• 조명전기설비학회논문지
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• 제23권1호
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• pp.59-68
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• 2009

분산진원으로서 연료전지 발전장치는 100w부터 수백[kw]의 용량을 가지며 종전의 대규모 전력설비와 비교하여 높은 신뢰도를 갖는 고품질의 전력을 공급할 수 있다. 본 연구에서는 소형 분산전원으로서 PEMFC(polymer electrolyte membrane fuel cell)연료전지 발전장치에 대한 PSIM(power electronics simulation tool) 모델을 설정하고 이를 바탕으로 DSP(digital signal processor)기반의 연료전지 하드웨어 시뮬레이터를 구현하였다. 연료전지 전류와 출력전압과의 관계는 연료전지의 전압-전류(V-I) 곡선 중 ohmic영역에서 1차 함수로 간략화 하였다. 구현된 시스템은 PEMFC 하드웨어 시뮬레이터, 절연형 풀 브리지 직류 부스트 컨버터 그리고 60[Hz] PWM인버터로 구성되어있다. 부하변동 및 과도상태에 대한 연료전지 하드웨어 시뮬레이터의 전압-전류-전력(V-I-P) 특성을 파악하였으며, 저항 부하 및 비선형 부하에 대한 전력변환기의 60[Hz] 정현파 교류출력 전압파형을 고찰하였다.

• 전력전자학회논문지
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• 제15권3호
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• pp.218-225
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• 2010

본 논문은 인버터 AC 스폿용접시스템의 용접시간을 최소화하기 위한 방법에 관한 것이다. 기존의 SCR 회로방식을 이용한 스폿용접시스템의 경우 제어속도가 느리고 전류제어가 정밀하지 않다. 따라서 최근에는 인버터를 이용한 용접시스템이 점차 증가하고 있다. 2차전지의 전극과 같은 박판을 용접해야 하는 경우에는 용접시간이 수 [ms] 정도로 짧아야 한다. 수 [ms] 정도로 용접시간을 최소화하면서 수 천 [A]에 달하는 대전류를 흘리기 위해서 일반적으로 수십개의 스위칭 소자들을 병렬로 연결하여 사용하기도 한다. 본 논문에서는 단지 4개의 IGBT로 구성된 인버터와 60[Hz] 변압기만으로 수 [ms] 대의 용접이 가능한 비용절감형 용접시스템을 제안하고 특성을 분석하였다. 그리고 실험을 통하여 타당성과 효용성을 입증하였다.

• 전력전자학회논문지
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• 제7권2호
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• pp.194-204
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• 2002

본 연구에서는 각 상의 PWM 펄스를 개별적으로 랜덤하게 위치시킬 수 있는 새로운 2상 공간벡터 RPWM (Random PWM) 기법을 제안하고 있다. 제안된 방식은 각 2상 펄스들을 변조 구간 내에서 임의의 위치에 랜덤하게 배치하고 이를 기준으로 한 인버터 스위칭에 의해 고조파의 스펙트럼을 광대역화 하는 RPWM 기법이다. 제안된 방법의 타당성을 검증하기 위하여, 16비트 고성능 마이크로 콘트롤러Cl67 기반의 실험을 수행하였다 제안된 2상 RPWM에 의한 인버터 출력 선간 전압과 직류 링크 전류의 고조파 스펙트럼 및 모터의 가청 스위칭 소음 저감효과를 종전의 방식과 비교 검토하였으며, 제안된 방법의 우수성을 입증할 수 있었다.

• 전기학회논문지
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• 제59권4호
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• pp.707-714
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• 2010

When problems such as line fault, breakdown of a substation or a generator, etc. arise on the grid, the Microgrid is designed to be separated or isolated from the grid. Most existing DGs(Distributed Generators) in distribution system use rotating machine. However, new DGs such as micro gas turbine, fuel cell, photo voltaic, wind turbine, etc. will be interfaced with the Microgrid through an inverter. So the Microgrid may have very lower inertia than the conventional distribution system. By the way, the rate of change of frequency depends on the inertia of the power system. Moreover, frequency has a strong coupling with active power in power system. Because the frequency of the Microgrid may change rapidly and largely during transient, appropriate and fast control strategy is needed for stable operation of the Microgrid. Therefore, this paper presents a power balancing strategy in Microgrid during transient. Despite of strong power or frequency excursions, power balancing in the Microgrid can be maintained.

• Journal of Power Electronics
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• 제1권1호
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• pp.56-64
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• 2001

This paper presents the switching angle and voltage for maximizing the torque or efficiency and minimizing torque ripple of an 8/6, SRM. The approximate analysis and computer simulation determine the switching angle and voltage by using SIMULINK$^\textregistered$. This is performed as a function of the speed and torque required by the load. From the results, new three facts can be known: First, the maximum torque depends on voltage and speed depends on switching angle. The others, the maximum efficiency and minimum torque ripple relay on switching angle. We control the switching angle and voltage of and asymmetrical inverter for the SRM with one-chip micro controller.

• 전기학회논문지
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• 제58권6호
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• pp.1138-1145
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• 2009

This paper presents an active and reactive power compensator for the wind power system with squirrel-cage induction generator. The output power of a wind power system changes irregularly according to the variation of wind speed. The developed system is able to continuously compensate the active and reactive power. The 3-phase inverter operates for the compensation of reactive power, while the DC/DC converter with super-capacitors operates for the compensation of active power. The operational feasibility of the proposed model was verified by simulations with PSCAD/EMTDC and the feasibility of hardware implementation was confirmed by experimental works with a scaled hardware model. The proposed compensator can be expected that developed system may be used to compensated the abrupt power variation due to sudden change of wind speed or sudden power-drop by tower effect. It can be also applied for the distributed generation and the Micro-Grid.

• 전기학회논문지
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• 제58권1호
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• pp.86-92
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• 2009

This paper presents development of 6kw ZVS(Zero Voltage Switching) boost converter by 4-parallel operation. To realize a high capacity converter with 6 kw, 4-parallel operation of 1.5kW unit module is proposed in this paper. To meet high ratio input to output voltage, isolated type booster converter is designed. To achieve ZVS operation of 4-switches of full bridge and protect a voltage overshoot caused by switch turn-off, simple active-clamp circuit is applied to the primary side. For parallel operation of 4-modules, master-slave control method is proposed to achieve input current sharing of 4-unit converter modules accurately. For performance tests, simulation is carried out. Also, load and experimental tests of the developed booster converter, 230Vdc/6kW, are carried out under various conditions. For field tests, the developed converter is applied for boosting a battery power to high DC_link voltage for a VSI inverter which starts a micro-turbine(MT) installed in vehicle and it's performance is verified through high speed motoring a MT up to tens of thousands of rpm.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2002년도 전력전자학술대회 논문집
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• pp.228-232
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• 2002

In this paper, In order to solve the problem is proposed using a new type of electronic ballast that the traditional magnetic ballasts operated at 50-60Hz have been suffered from noticeable flicker, high loss, large crest factor and heavy weight which is composed of rectifier, active power corrector, series resonant half bridge inverter, micro-controller and piezoelectric transformer for driving for driving T5 fluorescent lamp were manufactured. The proposed electronic ballast operated at high frequency (about 75kHz) shows a input power factor of more than 0.995, total harmonic distortion of less than $12\%$ and lamp current crest factor of less than 1.5, respectively. Output power and efficiency showed 28w and $85\%$, respectively. Accordingly, it is considered that the ballast using piezoelectric transformer can replace the typical electronic ballast.

• 전력전자학회논문지
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• 제18권5호
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• pp.477-484
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• 2013

This paper proposes a novel switching method of active clamp snubber for efficiency improvement of PV module integrated converter(MIC) system. Recently, MIC solar system is researched about the efficiency and safety. PV MIC system is used active clamp method of snubber circuit for the price and reliability of the system. But active clamp snubber circuit has the disadvantage that system efficiency is decreased for switch operating time because of heat loss of resonant between snubber capacitor and leakage inductance. To solve this problem, this paper proposes a novel switching method of the active clamp. The proposed method is a technique to reduce power consumption by reducing the resonance of the snubber switch operation time and through simulations and experiments proved the validity.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2006년도 춘계학술대회
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• pp.195-198
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• 2006

The technology of Solar Power conversion System is defined as a solar cell that changes the sol ar energy into the direct electric energy, power conversion and control technology that convert the dc power into ac power The solar cell module, power conversion, and a control part in component parts consisting a solar power conversion system have influence on its performance. The roles of power conversion and a control part supply the direct current generated by solar cell module for a load with high efficiency as conveniently as possible in this study, the power conversion systen that can generate solar power using DSC module was developed and its characteristics was experimented. The characteristics of the DSC power conversion system including MOSFET and DSP micro processor, high speed devices, was simulated using Psim. According to the results, converter and inverter was manufactured in detail and the performance characteristics were studied.