Battery technology continues to improve, electric cars will bid farewell to 'charging anxiety'

At the centralized charging station in shenzhen, more and more electric car drivers are charging their vehicles with multi-power charging stack devices. In addition, with the continuous breakthroughs in power battery technology, the energy density of lithium battery increases in parallel with the power density, which on the one hand increases the driving range of electric cars, and on the other hand makes it possible for "quick charging" which can be comparable with the refueling time of fuel cars. In the accelerated iteration of technological innovation, electric vehicle users are gradually saying goodbye to the "charging anxiety" that has been troubling them for a long time.

"Power sharing" charging reactor solution

Matrix flexible charging reactor technology can not only meet the current battery charging needs, but also meet the future "battery upgrade" needs, avoiding repeated withdrawal and construction of charging piles

By the end of last year, China had 450,000 charging piles of various types, 14 times as many as at the end of 2014. 8:1. However, with the steady progress of charging network construction, there is also a certain degree of structural supply shortage. The mismatch of resources leads to the coexistence of "difficult charging" and a large number of idle public charging piles. In addition, for a long time, most of the ev public charging piles put on the market are fixed power charging piles, and the design of charging piles should meet the current automobile battery standards. 40kW, 60kW, 80kW, 110kW...... With the increasing power of new models on the market, charging piles will face replacement or expansion.

The coexistence of multiple power electric vehicles has become a fait accompli of the electric vehicle stock market. Therefore, in the centralized charging station, how to improve the power compatibility of charging equipment is the key. "Under the same charging current, when the voltage is raised to 1000V, if the car with a voltage platform of 350V is still charged, the power utilization rate of the existing technical scheme is only less than one third of the original, and the equipment utilization rate is particularly low. Xiao xia, chairman of Shenzhen Auto Electric Power Plant Co., Ltd., said, "the charging pile technology can not only meet the current battery charging demand, but also meet the future 'battery upgrade' charging demand, avoiding the repeated withdrawal and construction of charging piles."

It is reported that the matrix flexible charging reactor technology developed by aotson concentrates all or part of the charging modules of the ev charging station together and dynamically distributes the charging modules according to the actual charging power required by the ev through the power distribution unit. That is to say, in the charging station applying the charging pile technology, the power of the same charging pile can be Shared, which can satisfy both 100kW battery charging and 300kW battery charging, ensuring that each new energy vehicle can be charged at the maximum power. In shenzhen, aotexun has invested, built and operated more than 80 Chinese charging stations for flexible charging.

OTT fast power equipment engineer host said, "power sharing" is somewhat like "sharing bandwidth", "before without charging pile, the fixed power charging equipment such as fixed bandwidth of the network, if the total bandwidth is 100 million, has 10 users, each user of the fixed bandwidth is 10 million, so even if there are a lot of broadband users didn't use, other users the highest bandwidth is 10 million; The charging stack is like Shared bandwidth, which can be dynamically adjusted according to the number of users and the bandwidth demand. If there is only one user, the maximum bandwidth can reach 100 megabytes.

Wei jian, deputy general manager of shenzhen qianhai aotexun new energy services co LTD, said the amount of power that the charging terminal can allocate will be determined by the recharged electric vehicle. Otsu's technical team designed a huge computing system, built a cloud platform, and conducted intelligent management on the platform after big data collection of identity information of hundreds of electric cars. When the charging gun is inserted into the charging port and "shakes hands", all the vehicle information is read out and distributed intelligently to charge the vehicle.

Since December last year, shenzhen municipal market supervision administration and shenzhen development and reform commission jointly organized and formulated shenzhen standardization guiding technical document -- technical requirements for flexible charging piles of electric vehicles, which is the first local standard on flexible charging piles of electric vehicles in China. Shenzhen Auto Electric Power Plant Co., Ltd., as a leading enterprise in Power automation Power supply industry, is the lead drafting unit of the standard.

"For operating vehicles such as taxis and vans, the power adaptability of centralized charging stations directly determines the convenience of charging." Ni feng, deputy director of the international department of guodian nanrui technology co., LTD., said, "in the application scenario of centralized charging stations, the charging reactor technology has the characteristics of accurate and efficient matching, which will undoubtedly be of great use."

High power quick charge

It is generally believed that "quick charge" in electric vehicles refers to the charging technology that takes less than 30 minutes for the battery to charge 80% of the time from 0%

At the symposium on high-power charging of electric vehicles held recently, ningde times showed the charging process of the super-iron-lithium battery using the system of "super-iron-lithium + high-energy density fast-charging graphite" to the participants. The product can be charged "5C", and the demonstration process only took 7 minutes and 12 seconds to complete 20% to 80% of the charge, while 20% to 100% of the charge only took 13 minutes and 8 seconds.

"Super-power charging USES high-voltage direct current (HVDC) technology, which literally dumps electricity into the battery," said Dr. Lei wang, an energy storage technology expert and Ecoflow founder. The unit "C" in "5C" refers to the charging rate, which can be understood as the charging and discharging rate. The charge and discharge rate of a lithium-ion battery determines how quickly it can store energy in the battery, or release it. The current of "1C", from full charge to discharge, takes 1/1 = 1 hour. 2C is 1/2 hour, which is 30 minutes; 5C takes 12 minutes. It is generally believed that "quick charging" of electric vehicles means that the charging current is greater than 1. 6C charging mode, namely from 0% charging time to 80% time less than 30 minutes of technology.

The core technology of quick charge of lithium battery is to accelerate the speed of lithium ion moving in the positive and negative poles through chemical system and design optimization on the premise of not affecting the life and reliability of the cell. Ningde era of new energy co., LTD. Quick charge project director Wang Sheng wei, "said Dr In anode graphite surface, ningde times using the technique of" fast ionic ring ", is equivalent to create a ring of high-speed runway in the surface of graphite, greatly accelerate the lithium ions in the graphite layer embedded, after modification of graphite/super quick charge and the characteristics of high energy density. In addition, the internal heat dissipation rate of the battery is also an important factor affecting the multiplier performance. If the rate of heat dissipation is slow, the heat accumulated during charging and discharging at a high rate cannot be transferred out, which will affect the reliability and service life of lithium ion batteries. The quick charging products developed in ningde era are equipped with the self-developed thermal management system, which can fully identify the "healthy charging range" of the fixed chemical system in different environments and broaden the operating temperature range of lithium battery.

"The demand for high-power charging is very clear, both at home and abroad, commercial vehicles, taxis, ride-hailing vehicles and other vehicles have an urgent need. Especially in the extremely large cities such as Beijing, Shanghai, guangzhou and shenzhen, where parking Spaces and charging piles are in short supply, car owners will have a strong demand for high-power charging when it is difficult to find a parking space for charging. "However, the high-power and fast-charging products above 300kW are still in their infancy globally," ni said. "battery heating, equipment volume, safety isolation and other technical issues need to be optimized, and there is still a long way to go from technology maturity to market maturity. In addition, the construction of charging stations, power grid and other supporting infrastructure problems still need to be solved.

Management and services need to be more sophisticated

Experts said, in order to promote the healthy development of electric vehicles, charging service intelligent fine management, is the trend.

China has been the world's largest producer and marketer of new energy vehicles for three consecutive years. By the end of last year, China had sold 1.8 million new energy vehicles, accounting for more than 50% of the global total. "" according to the market trend, after 2020, there will be more and more high-power electric vehicles with 300 to 400 kilowatts or more. "There is no problem with the technology, whether it's the charging stack or the battery itself," ni said. In addition, although earlier operators did not consider power expansion, in recent years, more and more operators have reserved space for capacity expansion in centralized charging stations.

Liu yongdong, deputy director of the standardization management center of the China electric power enterprise federation, said that in terms of charging methods, the future trend of electric vehicles will be the long-term coexistence and combination of "daily slow charging of private ac charging piles" and "quick charging of public charging stations". "For urban families using electric cars to commute, they can use private charging piles to charge at home after work, and a long period of slow charging can meet most of their needs. "" using fast charging at charging stations, more charging will be a necessary complement." "

The optimization of charging management system is expected by many experts. Ni feng gave an example of a charging station's power module cooling scheme. The main cooling schemes of power module are water cooling and air cooling. The latter is cheap, but high requirements for the environment, the use of long time prone to dust blockage and other phenomena. "The mechanism of 'the lowest bidder' in China allows many operators to adopt the air-cooling mode, but they need to replace all of them after less than two years, so the comprehensive use cost is higher than the use of water cooling." Ni feng said.

In liu yongdong's opinion, there is still a large space for the installation and management of private charging piles. "Many residential areas, especially old residential areas, due to limited power distribution capacity, property does not cooperate with other reasons can not be universal installation; The use of technology platforms to promote and manage off-peak charging needs to be further advanced. Smart fine management of charging service is the general trend.

"Today, we are talking about the improvement of charging technology, management and service on the premise of the healthy development of electric vehicles." "The fundamental power of electric cars still comes from the electric cars themselves, from the adjustment and change of the whole industrial chain ecology," ni said. "What we are most concerned about is still how strong the desire of users to consume and use electric vehicles is after the removal of relevant subsidies, which is the key to the long-term development of the whole industry.

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