Which is stronger, China or America?

May 25, 2019   Pageview:80

technology of electric vehicles is an important link for the United States to contain China. The United States restricts Chinese investment in American new energy companies to prevent the loss of core technologies related to patent transfer. Electrification of vehicles is one of the major trends of new energy. The most important core of electric vehicles is the "three-power technology" -- battery, motor and electronic control. So the question is, at what level is China's "three-power" technology? Which is stronger, China or America? Wu conducted in-depth research and reached three conclusions.


Battery PK: battery technology has its pros and cons


Since 1991, when Panasonic produced the first on-board lithium battery, Japan has basically monopolized the global battery market, with Japan accounting for 60% of the world market, South Korea for 30% and China for less than 10%. In recent years, China, Japan and South Korea have averaged their share of the global lithium battery industry. According to the data in 2017, the top 10 power battery companies in the world mainly include ningde times, Panasonic, byd, walmart, LG chemical, guoxuan high-tech, Samsung SDI, Beijing guosen, bick, and fu neng technology. Seven of the ten belong to China, with Panasonic alone in Japan and LG chem and Samsung in South Korea.


China's automotive power lithium battery industry (EVLIB) from March 2014. Shipments of 7Gwh jumped to 15 in 2015. 7Gwh, up 352% year on year, and 28Gwh power battery shipments in 2016, up 79% year on year. Last year, in 2017, 38 Chinese cars were shipped with lithium batteries. 0Gwh, accounting for 65 per cent of global EVLIB shipments. 4%.


There are basically several types of power batteries for new energy vehicles: nickel-metal hydride batteries, lithium cobalt 18650 batteries, lithium iron phosphate batteries, lithium ternary batteries, graphene batteries and hydrogen fuel cells.


Tesla ModelS USES the lithium cobalt oxide 18650 battery, which has a mature production technology. The battery has a high energy density, about twice that of lithium iron phosphate batteries, but its stability at high temperature is slightly worse than other batteries. Take battery stability as an example, Tesla has already had two accidents in which the battery of the vehicle caught fire twice, namely the accident in California in March and the accident in Florida in May, which caused serious casualties.


BYD of China has made a completely opposite choice with Tesla in terms of batteries. BYD's cars like qin and tang all use ferrophosphorus sulfate batteries, which are the most stable lithium batteries for cars. Safety and stability are of utmost importance to a car. In the extreme cases of accidents, lithium iron phosphate batteries ensure that passengers on board are not harmed by battery explosions or secondary fires.


Ternary lithium battery is the development trend nowadays, BYD hybrid song, Yuan, baic EV200, EV260 and Tesla Model3 all use this kind of battery. The safety and energy density of ternary lithium battery are between lithium iron phosphate battery and lithium cobalt acid 18650 battery, which are relatively balanced in all aspects. Moreover, the battery is more stable at low temperature, which can better meet the current demand of new energy vehicles for power batteries.


Nickel-metal hydride battery, which once competed with lithium battery, has the advantages of long life, multiple charge and discharge times, no maintenance, and can maintain relatively good performance index for a long time. Today, Toyota prius nimh batteries have quietly been replaced by lithium batteries, while ford cars like the ford cape, the Chevrolet ChevroletMalibu, and Honda's HondaCivicHybrid still use nimh batteries.


Some researchers have found that adding graphene to the inside of lithium batteries can reduce the energy loss of lithium batteries, reduce the damage of heat to the battery and improve the service life of the battery. Hydrogen fuel cell is the real zero pollution energy, is the most perfect car fuel, but hydrogen fuel safety and storage technology is not very mature. Graphene batteries and hydrogen fuel cells will not be used in new energy vehicles in a short time, but this is the future of our new energy vehicle power battery research direction.


Motor PK: China has obvious advantages in motor technology


There are two main motors used in new energy vehicles: asynchronous motor and permanent magnet synchronous motor. The advantages of asynchronous motor are low cost, simple structure, convenient production, good reliability, but large size, large energy consumption, which means that in the same battery capacity and the same car condition, the use of synchronous motor car than the use of asynchronous motor car range more. For example, the Tesla ModelSP85D has a mass of over 2. 1 ton, is because of the asynchronous motor battery utilization efficiency low volume, so must pack more batteries.


Permanent magnet synchronous motor, although the cost of slightly higher than asynchronous motor, but compact structure, small size, with a high power density. Domestic new energy vehicle enterprises represented by BYD and later Tesla Model3 all chose permanent magnet synchronous motor, just to achieve the best range under the limited battery capacity. For new energy vehicles, permanent magnet synchronous motor is a major development trend.


Electronic control PK: electronic control technology gap is not big


The electric control system is the nerve center connecting the motor and the battery, mainly for dynamic monitoring of the whole vehicle, timely feedback and adjustment of technical parameters. In the new energy vehicle, electronic control system can be divided into two categories.


Battery management system (BMS)


The battery management system can detect and adjust the working state of the battery in time to ensure the working safety of the battery, so as to increase the driving range and extend the service life. Tesla has a very powerful battery management system, ModelS USES a total of 7,104 18650 batteries, which are connected in parallel every 74 batteries, connected in series every 6 battery packs, and then connected in series of 16 battery packs to form the overall power battery of Tesla. BMS monitors each stage in real time, cooling each battery unit in time, reducing the temperature difference between each other to prevent spontaneous combustion. However, Tesla can monitor every battery unit, but it cannot solve the situation that the battery pack is destroyed by the extreme impact force, resulting in combustion and explosion. This is the reason why two Tesla cars in the United States caught fire twice this year.


For safety reasons, BYD chose a more reliable lithium iron phosphate battery for its power batteries. Lithium iron phosphate batteries at high temperature stability, can reach more than 390 ℃, guarantees the high security, the battery will not due to overcharge, high temperature, short circuit, the impact produced by explosion or burning, the greatest extent to ensure the safety of the personnel on the car. Due to different battery choices, the two auto companies have different development directions. The reliability of lithium iron phosphate battery decides that byd does not need to make the battery management system as complicated as Tesla ModelS.


Driver3, e-motiondriver3, in the beiqi EU5, another independent brand of baic new energy in China. 0 is the third generation super electronic control technology with complete intellectual property rights owned by baic new energy. As the brain of baic EU5, EMD3. It can detect the data of 260 parts of the whole car, monitor and adjust the battery in real time, protect the battery in the process of charging and discharging, automatically warn the abnormal situation and pre-heat the low charging temperature, and realize the normal start and charging in the environment of -35 degrees Celsius. EMD3. Not only is 0 a leader in battery control technology, but the car's cumbersome human-computer interaction is the most powerful part of Darwin's system, which is also known as the "strongest brain" in the industry.


Motor control system


Motor control system as commander of the principle of its core is IGBT element (InsulatedGateBipolarTransistor, insulated gate bipolar transistor) chip. The power battery of the new energy vehicle provides direct current, while the drive motor needs three-phase alternating current, which requires the motor control system to work, to convert the direct current to alternating current, and the key component to complete the transformation is IGBT. For the design and manufacturing of automotive IGBT, byd has broken the international technology blockade, has broken through the IGBT pipe design, module heat dissipation, packaging and manufacturing and other key technologies, to achieve the industrialization of automotive IGBT power module, breaking the Japanese mitsubishi and infineon market monopoly. Byd automotive IGBT module was awarded the title of "best power device of the year 2018 China IC design achievement award" in the global electronic technology field, which is the highest honor of China's IC industry. Now pure electric vehicles equipped with IGBT "China core" have been widely used in the world.


From the point of view of the core technology of sanpower, the battery from the United States panasonic, China's independent research and development. In terms of motors, the permanent magnet synchronous motor independently developed by byd is more suitable for the needs of the public. In the electronic control technology, China's independent research and development of IGBT already ahead of the United States.


Since the beginning of new energy vehicles to now more than ten years, whether domestic or foreign new energy vehicle technology is still in the stage of constant exploration, no matter which car companies can not directly determine, their own enterprises use the configuration must be the best. China and the United States now have their own tri-electric technology, there is no strong or weak. What we can do is to continuously research and improve to produce the most suitable battery, motor, electric control system and so on for new energy vehicles. Countries should also be open to cooperation and exchanges to lead the new energy vehicle industry to a more mature tomorrow.


The page contains the contents of the machine translation.

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