As energy shortages, oil prices, worsening pollution in the urban environment, alternatives to oil development and utilization of new energy is increasingly valued by governments. In the new energy system, the battery system is an integral important part. In recent years, lithium battery-powered electric Electric Bikes, hybrid vehicles, electric vehicles, fuel cell vehicles are being subjected to the market more and more attention. Battery applications in the transport sector, the reduction of greenhouse gas emissions, reduce air pollution and application of new energy has an important significance. In which lithium batteries with high energy density, high-repetition-cycle times, light weight, and green and other advantages more and more people concerned, so mobile phones, laptops, power tools and other portable handheld devices have been widely used, and has begun to enter the electric car, electric cars and other high-power applications, the development of electric vehicles to become the world's hot spots

However, due to lithium in the heat, over charge / discharge current, vibration and compression abuse conditions that may cause damage to battery life, and even caught fire, explosion and other incidents, security issues become a driving force to promote the commercialization of lithium batteries The main constraints. Safe, low-cost, long-life lithium-ion battery safety standards, safety assessment, the battery manufacturing process control, and security and reliability through the anode and cathode materials, electrolyte and separator optimized to improve battery safety and reliability is achieved to ensure that large-scale lithium ion batteries safe, reliable, practical key. The battery management system as a battery protection and management of core components, not only to ensure safe and reliable use of the battery, but also to give full play to the capacity and extend battery life, battery and vehicle management systems as well as a bridge drivers, battery management system For the performance of electric vehicles play an increasingly critical role.

The main function of the battery management system

Battery management system and battery mini electric scooter close together, the battery's voltage, current, temperature detection time, and also for leakage testing, thermal management, battery balance management, alarm reminders, calculate the remaining capacity, discharge power, the report SOC & SOH state, but also according to the battery voltage and current and temperature control with a maximum output power algorithm to maximize mileage, and using the best algorithm to control the charging current of the charging machine, through the vehicle CAN bus interface and the total controller, motor controller, energy control systems, automotive display systems for real-time communication. Figure 1 shows a simple block diagram of the battery management system.

Battery management system of basic functions: 1) monitoring the working conditions of monomer batteries, such as single cell voltage, current, temperature and so on. 2) to protect the battery to avoid battery in place under extreme conditions, battery life, damage, or even an explosion, fire and other hazards to human safety incidents.

In general, the battery management system must have the following circuit protection: overvoltage and undervoltage protection, overcurrent and short circuit protection, high temperature and over-temperature protection, protection for the battery to provide multiple protection and management systems to improve reliability (hardware implementation of protection with high reliability, the software implementation of the protection of greater flexibility, management systems to protect key components of failure to provide the third layer of protection for the user). These functions satisfy most mobile phone batteries, power tools and electric bicycle applications.

Electric vehicle battery management system for the challenges of higher

Electric vehicle battery integrated power system is an open system, which through the automotive CAN bus communication, and vehicle management systems, battery chargers, motor controllers to work together to meet the safety car driving people-oriented concept. Therefore, automotive battery management system must do: meet the requirements of TS16949 and automotive electronics, high-speed data acquisition and high reliability automotive CAN bus communication, high resistance to electromagnetic interference (the highest level of EMI / EMC requirements), online diagnostics.

Its main functions are: battery voltage and temperature information of high-speed acquisition; to achieve high efficiency battery balancing, battery fully integrated system to improve the capacity of the battery life of integrated systems, while reducing heat generation; health status and remaining battery power estimates and display; highly reliable communication protocol (automotive CAN communication network); battery powertrain technology to ensure safe use of any premise, give full play to the potential of the battery, ensure that the battery performance, improved battery life; battery temperature and thermal management, battery system is working in a relatively stable temperature environment conditions; ground leakage detection and complex designs.

Because the distribution of electric vehicle batteries the environment is very complex, high-voltage high-power work in the state, on the EMI / EMC requirements are very high, which is designed for the battery management system brings greater challenges.
Electric vehicle battery system of hierarchical, modular design

As the electric vehicle battery system is composed of hundreds of batteries integrated unit, taking into account the car's space, weight distribution and safety requirements, these batteries are divided into standard units of the battery module, located in the chassis a different location from the powertrain and unified management of the central processing unit; each standard battery module also has multiple batteries in parallel and in series, by the module's electronic control unit to manage the battery module through the CAN bus to the central processing of information reporting and powertrain control modules, the central processing unit and power assembly after the information is processed, the final integrated system for information such as remaining capacity, the ability of health status and battery-related information reported to the vehicle through the CAN bus management the system. Electric vehicle battery system of hierarchical, modular design requires that the level of battery management system design, modular (Figure 2).

Battery management system chip integration technology

Car battery system reliability is extremely demanding, especially the high-pressure monitor parts, battery equalization part, due to less integrated solution, with many programs made using discrete components, resulting in: poor matching components, precision signal acquisition decreased; external node number, it is difficult to do automated testing, improve test costs, reduce test coverage, system reliability is low; difficult to control the power consumption of external components; system size, high cost.

Bump Technology (O2Micro) to provide the world's first support for the> 5 cells in series single-chip protection and detection program OZ89xx, the program also supports the application of multi-chip cascade. The chip currently used battery management system program has been successfully used in battery electric vehicles and hybrid electronic control unit module.

Thus, the integrated chip solutions to improve system reliability, reduce costs with a very important role, he is the battery technology integration in the core hardware design.

Conclusion

The future, power lithium batteries in electric vehicles and has broad prospects, and battery management system for the safe use of batteries, and vehicle management and communication plays a key role as a bridge. Battery management technologies, including hardware design and software design techniques, and one high-voltage mixed-signal process technology and chip design is the core hardware design, not only in the automotive environment is to ensure high reliability, high-speed, high-precision signal acquisition and processing of the key, but also improve test coverage, online testing and reducing costs to support the key; the core of the software include battery management algorithms, communication protocols, and powertrain-related technologies. Bump Technology (O2Micro) is the world's leading battery management solutions providers, with their years of battery protection and management of chip design and program design experience, to master the international advanced level battery management technology for the global battery manufacturers The system provides high-quality technology vendor services for the development of electric vehicles in China contributed to their strength.