Nonlinear Model Predictive Control for a Simulated Reconfigurable Battery Pack

Due to factory production discrepancies and different operation conditions, cells integrated in conventional battery systems are not similar. In a static series connection, the weakest cell limits the battery pack capacity. Self-reconfigurable batteries (SRB), where semiconductor switches allow cells to be connected or bypassed dynamically, are used to by-pass the weakest cell and so use the full battery capacity at any time. The in-line configuration even allows the direct generation of AC current without any power converter. This paper proposes an optimal lifetime management strategy for SRB generating AC current. A full battery cell model including ageing mechanisms is used to perform the minimization of the SRB capacity losses with the aim of demonstrating the SRB capabilities in terms of lifetime extension. A direct multi-shooting numeric method is used to solve the minimization problem on battery partial discharge, which is often encountered, like in the electric vehicle usage. Simulation results validate the proposed method and a major lifetime extension of 54% compared to conventional battery pack has been observed.

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“…The same remark applies for the ageing model (6). However, the empirical function J makes it difficult to evaluate the non-linearity.…”

Section: B Average Current Modelmentioning

confidence: 94%

Optimal lifetime management strategy for Self-Reconfigurable Batteries

Blatter

Heiries

Thomas

et al. 2022

2022 IEEE 95th Vehicular Technology Conference: (VTC2022-Spring)

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“…Battery packs are generally modelled with a single-cell equivalent, stacking a single model [4], or stacking This work has received funding from the IFD funded TOPchargE project under the Grant Agreement No. 9090-00035A (http://topcharge.eu/) individual models [5]. Although [6], [7] show that the singlecell equivalents are more accurate than the stacked versions, reconfiguration requires knowledge about individual cells.…”

Section: Introductionmentioning

confidence: 99%

Validation of a Single-Cell Reference Model for the Control of a Reconfigurable Battery System

Pinter

Engelhardt

Rohde³

et al. 2022

2022 International Conference on Renewable Energies and Smart Technologies (REST)

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This paper presents the experimental validation of a lithium-iron phosphate cell model. The modelling of dynamic cell behaviour is crucial to improve the performance of reconfigurable battery systems, in which monitoring of the dynamics allows more resoluted leveraging of the battery cells. However, the models of lithium-ion cells are generally inaccurate due to nonlinearities, measurement noise and because the most descriptive state, the state of charge is hidden. Furthermore, the parameter identification of the model requires time and precise measurements, while they differ among the cells, and change as the cells age. The burden of the detailed modelling of a battery system can be alleviated by modelling a single cell, and using the model for each cell in the system. In this work, this possibility is explored by validating a single-cell reference model for a reconfigurable battery system. The terminal voltage residual (error between model and measurement) is presented, and its correlations with internal and external variables are investigated. These correlations can also be used to alleviate the modelling errors. It is concluded that the reference model can qualitatively describe the cell behaviour. By applying small modifications, the model could be used for online estimation.

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“…This approach is already studied in [5], [6], where nMPC strategy focus on balancing the battery cells capacities and temperature in order to maximize the autonomy and improve the battery ageing due to temperature dispersion. Lifespan increase is therefore an indirect consequence of these controls.…”

Section: Introductionmentioning

confidence: 99%

“…In section II, the battery model used for this study is presented. It is similar to the one used in [5] and include an electrical model, a thermal model, a Li-ion cell-ageing model and a SRB reconfiguration model. Section III formulates the optimization problem and describes the nMPC approach.…”

Section: Introductionmentioning

confidence: 99%

Nonlinear Model Predictive Control for Lifetime Extension of Self-Reconfigurable Batteries

Blatter

Heiries

Thomas

et al. 2022

2022 Smart Systems Integration (SSI)

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Self-reconfigurable batteries (SRB) are advance battery systems where semiconductor switches allow cells to be connected or bypassed dynamically. The in-line configuration even allows the direct generation of AC current without any power converter while allowing a flexible cell usage. This paper introduces a new method of SRB control with nonlinear Model Predictive Control (nMPC) with the aim to reduce battery ageing. A full battery cell model is used to perform the minimization of the SRB capacity losses. Simulation results on WLTP profile validate the proposed method with a capacity loss reduction of 12.4%.

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Nonlinear Model Predictive Control for a Simulated Reconfigurable Battery Pack

Cited by 5 publications

References 19 publications

Optimal lifetime management strategy for Self-Reconfigurable Batteries

Optimal lifetime management strategy for Self-Reconfigurable Batteries

Validation of a Single-Cell Reference Model for the Control of a Reconfigurable Battery System

Nonlinear Model Predictive Control for Lifetime Extension of Self-Reconfigurable Batteries

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