Evaluation of Advanced Control for Li-ion Battery Balancing Systems Using Convex Optimization

Smart and Hybrid Balancing System: Design, Modeling, and Experimental Demonstration

“…Cell-to-cell topologies allow the transfer between individual cells; they can be divided into distributed variants [8] (transfer of energy is only allowed between neighbor cells) and shared [9], [10] (energy is first transferred to an energy accumulator and then moved to another cell). In our previous research [11], a benchmarking of several balancing configurations was performed. It was concluded that the cell-to-cell shared (CCS) is one of most promising battery balancing configurations, offering superior energy efficiency and thermal performance.…”

“…In comparison with other optimization frameworks -such as dynamic programming [20], [30], non-linear optimization [15] or gradientfree algorithms [31] -convex methods offer computationally efficient solutions and attractive theoretical properties (e.g., guarantee of an unique optimum [32]). These advantages have encouraged the application of convex optimization in several automotive applications, including powertrain sizing [33], energy management [34] and battery balancing circuits [11]. To the best of the authors' knowledge, it is the first time that convex methods have been applied to the control of hybrid balancing systems.…”

Influence of Cell-to-Cell Variations on the Inhomogeneity of Lithium-Ion Battery Modules

“…An alternative to cell matching during module assembly is to implement a balancing system within the battery management system. Whereas state of charge (SOC) balancing is state of the art and commonly used, also other balancing approaches have been reported, such as balancing the cell temperature [21][22][23] or compensating cell terminal voltage variations due to cell-to-cell impedance differences. 22,23 Effective matching during battery module assembly requires the knowledge of the varying parameters for each single cell.…”

“…Whereas state of charge (SOC) balancing is state of the art and commonly used, also other balancing approaches have been reported, such as balancing the cell temperature [21][22][23] or compensating cell terminal voltage variations due to cell-to-cell impedance differences. 22,23 Effective matching during battery module assembly requires the knowledge of the varying parameters for each single cell. As related measurements are time consuming and are rarely to be realized in practice, the aim of this work is to quantify and compare the impact of manufacturing related parametric cell-to-cell variations on the evolving inhomogeneity within a battery module by simulation.…”

“…[25][26][27] Investigations which model the inhomogeneity in battery modules have mostly used equivalent circuit models (ECMs) for the single connected cells. [6][7][8][9][10]14,15,[21][22][23][24]26,[29][30][31]33 Only a handful of groups have used physicochemical models (PCMs) for the cells 16,19,28,32 which are more demanding in terms of model parameterization and computational time compared to ECMs. However, using PCMs allows for an implementation of temperature dependent transport and kinetics parameters and moreover for a discussion from an electrochemical point of view due to a deeper insight into the electrochemical reactions during module operation.…”