“In recent years, my country’s electric vehicle industry has developed rapidly, the ownership has continued to grow, and the penetration rate has gradually increased. The latest data released by the Ministry of Industry and Information Technology show that China’s electric smart cars have formed a certain first-mover advantage globally, and the production and sales of new energy vehicles have ranked first in the world for six consecutive years. The release of the “carbon peak” and “carbon neutral” dual carbon targets has opened a new round of “golden age” for China’s electric vehicle industry.
In recent years, my country’s electric vehicle industry has developed rapidly, the ownership has continued to grow, and the penetration rate has gradually increased. The latest data released by the Ministry of Industry and Information Technology show that China’s electric smart cars have formed a certain first-mover advantage globally, and the production and sales of new energy vehicles have ranked first in the world for six consecutive years. The release of the “carbon peak” and “carbon neutral” dual carbon targets has opened a new round of “golden age” for China’s electric vehicle industry.
As the core component of electric vehicles, the power battery is also the key to the increasingly fierce cooperation and competition between global automakers and battery manufacturers. Can you master the safety of the power battery supply chain and achieve stronger power battery manufacturing? Cost and performance competitive advantages are very important in the current market competition in the electric vehicle industry where more and more new forces are entering the game.
Consistency is still a key constraint in battery manufacturing, and chemical composition technology leads innovation
In the past few decades, lithium-ion batteries for power and energy storage have made unprecedented progress in large-scale commercialization. Battery manufacturers and supply chain manufacturers have realized that if they want to get a share of this emerging industry, Enlarging the production scale of the battery and improving production efficiency are the keys, and at the same time, the performance and quality of the battery must be put in the first place. “The chemical composition of the battery manufacturing process is a time-consuming process, involving multiple charging and discharging to activate the chemical properties of the battery, which is essential for ensuring the consistency, safety, and high quality of the power battery pack with a long cycle life. Especially critical.” ADI marketing manager Zhu Zhen mentioned in a recent public interview.
ADI marketing manager Zhu Zhen accepted an interview
Formation refers to the electrochemical process in which the positive and negative active materials of the lithium battery are excited by applying a certain current to the battery after the lithium battery is assembled, and finally the battery has the discharge capacity. The factors that affect the formation are formation current, SOC, aging time and temperature, etc. The battery material system and production capacity requirements also need to be considered. Therefore, formation is not only a simple charging and discharging process, but a comprehensive measurement of the impact of different parameters on battery performance, requiring a large number of accurate data tests and research verifications using instruments and equipment.
The capacity classification is to charge and discharge the formed battery. The charge and discharge current of different types of batteries are slightly different, so that the battery capacity, charging constant current ratio, discharge platform voltage, internal resistance, etc. can be counted to distinguish, and the same indicators can be screened out. The monomers can be classified into groups, and only those with similar performance can form a battery pack. On the other hand, the poor consistency of the single battery may also lead to a decrease in the safety of the battery pack. For example, in order to meet the energy requirements of electric vehicles, power battery packs often require dozens to thousands of batteries. Affected by the complexity of the system, the behavior of the battery pack has its own uniqueness, and it is not a simple addition and subtraction of single cells. The method can obtain the performance of the battery pack.
Lithium-ion battery manufacturing process
Therefore, in order to improve the cycle life, stability, self-discharge, safety and other electrochemical properties of the battery, the consistency of the battery must be strictly controlled and the battery grade must be accurately evaluated. The current and voltage measurement accuracy of the chemical composition and capacitance detection equipment is very high. The requirements for battery manufacturers and test equipment providers will also help battery manufacturers and test equipment providers to expand battery production scale and improve efficiency, and seize the key opportunity for the outbreak of production and sales in the electric vehicle market.
How to balance cost and flexibility?Traditional solutions face new challenges
Limited to the accuracy of sensor acquisition, and in order to reduce battery costs, manufacturers need to make overall plans and use the supplier’s system-level expertise to reduce the overall battery test circuit area, while increasing the number of channels, and must maintain the accuracy and reliability of test and measurement Performance and speed, even under harsh factory conditions, an accuracy of ±0.05% or more must be achieved.
According to Zhu Zhen, the bidirectional DC-DC converter module solutions used in traditional battery-based content-capacity equipment are divided into two categories, namely, discrete device-based solutions and digital solutions. Discrete device solutions are generally used in small and medium power scenarios, while digital solutions are It can adapt to different power scenarios of large, medium and small at the same time.
Solutions based on discrete devices are more flexible in device selection and procurement. It is necessary to consider the accuracy requirements of each device to select the corresponding device, which corresponds to a device with a certain range of output voltage, current, and number of channels. However, its shortcomings include too many devices, and it takes a lot of man-hours to develop, debug, test, and system calibration. The realization of channel staggered parallel connection and the current sharing function between channels requires additional circuits, and has significant disadvantages such as more complexity, making it a single unit Under the trend of increasing cell capacity, the overall cost disadvantage is becoming more and more significant.
The traditional digital cored component capacity device uses DSP or a processor with DSP function as the main controller of the power conversion loop. The PID loop uses software or hardware mode, uses digital PWM control switch tube, peripheral voltage and current sampling, and buffer amplifier. There is not much difference between the op amp used and the hardware solution. Its advantage is that the control is more flexible, and the debugging of the digital scheme is also more convenient. It can realize more complicated functions, such as interleaved parallel operation, multi-channel parallel current sharing, voltage feedforward and so on. However, its software development is difficult, costly, long cycle, and later maintenance costs are relatively high.
It can be seen that the traditional solutions have their own advantages in their respective application fields, but there are also corresponding inherent shortcomings that cannot be overcome. “This is why ADI integrates the analog front-end, power control and monitoring circuits into a single IC. The test components are combined into a complete solution, which not only has the cost advantage of a discrete device solution, but also has the multi-functional flexibility of a digital solution. .” Zhu Zhen said.
Control from analog to digital, interpretation of ADI’s new generation of chemical composition test program
ADI’s latest generation of digital four-channel bidirectional DC-DC controller ADBT1000/1/2 series integrates the bidirectional DC-DC solution applied to the battery-based capacitor industry on a single-chip system level, and integrates an analog front end for voltage and current sampling. And auxiliary ADC, using digital core, can realize multi-channel interleaved parallel operation, digital current sharing between channels and other operations.
It is worth mentioning that the previous generation product AD8452 of ADI’s chemical composition is based on the architecture of analog control loop, and its design concept is also very advanced, which has been widely used and widely recognized by customers. However, for different battery test parameters, the traditional analog loop can only improve the value by modifying or adjusting the capacitor or resistor network on the circuit board, which not only places high requirements on the circuit design, but also in the debugging of different products. It would be very inconvenient. The needs of the battery formation industry are relatively uniform. If various functions can be realized through register configuration, the test efficiency will be greatly improved. This is one of the reasons why the battery-based composition test equipment has gradually evolved from analog control to digital control.
“ADBT1000/1/2 series chips are based on digital loop control design, including four-channel analog front end, four-channel digital PWM generator, digital GPIO port, interrupt interface, 8-channel 12-bit auxiliary ADC, of which four ADCs have current sources Output function, convenient to realize temperature monitoring.” Zhu Zhen pointed out, “Compared with the single-channel solution of AD8452, ADBT1000 series chips have up to 4 data acquisition channels. Customers can combine multiple channels freely, and can output larger output through two channels in parallel. 4 channels can also be connected in parallel at the same time. A single chip can achieve a high current charge and discharge of up to 240A or even higher, which is in line with the current trend of continuous improvement of battery capacity. The built-in state machine to achieve PID adjustment mode will bring Faster loop response capability, while avoiding the risk of program runaway caused by software control.”
The many features and functions of the ADBT1000 series of chips are integrated, simplifying the hardware design of battery-based charging and discharging channel equipment. The digital core is equipped with dedicated GUI software that can directly set registers, which directly avoids complex DSP code and algorithm development. The cost of later maintenance greatly optimizes the design threshold and development difficulty for high-power applications. The integrated high-precision analog front end can ensure system accuracy and temperature drift, and also greatly reduce the time for customers to develop battery-based component capacity test systems.
With the explosive growth of the power battery market, the demand for large-capacity batteries has also increased. “ADI has continued to develop many new products, reference designs and integrated solutions. The new generation of ADBT1000 series test chips provide high precision while realizing digital loop control instead of analog control in a state machine mode, which improves the factory’s battery-based composition. Rong’s testing capabilities have expanded the scale of testing and increased the stability of battery formation equipment, enabling manufacturers to produce safe and powerful power battery packs more efficiently.” Zhu Zhen emphasized.