A Modulated Frequency Control Reducing Balancing Time in Switched Capacitors based Equalizers for Lithium-Ion Series Battery Modules

Abstract—Effective cell-balancing circuits are essential to equalize voltages across battery cells, for reducing safety risk, increase efficiency and prolonging battery lifespan. Active battery cell balancing systems based on switched capacitor circuit topology (SCCT) are very promising because they have easier implementation but present slow balancing time. This paper presents a modulated frequency (FM) control that varies the switching frequency value of the SCCT according to a two stages strategy. A Simulink simulation scheme of an 8 series NMC cells battery module has been implemented to prove the effectiveness of the proposed FM control. The results obtained show a reduction in balancing times, even if this results in a small increase in power losses compared to those of conventional SCCT, but still significantly lower than passive balancing.