More than a decade ago, the mobile phone battery needed to be disassembled and charged separately. Now it has been integrated into the mobile phone, and some components used for packaging and protection can be omitted without disassembling. Although the automobile power battery does not need to be disassembled and recharged, with the improvement of integration, redundant components are constantly being discarded. At the same time, just like mobile phone batteries, with the upgrade of OTA, it will be continuously optimized.
"Slimming History" of Power Battery
The design of power battery can be roughly divided into three stages, namely, the era of 1.0 with standardized modules and the era of CTP 2.0 with large modules, which represents the highest level of CTC 3.0 in the industry at present.
In the era of 1.0, power battery is called standardized module, and its structure is very complicated, including battery cell, module and battery pack from the inside out. Many batteries are packaged into a module, and many modules are packaged into battery packs, which are finally installed in the car. However, only battery cells are used for power supply. This "over-packaging" not only requires the design and production of additional components, but also takes up additional space, resulting in a decrease in the space ratio of battery cells.
The 2.0 era is called the "big module" era. The main idea is to design larger modules and reduce the number of modules or even no modules, so as to minimize the number of parts and space occupation at this level. The most representative ones are CTP technology of Contemporary Ampere Technology Co., Ltd. and BYD's blade battery.
The 3.0 era marks the beginning of the integrated design of battery and chassis. CTC is the abbreviation of "cell-to-chassis", which means "integrated battery and chassis design". At the same time, there must be a more intelligent BMS (Battery Management System) to monitor, manage and optimize the use of batteries more intelligently.
What are the difficulties of CTC technology?
That's easy to say, but there are many technical problems in realizing CTC. The purpose of battery and chassis integration is to reduce the number of parts, compress the space volume and improve the power and endurance of the whole vehicle through this integrated design. But how to integrate, how to ensure the waterproof performance of the battery, how to ensure the safety of the battery after reducing the layer-by-layer packaging, how to adjust the production line, how to test, mass production and maintenance are all issues that need to be considered.
The earliest concept of CTC was put forward by Zero Run, which was the first in China to realize mass production of CTC technology.
Zhu, the chairman of 20 16 Zero Run Automobile, was inspired by the integrated design of smart phone battery, and took the lead in putting forward the idea of integrating power battery and chassis internally. After six years of continuous research and development, testing and improvement, the mass production of CTC technology has finally been realized, and it will be carried on their new flagship model Zero Run C0 1 for synchronous mass production.
In the hardware innovation of CTC technology, the most basic and key thing is "how to integrate the chassis and battery", and the answer given by Zero Run is "integrated tray structure". The design idea is to put the battery in a battery tray, and then put the tray under the chassis, like an inverted dinner plate. In order to improve the firmness of the battery, the top and bottom of the battery are also fixed with a tray and a chassis. The whole integrated design is not only the body structure, but also the battery structure.
Just as most mobile phones are waterproof in battery and circuit structure, electric vehicles also need waterproof in rainy days and wading road conditions. In the 2.0 battery structure of 1.0, it is not difficult to realize the waterproof performance of power battery through layer-by-layer encapsulation. However, in the CTC era of 3.0, the module and battery structure have been simplified, and how to realize waterproof through chassis and tray structure is a very difficult problem.
Large area metal plates are assembled by welding. Considering the waterproof performance, the traditional welding and testing methods are no longer applicable. In order to solve this problem, a special process is adopted to improve the welding quality, precision control and welding consistency, and a new air tightness detection method and a factory-returning maintenance scheme are put forward. At the joint of chassis and tray, the combination of "rivet+sealing strip" is adopted to ensure waterproof performance.
In addition to waterproof, bumps and bumps are inevitable during driving. The battery should be able to remain "firm" under these external forces, and the integrated tray structure can also achieve this well. For example, the pallet is not flat, and there are criss-crossing beams as the skeleton, which can enhance the strength of the chassis and pallet. On the side of the car body, there is also an energy-absorbing structure, which is really important in some cases: when a serious side collision occurs, the impact force will be transmitted to the energy-absorbing plate first, and the energy-absorbing plate will deform to absorb the impact force, thus minimizing the impact on the supporting structure and the battery and ensuring the safety of the battery.
More and more "smart" batteries
With the innovation and breakthrough of hardware, of course, there must be the same software innovation as a support. Zero Run combines BMS and cloud platform into an AI BMS big data intelligent battery management system. It is like a smart housekeeper who can learn and improve constantly, guarding the battery at all times, and updating the software in the whole life cycle through OTA to make the battery safer, longer and more efficient.
For example, the AI BMS can monitor the indicators of the battery in real time, send the data to the cloud for AI data modeling, obtain the current state of the battery, and feed it back to the owner through the APP. With these data and status, AI BMS can conduct deep learning according to the historical faults that have occurred, and make early warning before the next fault occurs. It can also automatically correct the wrong way of using the battery, and provide a smarter charging strategy to keep the battery working in the best state.
If the integrated tray structure gives the battery a pair of reliable and powerful "steel bars and iron bones", then AI BMS gives the battery a "brain" and makes the battery more and more "smart". The overall evolution of body and mind makes zero-running CTC chassis become the energy matrix of a new generation of vehicles, which can not only adapt to highly integrated and modular production, but also have very strong functional expansibility in the future.
What's it like to drive with batteries?
Zero-run CTC technology not only improves the battery system, but also improves the performance of the whole vehicle to varying degrees. CTC technology has brought four major improvements in safety, performance, driving experience and cost on the upcoming zero-run C0 1 car.
The safety of battery is absolutely the most basic and important index of electric vehicle. Before leaving the factory, the batteries of electric vehicles have to go through various tests such as "going up the mountain and going to the sea". Zero running has eight stricter standards than the national standard, which proves that the battery safety has been greatly improved through the complementary strength of the battery and the body structure and the full-time protection of the AI BMS.
Thanks to the structural design of CTC chassis and the economic management of energy consumption by AI BMS, it can reach the endurance of more than 700 kilometers under comprehensive working conditions. At the same time, CTC technology improves the torsional stiffness of the car body by 25%, reduces the vehicle weight by 15kg, and further improves the handling performance.
CTC is highly integrated, eliminating the installation gap between the battery and the car body. The longitudinal space of the car body is increased by 10mm, and the 5-meter-long transverse car body also makes the interior space very sufficient, and the driving experience is excellent.
Finally, thanks to the structure simplification brought by CTC, the number of C0 1 vehicle parts is reduced by 20% compared with the traditional scheme, and the cost of structural parts is reduced by 15%, which is more convenient for mass production.
Under these performance improvements, the zero-run C0 1 has become a medium-sized and large-sized car with large space, long battery life, better handling and safety.
The most commendable thing is that Zero Run not only put forward the concept of CTC technology, but also turned this concept into reality through six years of hard work, research and overthrow, becoming the first enterprise in the world that can mass-produce CTC battery technology without independent battery packs. Through zero run C0 1, it is proved that CTC technology has improved the performance of the whole vehicle, and the power battery technology has officially entered a new era of 3.0. I believe that in the future, electric vehicles will get rid of the heavy shackles again and lose weight again. We don't have to worry about electricity anymore, and we can run with zero energy consumption more freely.
refer to
[1] Integrated structure of electric vehicle body and battery pack CN202121278218.5
[2] Song Shaoling. Investment strategy of new energy vehicle power battery industry: global electrification wave, high-quality supply chain benefits. CITICS