The difficulty of electric vehicle lies in that the energy stored in the battery per unit weight is too little at present, and the battery of electric vehicle is expensive and does not form an economic scale, so the purchase price is relatively expensive. As for the use cost, some trial results are more expensive than cars, and some results are only 1/3 of cars, mainly depending on battery life and local oil and electricity prices. Electric vehicle refers to a vehicle that is powered by on-board power supply and driven by motor and meets the requirements of road traffic and safety regulations. Because it has less impact on the environment than traditional cars, its prospect is widely optimistic, but the current technology is not mature. Editing the key batteries developed in this paragraph is the primary key to the development of electric vehicles. It is difficult for automobile power batteries to meet the requirements of "low cost", "high capacity" and "high safety". In order to widely use electric vehicles, we must rely on advanced batteries, which have been screened by 10 for many years. At present, Ni-MH batteries, iron batteries, lithium-ion batteries and lithium polymer batteries are generally optimistic. Ni-MH battery has twice as much energy storage per unit weight as lead-acid battery, and other properties are also better than lead-acid battery. However, the current price is 4-5 times that of lead-acid batteries, and efforts are being made to reduce it. Iron battery is made of iron, which is rich in resources and low in price, greatly reducing the cost, and is also adopted by some manufacturers. Lithium is the lightest metal and has very active chemical characteristics. The energy storage per unit weight of lithium-ion battery is three times that of lead-acid battery and four times that of lithium polymer battery. Moreover, lithium is rich in resources and not very expensive, so it is a promising battery. China has made rapid progress in the industrial development of nickel-hydrogen batteries and lithium-ion batteries. Other related technologies of electric vehicles have also made great progress in recent years, such as AC induction motor and its control, rare earth permanent magnet brushless motor and its control, battery and vehicle energy management system, intelligent fast charging technology, low resistance tires, lightweight and low wind resistance body, braking energy recovery and so on. These technological advances make electric vehicles more and more perfect and practical. The air pollution in big cities of China can't be ignored, and automobile exhaust is one of the main pollution sources. There are 10 cities in China, which are listed as the 20 cities with the most serious air pollution in the world. At present, China's per capita car ownership is per 100 people 100 cars, but the oil resources are insufficient, and tens of millions of tons of oil are imported every year. With the development of economy, if the per capita car ownership in China reaches the current global level-1100 /65438 people, then the car ownership in China will become 65438. Therefore, the research and development of electric vehicles in China is not a temporary short-term measure, but a significant and long-term strategic consideration. Edit the structure and characteristics of this paragraph. Compared with fuel vehicles, pure electric vehicles are mainly different in four parts: drive motor, governor, power battery and vehicle charger. Compared with gas stations, it consists of public ultra-fast charging stations.
The quality difference of pure electric vehicles depends on these four components, and its value also depends on the quality of these four components. The use of pure electric vehicles is also directly related to the selection and configuration of the four components.
The speed and starting speed of a pure electric vehicle depend on the power and performance of the driving motor, the length of its continuous driving mileage depends on the capacity of the vehicle-mounted power battery, and the weight of the vehicle-mounted power battery depends on which power battery is selected, such as lead acid, zinc carbon and lithium battery. And their volume, specific gravity, specific power, specific energy and cycle life are different. This depends on the manufacturer's positioning and use of vehicle grades, as well as market definition and market segmentation.
At present, the driving motors of pure electric vehicles are divided into DC brushless, permanent magnet, electromagnetic and AC stepping motors, and their selection is also related to the configuration, use and grade of the whole vehicle. In addition, the speed regulation of driving motor can be divided into step speed regulation and stepless speed regulation, including electronic speed regulation and stepless speed regulation. Motor includes hub motor, inner rotor motor, single motor drive, multi-motor drive and combined motor drive. The selection and preparation of motor and governor also have an impact on the grade and price of the whole vehicle.
Public ultra-fast charging station is the infrastructure for commercialization of pure electric vehicles. Only when perfection is in place can the former run smoothly and worry-free, on the contrary, it is restricted and influenced by it. The commercial practice of electric vehicles in Europe and America fully illustrates this point. We have realized this, but our actions are not effective. In addition, the cable connector between the charger and the on-board battery must be standardized to form the consistency of battery variety, voltage classification and speed (power), otherwise the pure electric vehicle and the public ultra-fast charging station cannot be effectively docked. This industry is blank at present, and we need to develop it, but we must plan, design and implement it after it is formed, so as to avoid wasting life and money in vain.
The four major components of pure electric vehicles, large chargers in public charging stations, special cables, cable connectors and even charging and charging systems are all new parts in the automobile industry. Without them, cooking without food is impossible, and short legs will be restricted by them. At the same time, related parts manufacturers should form an industrial chain and develop accordingly.
The National Development and Reform Commission's "Management Measures and Implementation Rules for Announcement of New Energy Vehicles" was implemented on June 165438+ 10/day, 2007. "General technical requirements for rural agricultural (special) electric vehicles in cities and towns" is also in the pipeline, and the commercialization of pure electric vehicles in rural areas has begun to take shape, so it cannot be ignored.
To meet the international and market demand in the future, pure electric vehicles must meet the following requirements: 1. R&D, the manufacture and operation of electric vehicles must comply with various relevant national laws and regulations. The performance of the whole vehicle and parts must meet the national technical standards and specific requirements. 2. Electric vehicles use electricity as energy and are driven by motors, which will not cause new pollution and inflammable and explosive hazards. 3. The battery for electric vehicle energy storage must be pollution-free and environmentally friendly. And it has ultra-fast charging function (current above 2 3C). The continuous mileage of one charge is determined according to the purpose of the vehicle, so as to install a battery pack with sufficient electricity, and make full use of the ultra-fast charging of public charging stations to extend the continuous mileage. 4. The motor unit should have high energy conversion efficiency. The direct utilization and recovery of braking and deceleration energy strive for high efficiency of comprehensive utilization of vehicle energy. 5. Set the maximum speed according to the purpose of the vehicle and the driving occasion, which shall not exceed the limit of traffic regulations, so as to reasonably select the motor power and configure the battery capacity. 6, vehicle driving operation, simple and effective control, reliable work, to ensure driving safety. 7. Mechanical and electrical equipment is durable and needs little maintenance. The vehicle operation cost is low. 8. Based on the target market demand, provide practical and suitable models to meet it, and strive to achieve a comprehensive unity of technology, economy, practicality and function.
The electric vehicles that will be industrialized and commercialized by users in the future must meet the following characteristics: accurate positioning, proper use, suitable driving area and best efficiency. Suitable vehicle type and economical configuration. Reliable performance and simple operation. Environmental protection battery, long battery life, sufficient power, ultra-fast charging, perfect network and service in place. Low cost and minimal maintenance.
A brief history of electric vehicles
As early as the second half of the 9th century, the Englishman Robert Davidsson made the world's first practical electric car. This was more than 65,438+00 years before Daimler and karl benz CI invented the gasoline engine car.
The electric car invented by Davidson is a truck with a length of 4800mm and a width of 1 1,800 mm. It uses a primary battery, in which iron, zinc and amalgam react with sulfuric acid. Since then, rechargeable secondary batteries have been used since 1880. The development from primary electronic watch pool to secondary battery was a major technological change for electric vehicles at that time, and the demand for electric vehicles was greatly improved. /kloc-became an important product of transportation in the second half of the 0/9 century, and wrote that the demand for electric vehicles has been greatly improved. /kloc-in the second half of the 0/9th century, it became an important product of transportation, and wrote a brilliant page of electric vehicles in the history of human transportation. 1890, electric buses ran on the streets of France and London, England. At that time, the technology of vehicle internal combustion engine was still quite backward, with short mileage, many faults and difficult maintenance, while electric vehicles were convenient to maintain.
In Europe and America, the peak of electric vehicles is at the end of 19. 1899, Frenchman Coleman Gina drove a 44kW rear-wheel drive electric vehicle driven by dual motors, setting a speed record of 106km.
1900 Among the cars made in the United States, there were 15755 electric cars, 1684 steam engines and only 936 gasoline engines. After entering the 20th century, due to the continuous progress of internal combustion engine technology, 1908, Model T of Ford Motor Company of the United States came out, and mass-produced cars on the assembly line made gasoline-powered vehicles popular, resulting in insufficient technical and economic performance in the market competition, so that the former was eliminated by ruthless years, while the latter was shrinking day by day. Edit this paragraph. Experts look at electric cars. Lin Cheng, Deputy Director of Beijing Institute of Technology Electric Vehicle Engineering Technology Center.
A breakthrough has been made in the research of lithium iron phosphate battery in China.
Lin Cheng told reporters that the requirements for lithium batteries for vehicles are higher. It requires vehicles to ensure safety under various conditions of use, and accidents such as open flames and explosions cannot occur. Power battery was first used in electric vehicles, and it has made a great breakthrough in China, and began to take the scale of industrialization. But five or six years ago, some accidents often happened in electric vehicles equipped with the battery, and the battery was gradually diluted. At present, the research on lithium batteries in China has made rapid progress, especially in the safety of batteries.
Lin Cheng told reporters that lithium batteries mainly include lithium manganate batteries and lithium iron phosphate batteries. At present, the development of lithium manganate batteries in China has begun to take shape. Lithium iron phosphate battery, with its higher safety and longer service life, will become an important direction of lithium battery development in the future and also the focus of research and development of foreign automobile enterprises. At present, the research on lithium iron phosphate battery in China is progressing smoothly, especially in some patents. The lithium iron phosphate battery provided for the Beijing Olympic Games is a self-developed lithium iron phosphate battery.
"Of course, compared with foreign research on lithium batteries, there is still a certain gap in domestic research on lithium batteries, but domestic attention to lithium batteries is getting higher and higher, and it will become the focus of research and development in the future." Lin Cheng told reporters.
Deng Lunhao, Deputy Chief Engineer of Lithium Battery Industry Technology Department of Henan Yuhuan Group
It will take some time for lithium batteries to be widely used in electric vehicles.
Henan Yuhuan Group is an enterprise group with a complete industrial chain from battery parts to battery plastic hardware and related battery manufacturing, equipment manufacturing and electrical appliance manufacturing, and undertakes the research and development of lithium battery projects of the Ministry of Science and Technology.
"At present, compared with foreign countries, the gap between domestic research on lithium batteries is mainly reflected in the battery control system and [font color=#0000ff] power supply [/font] management system." Deng Lunhao told reporters that the research on lithium batteries in China is now in a state of fragmentation. At present, some companies have been able to provide corresponding lithium battery supporting products for electric vehicles, and the supporting lithium batteries can generally run about 200~500 kilometers.
Deng Lunhao told reporters that the price of domestic lithium batteries is too high now, and the problems of power management system have not been well solved. Electric vehicles are also facing the problem of charging. At present, ordinary lines at home can't charge the lithium battery of electric vehicles, so a small special charger must be equipped, which takes a long time and is very troublesome. In foreign countries, in order to solve this problem, charging stations and gas stations are generally put together. At present, domestic charging stations have not been established on a large scale.
Deng Lunhao believes that it is still difficult for domestic consumers to accept electric vehicles equipped with lithium batteries: "The price of an ordinary electric vehicle is likely to be twice or even higher than that of a gasoline locomotive with the same configuration, and domestic consumers do not have enough economic strength and psychological preparation to accept electric vehicles."
Zhuang Tong, engineer of China Electric Power Research Institute
Optimistic about the development prospect of lithium iron phosphate battery
Zhuang Tong told reporters that the research and development of electric vehicle batteries has gone through the development process from lead-acid batteries, nickel-hydrogen batteries to lithium batteries, and each battery has its own advantages and disadvantages.
Lead-acid battery appeared the earliest and used for the longest time, belonging to battery series. Lead-acid batteries have the best safety performance, with few explosions and fires, but the energy storage effect is not ideal. Later, people developed the Ni-MH battery, which is better than the lead-acid battery in storing electric energy and electricity. The hydrogen produced by Ni-MH battery is easy to explode during charging, so the enterprise is in a dispensable state.
Around 2000, people successfully developed lithium batteries. Lithium batteries store 2~3 times as much electric energy as lead-acid batteries, but because the lithium ions contained in them are active on the surface of metal layer, they are prone to spontaneous combustion and explosion in the air, which is more dangerous. Therefore, the research and development of lithium batteries in various countries is mainly to control their safety and stability.
"A lithium battery can be charged about 1000 times. The energy storage effect of lithium iron phosphate battery is worse than that of lithium cobalt oxide battery and lithium manganese oxide battery, but its safety performance is the best, and its energy storage is much higher than that of lead-acid battery, so now it is the most optimistic about lithium iron phosphate battery." Zhuang Tong said.
Chen Quanshi, Director of Electric Vehicle Branch of China Automotive Engineering Society
There are three major problems in domestic lithium battery research.
Chen Quanshi said in an interview with reporters: "At present, the country attaches great importance to the research work of lithium batteries. In the "863" project, the state invested 66 million yuan, all of which were used for the research and development of lithium batteries. Compared with developed countries such as * * and the United States, which are at the forefront of lithium battery research and development, there is a certain gap in the research and development details of lithium battery manufacturing accuracy, equipment and standards in China. "
Chen Quanshi told reporters that there are three major problems in domestic lithium battery research. The first is the consistency of manufacturing. Due to the gap between lithium battery manufacturing technology and equipment, China's lithium battery manufacturing technology is uneven and the manufacturing standards are not consistent. Lithium batteries for electric vehicles are all connected in series or in parallel. If the consistency problem is not solved well, the produced lithium battery cannot be applied to electric vehicles on a large scale.
Second, intellectual property rights. At present, China has made a breakthrough in the research of lithium iron phosphate battery, but because the United States has a patent in this field, although we can independently develop some links, we still don't know how to deal with intellectual property issues.
The third is the screening of raw materials. At present, it is impossible to import all raw materials for lithium battery production, mainly from China. However, domestic raw materials have to pass international certification before the lithium battery produced can be internationally recognized, so there are still some problems in the certification of raw materials.
China automobile enters "oil-free era"
There are many development directions of new energy vehicles, but one of them, hydrogen fuel cell technology is immature and expensive, and it is a technology after 20 years. On June 5438+ 10, 2007, Dr. Menahem Anderman, an expert in automobile and power batteries, made this conclusion when testifying before the Energy and Resources Committee of the US Senate. China also does not have the platinum needed for the reaction of hydrogen fuel cells. Although there is no public statement, it is said that the decision-makers in the country have made it clear that China is not suitable for developing hydrogen fuel cell vehicles, and it is only a scientific research tracking project.
In addition, as far as technologies that mainly use low-cost liquid fuels such as methanol and ethanol are concerned, because a large number of corn and grain are used as raw materials, the global food price continues to rise, and it is unlikely to become China's technological choice.
There is also a fuel technology, clean diesel, that is, low-sulfur diesel (diesel with sulfur content below 350ppm), which saves energy by 30% on average compared with gasoline engines. However, due to the poor quality of domestic diesel oil, the frequent oil shortage always starts with diesel oil, and diesel oil can not be supported by national policies.
Judging from the maturity of technology development and China's national conditions, pure electric vehicles should be the development direction to be vigorously promoted, while hybrid power is the transitional technology before the establishment of a large-scale charging network. This year, Chinese and foreign automakers have successively introduced hybrid and pure electric vehicles. BYD has successively demonstrated F6DM and F3DM dual-mode electric vehicles and F3e pure electric vehicles. Changan cooperated with Electrovaya, a Canadian green battery manufacturer, to expand the Canadian new energy vehicle market and launch the Benben pure electric version. General Motors introduced the Chevy Volt hybrid, and Mini Cooper introduced the pure electric version.
However, the power system of hybrid electric vehicle is complex and expensive. BYD F3DM has two power systems, and its announced power system cost has increased by 50,000 yuan, which is equivalent to saving 8,000 yuan in fuel cost every year, which is more economical than traditional gasoline vehicles. However, the fuel economy of hybrid electric vehicles is limited. The fuel economy of Toyota Prius is about 10%-20%, and the fuel economy parameter released by Chery A5-ISG during the test run of Beijing Olympic Games is 10%. It can be calculated as an account. Suppose a family travels 20,000 kilometers a year, the fuel consumption of a gasoline car is 7.5 liters per 100 kilometers, the annual fuel cost is 9,450 yuan, and the fuel consumption of a hybrid car is 20%, saving 1.890 yuan, which cannot offset the increase in the price and cost of its vehicles.
The advantage of hybrid power is that it retains the lifestyle of traditional gasoline vehicles. According to the mixing degree of gasoline engine and motor, the charging times are equivalent to those of traditional gasoline vehicles, or charging is not needed. Unlimited driving distance.
Pure electric vehicle saves fuel tank, engine, transmission, cooling system and exhaust system. Compared with the traditional power system of internal combustion gasoline engine, the cost of motor and controller is lower, and the energy conversion efficiency of pure electric vehicle is higher. Because the energy of electric vehicles-electricity comes from large generator sets, its efficiency is incomparable to that of small gasoline engines or even hybrid engines. Therefore, the use cost of pure electric vehicles is decreasing. According to the data released by BYD F3e pure electric vehicle, the power consumption per 100 kilometers is 12 kWh. According to the electricity price in 0.5 yuan, the cost per 100 kilometers is only 6 yuan. And its prototype F3 gasoline car consumes 7.6 liters of fuel per 100 kilometers, and the cost is 46.5 yuan according to the current oil price in 6.2 yuan. In contrast, the use cost of electric vehicles is only one-eighth of that of traditional gasoline vehicles.
The disadvantage of pure electric vehicles is that they change the lifestyle of traditional cars and need to be recharged every day. The traditional habit of using a car is to refuel once or twice a week. In addition, although a family may only travel a few times a year, there is a distance limit of several hundred kilometers for each trip.
Edit the technical overview of this paragraph.
Electric vehicle refers to a vehicle that is powered by on-board power supply and driven by motor and meets the requirements of road traffic and safety regulations. It is driven by the electricity stored in the battery. Sometimes 12 or 24 batteries are used for driving, and sometimes more is needed.
Technical characteristics of electric vehicles
● No pollution and low noise.
The exhaust gas produced by electric vehicles without internal combustion engines does not produce tail gas pollution, which is very beneficial to environmental protection and air purification, and is almost "zero pollution". As we all know, CO, HC, NOX, particulate matter, odor and other pollutants in automobile exhaust of internal combustion engines form acid rain, acid fog and photochemical smog. Electric cars have no noise generated by internal combustion engines, and the noise of motors is also smaller than that of internal combustion engines. Noise is also harmful to people's hearing, nerves, cardiovascular system, digestion, endocrine and immune system.
● Energy efficiency and diversification
The research on electric vehicles shows that their energy efficiency has surpassed that of gasoline-powered vehicles. Especially in cities, cars stop and go, and the driving speed is not high, so electric cars are more suitable. The electric car stops and does not consume electricity. During the braking process, the motor can be automatically converted into a generator, and the energy can be reused during braking deceleration. Studies have shown that the same crude oil, after rough refining, is sent to a power plant to generate electricity, and then charged into a battery-driven car. Its energy utilization efficiency is higher than that of refined gasoline and then driven by a gasoline engine, so it is conducive to saving energy and reducing carbon dioxide emissions.
On the other hand, the application of electric vehicles can effectively reduce the dependence on oil resources, and the limited oil can be used in more important aspects. The electricity charged into the battery can be converted from coal, natural gas, hydropower, nuclear energy, solar energy, wind power, tides and other energy sources. In addition, if the battery is charged at night, it can avoid the peak of electricity consumption, which is beneficial to balance the power grid load and reduce the cost.
● Simple structure and convenient use and maintenance.
Compared with internal combustion engine vehicles, electric vehicles have simpler structure, fewer running and transmission parts and less maintenance workload. When using AC induction motor, the motor does not need maintenance, and more importantly, the electric vehicle is easy to operate.
● High cost of power supply and short driving range.
At present, the technology of electric vehicles is not as perfect as that of diesel locomotives, especially the short life of power supply (battery) and high use cost. The storage capacity of the battery is small, the mileage after one charge is not ideal, and the price of electric vehicles is relatively expensive. However, from the perspective of development, with the progress of science and technology, the problem of electric vehicles will be gradually solved by investing corresponding manpower and material resources. Make full use of strengths and avoid weaknesses, electric vehicles will gradually become popular, and its price and use cost will inevitably decrease.