• Title/Summary/Keyword: equalization charging

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Improvement of Step-charging Characteristic for Ni-MH Battery by Selective Cut-off Method (선택적 충전단계절환에 의한 Ni-MH 전지의 계단충전 특성 개선)

  • 안재영;강신영;김광헌;임영철
    • The Transactions of the Korean Institute of Power Electronics
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    • v.3 no.4
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    • pp.273-279
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    • 1998
  • In this paper, the proposed charging system consists of step charging mode and time-sharing equalization charging mode. As $\Delta$V=O point is detected, the proposed cut-off method will selectively cut off the only battery to reach the $\Delta$V=O point, preventing serial-connected batteries from undercharging. In the start of each step, the equalization charging mode is performed to reduce the capacity difference among the batteries. Though it is added to simple circuit for selective cut-off, comparing with recently used step-charging method, this system can improve the life cycle of battery and charging efficiency, and be also very effective for preventing the batteries from overcharging and undercharging.

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Low-Voltage-Stress AC-Linked Charge Equalizing System for Series-Connected VRLA Battery Strings

  • Karnjanapiboon, Charnyut;Jirasereeamornkul, Kamon;Monyakul, Veerapol
    • Journal of Power Electronics
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    • v.13 no.2
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    • pp.186-196
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    • 2013
  • This paper presents a low voltage-stress AC-linked charge equalizing system for balancing the energy in a serially connected, valve-regulated lead acid battery string using a modular converter that consists of multiple transformers coupled together. Each converter was coupled through an AC-linked bus to increase the overall energy transfer efficiency of the system and to eliminate the problem of the unbalanced charging of batteries. Previous solutions are based on centralized and modularized topologies. A centralized topology requires a redesign of the hardware and related components. It also faces a high voltage stress when the number of batteries is expanded. Modularized solutions use low-voltage-stress, double-stage, DC-linked topologies which leads to poor energy transfer efficiency. The proposed solution uses a low-voltage stress, AC-linked, modularized topology that makes adding more batteries easier. It also has a better energy transfer efficiency. To ensure that the charge equalization system operates smoothly and safely charges batteries, a small intelligent microcontroller was used in the control section. The efficiency of this charge equalization system is 85%, which is 21% better than other low-voltage-stress DC-linked charging techniques. The validity of this approach was confirmed by experimental results.

A Three-Port Bidirectional Modular Circuit for Li-Ion Battery Strings Charge/Discharge Equalization Applications (리튬-이온 배터리 충방전 균등화를 위한 3-단자 양방향 모듈 회로)

  • Lee, Kui-Jun;Park, Nam-Ju;Wang, Xiongfei;Hyun, Dong-Seok
    • Proceedings of the KIPE Conference
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    • 2008.06a
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    • pp.37-39
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    • 2008
  • In this paper, a three-port bidirectional modular circuit applied in charging and discharging equalization for lithium-ion battery strings is proposed. This circuit consists of four MOSFETs and one transformer which provide a simple structure to be easily modularized. Compared to conventional individual cell equalization schemes, it utilizes the transformer as the energy transfer element, allowing direct transfer of energy between arbitrary two cells of three-cell battery module, thus improving the equalization efficiency significantly by using much less number of equalizers for long battery strings. Simulation results are presented to validate the circuit operation and confirm its capability to equalize the three-cell battery module.

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A Modularized Charge Equalization Converter for a Hybrid Electric Vehicle Lithium-Ion Battery Stack

  • Park, Hong-Sun;Kim, Chong-Eun;Kim, Chol-Ho;Moon, Gun-Woo;Lee, Joong-Hui
    • Journal of Power Electronics
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    • v.7 no.4
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    • pp.343-352
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    • 2007
  • This paper proposes a modularized charge equalization converter for hybrid electric vehicle (HEV) lithium-ion battery cells, in which the intra-module and the inter-module equalizer are Implemented. Considering the high voltage HEV battery pack, over approximately 300V, the proposed equalization circuit modularizes the entire $M^*N$ cells; in other words, M modules in the string and N cells in each module. With this modularization, low voltage stress on all the electronic devices, below roughly 64V, can be obtained. In the intra-module equalization, a current-fed DC/DC converter with cell selection switches is employed. By conducting these selection switches, concentrated charging of the specific under charged cells can be performed. On the other hand, the inter-module equalizer makes use of a voltage-fed DC/DC converter for bi-directional equalization. In the proposed circuit, these two converters can share the MOSFET switch so that low cost and small size can be achieved. In addition, the absence of any additional reset circuitry in the inter-module equalizer allows for further size reduction, concurrently conducting the multiple cell selection switches allows for shorter equalization time, and employing the optimal power rating design rule allows fur high power density to be obtained. Experimental results of an implemented prototype show that the proposed equalization scheme has the promised cell balancing performance for the 7Ah HEV lithium-ion battery string while maintaining low voltage stress, low cost, small size, and short equalization time.

Distribution Technique of Bus Charging Power Using Rapid Charging Information (급속 충전 정보를 활용한 버스 차량 충전 전력 분배 기법)

  • Tae-Uk Chang;Yu-Min Jo;Ji-In Shin;Ji-Sook Park;Jong-Ho Paik
    • Journal of Internet Computing and Services
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    • v.24 no.1
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    • pp.87-97
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    • 2023
  • Charger infrastructure facilities are designed and installed based on a constant power supply. Initially designed charging facilities support charging of rapidly growing electric vehicles on a limited power supply basis. In addition, current commercial vehicles can only be fully charged, and are supported by the rapid equalization charging method. However, commercial vehicles operate according to a set schedule, so flexible charging is essential. In this paper, we propose a power operation method with more than 20% efficiency improvement by using a fixed schedule-based charging scheduling and power distribution technique of a commercial bus based on the same amount of power in accordance with the rapid growth and increase of electric vehicles.

Power Distribution Control Scheme for a Three-phase Interleaved DC/DC Converter in the Charging and Discharging Processes of a Battery Energy Storage System

  • Xie, Bing;Wang, Jianze;Jin, Yu;Ji, Yanchao;Ma, Chong
    • Journal of Power Electronics
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    • v.18 no.4
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    • pp.1211-1222
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    • 2018
  • This study presents a power distribution control scheme for a three-phase interleaved parallel DC/DC converter in a battery energy storage system. To extend battery life and increase the power equalization rate, a control method based on the nth order of the state of charge (SoC) is proposed for the charging and discharging processes. In the discharging process, the battery sets with high SoC deliver more power, whereas those with low SoC deliver less power. Therefore, the SoC between each battery set gradually decreases. However, in the two-stage charging process, the battery sets with high SoC absorb less power, and thus, a power correction algorithm is proposed to prevent the power of each particular battery set from exceeding its rated power. In the simulation performed with MATLAB/Simulink, results show that the proposed scheme can rapidly and effectively control the power distribution of the battery sets in the charging and discharging processes.

A Novel Cell Balancing Circuit for Fast Charge Equalization (빠른 전하 균일화를 위한 새로운 구조의 셀 밸런싱 회로)

  • Park, Dong-Jin;Choi, See-Young;Kim, Yong-Wook;Kim, Rae-Young
    • The Transactions of the Korean Institute of Power Electronics
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    • v.20 no.2
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    • pp.160-166
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    • 2015
  • This study proposes an improved cell balancing circuit for fast equalization among lithium-ion (Li-ion) batteries. A simple voltage sensorless charge balancing circuit has been proposed in the past. This cell balancing circuit automatically transfers energy from high-to low-voltage battery cells. However, the circuit requires a switch with low on-resistance because the balancing speed is limited by the on-resistance of the switch. Balancing speed decreases as the voltage difference among the battery cells decrease. In this study, the balancing speed of the cell balancing circuit is enhanced by using the auxiliary circuit, which boosts the balancing current. The charging current is determined by the nominal battery cell voltage and thus, the balancing speed is almost constant despite the very small voltage differences among the batteries. Simulation results are provided to verify the validity of the proposed cell balancing circuit.

A CHARGER/DISCHARGER FOR MODELING OF SERIAL/PARALLEL CONNECTED NI-MH BATTERY

  • Heo, Min-Ho;Ahn, Jae-Young;Kim, Kwang-Heon
    • Proceedings of the KIPE Conference
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    • 1998.10a
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    • pp.554-559
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    • 1998
  • Equalizing the state of charge of cell that affects the charge/discharge quality and efficiency of the battery through the charge/discharge characteristic experiments of battery source, we develope the high efficiency charge/discharge system which would be used in serial HEV with the constant engine-generator output. For this, establishes the electrical model of Ni-MH battery appropriate to the high efficiency charge/discharge conditions. There is no model of Ni-MH cell, so we used Ni-Cd model and obtain the Ni-MH model through the experiment. A reason that each cell has the same charge/discharge property for applying the cell model to serial/parallel connected battery source extensively is needed. Therefore, in this paper, propose the Ni-MH charger/discharger has the equalization charging function and selectable cut-off function.

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Time-sharing Charge System for Equalization of Lead-Acid Battery (전기자동차용 납축전지의 시분할 균등충전기)

  • 강신영;김광헌;임영철
    • The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.11 no.2
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    • pp.94-101
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    • 1997
  • This paper proposes the equalizing charger of series connected batteries which are controlled by the time-sharing method. One-chip microprocessor dectcts the terminal voltage of each battery and then determines the charging time inversely proportional to the terminal voltage so that it decrease the un¬balanced capacity. This system is compact and light, therefore it can be applied to portable equipment such as charger for electric vehicle. And it's so effective as to prevent from overcharging which causes their life to shorten.

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A New Modularized Balancing Circuit for Series Connected Battery cells

  • Lee, Hyo-Jae;Jung, Young-Seok
    • Journal of Power System Engineering
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    • v.18 no.6
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    • pp.193-199
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    • 2014
  • The series connected battery cells are mainly used in high voltage battery pack application. However parameter inequality of each battery cell makes battery voltage imbalance problem. In this paper, a new balancing circuit utilizing converter scheme for the series connected battery cells is proposed. Proposed circuit offers easy control and fast equalization time. Moreover the circuit can be used in a practical application because it has high modularity and can operate during the charging/discharging cycle. To show its superiorness and effectiveness, the principle of proposed circuit is explained with computer simulation and experiment is carried out using lithium-ion battery.