Lithium-ion battery pack capacity directly determines the driving range and dynamic ability of electric vehicles (EVs). However, inconsistency issues occur and decrease the pack capacity due to internal and ext. ••Battery pack equalization strategy based on UCCVC hypothesis is. The energy revolution has ravaged the world to solve the escalating energy consumption and environmental pollution. With excellent merits of high power density, high energy dens. 2.1. Battery pack capacityCell capacity is commonly defined as the total available electricity that cell discharges from the upper cutoff voltage to the lower cutoff voltage un. 3.1. Equalization strategyBased on the UCCVC hypothesis, the cells in a series-connected module fulfill their requirements. As shown in Fig. 3, all cells (cells 1–4) theore. 4.1. Single cell modelAmong battery models, such as equivalent circuit model (ECM), pseudo two-dimensional model (P2D), and single particle model [3.
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The purpose of battery capacity-based equalization is to control the maximum usable capacity of the battery group to converge, and the battery capacity can intuitively reflect the inconsistency of the battery group.
According to the equalization control scheme proposed in this study, the equalization system starts to work and equalizes battery packs in series. Bat4 has the smallest initial voltage and its voltage rise rate is relatively fast during the charging process, while the charging speed of other batteries is relatively slow.
Finally, the results of simulation and experiment both show that the equalization strategy not only maximizes pack capacity, but also adapts to different consistency scenarios. Pack capacity and consistency in the fresh or aged state are significantly improved after battery equalization.
What is a battery equalization strategy?
The equalization strategy is embedded in a real BMS for practical application analysis. Lithium-ion battery pack capacity directly determines the driving range and dynamic ability of electric vehicles (EVs). However, inconsistency issues occur and decrease the pack capacity due to internal and external reasons.
Equalization is defined as the least square sum of the battery pack's SOC and its average SOC being less than 0.01, and the equalization time is defined as the time from start to end of equalization. The specific simulation parameters are shown in Table 3 and Table 4. Figure 3. External current for the battery pack. Table 3.
A layered battery equalization method is proposed, which reduces the calculation difficulty of the equalization current by layered equalization of the batteries in the group and calculates the equalization current in real-time according to the state of the batteries in the group.