• Title/Summary/Keyword: Parallel-connected cells

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Battery Equalization Method for Parallel-connected Cells Using Dynamic Resistance Technique

  • La, Phuong-Ha;Choi, Sung-Jin
    • Proceedings of the KIPE Conference
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    • 2018.11a
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    • pp.36-38
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    • 2018
  • As the battery capacity requirement increases, battery cells are connected in a parallel configuration. However, the sharing current of each battery cell becomes unequal due to the imbalance between cell's impedance which results the mismatched states of charge (SOC). The conventional fixed-resistance balancing methods have a limitation in battery equalization performance and system efficiency. This paper proposes a battery equalization method based on dynamic resistance technique, which can improve equalization performance and reduce the loss dissipation. Based on the SOC rate of parallel connected battery cells, the switches in the equalization circuit are controlled to change the equivalent series impedance of the parallel branch, which regulates the current flow to maximize SOC utilization. To verify the method, operations of 4 parallel-connected 18650 Li-ion battery cells with 3.7V-2.6Ah individually are simulated on Matlab/Simulink. The results show that the SOCs are balanced within 1% difference with less power dissipation over the conventional method.

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SOC-based Sequencing Equalizer for Parallel-connected Battery Configuration using ANFIS Algorithm

  • Duong, Tan-Quoc;La, Phuong-Ha;Choi, Sung-Jin
    • Proceedings of the KIPE Conference
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    • 2019.11a
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    • pp.174-175
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    • 2019
  • Battery cells are connected in parallel to enlarge the system capacity. However, cell inconsistency may reduce the overall system capacity and cause the over-charging or over-discharging issue. This paper proposes a SOC-based sequencing equalizer for parallel-connected battery configuration that uses the ANFIS (adaptive neuro-fuzzy inference system) algorithm to make the switching decision. Depend on the load current and the SOC (state-of-charge) rate of cells, the switching decision is made to equalize the SOC of the battery cells. The simulation results show that the system capacity is maximized and the controller is adaptive for a large number of parallel-connected in dynamic load profile.

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Degradation diagnosis of parallel-connected lithium-ion battery cells via non-constructive electrochemical approach (병렬 연결된 리튬이온전지 셀의 비파괴 전기화학적 열화상태 진단)

  • Lee, Garam;Jeong, Jiyoon;Kim, Yong-Tae;Choi, Jinsub
    • Journal of the Korean institute of surface engineering
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    • v.55 no.4
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    • pp.231-235
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    • 2022
  • As environmental pollution becomes more serious, the demand for electric vehicles (EVs) and lithium-ion batteries for electric vehicles is rapidly increasing worldwide. Accordingly, the amount of waste batteries is also increasing, and a technology for recycling and reusing them is required. In order to reuse a used battery, it is necessary to non-destructively diagnose the deterioration condition of the battery. Therefore, in this study, we investigate the diagnosis of degradation for parallel-connected lithium-ion battery cells through non-constructive electrochemical approach. As the number of parallel-connected cells increased, in addition to linear degradation, abrupt step-like degradation occurred, which is attributed to the predominant degradation of specific cells. In addition, it is confirmed that deteriorated cells among multiple cells can be distinguished through a simple measurement of open circuit voltage (OCV).

A Study on the I-V Characteristics of Fuel Cell (수소-산소 연료전지의 전압-전류 특성)

  • Jung, You-Ra;Choi, Yong-Sung;Hwang, Jong-Sun;Lee, Kyung-Sup
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2009.11a
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    • pp.121-121
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    • 2009
  • A clean and highly efficient energy production has long been sought to solve energy and environmental problems. A fuel cell energy is expected to be a key to solve the problems. The emissions of fuel cell is low, the by-product is low, the by-product is pure water. This paper shows the I-R and V-R characteristics of fuel cell which are connected in parallel and series. In addition, the voltage of the fuel cells which are connected in parallel is less than the voltage of the fuel cells which are connected in series.

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Applications of Current Limiting Diode to Chip on Board Type Light Source and Lighting Equipment Circuits (정전류다이오드를 이용한 COB 타입 LED 광원 및 조명기기 회로)

  • Park, Hwa Jin;Yu, S.J.;Park, Jong Min;Kim, Y.J.
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.26 no.6
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    • pp.488-492
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    • 2013
  • Current limiting diode (CLD) was fabricated using junction field effect transistor (JFET) structured two small cells and eight large cells. Two small cells and eight large cells were connected in parallel and the obtained constant current was 110 mA. The application of CLD in each of the parallel circuits on chip on board (COB) type LED lighting source, could significantly reduce the current deviation within the parallel circuits. The applications of CLD on AC power small lighting source, battery power low voltage parallel lighting source and AC flat lighting source were investigated.

Optimal Design for Dynamic Resistance Equalization Technique to Minimize Power Loss and Equalization Error

  • La, Phuong-Ha;Choi, Sung-Jin
    • Proceedings of the KIPE Conference
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    • 2019.07a
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    • pp.50-52
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    • 2019
  • Dynamic resistance equalization is a viable technique to balance SOC of cells in a parallel-connected battery configuration due to high equalization performance, simplicity and low-cost. However, an inappropriate design of the equalization resistor can degrade the equalization performance and increase the power loss. This paper proposes an optimization process to design the equalization resistors to minimize power loss and equalization error. The simulation results show that the optimally designed resistor significantly enhance the performance in comparison with the conventional fixed-resistor equalization.

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A study of small size battery charging characteristic by serial-parallel connected DSC module (단위 DSC셀의 직병렬 연결을 통한 소형 배터리 충전특성에 관한 연구)

  • Hong, Ji-Tae;Choi, Jin-Young;Seo, Hyun-Woong;Kim, Mi-Jeong;Sim, Ji-Young;Kim, Hee-Je
    • 한국신재생에너지학회:학술대회논문집
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    • 2006.06a
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    • pp.192-194
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    • 2006
  • To elucidate possible challenges for outdoor practical use of dye-sensitized solar cells(DSC), compared with conventional Si solar cells. DSC modules still need the larger area than conventional Si solar modules to attain the same rated output because of lower photoelectron-chemical conversion efficiency. However, using batteries backup systems, the measured data shows that DSCs gathered over 12% more electricity than Si solar cells of the same rated output power in same outdoor condition. Moreover, battery charging time of DSC is about 1 hour faster than same rate of Si solar module. In this paper, 12 single DSC cells prepared for 4 serialized DSC cells was connected in 3 row parallel which have same output power rate of Si solar module. This DSC module was practiced generating characteristic experiment over outdoor daylight condition and applied with PV battery charger by using DC-DC converter. The main advantages of DSC module battery charger as compared with conventional Si solar module one are shorter charge time and lower cost.

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Individual Charge Equalization Converter with Parallel Primary Winding of Transformer for Series Connected Lithium-Ion Battery Strings in an HEV

  • Kim, Chol-Ho;Park, Hong-Sun;Kim, Chong-Eun;Moon, Gun-Woo;Lee, Joong-Hui
    • Journal of Power Electronics
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    • v.9 no.3
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    • pp.472-480
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    • 2009
  • In this paper, a charge equalization converter with parallel-connected primary windings of transformers is proposed. The proposed work effectively balances the voltage among Lithium-Ion battery cells despite each battery cell has low voltage gap compared with its state of charge (SOC). The principle of the proposed work is that the equalizing energy from all battery strings moves to the lowest voltage battery through the isolated dc/dc converter controlled by the corresponding solid state relay switch. For this research a prototype of four Lithium-Ion battery cells is optimally designed and implemented, and experimental results show that the proposed method has excellent cell balancing performance.

Charge Equalization Converter with Parallel Primary Winding for Series Connected Lithium-Ion Battery strings (트랜스포머 1차측 병렬 구조를 가진 직렬 연결 리튬이온 배터리 전하 균일 컨버터)

  • Kim, Chol-Ho;Park, Hong-Sun;Kim, Chong-Eun;Moon, Gun-Woo;Lee, Joong-Hui
    • Proceedings of the KIPE Conference
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    • 2007.07a
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    • pp.256-258
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    • 2007
  • A charge equalization converter with parallel-connected primary windings of transformers is proposed in digest. The proposed work effectively balance the voltage among Lithium-Ion battery cells despite each battery cell has low voltage gap compared with its SOC. The principle of the proposed work is that the equalizing energy from all battery strings moves to the lowest voltage battery through the isolated dc/dc converter controlled by the corresponding bi-directional switch. In this digest, a prototype of four Lithium-Ion battery cells is optimally designed and implemented, and experimental results show that the proposed method has excellent cell balancing performance.

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Power Balancing Control Method of A Residential Distributed Generation System using Photovoltaic Power Generation and Polymer Electrolyte Fuel Cells (PV와 PEFC를 병용한 가정용 분산 전원 시스템의 전력평준화 제어법)

  • Yoon, Young-Byun;Mun, Sang-Pil;Park, Han-Seok;Woo, Kyung-Il
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.65 no.4
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    • pp.335-339
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    • 2016
  • Output power in photovoltaic systems changes steeply with the change of the sun intensity. The change of output power has influence on the electric power quality of the system. This paper proposes a residential distributed generation system using photovoltaic power generation and polymer electrolyte fuel cells(hybrid systems). In order to level the output power which changes steeply the polymer electrolyte fuel cells are connected to the photovoltaic power generation system in parallel. Thus the generated power of all the system can be leveled. However, the steep generated power in the photovoltaic power generation system can not be leveled. Therefore, the electric double layer capacitor(EDLC) is connected in parallel with the hybrid systems. It is confirmed by the simulation that the proposed distributed generation system is available for a residential supply.