Fuzzy-controlled individual-cell equaliser using discontinuous inductor current-mode Cuk convertor for lithium–ion chemistries

Abstract

An intelligent battery equalisation-scheme based on fuzzy-logic control (FLC) is presented to adaptively control the equalising process for series-connected lithium-ion batteries. The proposed individual-cell equalisation scheme (ICE) is a bidirectional DC-DC convertor based on the C# uk convertor operated in the discontinuous inductor current mode (DICM). The proposed method can be used to achieve a zero-current-switching (ZCS) cell-balancing control scheme to reduce the switching losses in MOSFET switches. Further, a fuzzy-logic-controlled strategy is constructed with a set of membership functions to prescribe the cell equalising behaviour within a safe equalising region for reduced cell-equalisation time. The simulation and experimental results show the advantage of the predicted equalising performance for lithium-ion battery stacks. The proposed fuzzy-logic-control battery-equalisation controller (FLC-BEC) abridges the equalisation time by about 30% compared with the equaliser without FLC. The power losses of the MOSFET switch are significantly reduced by about 33.8%, and the equalisation efficiency is increased by about 8.5% compared with the same equalisation scheme in continuous-inductor-current mode (CICM). The proposed equalisation method maintains safe operations during the charge/discharge state to increase the charge capacity of lithium-ion battery-pack cells.

Research on Retired Battery Equalization System Based on Multi-Objective Adaptive Fuzzy Control Algorithm

“…FLC is applied not only to the equalization threshold solution but also to the equalization current and other parameters in the equalization strategy, and good results are achieved. Some scholars [27] used the voltage difference between two cells and the cell voltage as the two inputs of FLC. The inference results are converted into numerical output equalization currents to reduce equalization time and improve equalization efficiency and battery pack capacity.…”