Effects of imbalanced currents on large-format LiFePO 4 /graphite batteries systems connected in parallel

Shi, Wei; Hu, Xiaosong; Jin, Chao; Jiang, Jiuchun; Zhang, Yanru; Yip, Tony

doi:10.1016/j.jpowsour.2016.02.087

Cited by 91 publications

(33 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…As for the battery pack with cells connected in parallel, the current flow conforms to Kirchhoff's law, forming self‐balance effect in the parallel‐connected battery pack. Detailed discussions can be found in the previous studies …”

Section: Resultsmentioning

confidence: 99%

A graphical model for evaluating the status of series-connected lithium-ion battery pack

Feng

et al. 2018

Int J Energy Res

View full text Add to dashboard Cite

Summary State evaluation of battery pack is essential for battery management but laborious when dealing with massive information of cells within the pack. A graphical model for evaluating the status of series‐connected Li‐ion battery pack is established to release the burden. The model is founded by a 2D diagram, with the electric quantity “E” and the capacity “Q” as its axes, therefore called by the “E‐Q diagram.” The new graphical diagram presents the dynamics of cell variations in a linear way, thereby benefiting the design and management of battery pack, including (1) quantifying the cell variations by region, (2) illustrating the evolution of cell variations during aging, (3) guiding the estimation of pack states considering algorithm error in cell states, and (4) solving the balancing problem. The experimental results conform to the theoretical analysis, indicating that the E‐Q diagram will be pervasively applied in the design and management of series‐connected battery pack. Moreover, the E‐Q diagram is suitable for education on the basics of a battery pack, because it is a graphical model.

show abstract

Section: Resultsmentioning

confidence: 99%

A graphical model for evaluating the status of series-connected lithium-ion battery pack

Feng

et al. 2018

Int J Energy Res

View full text Add to dashboard Cite

show abstract

“…Furthermore, a capacitor was incorporated into the equivalent‐circuit model to describe the battery polarization effects. The first‐order RC (resistor–capacitor) equivalent‐circuit model is the most common circuit model for lithium‐ion batteries . Gong et al .…”

Section: Introductionmentioning

confidence: 99%

“…studied the inconsistent current characteristics for a parallel battery pack composed of different degradation‐level cells. Shi et al . investigated the continuous variations of imbalanced currents for two parallel‐connected cells during different charging/discharging cycles and they found that large imbalanced currents occurred near the end of the charge and discharge processes.…”

Section: Introductionmentioning

confidence: 99%

“…Furthermore,acapacitor was incorporated into the equivalent-circuit model to describe the battery polarization effects.T he first-order RC (resistor-capacitor) equivalent-circuit modeli st he most commonc ircuit model for lithium-ion batteries. [15][16][17][18] Gong et al [15] and Bruen et al [16] studied the inconsistent current characteristics for ap arallel battery pack composed of different degradation-level cells.S hi et al [17] investigated the continuous variations of imbalanced currentsf or two parallelconnected cells during different charging/dischargingc ycles and they found that large imbalanced currents occurred near the end of the charge andd ischarge processes.W ang et al [18] developed an equivalent-circuit modelf or the battery pack based on the Matlab-Simscape platform and numerically studied the influence of the battery cell variations on the performanceo faparallel battery module.T he equivalent-circuit model can easily be incorporated into as ystem model of electric vehicles and is generally not computationally expensive.H owever, the equivalent-circuit model is less well suited to study the influence of the temperature differenceo nt he discharging characteristics of the battery pack because the exothermic phenomena of the battery are not considered in this type of model, where the battery temperature rise is often neglected duringt he charging/discharging process. [21] Besides,t he equivalent-circuit model cannot accurately capture the dynamic changes of some importantc haracteristic parameters (e.g.,c ell temperature,L i( Li + ), concentration), because it is difficult to obtain ap recisev aluesf or the battery resistor and capacitor parameters.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Effects of Temperature Differences Among Cells on the Discharging Characteristics of Lithium‐Ion Battery Packs with Series/Parallel Configurations during Constant Power Discharge

Yang

Zhang

et al. 2018

Energy Tech

View full text Add to dashboard Cite

This work aims to make a comparative analysis of the unbalanced discharging phenomenon for battery packs with series/parallel configurations due to the temperature differences among the cells. A theoretically‐based model is developed for the battery pack and constant power discharging processes are simulated by the model. At a constant temperature difference, lowering the operating temperature increases the divergence among the cell terminal voltages for the series pack and the cell discharging currents for the parallel pack. Increasing the temperature differences decreases the dischargeable energy of the series battery pack, whereas it has little effect on that of the parallel configuration. Given the same temperature difference, the cell energy differences within the parallel battery pack are 5–10 times higher than those within the series configuration, which shows that the temperature can be maintained much more uniformly for a parallel battery pack than for series configuration.

show abstract

“…Nonetheless, the lithium battery has been considered one of the major viable energy storage media in electric cars [4][5][6][7]. To meet the voltage and power requirements of cars, if we use small-capacity and low-power lithium cells, as in Tesla's Model S, then the cells should be connected in parallel or/and series fashion [8][9][10][11]. A parallel-connected cell pack (PCCP) can be regarded as a larger single cell by omitting the differences among cells.…”

Section: Introductionmentioning

confidence: 99%

Energy Management of Parallel-Connected Cells in Electric Vehicles Based on Fuzzy Logic Control

et al. 2017

View full text Add to dashboard Cite

Abstract:Inconsistencies that are associated with parallel-connected cells used in electric vehicles induce varied states of charge (SOCs) in each cell. Thus, loop current in the battery pack is inevitable, and this reduces overall capacity, energy utilization rate, and pack lifetime. However, no method is available to address loop current. To reduce loop current and the resulting battery inconsistency, a parallel-connected cell pack (PCCP) model that considers thermal effects is established, and a novel Simscape model that is based on PCCP is successfully constructed. Furthermore, the strategy of parallel-connected cell energy management (PCCEM) is proposed to utilize fuzzy logic control (FLC) strategy, which automatically adjusts the number of cells in a circuit in accordance with the load demand, and turns on the first N switches in the corresponding SOC order. The New European Driving Cycle (NEDC) driving cycle simulation shows that the PCCEM strategy considerably reduces loop current and improves the consistency of battery performance and the utilization rate of battery power.

show abstract

Effects of imbalanced currents on large-format LiFePO 4 /graphite batteries systems connected in parallel

Cited by 91 publications

References 16 publications

A graphical model for evaluating the status of series-connected lithium-ion battery pack

A graphical model for evaluating the status of series-connected lithium-ion battery pack

Effects of Temperature Differences Among Cells on the Discharging Characteristics of Lithium‐Ion Battery Packs with Series/Parallel Configurations during Constant Power Discharge

Energy Management of Parallel-Connected Cells in Electric Vehicles Based on Fuzzy Logic Control

Contact Info

Product

Resources

About