New energy vehicle is a kind of vehicle with advanced technical principle, new technology and new structure, which uses unconventional vehicle fuel as power source and integrates advanced technology of vehicle power control and drive. Battery management system is a set of control system to protect the use safety of power battery. It monitors the use status of the battery at all times, alleviates the inconsistency of the battery pack through necessary measures, and provides guarantee for the use safety of new energy vehicles.
As a domestic high-quality power system supplier, Hengrun technology has strong strength and rich experience in control system development, and can provide high-quality engineering and supporting services for customers in battery management system development.
Hardware topology of BMS
The topology of BMS hardware is divided into two types: centralized and distributed.
Centralized is to concentrate all the functions of the battery management system in one controller, which is suitable for small battery pack capacity and fixed module and battery pack type, and can significantly reduce the system cost.
Distributed is to separate the main control board and slave control board of BMS, even the low-voltage and high-voltage parts, so as to increase the flexibility of system configuration and adapt to modules and battery packs of different capacities and specifications.
Hengrun technology can provide the above centralized or distributed BMS hardware solutions.
State estimation and balance control of BMS
In view of the inconsistency in the process of battery manufacturing and use, as well as the change of battery capacity and internal resistance with the battery life cycle, Hengrun technology team creatively applied multi state joint estimation, extended Kalman filter algorithm, internal resistance / capacity online identification and other methods to achieve high-precision state estimation of battery life cycle. According to the calculation, for ternary lithium battery, the SOC estimation deviation of single battery at room temperature is up to 2%, and the average estimation deviation is 1%.
At the same time, aiming at the inconsistency between battery cells, the balance strategy based on the consistency of residual charge is used to maximize the maximum energy efficiency.
Fast identification of short circuit in battery
Short circuit in battery is the most complex and difficult cause of thermal runaway, which is an international problem in the field of battery safety and can lead to disastrous consequences. The short circuit inside the battery can not be eliminated fundamentally. At present, it is generally through a long time (more than 2 weeks) of shelving observation in order to find the problem early.
In the aspect of internal short circuit identification of battery, Hengrun technology has more than 10 world leading patents and patent licenses. By using the symmetrical ring circuit topology (SLCT) and related algorithms, the batch internal short circuit detection of multiple battery cells can be carried out in a very short time (within 5 minutes), and the internal short circuit in the order of 0 ~ 100k & omega; can be identified and the internal short circuit resistance can be accurately estimated. This method can significantly reduce the operating costs of cell manufacturers or module assembly manufacturers, and improve the safety of battery production and use process.