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

Altaf, Faisal; Johannesson, Lars; Egardt, Bo

doi:10.3182/20121023-3-fr-4025.00024

Cited by 12 publications

(21 citation statements)

References 21 publications

(24 reference statements)

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“…See [18] for the detailed derivation of all the averaged variables. Now using these averaged quantities, the averaged-model of PC i can be written as follows:…”

Section: B Averaged-state-space Model Of a Power Cellmentioning

confidence: 99%

“…In [18], the potential benefit of using the MLC to balance both the SoC and the temperature among the battery cells under unidirectional flow (UF ) has been thoroughly investigated and compared to UDCO . The main contribution of the current article is to do the similar investigation for OP under RF and then compare the results with those of OP under UF .…”

Section: Introductionmentioning

confidence: 99%

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Performance evaluation of Multilevel Converter based cell balancer with reciprocating air flow

Altaf

Johannesson

Egardt

2012

2012 IEEE Vehicle Power and Propulsion Conference

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Abstract-The modeling and design of an active battery cell balancing system using Multilevel Converter (MLC) for EV/HEV/PHEV is studied under unidirectional as well as reciprocating air flow. The MLC allows to independently switch ON/OFF each battery cell in a battery pack. The optimal policy (OP ) exploiting this extra degree-of-freedom can achieve both temperature and state-of-charge (SoC) balancing among the cells. The OP is calculated as the solution to a convex optimization problem based on the assumption of perfect state information and future driving. This study has shown that OP gives significant benefit in terms of reduction in temperature and SoC deviations, especially under parameter variations, compared to uniformly using all the cells. It is also shown that using reciprocating flow for OP gives no significant benefit. Thus, reciprocating flow is redundant for MLC-based active cell balancing system when operated using OP .

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“…See [18] for the detailed derivation of all the averaged variables. Now using these averaged quantities, the averaged-model of PC i can be written as follows:…”

Section: B Averaged-state-space Model Of a Power Cellmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Performance evaluation of Multilevel Converter based cell balancer with reciprocating air flow

Altaf

Johannesson

Egardt

2012

2012 IEEE Vehicle Power and Propulsion Conference

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“…Algorithms for controlling the balancing system are also not model based and are often open loop, typically based on periodically checking the cells' voltages and switching cell balancing circuits on or off accordingly, see for example Lee et al (2011), Zhi-guo et al (2006. Algorithms for specific balancing systems are proposed in Samadi & Saif (2014) and Altaf et al (2012), which show the potential for using model predictive control. Both rely on genetic algorithms to solve a nonlinear constrained minimization function, which is computationally expensive for real time applications.…”

Section: Introductionmentioning

confidence: 99%

Model Based Design of Balancing Systems for Electric Vehicle Battery Packs

2015

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Original citation:Bruen, Thomas, Marco, James and Gama, Miguel (2015) Copies of full items can be used for personal research or study, educational, or not-forprofit purposes without prior permission or charge. Provided that the authors, title and full bibliographic details are credited, a hyperlink and/or URL is given for the original metadata page and the content is not changed in any way. Publisher's statement: A note on versions:The version presented in WRAP is the published version or, version of record, and may be cited as it appears here. Abstract: Battery packs containing multiple cells in series require a balancing system in order to ensure energy and power requirements for the battery pack are maintained throughout its life. Based on the equivalent circuit model (ECM) of a cell, a new framework is proposed which can accommodate a controloriented model of a balancing system while maintaining the same measured input and output as an ECM. This allows for model-based design of the balancing control system and other battery management system functions such as state estimation. Three examples of balancing system models are presented to show how balancing systems can be designed and analyzed. A model-based controller is then designed for one balancing system to show how the framework can be used to generate less heat while removing imbalance at the same rate.

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“…Similar to the RF case, OP simultaneously achieved good thermal and SoC balancing by using Cell 5 , which is the most downstream cell with 50% higher resistance, least compared with the others whereas Cell 1 is used most. [20] presents a more detailed comparison between OP and UDCO under UF. Fig.…”

Section: Op Versus Udco Under Ufmentioning

confidence: 99%

“…In this study, the PS-PWM scheme is referred to as the uniform duty cycle operation (UDCO), whereas the optimal scheme that controls the duty cycle of each PC to balance both SoC and temperature is referred to as optimal control policy (OP). The potential benefit of using MLC to balance both SoC and temperature of battery cells under a uni-directional flow (UF) has been thoroughly investigated and compared with that of UDCO [20]. Thus, the main contribution of the current study is to investigate OP under RF, and then to compare the results in detail with those of OP under UF.…”

Section: Introductionmentioning

confidence: 99%

On Thermal and State-of-Charge Balancing using Cascaded Multi-level Converters

Altaf¹,

Johannesson²,

Egardt³

2013

Journal of Power Electronics

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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.

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

Cited by 12 publications

References 21 publications

Performance evaluation of Multilevel Converter based cell balancer with reciprocating air flow

Performance evaluation of Multilevel Converter based cell balancer with reciprocating air flow

Model Based Design of Balancing Systems for Electric Vehicle Battery Packs

On Thermal and State-of-Charge Balancing using Cascaded Multi-level Converters

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