Lithium battery equalization system can solve the problem of inconsistent voltage of single cells in the battery pack

The lithium battery equalization system can solve the problem of inconsistent voltage of the single cells in the battery pack. Under normal circumstances, due to technical and production reasons, there will be certain differences in the lithium battery cells, making the utilization, service life, safety and other aspects of the lithium battery pack after the PACK far inferior to the single battery. In order to solve this industry problem, the use of a battery management system with efficient and balanced management functions can greatly improve the overall performance of the power lithium battery pack and extend the service life of the lithium battery pack. Reduce the use and maintenance costs of the entire vehicle. Provide strong technical support for the promotion of electric vehicles. The consistency problem of lithium battery pack refers to the difference in capacity, internal resistance, SOC (voltage), etc. between single cells in series in the battery pack, which directly determines the performance of the entire battery pack, thereby affecting the electric The power and cruising range of the car. The reason for the inconsistency of lithium batteries in groups is mainly due to the initial differences of single cells and the differences caused by the structure, operating conditions and environment of the batteries after they are grouped. We can optimize the manufacturing process of lithium batteries and reduce the initial differences of batteries to alleviate the problems of performance degradation and life reduction caused by lithium batteries after grouping; for example, screening before batteries are grouped will reduce the inconsistency. Lithium battery cell combination package; fully consider the influence of connection method and structure on inconsistency in the battery structure; and carry out reasonable battery management, effective balance and thermal management during use, and reduce the cost caused by different use conditions or environmental factors. The body cells are inconsistent. The electronics explain the reasons for the inconsistency of lithium battery packs ①In the manufacturing process of single lithium battery, the unbalanced process and material selection caused the nuances and the inconsistent lithium battery parameters. ②When the genuine lithium battery is installed in the car, due to the difference in electrolyte density, temperature and ventilation conditions, self-discharge degree, and charge-discharge process of each single cell in the lithium battery pack, it will appear in each charge and discharge. The imbalance caused by the accumulation of small differences. What are the balancing technologies for lithium batteries? 1. Passive balancing method: Passive balancing method is to discharge a single battery with high voltage through a circuit through a load resistor, and judge whether its voltage is the same as the voltage of other single batteries through a comparison circuit, and if it is the same, Stop discharging, the disadvantage of the passive equalization method is that it consumes the energy of the single battery, generates heat, and takes a long time to equalize. 2. Active equalization method: Active equalization method means that the energy of the higher voltage battery is not consumed through the resistor during charging and discharging, but the energy is transferred to the lower voltage battery, so as to realize the balanced charging and discharging of the lithium battery pack ; The active equalization circuit is complicated and cannot equalize all the batteries at the same time. The reliability needs to be improved. 3. Internal equalization method: The internal equalization method uses BMS to adjust the charging current and control the topological algorithm of the charging voltage in the process of charging the battery in series, so that the charge of each single battery in the battery pack is basically the same. The internal equalization technology is characterized by simple algorithm, no energy loss, no additional charge and discharge process, no impact on battery life, no increase in hardware equipment, but if the battery charge varies greatly, it will take a longer time to balance. From the perspective of the battery management system, detect the parameters of the single cells during the use of the battery pack, especially the voltage distribution under dynamic and static conditions, grasp the inconsistency development law of the single cells in the battery pack, and adjust or replace the battery with extreme parameters in time , To ensure that the inconsistency of battery pack parameters increases with the use of time. At the same time, from the perspective of energy management and strategy, a practical battery pack energy management and balancing system is introduced, and a reasonable battery balancing strategy is formulated to actively intervene and reduce battery inconsistencies. The inconsistency of the battery comes from the internal resistance, capacity and SOC of the battery, and the traditional consistency evaluation method and the voltage consistency other than the equalization method are used as the control target, which does not effectively increase the available capacity of the battery pack, so it cannot improve the consistency of the battery pack. The problem has an adverse effect on the use of battery packs. Since the DC internal resistance, polarization voltage, and maximum usable capacity are specific parameters of the battery, there is basically no change during one or several consecutive charging and discharging processes, so the balance of the battery pack is mainly achieved by adjusting the SOC of each single battery . After research, the SOC is used as the reference object of balance, the balance object is relatively fixed, the balance time is fully utilized, the balance utilization rate is improved to reduce the balance current capacity. 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