Electrical Properties and Equalization of Lithium-Ion Cells in Automotive Applications

Kuhn, Bernd; Pitel, Grant; Krein, P.T.

doi:10.1109/vppc.2005.1554532

Cited by 92 publications

(40 citation statements)

References 3 publications

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“…Therefore, the voltage of each cell ͑or groups of cells connected in parallel͒ in a lithium-ion battery pack must be monitored individually to ensure safe operation, and many investigators have proposed a variety of different control schemes to ensure safe operation while maximizing energy delivery and recovery. [36][37][38][39] Kuhn et al 37 showed that for certain batteries, charge equalization can extend usable life. A review of the basic charge equalization schemes was presented by Moore and Schneider.…”

Section: Thermal Effects In Lithium-ion Batteriesmentioning

confidence: 99%

A Critical Review of Thermal Issues in Lithium-Ion Batteries

Bandhauer

Garimella

Fuller

2011

J. Electrochem. Soc.

1,672

915

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Lithium-ion batteries are well-suited for fully electric and hybrid electric vehicles due to their high specific energy and energy density relative to other rechargeable cell chemistries. However, these batteries have not been widely deployed commercially in these vehicles yet due to safety, cost, and poor low temperature performance, which are all challenges related to battery thermal management. In this paper, a critical review of the available literature on the major thermal issues for lithium-ion batteries is presented. Specific attention is paid to the effects of temperature and thermal management on capacity/power fade, thermal runaway, and pack electrical imbalance and to the performance of lithium-ion cells at cold temperatures. Furthermore, insights gained from previous experimental and modeling investigations are elucidated. These include the need for more accurate heat generation measurements, improved modeling of the heat generation rate, and clarity in the relative magnitudes of the various thermal effects observed at high charge and discharge rates seen in electric vehicle applications. From an analysis of the literature, the requirements for lithium-ion thermal management systems for optimal performance in these applications are suggested, and it is clear that no existing thermal management strategy or technology meets all these requirements. Thomas-Alyea (kethomas@alumni.princeton.edu) and Kandler Smith (kandler.smith@gmail.com). This article was reviewed by KarenElectric and hybrid electric vehicles ͑EV and HEV͒ may present the best near-term solution for the transportation sector to reduce our dependence on petroleum and to reduce emissions of greenhouse gases and criteria pollutants. Rechargeable lithium-ion batteries are well-suited for these vehicles because they have, among other things, high specific energy and energy density relative to other cell chemistries. For example, practical nickel-metal hydride ͑NiMH͒ batteries, which have dominated the HEV market, have a nominal specific energy and energy density of 75 Wh/kg and 240 Wh/L, respectively. In contrast, lithium-ion batteries can achieve 150 Wh/kg and 400 Wh/L, 1 i.e., nearly 2 times the specific energy and energy density.Whereas lithium-ion batteries are rapidly displacing NiMH and nickel-cadmium secondary batteries for portable and hand-held devices, they have not yet been widely introduced in automotive products. The main barriers to the deployment of large fleets of vehicles on public roads equipped with lithium-ion batteries continue to be safety, cost ͑related to cycle and calendar life͒, and low temperature performance 2 -all challenges that are coupled to thermal effects in the battery. Since the recent introduction of HEV fleets, the industry trend is toward larger batteries required for plug-in hybrids, extended-range hybrids, and all-electric vehicles. These larger battery designs impose greater pressure to lower costs and improve safety.Furthermore, most of the research on these types of batteries has been related to fin...

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Section: Thermal Effects In Lithium-ion Batteriesmentioning

confidence: 99%

A Critical Review of Thermal Issues in Lithium-Ion Batteries

Bandhauer

Garimella

Fuller

2011

J. Electrochem. Soc.

1,672

915

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“…As each cell has unequal properties such as capacity, ESR and self-discharge current, cell voltages can become unbalanced as the charging and discharging sequences are repeated in the series connection configuration [9][10]. Even though the BMS prevents safety problems associated with the unbalanced state, the available capacity of the battery or super-capacitor pack may be dramatically reduced, as the BMS applies upper and lower limits to the highest and lowest voltage cells [11][12][13][14][15]. Fig.…”

Section: Introductionmentioning

confidence: 99%

Cell Balancing Method in Flyback Converter without Cell Selection Switch of Multi-Winding Transformer

Kim¹,

Park²

2016

Journal of Electrical Engineering and Technology

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-This paper presents a cell balancing method for a single switch flyback converter with a multi-winding transformer. The conventional method using a flyback converter with a multi-winding transformer is simple and easy to control, but the voltage of each secondary winding coil might be non-uniform because of the unequal effective turn-ratio. In particular, it is difficult to control the nonuniform effect using turn-ratios because secondary coil has a limited number of turns. The nonuniform secondary voltages disturb the cell balancing procedure and induce an unbalance in cell voltages. Individual cell control by adding a switch for each cell can reduce the undesirable effect. However, the circuit becomes bulky, resulting in additional loss. The proposed method here uses the conventional flyback converter with an adjustment made to the output filters of the cells, instead of the additional switch. The magnitude of voltage applied to a particular cell can be reduced or increased according to the adjusted filter and the selected switching frequency. An analysis of the conventional converter configuration and the filter design method reveals the possibility of adequate cell balancing control without any additional switch on the secondary side.

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“…The Depth-of-Discharge (DoD) is one of the most important factors that determines the degradation of the battery cells, see Kuhn et al (2005), Lukic et al (2008), and Smith et al (2010). To ensure uniform life-time of the cells it is therefore important to utilize each cell so that the State-ofCharge (SoC) and respectively the DoD, remains almost balanced in all cells of the battery pack.…”

Section: Introductionmentioning

confidence: 99%

Evaluating the Potential for Cell Balancing Using a Cascaded Multi-Level Converter Using Convex Optimization

Altaf

Johannesson

Egardt

2012

IFAC Proceedings Volumes

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The modeling and design of an active battery cell balancing system using MultiLevel Converter (MLC) for EV/HEV/PHEV is studied. The MLC allows to independently switch ON/OFF each battery cell in a battery pack . This extra degree-of-freedom (DoF) can be exploited to optimally use each cell in order to balance among them the temperature and state-of-charge (SoC). This study has shown that the constrained convex optimization based control policy, exploiting the extra DoF of MLC, gives significant benefit in terms of reduction in temperature and SoC deviations, especially under parameter variations, compared to uniformly using all the cells. Thus, the MLC has promising potential to offer extra benefit of achieving cell balancing while being simultaneously used as a motor driver.

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Electrical Properties and Equalization of Lithium-Ion Cells in Automotive Applications

Cited by 92 publications

References 3 publications

A Critical Review of Thermal Issues in Lithium-Ion Batteries

A Critical Review of Thermal Issues in Lithium-Ion Batteries

Cell Balancing Method in Flyback Converter without Cell Selection Switch of Multi-Winding Transformer

Evaluating the Potential for Cell Balancing Using a Cascaded Multi-Level Converter Using Convex Optimization

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