Lithium batteries have played an important role in electric vehicles, wind and solar energy storage, golf cart and mining locomotives. Lithium batteries have significant advantages such as pollution-free, lightweight, high energy density, no memory effect, high safety, low self-discharge rate, and long life cycle. Battery safety and reliability usually refer to product durability, maintainability, and design reliability. Due to the diversity of use environments, electric vehicle batteries have higher requirements for battery safety performance.
Factors that determine the safety of lithium batteries include battery raw materials and manufacturing processes, fault prediction and health management, battery management systems, etc. The battery management system(BMS) is the core of electric vehicles. BMS responsible for monitoring battery performance and adjusting the entire battery system to match the usage conditions and environment. BMS functions mainly include data collection, state estimation, thermal management, balance management, data communication, and fault diagnosis. BMS has practical significance for maintaining the long life, high efficiency, and reliable operation of power lithium-ion battery packs.
Balance Management System
The balance management system is one of the core components of a BMS. The performance and parameters of each battery may be more or less different when it leaves the factory, and the differences in voltage, SOC, and internal resistance will gradually increase with use. Inconsistency will cause the battery to be overcharged or over discharged, which will reduce battery life and safety. Therefore, it is necessary to achieve balanced management of batteries through balancing circuits, balancing variables, and corresponding balancing strategies, thereby improving battery consistency and safety.
Thermal Management Control
Temperature is an important factor affecting the performance and life of power lithium-ion batteries. The battery temperature will be too high and too low during use. The thermal management system in BMS can reduce battery temperature through air cooling, liquid cooling, and phase change material (PCM) cooling. When the ambient temperature is too low, internal and external heating will help to heat up battery in a short time. So battery can restart work.
