• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1339-1342
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• 2005

This paper presents a simple AC-DC power conditioner for a squirell-cage induction generator(IG) operating under variable shaft speeds. The necessary reactive power for the IG system is supplied by means of a capacitor bank and a voltage-source PWM converter. Using a capacitor bank to transfer the reactive power to the IG under the rated speed and no-load conditions starts the IG operation and reduces the PWM power converter size. A simple control compensating for changes in the electrical loads as well as the variation in speed was developed to regulate the voltages of the IG system by controlling the rotor flux through its reactive and active currents control implementation. This proposed power conditioning scheme can be used efficiently as a wind power generation system where the output voltage of the IG is maintained constant voltage despite the variable frequency and the DC bus voltage of the PWM converter can be used for either DC applications such as battery charging or AC power applications with 60/50 Hz by connecting a stand alone inverter. The experimental and simulated operating performance results of a 5 kW IG scheme at various speeds and leads are presented.

• Journal of Power Electronics
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• v.19 no.5
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• pp.1074-1086
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• 2019

This paper presents the design and implementation of an improved cascaded multilevel inverter topology with asymmetric DC sources. This experimental inverter topology is a stand-alone system with simulations and experiments performed using resistance loads. The topology uses four asymmetric binary DC sources that are independent from each other and one H-bridge. The topology was simulated using PSIM software before an actual prototype circuit was tested. The proposed topology was shown to be very efficient. It was able to generate a smooth output waveform up to 31 levels with only eight switches. The obtained simulation and experimental results are almost identical. In a 1,200W ($48.3{\Omega}$) resistive load application, the THDv and efficiency of the topology were found to be 1.7% and 97%, respectively. In inductive load applications, the THDv values were 1.1% and 1.3% for an inductive load ($R=54{\Omega}$ dan L=146mH) and a 36W fluorescent lamp load with a capacitor connected at the dc bus.

• Proceedings of the KIEE Conference
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• 1997.07a
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• pp.282-284
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• 1997

The harmonics are injurious on the operation of the motor, electric instruments etc. In this paper, it is certified the capability of the electric measuring devices at the input/output of inverter. And it is measured the harmonics of the voltage and current waveforms. Also, this paper presents the efficiency of the inverter's power conversion by measuring the fundamental and total power at the input, DC bus and output.

• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2003.06a
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• pp.161-164
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• 2003

This research presents the parallel control scheme of PID servo-driver for shaping of the curved glass. The designed system consists of a PC, main controller and 11 servo-drivers. Each elements are connected by using RS-232C and 8-bit bus communication. In order to guarantee the stability and the control performance, we use the LM629, a precision PID motion controller, and LMD18200, a H-bridge on the servo-drivers. PC calculates position values of 11 DC motors by using the pre-determined curvature value and offers the user interface environment operator.

• Proceedings of the KIPE Conference
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• 2019.07a
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• pp.107-109
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• 2019

본 논문에서는 직류 마이크로그리드의 버스 전압 진동을 감쇠하기 위한 에너지 저장장치의 제어기법을 제시한다. IDA-PBC 이론을 이용한 제어기를 설계하고, 직류 마이크로그리드의 안정도를 해석한다. PSIM 시뮬레이션을 이용하여 제안하는 기법의 타당성을 검증하였다.

• Proceedings of the KIPE Conference
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• 2016.07a
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• pp.223-224
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• 2016

본 논문은 상용급 전기버스의 24 V 전장전력공급장치로써 고전압배터리부터 저전압으로 변성하는 전력변환장치인 저전압 직류변환장치 (Low Voltage DC/DC Converter : LDC) 개발에 관하여 기술한다. 제안하는 LDC는 효율을 높이기 위해 트랜스포머 1차 측 위상천이 전브리지 스위칭 소자에 SiC MOSFET을 사용하고, 2차 측에 동기정류방식을 적용하였다. 고효율 성능을 검증하기 위해 시작품을 제작하고 시험을 통해 3 kW 97% 이상의 고효율, 고출력, 고밀도의 특성을 확인하였다.

• Journal of Electrical Engineering and Technology
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• v.2 no.3
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• pp.358-365
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• 2007

This paper deals with a novel solid state controller (NSSC) for parallel operated isolated asynchronous generators (IAG) feeding 3-phase 4-wire loads in constant power applications, such as uncontrolled pico hydro turbines. AC capacitor banks are used to meet the reactive power requirement of asynchronous generators. The proposed NSSC is realized using a set of IGBTs (Insulated gate bipolar junction transistors) based current controlled 4-leg voltage source converter (CC-VSC) and a DC chopper at its DC bus, which keeps the generated voltage and frequency constant in spite of changes in consumer loads. The complete system is modeled in MATLAB along with simulink and PSB (power system block set) toolboxes. The simulated results are presented to demonstrate the capability of isolated generating system consisting of NSSC and parallel operated asynchronous generators driven by uncontrolled pico hydro turbines and feeding 3-phase 4-wire loads.

• The Transactions of the Korean Institute of Power Electronics
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• v.5 no.1
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• pp.79-87
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• 2000

본 논문은 저 도전 손실을 갖는 새로운 단단, 단일 스위치 역률보상 부스트형 교류/직류 변환기를 소개한다. 제안한 변환기는 약간의 구조적 차이점을 제외하고 기존의 변환기와 동일하게 해석될 수 있다. 먼저, 제안한 변환기와 기존의 변환기의 동작원리를 파악하여 두 변환기의 차이점을 이해하고 1단 역률 보상 교류/직류 변환기의 구조적 문제점인 에너지 저장 커패시터에서의 직류 전압 상승을 방지하기 위한 직류 부스 전압 궤환 방식을 도입하여 제안한 변환기에 적용하였다. 100W급 변환기를 제작/실험하여 본 변환기의 타당성을 검증하였다.

• The Transactions of the Korean Institute of Power Electronics
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• v.6 no.3
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• pp.291-298
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• 2001

This paper deals with a full functional simulation of UPFC (Unified Power Flow Controller) which is a next generation FACTS (Flexible AC Transmission Systems) technology. Through analysis and modeling of he UPFC, power flow control is simulated. Active and reactive power controls, and input side bus voltage control are performed by EMTDC (Electro-Magnetic Transients in DC systems) which is a general purpose time domain simulation program for simulating power systems transients and its controls. Dynamic performances of the UPFC are verified by simulation results.

• Proceedings of the KIEE Conference
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• 1997.11a
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• pp.42-45
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• 1997

A synchronous solid-state var compensator(SSVC) system which employs a three-phase neutral-point-darned (NPC) inverter is presented and analyzed for high voltage and high power applications. The proposed SSVC system can compensate for leading and lagging displacement factor. An optimal pulse-width-modulation (PWM) is used as a means of reducing the size of reactive components. A equivalent model is obtained using DQ-transform, and the characteristic of open-loop system are archived from DC and AC analyzes. A $\alpha$ phase-shift control is suggested using a self-controlled dc bus.