Technical analysis of battery
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The temperature management, battery module design and battery packaging technology of universal lithium ion battery are deeply studied. According to the different characteristics of Micro Blue 7 and Micro Blue 6PHEV, their power batteries were specially developed. Both models adopt a new generation of highly integrated modular design, as well as key battery module design, battery single-stage intelligent temperature management system, three-electric system safety, battery packaging technology and other components. Designed separately and produced in different battery production lines.
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Compared with the whole battery packs purchased by battery suppliers, the ternary lithium batteries selected by Buick Micro Blue 7 and Micro Blue 6PHEV are based on the leading technical scheme of LGChem, and the exclusive formula and design are further optimized, with higher energy density, longer service life and better temperature adaptability, which fully guarantees the cycle life of the battery packs.
The battery pack of Buick MicroBlue7 has also adopted a more detailed design to ensure safety and longevity. For example, foam insulation and heat dissipation between batteries can alleviate the expansion of batteries during later charging; The battery cell frame and radiator are fastened with long bolts to ensure the stacking stability of batteries.
Buick Micro Blue 7 and Micro Blue 6PHEV power battery systems adopt GM's exclusive battery-level intelligent temperature management system, which are customized according to their respective structures, shapes and performance requirements. Among them, MicroBlue7 is provided with a heat conduction sheet between every two batteries, which is directly connected with the water cooling structure at the bottom of the battery pack, and can realize active cooling or heating according to the battery working conditions, thus achieving excellent temperature uniformity and excellent low-temperature discharge performance. At the same time, the water inlet and outlet pipes of the water-cooling structure at the bottom of the battery pack are designed in a double-channel zigzag way, which can also bring more benefits to the temperature management of the battery module and ensure the stable working performance of the battery pack at a wide ambient temperature of -35℃~55℃. ..
The blue 6PHEV battery pack has a layer-by-layer liquid cooling technology patented by General Motors. There is a heat conduction sheet with capillary liquid cooling tube between every two batteries, the thickness is only 0.2 mm, and the cooling liquid can flow in the capillary, which can accelerate the heat conduction more efficiently and effectively ensure the consistency of battery performance. Its environmental temperature adaptation range is wide to -35℃~55℃, which can bring longer service life and more stable performance.
Micro-blue7 and Micro-blue6PHEV power batteries are being developed according to the new energy platform, and a large number of advanced lightweight composite materials are applied to make the batteries more compact and lightweight, and more spacious spare space is reserved for the car body. While reducing the weight, MicroBlue7 and MicroBlue6PHEV also provide higher strength structural protection for the battery pack: IP67-level sealing design can ensure the highest requirements of dustproof and waterproof performance after being immersed in water at 1 m for 30 minutes, which can not only block any dust and solids, but also ensure the safe operation of the battery pack when the vehicle wades.
A steel tray with reinforcing ribs is also designed at the bottom of the micro blue 7 battery pack, which ensures the light weight and reasonable structural design, and ensures the collision safety of the battery pack. In addition, the micro-blue 7 fuselage adopts high-performance BFI integrated fuselage structure, and the application ratio of high-strength steel is as high as 78%. Ultra-high-strength thermoformed steel with tensile strength of 1500Mpa is used in A-pillar, B-pillar, inner plate of hinge pillar, sliding plate, front and rear longitudinal beams, etc., which fully ensures the strength and safety of the whole vehicle and battery pack.
In terms of the safety of the battery pack system, the high-voltage wiring harness in the front cabin of Buick Micro Blue 6PHEV adopts transverse outgoing wires, which ensures the integrity of the high-voltage wiring harness in collision, and the high-voltage wiring harness is specially used to wrap the anti-cutting sleeve in key areas, effectively providing double protection. At the same time, the connection part of the high-voltage wire harness adopts a secondary locking structure to avoid the looseness and accidental touch of the high-voltage wire; In addition, the shell of components connected with high-voltage lines adopts double grounding design to prevent electric shock accidents caused by internal insulation damage.
Buick Micro Blue 7 has battery management technologies such as intelligent charging protection, dual-channel temperature detection of charging port, intelligent fault reminder, automatic collision power failure and automatic power balance. It can monitor the voltage, temperature, current and other states of the power battery whether it is driving or charging, and give a coordinated alarm in the car, outside the car and in the background cloud when problems occur. In addition, when a collision occurs, the high-voltage system can simultaneously meet the four requirements of voltage safety assessment, electric energy safety assessment, physical protection safety assessment and load insulation resistance assessment. Its dual redundant active disconnection function can turn off the relay within 1 second after the collision, complete the active discharge voltage to below 60V within 5 seconds (60s required by the national standard), and forcibly turn off the high-voltage system and airbag system outside the vehicle.
Micro-blue 7 and micro-blue 6PHEV batteries have passed more than ten kinds of limit tests, such as extrusion, collision, soaking, fire, overcharge, overdischarge, short circuit and salt spray, among which the vibration test time is 9 times that of the national standard, the alternating test time of high and low temperature is 0/0 times that of the national standard, and the corrosion strength test time is 0/2 times that of the national standard. Simulate extreme heat and extreme heat in the environmental cabin with the temperature difference of -40℃~85℃. The battery pack will also undergo more than 65,438+000 system and vehicle tests, covering mechanical, thermal, electrical, life and performance aspects to ensure the safety of the battery pack in a longer life cycle.
Fully automatic production process
In the process of battery cell stacking and battery module assembly, the whole process of battery cell and module charging, assembly, transportation and battery module testing is intelligently completed by robots or manipulators, and the automation rate is 100%, thus avoiding the safety risks caused by manual operation, ensuring the consistency of each battery module product and improving the quality and reliability of the battery.
In the process of stacking battery cells and assembling battery modules, the accuracy of the robot in each loading and unloading/transportation process is within 0. 1mm, which greatly improves the assembly efficiency, accuracy and quality stability of products. After the assembly process, the overall quality stability is ensured by pressure control re-inspection.
Through the application of digital technology, every key component of MicroBlue7 and MicroBlue6PHEV, such as battery cell, modular stacked electronic components, high-voltage wiring harness, not only realizes the real-time collection, monitoring and early warning of component data in the assembly process, but also ensures the orderly production. Moreover, through a complete product information traceability system, we have our own "ID card", which can be traced accurately in the future.
Using advanced ultrasonic welding technology to weld battery tabs not only has no welding defects, but also can adopt different ultrasonic welding technologies for different materials. Its advantages are that it will not cause high-temperature pollution and damage to materials such as semiconductors, reduce the risk of tearing the pull ring, ensure the safety of the battery cell, and especially facilitate the welding of materials with high thermal conductivity and high conductivity such as aluminum and copper. Under the guidance of the vision system, the industrial robot accurately locates and automatically manipulates the ultrasonic welding head to complete the welding of the positive and negative plates of the battery cell, so that the battery module forms a channel.
In the process of battery assembly, there are three levels: battery core, module and battery pack, which need to be tested and evaluated from the aspects of functionality, electrical performance and electrical insulation to ensure the safe production and product quality of battery assembly line.
Among them, the electrical performance test of battery pack needs infrared thermal imaging detection technology with high thermal sensitivity and ultra-wide temperature range from-20℃ to 350℃, which can realize non-contact real-time temperature change monitoring within the whole product contour range and ensure the quality and test safety of micro blue 7 and micro blue 6PHEV power battery systems. GM's patented welding resistance testing equipment can be used to test the welding quality of modules. If false welding or missing welding is found, the solder joint will be repaired by manual repair welding. In order to ensure that the liquid-cooled heat-conducting fins of Buick Micro Blue 6PHEV and the liquid-cooled loop system of Micro Blue 7 have no leakage points, the module assembly line will adopt the mass flow method for leakage testing, which improves the testing accuracy and shortens the testing time.
abstract
From the product development and overall battery technology characteristics, the micro-blue series of new energy vehicles have given Buick certain advantages in the competition of electrified products. How to compete with the new forces of the same class and making cars in sales volume, Micro Blue still needs to stand the test of time.
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