• 전력전자학회논문지
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• 제25권3호
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• pp.213-218
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• 2020

In this study, we propose a control algorithm to reduce the unbalanced characteristics of a three-phase system power caused by the unbalanced load of the AC electric railway. Then, we verify its performance through the design of a power compensator and experiments applying it. Like electric railway systems, a Scott transformer is applied, and the load and single-phase back-to-back converters are connected to the M-phase and T-phase outputs. The back-to-back converter monitors the difference in active power between the unbalanced loads in real-time and compensates for the power by using bidirectional characteristics. The active power is performed through PI control in the synchronous coordinate system, and DC link overall voltage and voltage balancing control are controlled jointly by M-phase and T-phase converters to improve the responsiveness of the system. To verify the performance of the proposed power compensation device, an experiment was performed under the condition that M-phase 5 kW and T-phase 1 kW unbalanced load. As a result of the experiment, the unbalance rate of the three-phase current after the operation of the power compensator decreases by 58.66% from 65.04% to 6.38%, and the excellent performance of the power compensator proposed in this study is verified.

• 전력전자학회논문지
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• 제22권1호
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• pp.82-88
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• 2017

This study proposes a new topology for the performance test of a valve consisting of a modular multilevel converter (MMC)-based static synchronous compensator (STATCOM). The conventional valve performance test equipment requires high-voltage AC source of several kV rating because the number of submodules to be tested in a valve should be at least six or eight. However, the power source of the proposed scheme is DC and not AC source. The DC power source voltage range of the proposed test circuit is from several volts to several tens of volts. Therefore, the size and cost for the performance test equipment can be reduced considerably compared with the conventional method. The proposed scheme satisfies the requirements of the IEC 62927 standard. Simulations are conducted for a valve of 50[MVA] MMC-based STATCOM. Experimental results with a scale-downed setup show the validity of the proposed performance test topology.

• Journal of Power Electronics
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• 제15권5호
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• pp.1380-1391
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• 2015

This paper provides a loss analysis and comparison of high power semiconductor devices in 5MW Permanent Magnet Synchronous Generator (PMSG) Medium Voltage (MV) Wind Turbine Systems (WTSs). High power semiconductor devices of the press-pack type IGCT, module type IGBT, press-pack type IGBT, and press-pack type IEGT of both 4.5kV and 6.5kV are considered in this paper. Benchmarking is performed based on the back-to-back type 3-level Neutral Point Clamped Voltage Source Converters (3L-NPC VSCs) supplied from a grid voltage of 4160V. The feasible number of semiconductor devices in parallel is designed through a loss analysis considering both the conduction and switching losses under the operating conditions of 5MW PMSG wind turbines, particularly for application in offshore wind farms. This paper investigates the loss analysis and thermal performance of 5MW 3L-NPC wind power inverters under the operating conditions of various power factors. The loss analysis and thermal analysis are confirmed through PLECS Blockset simulations with Matlab Simulink. The comparison results show that the press-pack type IGCT has the highest efficiency including the snubber loss factor.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2003년도 춘계전력전자학술대회 논문집(1)
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• pp.461-466
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• 2003

This paper presents the speed control of the surface-mounted permanent-magnet synchronous motors (SMPMSM) for the elevator drive. The elevator motor needs to be a compact and slim type. Essentially, the proposed scheme uses a vector control algorithm for a speed and torque control. This system is implemented using a high speed 32-bit DSP (TMS320C31-50), a high-integrated logic device FPGA (EPF10K10-Tl144-3) to design compactly and Inexpensively The proposed scheme is verified through digital simulation and experiments for a three-phase 13.3kW SMPMSM as a MRL(MachineRoomless) elevator motor ill the laboratory. Finally, experiment of the test tower was performed with a 48kW PWM converter-inverter system for a high- speed elevator .

• ETRI Journal
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• 제30권3호
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• pp.347-354
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• 2008

In this paper, the design of a low-power 512-bit synchronous EEPROM for a passive UHF RFID tag chip is presented. We apply low-power schemes, such as dual power supply voltage (VDD=1.5 V and VDDP=2.5 V), clocked inverter sensing, voltage-up converter, I/O interface, and Dickson charge pump using Schottky diode. An EEPROM is fabricated with the 0.25 ${\mu}m$ EEPROM process. Power dissipation is 32.78 ${\mu}W$ in the read cycle and 78.05 ${\mu}W$ in the write cycle. The layout size is 449.3 ${\mu}m$ ${\times}$ 480.67 ${\mu}m$.

• 조명전기설비학회논문지
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• 제25권9호
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• pp.14-25
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• 2011

The solar vehicle is in the spotlight in the eco-friendly aspect of photovoltaic system using unlimited solar energy. The solar vehicle uses energy of photovoltaic and battery. The solar vehicle uses stored energy in battery when photovoltaic power is lower than consumption power by solar vehicle and if photovoltaic power is higher than consumption power by solar vehicle then photovoltaic power is stored to battery. To improve use efficiency of photovoltaic, the researches about MPPT method to operate maximum power point and interior permanent magnet synchronous motor(IPMSM)drive system using photovoltaic is necessary. This paper proposes MPPT control algorithm for solar vehicle using new fuzzy control(NFC). In this paper, to reduce switching loss, the DC-DC converter is omitted. The NFC controller can be use instead of PO. The NFC controller is performed MPPT control using solar cell voltage and q -axis current of IPMSM. The output of NFC is command q -axis current of IPMSM and this current is operated IPMSM. The response characteristics of algorithm proposed in this paper is compared response characteristics of conventional PO method by PSIM program and validity of this paper prove using this result.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 F
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• pp.1977-1980
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• 1998

본 논문에서는 출력단에 동기정류기를 사용하는 영전압 스위칭 방식의 고효율 하프 브리지(H-B)컨버터에 대해 다루고자 한다. 컨버터 손실의 대부분은 출력단 정류기 부분, 주 스위치, 트랜스 등에서 발생되며, 이중 출력단 정류기에 쇼트키 다이오드를 이용하는 경우 쇼트키 다이오드의 on-drop에 의한 손실이 적지 않게 된다. 따라서 이를 감소시키기 위해 쇼트키 다이오드를 MOSFET동기 정류기로 대치하고자 한다. 동기 정류기 방식에 이용되는 MOSFET에는 도통손실이 있으나 이는 쇼트키 다이오드의 on-drop에 의한 손실에 비해 매우 작으며, 특히 MOSFET의 기생 성분을 이용하여 영전압을 구현함으로써 MOSFET의 도통 손실을 현저히 감소시킬 수 있게 된다. 또한 H-B 컨버터의 경우 주 스위치에 전원전압과 동일한 크기의 전압이 인가되므로 내압이 작은 소자의 이용이 가능하게 되며, 이와 같이 함으로써 사용 부품 수의 감소, 내압이 낮은 주 스위치의 사용, 더 나아가 효율이 높은 고효율 컨버터를 구현 할 수 있다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 학술대회 논문집 정보 및 제어부문
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• pp.524-525
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• 2008

본 논문에서는 각각의 스위치 시비율(Duty ratio)의 변화를 이용한 기존의 풀-브릿지 방식과 두 쌍의 스위치 신호 위상 변화를 이용한 위상천이 풀-브리지(Phase-shift Full-bridge) 방식의 차이점을 서술하였다. 위상천이 컨버터의 안정성을 연구하기 위하여, 출력 전류의 맥동(ripple)을 작게 하는 배전류(Current Doubler) 정류회로와 효율을 높이기 위한 동기 정류기(Synchronous Rectifier)를 포함한 평균화 된 스위치 모델을 제안한다. 이 모델을 이용하여 PSPICE 시뮬레이션을 통해 안정성을 고찰하였으며 1.2kW급 170-14V DC-DC 컨버터의 시작품을 제작 후 시뮬레이션 결과와 시작품 결과를 비교하였다. 시뮬레이션의 경우 위상여유는 $58^{\circ}$ 시작품의 위상여유는 $68^{\circ}$로 나타났으며 교차주파수는 12kHz로 동일하게 나오는 것을 확인하였다. 따라서 제안한 시뮬레이션 모델을 이용하여 실제 회로의 안정성을 예측할 수 있으며 이를 실제 회로 제작에 활용 할 수 있다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2017년도 추계학술대회
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• pp.7-8
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• 2017

The Phase-Locked Loop (PLL) is widely used in grid-tie inverter applications to achieve the synchronization between the inverter and the grid. However, its performance is deteriorated when the grid voltage is not pure sinusoidal due to the harmonics and the frequency deviation. Therefore it is important to design a high performance phase-locked loop (PLL) for the single phase inverter applications to guarantee the quality of the inverter output. In this paper a simple method to improve the performance of the PLL for the single phase inverter is proposed. The proposed PLL is able to accurately estimate the fundamental frequency component of the grid voltage even in the presence of harmonic components. In additional its transient response is fast enough to track a change in grid voltage within two cycles of the fundamental frequency. The effectiveness of the proposed PLL is confirmed through the PSIM simulation and experiments.

• 전기학회논문지
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• 제57권10호
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• pp.1796-1801
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• 2008

In this paper, a new current based maximum power point tracking (CMPPT) method is proposed for a single phase photovoltaic power conditioning system and the current based MPPT modifies incremental conductance method. The current based MPPT method makes the entire control structure of the power conditioning system simple and uses an inherent current source characteristic of solar cell array. In addition, digital phase locked loop using an all pass filter is introduced to detect phase of grid voltage as well as peak voltage. Controllers about dc/dc boost converter, dc-link voltage, dc/ac inverter is designed for a coordinated operation. Furthermore, PI current control using a pseudo synchronous d-q transformation is employed for grid current control with unity power factor. 3kW prototype photovoltaic power conditioning system is built and its experimental results are given to verify the effectiveness of the proposed control schemes.