Power battery packs generally refer to packaging, packaging, and assembly. For example, if two batteries are connected in series and the customer requests to form a specific shape, we call it PACK.
The PACK grouping process is a key step in the production of power battery packs, and its importance has become increasingly apparent as the electric vehicle market continues to expand. At present, the battery PACK industry is still a new industry in China, and the technology and equipment are not yet mature. The overall quality of technical personnel is not high. Its high technical threshold also makes it difficult for companies to enter the industry. The upcoming "2017 Power lithium-ion battery pack production process training" to be held in Tianjin will help solve these problems. It is understood that this is a training course for technical personnel in the front line of the power battery PACK industry. It will conduct detailed training on the connection process, packaging process, welding process, and injection molding process in the battery PACK process. It will also explain the power battery system. Design, power battery pack off the line detection, the actual production process in the various problems and solutions and other content.
In the battery pack, the BMS (Battery Management System) is the core, which determines whether the various components and functions of the battery pack can be coordinated and directly related to whether the battery pack can provide safe and reliable power output for the electric vehicle. Of course, the connection process, space design, structural strength, system interface, etc. of the structural components also have an important influence on the performance of the battery pack.
In short, the PACK grouping process level of the battery pack is directly related to the power performance and safety performance of the electric vehicle. It can be said that it is also a battery, and it is also a battery. Power battery pack PACK is good or bad, it is a matter of life and death.
This needless to say, if the battery PACK is compared to a human body, then the module is the "heart", responsible for storing and releasing energy, to provide power for the car.
2) Structure systemThe structural system is mainly composed of a battery PACK cover, trays, various metal brackets, end plates and bolts. It can be regarded as the “skeleton†of the battery PACK, supporting, mechanical shock, mechanical vibration and environmental protection (waterproof and dustproof. The role of
3) Electrical systemThe electrical system consists of high-voltage jumpers or high-voltage harnesses, low-voltage harnesses, and relays. The high-voltage wire harness can be regarded as the "macro-artery blood vessel" of the battery PACK. The power of the heart of the power battery system is continuously transmitted to various required components. The low-voltage wire harness can be regarded as the "neural network" of the battery PACK to transmit the detection signal and control in real time. signal.
4) Thermal Management SystemThere are four main categories of thermal management systems: air-cooled, water-cooled, liquid-cooled, phase change materials. Taking a water-cooled system as an example, the thermal management system is mainly composed of a cooling plate, a cooling water pipe, a heat insulation pad, and a thermal pad. The thermal management system is equivalent to installing an air conditioner for the battery PACK.
Some people will ask why the battery needs a thermal management system? In fact, it is very simple, because the process of charging and discharging the battery is actually the process of chemical reaction, the chemical reaction will release a lot of heat, need to take away the heat, so that the battery is within a reasonable operating temperature range, in order to improve the battery life and reliability Sex.
5) BMSBMS: Battery management system, can be seen as the battery's "brain." Mainly composed of CMU and BMU.
CMU: CellmonitorUnit monitoring unit is responsible for measuring parameters such as battery voltage, current, and temperature, as well as balancing and other functions. (The green circuit board at the right end of the module picture above is the CMU). When the CMU measures these data, it transmits the data to the BMU through the previously mentioned battery "neural network."
BMU: BatterymanagementUnit battery management unit.
Responsible for evaluating the data transmitted by the CMU. If the data is abnormal, the battery is protected, the request for lowering the current is issued, or the charge-discharge path is cut off to prevent the battery from exceeding the permitted usage conditions, and the battery power and temperature are also managed. According to the previously designed control strategy, the parameters and status of the warning need to be judged, and the warning is sent to the vehicle controller and finally conveyed to the driver.
Benefited from the strong support of domestic policies for the development of new energy vehicles and power lithium battery industry, the shipment of power battery has increased rapidly. There is no doubt about the long-term application of power batteries, but safety performance is the primary criterion for consumers to choose products. In terms of using safety, most of the power battery PACK structure design will guarantee the safety of battery use from the following aspects:
(1) The battery cell can be flexibly selected and has good safety and is not prone to fire or explosion. The specific energy of the small-capacity single-cell battery can reach 140Wh/kg, and the cycle life can reach 1000 times under the condition that the end-of-charge voltage is 4.1V. The battery pack is much worse than that, the more the number of batteries in series, the more battery The shorter the cycle life of the group.
(2) Increase the automatic fire extinguisher, and automatically extinguish the fire after detecting the fire source. The automatic fire extinguishing of the battery box can effectively detect early fires such as lithium ion batteries or super capacitors in the energy storage device cabin, and give an alarm. At the same time, the fire can be automatically extinguished and continuously suppressed, and the fire of the battery and the capacitor can be prevented from rekindling.
(3) PUW pressure relief valve is added to the battery PACK box to prevent cavity pressure from accumulating.
(4) High temperature and flame retardant materials are selected for the box and each module. The battery case is made of high-temperature resistant materials. When the battery case is in operation, it will generate a lot of heat, and at the same time prevent the occurrence of abnormalities in the battery. Therefore, it is better to use high-temperature flame-retardant materials.
Some time ago, when Tesla designed the battery pack, a waterproof breathable valve (also known as PUW pressure relief valve) was designed on the top surface of the front of the PACK. Using gas molecules and liquid and dust particles in the volume order of magnitude, let gas molecules pass through. Liquids and dust cannot pass through, so as to achieve the purpose of waterproof and breathable, and avoid the condensation of water vapor inside the PACK.
China's power battery PACK market structure China's most pure electric passenger vehicle driving mileage <200kmAt present, the technical level of China's battery cell batteries is almost the same as that of foreign countries, but the technology, quality, and other indicators of the power battery system are not very different from those of foreign countries. On the one hand, it is because of the poor consistency of the power battery cells. On the other hand, the battery PACK process is also lacking, resulting in the battery system quality can not be expected.
The insufficiency of the quality of the power battery system also makes the driving range of pure electric vehicles in our country generally shorter. Especially in the low-temperature environment, users often have “mileage concernsâ€. Although the power battery technology has improved in the past two years, at present, the driving range of most of the pure electric passenger cars in China still does not exceed 200 km, which does not significantly ease the “range anxietyâ€.
Multiple Segments Help Accelerate Technology BreakthroughsAt present, the PACK market pattern of China's power battery is divided by the host factory, battery factory, and third-party PACK company. Among them, the host plant accounts for more than half of the market share of the passenger car market, while the battery plant is in the absolute dominant position in the field of special vehicles and passenger cars, although the third-party PACK companies have a certain share, but the proportion is not high.
2016 China PACK Market Structure
In the future, the power battery system business will be gradually split by the OEM, and its technology will be more clear. Structural parts, battery packs, modules, BMS (battery management system), high-voltage power distribution, etc., may all form different market segments.
Taking the BMS market segment as an example, in 2016, independent domestic third-party BMS companies took a dominant position, accounting for 43% of the market share. Several power battery companies and vehicle companies in the "first tier" and some PACK companies have the R&D capabilities of BMS, but their market share cannot be compared with that of third-party BMS companies.
2016 China BMS Market Competition
In fact, once a multi-segment market is formed, the existing market structure will be broken down, so that enterprises specializing in certain sub-sectors with certain technological accumulations will be able to develop rapidly, with more capital to invest in R&D and accelerate the subdivision of fields. Technological progress. Moreover, large and complete companies will be constrained by factors such as assets and equipment, and lack the flexibility to respond to the rapid iterative market environment. In the process of transformation and upgrading, enterprises in the subdivided areas will have more market sensitivity than large and comprehensive enterprises and will easily gain opportunities for development.
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