Why are power management chips the key to electric vehicles?
Latest update time：2021-09-04 18:16
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Source: Content from "China Electronics News", author: Zhang Yiyi, thank you.
In recent years, new energy vehicles such as Tesla and BYD have entered thousands of households. New energy vehicles "running all over the streets" have become a scene of urban traffic, and the construction of "new infrastructure" has installed a "booster" for new energy vehicles. As one of the most critical components, power batteries have become the focus of attention in the industry, and battery safety has become a top priority. Recently, new energy vehicle spontaneous combustion accidents have occurred in Qingyuan, Guangdong, Qingdao, Shandong, and Huizhou, Guangdong. The news of power battery fires has been frequent, casting a shadow on the safety of batteries.
As the core component of the power battery pack, the battery management system (BMS) is the link between the battery pack, the vehicle system and the motor. It can effectively manage and control the battery to ensure the safety of the power battery. Therefore, countries around the world have invested a lot of manpower and material resources to carry out in-depth research on this.
BMS market is divided into three parts
The popularity of new energy vehicles has led to the continuous expansion of the global BMS market. Yu Xuesong, deputy director of the Electronic Information Research Institute of CCID Think Tank, told the reporter of China Electronics News that the global BMS output value was about US$6 billion in 2019 and is expected to exceed US$12 billion in 2025. In 2019, my country's new energy vehicle production reached 1.242 million units, accounting for about 57% of the world's total, and the BMS market size was about 24 billion yuan.
Liang Rui, vice president of Xinwanda Electronics Co., Ltd., told reporters that there are three types of companies participating in the layout of BMS at this stage, namely vehicle manufacturers, power battery companies and professional third-party BMS companies, and the market presents a "three-way split" situation. Long-term R&D accumulation and strong financial strength have enabled vehicle manufacturers to have strong competitiveness in the BMS industry. Yu Xuesong said that currently domestic and foreign automobile manufacturers, such as Tesla, GM and BYD, all have teams responsible for the R&D of BMS. Dr. Lin Jian, an industry insider, said that almost all domestic vehicle manufacturers are engaged in BMS, and car companies without the ability have also put it on the agenda.
Power battery companies have mastered the entire set of technologies from battery cells to battery packs, and are familiar with the development and production of battery cells. It is reported that the well-known power battery companies currently include Panasonic, Samsung, LG, CATL, BYD and Xinwanda. Liang Rui pointed out that the interconnection between batteries and vehicles is an important prerequisite, and power battery companies still need to deepen their understanding of the needs of car companies.
Professional third-party BMS companies play an important role in the supply chain of vehicle manufacturers. Liang Rui told reporters that the third-party BMS companies currently at the forefront of the competition include Bosch, Hella, Preh and Yineng Electronics. Liang Rui pointed out that third-party BMS companies have certain disadvantages in grasping the needs of car companies and cooperating with each other, and therefore their living space is limited. Yu Xuesong also said that third-party BMS companies are currently facing a "double squeeze" from vehicle manufacturers and power battery companies. "In recent years, the BMS market is showing the following development characteristics: gradually concentrating on leading companies, and the market share of small and medium-sized enterprises continues to shrink; under the double squeeze of vehicle manufacturers and power battery companies, the living space of third-party companies continues to shrink." Yu Xuesong told reporters.
Power batteries still need to overcome three major obstacles to achieve a leap forward
BMS is the "protective umbrella" of power battery safety, and its cost accounts for about 10% of the cost of power battery modules. Yu Xuesong told reporters that BMS can estimate the battery's state of charge, detect the battery's usage status, control the battery's cycle life, and adjust the battery system's heating, cooling and temperature balance during the charging and discharging process.
Different BMS modules play different functions. Lin Jian pointed out that the BMS system usually includes a detection module and an operation control module. Detection refers to measuring the voltage, current and temperature of the battery cell and the voltage of the battery pack, and then transmitting these signals to the operation module for processing and issuing instructions. The control module generally includes hardware, underlying basic software and application layer software. The core part is the application layer software. The application layer software is generally divided into two parts: battery status estimation algorithm and fault diagnosis and protection.
Since the synergy of different modules of BMS can ensure the safety of power batteries, why do new energy vehicle battery fires still occur frequently? In this regard, Lin Jian said that battery manufacturing is the main reason, but BMS also has an unshirkable responsibility in many cases, such as only considering the average condition of the battery without considering the special conditions of each battery, or only considering the state of the battery at a constant temperature and ignoring the impact of temperature changes.
Therefore, it is urgent to promote the upgrading of the BMS industry and enhance the safety of power batteries. During the interview, the reporter learned that power batteries still need to overcome three major obstacles to achieve a leap. Lin Jian pointed out that first of all, there is a gap between my country and foreign countries in the core algorithm of BMS. In terms of control strategy, more than 90% of domestic manufacturers still use the ampere-hour integration method plus open-circuit voltage to calculate the charging state. However, the ampere-hour integration method has no error correction capability. When the battery is aged or the battery temperature changes greatly, the accuracy of the current will be very poor, and it is impossible to take into account the special circumstances of each battery. "In order to improve accuracy, the control algorithm generally uses open-circuit voltage correction, but it can only be corrected at the beginning or the last stage of charging. Therefore, the small current correction error is large and there are few correction opportunities." Lin Jian said.
In contrast, Lin Jian said that some foreign companies have already used intelligent algorithms to estimate all equivalent parameters of the battery through real-time online estimation, thereby accurately estimating the status of the battery pack. Therefore, whether it is a new battery or an aged battery, it can maintain high-precision and super error correction capabilities. In recent years, some domestic manufacturers have also tried to use similar methods, but they can only estimate some parameters or temporarily use similar algorithms for a short period of time. In general, my country's BMS still needs to be further improved in core algorithms. Only high-precision and highly robust algorithms can achieve true intelligence and help my country's BMS achieve a leap forward.
Secondly, Lin Jian pointed out that the reliance on imports for key chips is also one of the shortcomings that restricts the development of my country's BMS industry. In this regard, Yu Xuesong told reporters that the supply of key BMS chips in my country currently mainly relies on foreign companies such as Renesas, Infineon, TI, and Broadcom, and no domestic company can supply them on a large scale.
Finally, the BMS overheating management technology still needs to be improved. Yu Xuesong said: "Currently, most power battery modules use air cooling technology, and the BMS is responsible for monitoring the heating of the single battery. If signs are found, certain measures can be taken to prevent it. However, once a single battery overheats, there will be a lack of accurate means to deal with the overheated battery. Fire accidents in new energy vehicles are often caused by the inability to effectively deal with the thermal runaway of the single battery."
BMS ushers in a new era of intelligent development
The proportion of new energy vehicles in my country's automobile production and sales is increasing, and the production and sales volume is increasing year by year. Data shows that in 2019, my country's new energy vehicle production and sales volume were 1.242 million and 1.206 million respectively, both showing an upward trend.
The rapid development of the new energy vehicle industry and the high sales volume of new energy vehicles have brought bright prospects for the development of the BMS industry. At the same time, they have also put forward higher requirements on the safety of power batteries and the optimization and upgrading of the BMS industry. The intelligence of BMS is undoubtedly the inevitable result of adapting to this development trend.
Deng Linwang, the BMS factory manager of Fudi Battery (formerly BYD Lithium Battery), said that BMS can collect battery data and upload it to the cloud. Through the mining and research of battery data, with the help of tools such as big data and machine learning, it can do many meaningful things such as fault warning, model training, parameter update, residual value evaluation, etc., to enhance the value of the new energy vehicle industry chain. At the same time, the advancement of information technology will usher in a new era of intelligent development for BMS. With the intelligence of new energy vehicles, BMS will serve as the control and communication hub between batteries, vehicles and clouds, improving the intelligent control of batteries, the intelligent response of the whole vehicle and the intelligent experience of users.
Yu Xuesong also said that the intelligentization of automobiles will strengthen the coordination between BMS and vehicle systems, and algorithms such as charging status and balanced management are expected to be further optimized, and the technical level of BMS in my country will continue to improve. Some companies will gradually enter the core chip field, and the BMS industry chain will continue to improve. At the same time, the country has also introduced a series of measures to promote the application of new energy vehicles and increase support for key technologies of power batteries, which can promote the overall development of the BMS industry. With the intelligentization of BMS, the level of BMS of Chinese companies is expected to enter the ranks of international advanced levels and be recognized by domestic and foreign vehicle companies.
my country's new energy vehicle market has great development potential. Relevant plans propose that by 2025, my country's new energy vehicle sales will exceed 2 million. At the same time, my country's BMS market will continue to grow, and is expected to be close to 40 billion yuan by 2025. Liang Rui told reporters that with people's concern about the safety of power batteries and the increase in demand for BMS, my country's BMS industry will experience technology and product upgrades. In order to establish the advantages of my country's BMS industry, companies need to target the needs of foreign high-end car companies and enter the supply chain of foreign high-end car companies in the process of future development.
*Disclaimer: This article is originally written by the author. The content of the article is the author's personal opinion. Semiconductor Industry Observer reprints it only to convey a different point of view. It does not mean that Semiconductor Industry Observer agrees or supports this point of view. If you have any objections, please contact Semiconductor Industry Observer.
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