• 전기전자학회논문지
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• 제27권4호
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• pp.477-485
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• 2023

본 논문에서는 AC 리플이 리튬 이온 배터리의 수명에 미치는 영향을 실험적으로 분석한다. 에너지 저장 시스템(ESS)의 이용 효율을 높이기 위해 양방향 전력변환시스템(PCS)이 사용되며, 계통 연계 시 구조상 계통 주파수의 2배의 주파수를 갖는 전류 리플이 배터리에 인가되게 된다. 따라서, AC 리플이 Li-ion 배터리의 노화에 미치는 영향에 대해 분석하기 위해 DC 및 DC+AC 리플 사양의 충/방전 프로파일을 적용하여 노화 실험이 수행되었다. 실험 결과를 바탕으로 직류 내부 저항(DCIR), 증분 용량(IC), 표면 온도를 분석하였다. 결과적으로 AC 리플이 노화에 직접적으로 영향을 미치지 않으며 특정 주기 이 후 배터리 노화가 둔화되는 것을 확인하였다. 이러한 결과는 AC 리플이 발생하는 어플리케이션에서 전류 리플을 줄이기 위해 적용된 필터를 개선하는 데 도움이 될 수 있다.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• 제2B권3호
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• pp.133-139
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• 2002

In this paper, a prototype of an active auxiliary quasi-resonant DC link (QRDCL) snubber assisted voltage source bidirectional power converter (AC to DC and DC to AC) operating at zero voltage soft-switching (BVS) PWM nlode is presented for a Battery Energy Storage System (BESS). The operating principle of this QRDCL circuit and multifunctional control-based converter system, including PWM inverter mode in which energy flows from the battery bank to the three-phase utility-grid in addition to an active PWM converter mode in which energy flows from the utility-grid to the battery banks are described respectively by the control implementation on the basis of d-q coordinate plane transformation. The multifunctional operation characteristics of this three-phase ZVS PWM bi-directional converter with QRDCL is demonstrated fer a BESS under the power conditioning and processing schemes of energy supply mode and energy storage mode, and compared with a conventional three-phase hard switching PWM bi-directional converter for a BESS. The effectiveness of the three-phase ZVS PWM hi-directional converter with QRDCL is proven via the simulation analysis.

• Journal of Electrical Engineering and Technology
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• 제9권3호
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• pp.1132-1136
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• 2014

In the context of increasing electric energy consumption in a data center, energy efficiency improvement is strongly emphasized. In a data center, electric energy is largely consumed by DC power supply system, which is based on a rectifier composed by multiple parallel converters. Therefore, rectifier efficiency must be improved for minimizing loss of DC power supply system. Rectifier efficiency can be modulated by load allocation to converters because converter efficiency depends on input AC power. In this paper, we propose a new control method to maximize rectifier efficiency. The method can control load allocation to converters by introducing active power converter control scheme and start-and-stop of converters. In order to illustrate optimal load allocations in a rectifier, a maximization problem of rectifier efficiency is formulated as a nonlinear optimization one. The problem is solved by Lagrangian relaxation method and the computation results provide the validity of proposed method.

• Journal of Power Electronics
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• 제7권2호
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• pp.97-108
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• 2007

This paper describes simple control structures for a vector controlled stand-alone induction generator (IG) for use under variable speeds. Different control principles, indirect vector control and deadbeat current control, are developed for a voltage source PWM converter and the three-phase variable speed squirrel-cage IG to regulate DC-link and generator voltages with a newly designed phase locked loop circuit. The required reactive power for the variable speed IG is supplied by means of a PWM converter and a capacitor bank to buildup the voltage of the IG without the need for a battery, to reduce the rating of the PWM converter while using only three sensors and to eliminate the harmonics generated by the PWM converter. These proposed schemes can be used efficiently for variable speed wind energy conversion systems. The measurements of the IG systems at various speeds and loads are given and show that these systems are capable of good AC and DC voltage regulation.

• Journal of Power Electronics
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• 제15권4호
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• pp.939-950
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• 2015

A single-stage AC-AC converter has been designed for a wind energy conversion system (WECS) that eliminates multistage operation and DC-link filter elements, thus resolving size, weight, and reliability issues. A simple switching strategy is used to control the switches that changes the variable-frequency AC output of an electrical generator to a constant-frequency supply to feed into a distributed electrical load/grid. In addition, a modified random sinusoidal pulse width modulation (RSPWM) technique has been developed for the designed converter to make the overall system more efficient by increasing generating power capacity and reducing the effects of inter-harmonics and sub-harmonics generated in the WECS. The technique uses carrier and reference waves of variable switching frequency to calculate the firing angles of the switches of the converter so that the three-phase output voltage of the converter is very close to a sine wave with reduced THD. A comparison of the performance of the proposed RSPWM technique with the conventional SPWM demonstrated that the power generated by a turbine in the proposed approximately increased by 5% to 10% and THD reduces by 40% both in voltage and current with respect to conventional SPWM.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2016년도 전력전자학술대회 논문집
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• pp.147-148
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• 2016

본 논문에서는 원격 플라즈마 발생장치 (Remote Plasma Generator, RPG)에 적용하기 위한 공진형 토폴로지에 대해 비교한다. 원격 플라즈마 발생장치는 AC-DC 정류기, DC-AC 인버터, 공진탱크, 플라즈마 발생용 리액터, 점화장치로 구성되며, 이는 기존의 SMPS와 유사한 구성이다. 하지만 플라즈마 부하는 기존의 전력전자 어플리케이션들과는 달리 점화조건과 플라즈마 유지 조건을 충족시켜야 한다는 특징이 있다. 따라서 본 논문에서는 각 공진형 토폴로지들의 특성 비교 분석을 통해 원격 플라즈마 발생장치에 대한 적용 가능성에 대한 분석을 수행하였으며, 시뮬레이션을 통해 검증하였다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 Proceedings ICPE 01 2001 International Conference on Power Electronics
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• pp.390-394
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• 2001

A dynamic simulation model for the brush less dc (BLDC) motor drives using Matlab is presented. In this model, an entire BLDC motor drive, including power conversion unit, BLDC motor, and speed/torque control system, is investigated. Especially, the PWM inverter is modeled using switching function concept, so that the detailed voltage and current waveforms, such as line-to-line voltages, inverter input current, ac line current, and switch/diode currents, can be obtained and average/rms ratings of the components can be easily calculated. Also, the proposed model is made into modular blocks and it can be easily extended to other ac motor applications with a little modification. The detailed modeling method is explained and its actual implementation is described. The validity of the proposed model is verified by various simulation results.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2015년도 전력전자학술대회 논문집
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• pp.165-166
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• 2015

본 논문은 새로운 단일전력변환 SEPIC(Single-Ended Primary-Inductor Converter)-ZETA 절연형 양방향 컨버터를 제안한다. 제안된 컨버터는 SEPIC과 ZETA 컨버터가 결합된 구조로 절연을 통해 안정성을 강화했고, DC측 리플 전류가 낮아 에너지 저장장치의 수명을 연장시킨다. 그리고 SEPIC 컨버터 모드(DC/AC)와 ZETA 컨버터 모드(AC/DC)에서의 입출력 전압비가 동일해 양방향 제어 알고리즘이 간단하다. 또한, 기존 two-stage 구성의 양방향 컨버터와 달리 회로가 단순하며, 단일전력변환을 통한 고효율 저비용의 장점을 가지고 있다. 본 논문에서는 이론적 해석 및 제안한 컨버터의 250W급 시작품을 이용한 실험결과를 통해 컨버터의 우수성 및 성능을 검증한다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.351-354
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• 2006

Recently, a fuel cell with low voltage and high current output characteristics is remarkable for new generation system It needs both a DC-DC step-up converter and DC-AC inverter to be used in fuel cell generation system Therefor, this paper, consists of an isolated DC -DC converter to boost the fuel cell voltage 380[$V_{DC}$] and a PWM inverter with LC filter to convent the DC voltage to single phase 220[$V_{AC}$]. Expressly, a tapped inductor filter with freewheeling diode is newly implemented in the output filter of the proposed high frequency isolated ZVZCS PWM DC-DC converter to suppress circulating current under the wide output voltage regulation range, thus to eliminate the switching and transformer turn-on/off over-short voltage or transient phenomena Besides the efficiency of 93-97[%]is obtained over the wide output voltage regulation ranges and load variations.

• 조명전기설비학회논문지
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• 제22권7호
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• pp.7-15
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• 2008

A single active capacitor snubber-assisted soft-switching sinewave pulse modulation utility-interactive power conditioner with a three-winding flyback high frequency transformer link and a bidirectional active power switch in its secondary side has been proposed. With the aid of the switched-capacitor quasi-resonant snubber cell, the high frequency switching devices in the primary side of the proposed DC-to-AC sinewave power inverter can be turned-off with ZVS commutation. In addition to this, the proposed power conditioner in the DCM can effectively take the advantages of ZCS turn-on commutation. Its output port is connected directly to the utility AC power source grid. At the end, the prototype of the proposed HF-UPC is built and tested in experiment. Its power conversion conditioning and processing circuit with a high frequency flyback transformer link is verified and the output sinewave current is qualified in accordance with the power quality guidelines of the utility AC interactive power systems.