After entering the 21st century, the research and development of electric vehicles in various countries in the world has continued to develop on the existing basis, and has achieved a series of important results. Especially with the growing voice of global energy conservation and environmental protection, as well as the unified understanding of the development of electric vehicles reached by governments and major automobile companies, the development of electric vehicles has been further developed in China, Japan, the United States, Europe and other countries and regions. attention and develop towards industrialization and practicality. The development of electric vehicles has become an effective and feasible way to reduce environmental pollution and the shortage of oil resources. At the same time, the development of modern high-tech, the birth of new materials and the wide application of electronic information, motor and computer technology have greatly promoted the update and development of electric vehicle technology. Electric vehicles, represented by pure electric vehicles, hybrid electric vehicles and fuel cell vehicles, have entered a larger and more advanced stage of development. The promotion at this stage revolved around the theme of new energy and energy conservation and environmental protection. In the early stage, it mainly relied on the support of governments of various countries. Many energy companies, automobile manufacturers, battery suppliers and other related industries actively participated. With the increase of promotion efforts and new energy The rapid growth of the number of vehicles has gradually transformed into a development and production system of electric vehicles oriented by market demand and led by enterprises. The focus of this stage of technology research and development is to extend the driving range, shorten the charging time and solve problems such as charging infrastructure. Tesla is a typical representative of this stage, and the Leaf, Volta and the third-generation Prius have also been widely recognized and praised by the market. These four models are shown in Figure 1  respectively. Show.

Figure 1 Representative electric vehicle models

In addition, Daimler AG started mass production of the pure electric vehicle smart EV in 2010, Mitsubishi Motors began to sell the pure electric vehicle i-MiEV in Japan in 2009, and the pure electric vehicle MNIE developed by BMW based on the mature model MINI Cooper also Demonstration operations have been carried out in many countries, and BMW has ordered pure electric models and hybrid models for consumers to choose. In addition to the Toyota Prius, Honda's two-seater Insight hybrid electric vehicle has also gained a high market share, with cumulative sales of Honda's hybrid models exceeding 1 million units in 2012. Meanwhile, GM, DaimlerChrysler, Volkswagen, Peugeot Citroen, Renault, BMW, Nissan, Hyundai and Mitsubishi and other major auto companies in the world have also launched hybrid vehicles with their own characteristics and entered the stage of mass production and application.

smart EV

Plug-in hybrid electric vehicle (PHEV) combines the advantages of pure electric vehicle (EV) and hybrid electric vehicle (HEV), and has better practicability and lower price, so it has been favored by major automobile manufacturers. Highly valued and invested, and recognized by the market and consumers. General Motors of the United States has launched a series-hybrid-based PHEV, which uses a large-capacity lithium-ion power battery; Toyota of Japan has increased the capacity and charging plug of the on-board battery pack on the basis of the hybrid THS system; The type of hybrid electric vehicle has become one of the important technical ways to achieve energy saving and emission reduction of vehicles in the US federal government's new generation vehicle cooperation program. The key technical nodes and challenges faced by PHEVs are whether the cost, life, safety and low temperature performance of power battery technology can be broken through, and whether the overall performance of the motor drive system in terms of continuous operation, voltage level and thermal management can be significantly improved. At the same time, the large-scale promotion of PHEV also requires the establishment of a relatively complete electric vehicle charging network.

In terms of fuel cell electric vehicles, its feasibility has been technically proven. The current technical research direction is mainly focused on improving reliability and durability. At the same time, hydrogen source and infrastructure issues are also very critical. Developed countries such as the United States, Japan, Germany and France have done research earlier and have developed various types of prototypes. In 2013, the hydrogen fuel cell electric vehicle version ix35 rolled off the assembly line in South Korea. The car has a power of 100kW, a top speed of 151km per hour, and a driving range of 594km. 5.6kg of hydrogen can be stored in the hydrogen storage tank, and an average of 106km can be traveled per kilogram of hydrogen fuel. According to the energy contained in 1kg of hydrogen fuel, which is approximately equal to 3.7L. Gasoline, it can be calculated that the fuel efficiency of the car is about 28.6km/L, which has good economy. At the end of 2014, Toyota's newly developed hydrogen fuel cell electric car Mirai was launched. The car has a power of 113kW, a maximum torque of 335Nm, and a driving range of more than 500km. It only takes 3 minutes to fill up the fuel. The model has now been mass-produced, and the sales in Japan reached 400 by the end of 2015. The successful mass production and market launch of this model also shows that the technology of fuel cell electric vehicles has made a breakthrough in general. Judging from the price of Mirai, fuel cell electric vehicles are getting closer and closer to practicality.

fuel cell electric vehicle