Development status of domestic lithium battery management system (BMS)

The development status of domestic lithium battery management system (BMS). Lithium-ion batteries are currently the necessary power source for many portable electrical equipment, and they are also applied to many industries including electric vehicles. However, the use of Li Electronics must be equipped with a battery management system (BMS). This confuses novice engineers. The term'Battery Management System (BMS)' has never been heard in the past as a starter battery for dry batteries or fuel trucks. Why should there be a battery management system (BMS) for cars with lithium batteries? The author has obtained the technical specification data of the domestic battery management system (BMS) products, combined with this product for analysis, for your reference. The development status of domestic lithium battery management system (BMS) Why use battery management system (BMS)? From the hardware point of view, the smallest power unit in the lithium battery system structure is the battery unit. The basic unit is a module. Then the modules are assembled into a battery box, which is connected to the battery system. The basic principle is connected in series according to certain technical requirements. From the structural point of view, the battery is a complete product on the surface, but the internal structure is interconnected, and the process is very complicated. In addition to connecting battery units, modules, battery boxes and other hardware, there are also battery thermostat systems and safety fire protection systems. The exchange of information between these subsystems and the lithium battery must be coordinated. How to coordinate? Naturally, there is a need for management, where management refers to a computer management-level system, so the battery management system (BMS) appears. The basic functions of the battery management system 1) Manage battery types: lithium iron phosphate batteries, lithium manganese oxide, lithium gold oxide, lithium lead acid and other types of batteries and lithium super capacitors; 2) monitor and indicate battery/capacitor status (voltage, temperature, Current, remaining energy), send an alarm signal (sound and light) to the user under abnormal conditions; 3) Cut off the power transmission link according to the control strategy, which can protect the safety of the battery; 4) Use the energy balance to make the remaining energy of the system battery tend to be consistent. Extend the overall discharge time of the system, thereby prolonging the battery life; (Note: it is a basic function; (3) There is a certain accumulation of projects; there are great technical difficulties;) The basic function logic block diagram of the battery management system (BMS) is responsible for the battery Data display, sound and light alarm and record data. The central control module is responsible for the SOC calculation, the appearance of various alarm data, the control of the charging and discharging circuit, and the measurement of the insulation performance of the high-voltage line. The terminal module is responsible for measuring battery voltage and temperature, balancing battery energy, and controlling the battery box fan. 4. Analysis of the installation process From the perspective of the product shell, the lightweight design and aluminum drawing process are adopted to meet the automotive IP requirements. From the interface point of view, it is convenient to connect and insert, easy to install and maintain. Use two M6 hexagon bolts as side leads to fix the module. Enough space should be left at the lead to meet the requirements of the main engine factory's production line. 5. Active and passive integrated balance function This product mainly adopts passive integrated balance function, with a balance current of 50Ma. When charging, the BMS switches to the energy dissipation equilibrium mode, which is to discharge a battery with sufficient capacity. When discharging, the BMS switches to the supplementary equalization mode, that is, charging the low-capacity battery. Extend battery life. The working principle and technology of the system are introduced in detail. The equalization charging curve is shown in Figure 5. Battery management system (BMS) products, domestic and foreign manufacturers all claim to have passive balancing and active balancing functions. According to the introduction of major Japanese companies, the active balancing technology of power lithium batteries has been realized, but it is more complicated and costly, and there are currently no products in use. 6. Introduction of charging control strategy The charging setting has three kinds of control: advanced time control, temperature control and voltage control, and the final charging current is the smallest. The basic strategy is: (1) When charging for the first time, do not suddenly add the charging current to the rated charging current, it is better to have a gradual process. This product causes the charging current to linearly increase to the rated current within the set lead time; (2) When the maximum voltage of the monomer reaches the alarm threshold, the charging current cannot be too large, otherwise the battery voltage will easily cross the serious threshold and be in a dangerous state. Therefore, there is a corresponding relationship between the charging current and the highest single voltage; (3) At low temperatures, charging will seriously affect the performance of the battery, so the charging current is also controlled by temperature. 7. The author’s summary Through the analysis of domestic battery management system (BMS) product technology, we have the following experience: (1) Domestic battery management system (BMS) products have developed rapidly and have been exported to countries with advanced electric vehicle technology. The level can reach IP level; (2) Domestic battery management system (BMS) products are more suitable for the use environment of Chinese electric vehicles in terms of control strategy; (3) The products have done a lot of fruitful work in light weight and integration, and they have been more and more effective. More and more users have affirmed; (4) The important chip in the product is still foreign; (5) The product supplier service responds quickly, the product price has a comparative advantage, and the quality is getting better and better. Disclaimer: The articles published on this site are all from the Internet and do not represent the views of this site. 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