• Journal of Power Electronics
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• 제13권4호
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• pp.569-583
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• 2013

In this study, the simultaneous use of a multi-level converter (MLC) as a DC-motor drive and as an active battery cell balancer is investigated. MLCs allow each battery cell in a battery pack to be independently switched on and off, thereby enabling the potential non-uniform use of battery cells. By exploiting this property and the brake regeneration phases in the drive cycle, MLCs can balance both the state of charge (SoC) and temperature differences between cells, which are two known causes of battery wear, even without reciprocating the coolant flow inside the pack. The optimal control policy (OP) that considers both battery pack temperature and SoC dynamics is studied in detail based on the assumption that information on the state of each cell, the schedule of reciprocating air flow and the future driving profile are perfectly known. Results show that OP provides significant reductions in temperature and in SoC deviations compared with the uniform use of all cells even with uni-directional coolant flow. Thus, reciprocating coolant flow is a redundant function for a MLC-based cell balancer. A specific contribution of this paper is the derivation of a state-space electro-thermal model of a battery submodule for both uni-directional and reciprocating coolant flows under the switching action of MLC, resulting in OP being derived by the solution of a convex optimization problem.

• 멤브레인
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• 제22권5호
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• pp.285-300
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• 2012

바나듐 흐름전지는 오랜 사이클 수명, 높은 에너지효율, 낮은 제조단가 그리고 친환경성으로 인하여 에너지저장장치의 한 부분이 될 것으로 기대되고 있다. 바나듐 흐름전지 시스템의 핵심 부품의 하나로서 이온교환막은 이온이 계속적으로 전달되는 동안 양극과 음극 전해질의 투과를 저해하는 물성이 요구된다. 그러나 Nafion과 같은 이온교환막은 넓은 시장성의 확보를 위한 목표성능의 달성을 위한 몇가지 과제들에 직면하고 있다. 그러므로 이러한 문제들을 해결하기 위하여 최근까지 개발된 여러가지 이온교환막에 대하여 Nafion과 비교하여 바나듐 흐름전지특성에 대하여 조사하였다.

• 전기화학회지
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• 제13권2호
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• pp.123-127
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• 2010

Redox Flow Battery용 고내구성 및 고효율 전극의 제조를 위해 DSA(Dimensionally Stable Anode)를 집전체 및 전극으로 사용하고 흑연 입자를 이용한 전극을 제조하여 DSA와 압연하는 방법으로 일체화 된 흑연/DSA 전극의 전기화학적 특성을 조사하였다. 1 M $VOSO_4$ + 5M $H_2SO_4$ 혼합용액과 2 M $VOSO_4$ + 2.5M $H_2SO_4$ 혼합된 용액의 전해액 시스템에서 Cyclic Voltammetry(CV) 방법을 이용하여 -0.7 V에서 1.6 V vs. SCE의 전위범위에서 전극의 특성을 실험한 결과, 높은 농도의 2M $VOSO_4$ 전해액에서도 바나듐 이온들의 redox couple 반응을 잘 나타내고 있으며 가역성도 우수한 것으로 나타났다. 따라서 본 연구에서 제조된 일체화된 흑연/DSA 전극을 redox flow battery에 적용할 경우에 고내구성, 내부식성 및 전지의 에너지밀도, 출력밀도와 에너지효율을 향상시킬 것으로 판단된다.

• 방사선산업학회지
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• 제7권1호
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• pp.61-67
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• 2013

In this study, we developed ionic permselective membrane as a core material of redox flow battery using radiation grafting method. Two ionic permselective membranes, ETFE-g-PSSA and ETFE-g-PVBSA were prepared by radiation grafting with styrene and VBC followed by sulfonation, respectively. We confirmed that the prepared membranes were successfully prepared via FT-IR. The prepared ionic permselcetive membranes were characterized and the performance of the membranes were evaluated as ionic permselective membranes for vanadium redox flow battery.

• 한국표면공학회지
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• 제52권3호
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• pp.180-185
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• 2019

The demands to improve the performance of the vanadium redox flow battery have attracted an intense research on modifying the carbon-based electrode. In this study, the surface of graphite felt was reformed, using cobalt oxide. The cobalt oxide was implanted into graphite felt during hydrothermal and two step heat treatments. The cobalt was deposited by hydrothermal method and the two step heat treatments made lots of holes on the graphite felt surface which is called as porous surface. The porous surface acts as an electrochemically active site for the cathodic reaction of vanadium redox flow battery. The reformed electrode shows the electrochemically improved performance compared with the pristine electrode.

• 멤브레인
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• 제19권2호
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• pp.129-135
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• 2009

바나듐 레독스-흐름 전지용 격막으로 사용하기 위해 폴리설폰(Psf)에 폴리페닐렌설파이드설폰(PPSS)을 블록 공중합 시킨 폴리머를 사용하여 양이온교환막을 제작하여, 막 특성을 평가하였다. 제작한 양이온교환막은 Nafion117보다 열적 안정성이 뛰어나다는 것을 TG분석을 통해 알 수 있었고, 1몰 황산용액에서의 막 저항은 3 cc의 CSA를 도입하였을 때 $0.96{\Omeg}{\cdot}cm^2$로 제일 작은 저항 값을 나타냈다. 제작한 양이온교환막의 바나듐 레독스-흐름 전지에서의 전기화학적 특성에 대해 평가하였다. 제작한 양이온교환막을 사용한 바나듐 레독스-흐름 전지의 100% 충전상태에서의 기전력은 바나듐 레독스-흐름 전지의 기전력 값인 1.4V를 나타냈으며, 각 충전상태에서의 충 방전 셀 저항은 Nafion117을 사용한 전지의 값보다 작은 값을 나타냈다.

• Journal of Power Electronics
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• 제1권2호
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• pp.99-106
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• 2001

This paper describes the implementation of a Storage Power Flow Controller (SPFC) connected to the grid which can provide concomitant benefits associated with a Unified Power Flow Controller while at the same time providing several other very important benefits to power system operation such as, load leveling dynamic voltage stability inprovement, harmonic compensation and power factor correction. This Storage power Flow Controller (SPFC) was implemented using real time signal processors, three-phase inverter(s) and battery bank which can provide improved power system operation and control, added system security and reduced power system losses.

• 한국수소및신에너지학회논문집
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• 제33권6호
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• pp.803-807
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• 2022

In this study, the battery performance change according to the change of electrolyte flow rate. With increase of electrolyte flow rate the energy efficiency showed tendency of decrease. The electrochemical impedance spectroscopy results showed the increased resistance.

• Journal of Electrochemical Science and Technology
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• 제8권3호
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• pp.236-243
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• 2017

A fixed-bed zinc/nickel redox flow battery (RFB) is designed and developed. The proposed cell has been established in the form of a fixed bed RFB. The zinc electrode is immersed in an aqueous NaOH solution (anolyte solution) and the nickel electrode is immersed in the catholyte solution which is a mixture of potassium ferrocyanide, potassium ferricyanide and sodium hydroxide as the supporting electrolyte. In the present work, the electrode area has been maximized to $1500cm^2$ to enforce an increase in the energy efficiency up to 77.02% at a current density $0.06mA/cm^2$ using a flow rate $35cm^3/s$, a concentration of the anolyte solution is $1.5mol\;L^{-1}$ NaOH and the catholyte solution is $1.5mol\;L^{-1}$ NaOH as a supporting electrolyte mixed with $0.2mol\;L^{-1}$ equimolar of potassium ferrocyanide and potassium ferricyanide. The outlined results from this study are described on the basis of battery performance with respect to the current density, velocity in different electrolytes conditions, energy efficiency, voltage efficiency and power of the battery.

• 한국지열·수열에너지학회논문집
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• 제16권2호
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• pp.7-12
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• 2020

The battery of an electric vehicle is a key part of the energy supply to operate the vehicles. There are many factors affecting battery life such as charging method, discharge rate, and ambient temperature those are requires systematic monitoring and management. To solve the issues like environmental problems and fuel consumption reduction the battery needs more performance improvement. In this study, it was analyzed the thermal characteristics and securing battery stability for electric vehicle battery cooling system. The simulation test was operated using GT-suite software with several conditions like cooling capacity 1, 2 and 4 kW, cooling flow rate 5, 10, 20 and 30 LPM, and battery initial temperatures 40, 35, and 30℃ at the temperature of ambient 25℃. The results shown that the case of cooling flow rate at 20 LPM was most efficient among all above conditions.