반적으로 두 영구자석 동기전동기를 독립적으로 가변속 운전하기 위해서는 각각의 인버터가 필요하지만, 본 논문은 옵셋(Offset) 전압을 사용한 전압 펄스 폭 변조(PWM) 방식으로 인버터를 제어하여 단일 인버터를 사용한 3상 및 단상 전동기 동시 운전이 가능하다. 제안된 방식은 전력용 반도체 소자 수를 줄여 전동기 구동시스템의 가격을 절감시킬 수 있으며, PLECS 시뮬레이션을 통하여 제안된 토폴로지의 유효성을 검증하였다.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.12
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• pp.1285-1292
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• 2011

The characteristics of a semiconductor chiller system with EEV have been experimentally studied. Three experiments on temperature changes (increase and decrease), load variation, and control precision were conducted to investigate the operating characteristics of the semiconductor chiller. The power consumption was 8.9 kW during increase in temperature. The required time was 37.5 min for CH1 and 39.5 min for CH2. Moreover, the time required for falling temperature was 26.5 min. The control precision for partial load operation was relatively low compared to that of a full load operation. In addition, the CH2 equipped with a step motor showed better control precision. The power consumed by the chiller for process cooling water was 1.8 kW, which was one-half of that consumed during the refrigeration cycle. The objective of this study is to provide an optimal control guideline for the semiconductor chiller design.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.2
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• pp.89-96
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• 2015

This paper presents a high efficiency, PSM/DCM/CCM triple mode boost DC-DC converter for mobile application. This device operates at Pulse-Skipping Mode(PSM) when it enters light load, and otherwise operate the operating frequency of 1.4MHz with Pulse-Width Modulation(PWM) mode. Especially in order to improve the efficiency during the Discontinuous-Conduction Mode(DCM) operation period, the reverse current prevention circuit and oscillations caused by the inductor and the parasitic capacitor to prevent the Ringing killer circuit is added. The input voltage of the boost converter ranges from 2.5V ~ 4.2V and it generates the output of 4.8V. The measurement results show that the boost converter provides a peak efficiency of 92% on CCM and 87% on DCM. And an efficiency-improving PWM operation raises the efficiency drop because of transition from PWM to PFM. The converter has been fabricated with a 0.18um Dongbu BCDMOS technology.

• The Transactions of the Korean Institute of Power Electronics
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• v.13 no.6
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• pp.453-460
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• 2008

This paper proposes a new multi-output LLC resonant converter by using single control IC, which has the tight-regulated dual output voltage without additional power devices and controller. The proposed converter has master and slave outputs, of which regulations are achieved by the PWM(pulse width modulation) and PFM(pulse frequency modulation), respectively. Different from the conventional dual-output LLC resonant converter, the proposed converter has no additional post-regulators like a boost converter. Therefore, it features a low cost, small size, and high efficiency. To confirm the validity and prove the superiority of proposed converter, simulated and experimental results on a 50" FHD PDP power set prototype are presented.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.6
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• pp.1405-1410
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• 2015

In this study we designed the radiation-hardened sensor signal processing modules that can be commonly used for a variety of sensors during normal operation and even in high-radiation environments caused by an accident. First development module was designed to receive the change of the R and C value from the sensors and to process the signal as a PWM modulation scheme. This module was assessed to have ± 10% error to the Full-Scale in the radiation test in the range of 12 kGy TID. The main cause of the error was analyzed as the annealing of the common circuit in the switching element and the consequent increase in the duty ratio of the pulse width modulation circuit according to the radiation dose increasement. The redesigned module for higher radiation resistivity with Stub transistor circuit was found to have less than 5% error to the Full-scale from the radiation test results for 20.7 kGy TID range.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.1
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• pp.28-34
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• 2010

The pulse width modulation(PWM) method has been generally used as conventional method controlling luminance of LED(light emitting diode). PWM method as analog method with a relation that duty ratio of LED be proportional to luminance has weak point that it is not compatible with digital method of communication etc. In this paper, a experiment is conducted which the luminance of RGB LED be controlled by digital method. For this, the LED digital control system is developed which consist of LED driving circuits and digital logic circuits. By controlling the number of pluses on RGB LED versus digital input, various lighting colors is implemented and digital codes are optimized in order that measured x, y chromaticity coordinates of lighting colors are comprised in the CIE chromaticity coordinates area of targeted lighting colors. The result of this study can be utilized usefully in research on implementing full color by using remote control of LED lamp with digital communication.

• Proceedings of the KSME Conference
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• 2001.06b
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• pp.676-681
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• 2001

ABS is a safety device, which adds hydraulic system to the existing brake system to prevent wheel from locking, so we can obtain maximum braking force on driving. The hydraulic system to control braking pressure consists of sol-flow type using solenoid valve, flow control valve or consists of sol-sol type using two solenoid valve. In this paper, the hydraulic system in ABS is composed of sol type using a 3port-2position solenoid valve, and vehicle system is composed of 1/4 vehicle model. And slip ratio is controlled using PWM (Pulse-Width-Modulation) control algorithm. Braking friction coefficient and tracking friction coefficient which are described by slip ratio's function have maximum value when slip ratio has its value from 0.1 to 0.3. And slip ratio is controlled constantly in this boundary value even in the variation of road's condition in some boundary.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.6
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• pp.1469-1478
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• 1995

PWM control is a kind of nonlinear control. The merits of PWM control of hydraulic equipment are the robustness of the high speed on-off valve and its low price. And it is easily implemented to hydraulic equipments with microcomputer. The high speed on-off valve is directly digitally controlled without any D/A converter. The objectives of this study is to analyze the limit cycle which regularly appear in the position control system using high speed on-off valve, and to give a criterion for the stability of this system. To do this, the nonlinear characteristics of PWM and cylinder friction of this system are described by harmonic linearization and the effects of parameter variations to the system stability are examined theoretically and experimentally. Consequently, the availability of the proposed method is confirmed well.

• Proceedings of the KIPE Conference
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• 2000.07a
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• pp.313-316
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• 2000

This paper proposes a new solution by carrier-based SVPWM method to solve the most serious problem of Flying Capacitor Multi-level Inverter that is unbalance of capacitor voltages The voltage unbalance is occurred by the difference of each capacitor's charging and discharging time applied to Flying Capacitor Multi-level Inverter. It controls the variation of capacitor voltages into the mean'0' during some period by means of new carriers using the leg voltage redundancy in the Inverter. The solution can be easily expanded to the multi-level. Also this method can make the switching loss and conduction loss of device equal by the use of leg voltage redundancy. First the unbalance of capacitor voltage is analyzed and the conventional theory of self-balance using phase-shifted carrier is reviewed. And then the new method that is suitable to the Flying Capacitor Inverter is explained. The simulation results would be shown to verify the proposed method

• Proceedings of the KIPE Conference
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• 2011.07a
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• pp.421-422
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• 2011

본 논문에서는 직렬전압보상을 기반으로 한 직렬 전압 보상을 기반으로 한 자동 전압 조절기(AVR)가 제안된다. 제안된 AVR은 펄스 폭 변조 방식(PWM)의 교류 쵸퍼와 직렬 전압 보상을 위한 변압기로 구성된다. 제안된 AVR에 사용된 교류 쵸퍼는 commutation 문제가 해결되고 직접적인 교류전력변환이 이루어지기 때문에 따로 에너지를 저장할 소자가 필요없다. 따라서 크기와 가격이 줄어드는 장점이 있다. 직렬보상을 위한 변압기 때문에 교류 쵸퍼는 단지 보상을 위해 필요한 전압만 보상하면 되며, 따라서 스위치의 정격이 줄어든다. 제안된 AVR은 보상전압을 입력전압의 동상 또는 역상으로 만들어 줄 수 있기 때문에 입력전압의 증가 시 또는 감소시를 모두 보상할 수 있다. 실험을 통해 제안된 AVR이 입력전압의 증가 혹은 감소 조건에 대해 빠르게 보상해줌을 검증하였다.