With the popularization of new energy concepts, new energy vehicles have gradually entered thousands of households. As a new car choice for ordinary people, new energy vehicles have begun to invade the market that originally belonged to traditional fuel vehicles, as the largest new energy vehicle. In the market, Chinese enterprises rely on new energy vehicles to stand on the same starting line with foreign companies for the first time, and new technologies and processes that are constantly emerging have enabled China's new energy auto industry to have more sufficient enthusiasm to look to the world and focus on the future.
The core of the traditional fuel vehicle is naturally inseparable from the so-called "three big pieces": the engine, the chassis and the gearbox. In this "three big pieces", the Chinese automobile manufacturers behind the German technology are behind the German and Japanese companies. consensus. In the new energy electric vehicles, there are also commonly known as “three big piecesâ€: batteries, motors and electronic controls. Since new energy electric vehicles are still relatively new in the world, the start-ups of enterprises in various countries are not much different. Let Chinese enterprises have the same conditions as foreign companies in the multi-purpose power driving tools that the automobile was invented in 1886. This article focuses on the electronic control in the "three major pieces" of new energy electric vehicles (commonly known as battery management system BMS).
The biggest difference between new energy electric vehicles and traditional fuel vehicles is that they use power batteries as the power drive. As an important link between battery packs, vehicle systems and motors, the importance of battery management system BMS is self-evident. Many new ones at home and abroad. Energy car companies regard the battery management system as the core technology of the enterprise. The most famous example is Tesla, which is well known to all. Tesla's electric vehicle "three big pieces", the battery comes from Panasonic, the motor comes from Taiwanese suppliers, and only the battery management system is the core technology independently developed by Tesla. The core intellectual property rights applied by Tesla during 2008-2015 are mostly related to the battery management system. This shows that the battery management system is new energy. The importance of the car. Domestically, the R&D and production of battery management system BMS is mainly concentrated in these three types of enterprises:
1. New energy vehicle manufacturer, representative enterprise: BYD
2, battery PACK manufacturers, on behalf of the company: Waterma, Pride
3, professional BMS manufacturers, on behalf of enterprises: Huizhou billion, Shenzhen Guoxin Power
What is the role of the battery management system BMS?
The battery management system BMS is a new product born in this century. Because the electrochemical reaction is difficult to control and the performance change of the material in this process is elusive, it is necessary for such a housekeeper to supervise and adjust the behavior of limiting the battery pack. Safe to use, its main functions are:
1. Accurately estimate the state of charge of the power battery pack
Accurately estimate the state of charge (SOC) of the power battery pack, that is, the remaining battery power, to ensure that the SOC is maintained within a reasonable range, to prevent damage to the battery due to overcharge or overdischarge, thereby predicting the hybrid power at any time. How much energy is left in the car's energy storage battery or the state of charge of the energy storage battery.
2. Dynamically monitor the working status of the power battery pack
During the charging and discharging process of the battery, the terminal voltage and temperature, the charging and discharging current and the total voltage of the battery pack of each battery in the power battery pack are collected in real time to prevent overcharging or overdischarging of the battery. At the same time, the battery condition can be given in time, and the problematic battery can be selected to maintain the reliability and high efficiency of the entire battery operation, and the realization of the remaining battery estimation model becomes possible. In addition, it is necessary to establish a usage history file for each battery to provide data for further optimization and development of new types of electricity, chargers, motors, etc., and to provide a basis for offline analysis system failure.
3, the balance between the cells
That is, the single battery is uniformly charged, so that each battery in the battery pack reaches a state of equalization and consistency. Equilibrium technology is the key technology of a battery energy management system that the world is currently researching and developing.
What characteristics should the current state-of-the-art BMS have on the market?
Advanced technology, stable and reliable products will be the core characteristics of future BMS products. What kind of products are advanced, stable and reliable products? Because the BMS standards of major domestic enterprises are still not unified, the performance characteristics of BMS of Shenzhen Guoxin Power are taken as examples, which are illustrated by four dimensions: technology, function, quality and standard specifications.
Advanced technology:
1. The enterprise masters the battery SOC core algorithm;
2. Master health status estimation, maximum allowable instantaneous (5s/30s) and continuous charge and discharge power estimation;
3. Master efficient Equilibrium Management Technology, advanced heat dissipation mechanism, and support up to 200mA passive equalization current;
4. Master the industry's leading high-precision measurement technology, the total flow total pressure accuracy can reach 0.5% FSR;
5. Optional multi-function data logger to support cloud platform functions such as wireless transmission, large-capacity storage, and GPS;
6. Optional active equalization module, the maximum equalization current can reach 5A, and the 24-string of the single board can be flexibly matched;
Safe features:
1. Battery safety management: with reliable overcharge/overdischarge protection, overcurrent/overtemperature/low temperature protection, multi-level fault diagnosis and protection;
2. High-voltage safety management: high-voltage relay adhesion detection, high anti-interference high-voltage interlock detection, advanced high-voltage insulation monitoring;
3. With voltage and temperature acquisition line disconnection diagnostic function;
4. The battery voltage acquisition module has safety mechanisms such as loop overcurrent and short circuit protection, and the circuit is more reliable;
5. With 5~36 string, 5~48 string machine flexible configuration, suitable for all kinds of mainstream solutions in the industry;
Stable quality:
1. All components are selected by automotive grade components, with a high standard operating temperature range of -40 ° C ~ 85 ° C;
2. Wider and more reliable temperature monitoring, monitoring range up to -40~125 °C;
Meet the standard specifications:
1. Support charging national standard GBT 20234-2015 and GBT 27930-2015;
2. Support the requirements of product functional safety lifecycle management in ISO26262 international safety standards;
3. Support CCP calibration protocol, UDS, OBD-ii diagnostic protocol.
The dilemma of domestic battery management system BMS
The development of new energy vehicles is not smooth sailing. In the past two years, with the large-scale promotion and use of new energy vehicles, we have also heard a lot of "scandals" about new energy vehicles: spontaneous combustion, false mileage, etc., and why What are the usage problems? Not using a battery management system or using a poor quality immature battery management system is the main cause. In fact, the safety of new energy vehicles has always been one of the key tasks of the government and the automotive industry. Not long ago, the four ministries and commissions including the Ministry of Science and Technology, the Ministry of Finance, the Ministry of Industry and Information Technology and the National Development and Reform Commission have jointly issued a “safety order†for the demonstration and promotion of new energy vehicles (the “Letter on Strengthening the Safety Management of Energy Saving and New Energy Vehicles Demonstration and Promotionâ€), emphasizing "For plug-in hybrid vehicles and pure electric vehicles that are put into demonstration operation, all vehicles must be equipped with a real-time monitoring system for vehicle operation technology (BMS), especially to monitor the working status of power batteries and fuel cells."
There are many reasons for self-ignition of electric vehicles. You can sit back and relax without installing a battery management system. For example, in terms of safety, accuracy, life, and discharge capacity, the single battery can be charged and discharged 2000 times, and may only be 1000 times after being assembled into a battery pack. If the immature BMS is installed, it is impossible to accurately monitor the battery charge and discharge status in real time, which may cause the local power consumption of the battery core to be too large, generate local heat, and the information cannot be transmitted to the driver, which may easily cause spontaneous combustion of the battery. The industry believes that the installation of excellent battery management BMS can effectively improve the utilization of the battery, prevent overcharging and overdischarging of the battery, and extend the battery life, monitor the operating state of the battery pack and each battery core, effectively prevent the battery The group is self-igniting, and in the event of an emergency, the driver is alerted to the accident in advance to win time for security.
The future of new energy vehicles and battery management systems
China's new energy automobile industry began in the early 21st century and has only developed for more than a decade. Due to people's thirst for environmental protection and renewable energy, new energy vehicles have ushered in development opportunities, and then they are out of control. In the future, new energy vehicles will be used as a challenger to encroach on the vast market that originally belonged to traditional fuel vehicles, and due to the needs of social development, this market share encroachment can be expected.
While looking forward to the rapid development of new energy vehicles, we must clearly understand that the development of technology is the basis for the development of the industry, and stable, efficient, safe and reliable products are the embodiment of technology. We must know that the current domestic The new energy auto industry is not friendly. The frequent spontaneous combustion events and false cruising range of electric vehicles have exposed the imperfections in the design, testing and production standards of new energy battery packs and battery management systems in China.
At present, there are hundreds of BMS companies in China, but there are only a few developed countries in Europe and America. Large-scale new energy vehicle manufacturers either choose their own battery management system or use BMS production companies headed by Germany-Japan, which is internationally competitive. In fact, China There is no shortage of excellent BMS production enterprises in China. As mentioned in the article, Shenzhen Guoxin Power is a core competitiveness enterprise focusing on product quality. Its BMS system has been mass-produced and imported in Shaanxi Tongjia and Zhongtai. Some of the new energy models of the car can also be applied to low-speed vehicles with pure electric or hybrid power, passenger cars, logistics vehicles, venue cars, buses, tourist buses, energy storage systems, etc. according to actual needs, which are stable and efficient. The safe and reliable BMS platform products are highly regarded by customers.
The lack of technical parameters and standards, and no authoritative organization to conduct authoritative testing of BMS produced by manufacturers, this is the current dilemma of the domestic BMS market, resulting in the unevenness of BMS products, it is difficult to promote large areas. At the same time, many domestic automakers and battery PAC companies have insufficient understanding of the importance of BMS, thinking that as long as each single cell core can be linked, it can guarantee the operation of the vehicle, and it is lucky to be safe in BMS procurement. In pursuit of low prices, in order to sign contracts, some bad BMS suppliers only reduce the BMS function indicators or simply cast some functions, thus laying aside safety hazards, which is also irresponsible and harmful to the entire industry. Only by establishing a unified industry standard as soon as possible, suppressing producers that do not meet market requirements, and establishing a sound testing system, battery management systems and new energy vehicles can have a sustainable future. This is also the demand of many manufacturers and consumers.
Basic functions of the battery management system1) Monitor the working condition of the single cell, such as cell voltage, operating current, ambient temperature, etc.
2) Protect the battery to avoid battery life under extreme conditions, such as shortened battery life, damage, and even accidents such as explosions and fires that endanger personal safety.
In general, battery management systems must have the following circuit protection features: overvoltage and undervoltage protection, overcurrent and short circuit protection, over- and over-temperature protection, multiple protections for the battery to improve protection and manage system reliability (hardware The protection performed is highly reliable, the protection of software execution is more flexible, and the protection of critical components of the management system provides the user with a third protection). These features meet the needs of most mobile phone batteries, power tools and electric bicycle applications.
3 Electric vehicles pose a higher challenge to battery management systems
The electric vehicle battery integrated system is an open power system that communicates through the automotive-grade CAN bus and works in conjunction with the vehicle management system, charger, and motor controller to meet the car-oriented safe driving concept. Therefore, the automotive battery management system must: meet the requirements of TS16949 and automotive electronics, achieve high-speed data acquisition and high reliability, automotive-grade CAN bus communication, high immunity to electromagnetic interference (the highest level of EMI / EMC requirements), online Diagnostic function.
Its main functions are:
High-speed acquisition of battery voltage and temperature information; achieve high efficiency and balanced battery, fully utilize the capacity of the battery integrated system to improve the life of the battery integrated system, and reduce heat generation;
Estimation and display of battery health and remaining battery capacity;
Highly reliable communication protocol (automotive CAN communication network);
The powertrain technology should ensure the potential of the battery, ensure the performance of the battery, and improve the life of the battery under the premise of ensuring any safe use of the battery;
The temperature and heat management of the battery is the environmental condition in which the battery system operates at a relatively stable temperature;
Leakage detection and complex ground design.
Since the distribution environment of the battery in the electric vehicle is very complicated, the working condition of high voltage and high power has very high requirements for EMI/EMC, which brings greater challenges to the design of the battery management system.
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