Analysis of the most popular electric vehicle driv

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Analysis of China's electric vehicle drive motor and its controller industry

1 Drive motor type and its development

drive motor is the key component of electric vehicle, which directly affects the power and economy of the whole vehicle. The drive motor mainly includes DC motor and AC motor. At present, AC motors are widely used in electric vehicles, mainly including asynchronous motors, switched reluctance motors and permanent magnet motors (including brushless DC motors and permanent magnet synchronous motors). See Table 1 for the main characteristics of each type of motor

the development trend of vehicle motor is as follows: (1) permanent magnetization of motor body: permanent magnet motor has the advantages of high torque density, high power density, high efficiency, high reliability and so on. China has the most abundant rare earth resources in the world, so high-performance permanent magnet motor is an important development direction of vehicle drive motor in China

(2) motor control Digitization: the emergence of special chips and digital signal processors promotes the digitization of motor controllers, improves the control accuracy of motor systems, and effectively reduces the volume of the system

(3) motor system integration: through electromechanical integration (motor and engine integration or motor and gearbox integration) and controller integration, it is conducive to reducing the weight and volume of the drive system and effectively reducing the manufacturing cost of the system

2. Foreign development according to foreign data introduction

in recent years, electric buses developed in the United States and Europe mostly use AC asynchronous motors. See Table 2 for the technical parameters of typical foreign products. In order to reduce the vehicle weight, the motor shell is mostly made of cast aluminum. The constant power range of the motor is wide, and the maximum speed can reach 2 ~ 2.5 times of the base speed

from near to LED lighting in Japan, polycarbonate, a high-performance plastic material, is widely used because of its light weight, high transparency, firmness and easy molding. Most electric vehicles that have come out in recent years use permanent magnet synchronous motors. The power level of the product covers 3 ~ 123kw, the constant power range of the motor is very wide, and the maximum speed can reach 5 times of the base speed. See Table 3 for the overview of electric vehicle drive motors developed in Japan in recent years

3. Development status in China

(1) AC asynchronous motor drive system China has established a development platform for asynchronous motor drive system with independent intellectual property rights, forming a development, manufacturing, testing and service system for small batch production; The product performance basically meets the needs of the whole vehicle, and the high-power asynchronous motor system has been widely used in all kinds of electric buses; Through demonstration operation and small-scale market application, the reliability of the product has been preliminarily verified

(2) the switched reluctance motor drive system has formed the ability of optimal design and independent research and development. Through reasonable design of motor structure and improvement of control technology, the product performance basically meets the needs of the whole vehicle; Some companies have an annual production capacity of 2000 sets, which can meet the needs of small batch supporting. At present, some products have been supported by vehicle demonstration operation, and the effect is good

(3) brushless DC motor drive system domestic enterprises have effectively improved the product performance of Brushless DC motor through reasonable design and improved control technology, which basically meets the needs of electric vehicles; It has preliminary electromechanical integration design ability

(4) the permanent magnet synchronous motor drive system has formed a certain R & D and production capacity, and developed different series of products, which can be applied to all kinds of electric vehicles; Some technical indicators of the products are close to the international advanced level, but there is still a certain gap between the overall level and foreign countries; Basically have the ability of integrated design of permanent magnet synchronous motor; Most companies are still in small-scale trial production, and a few companies have invested in establishing special production lines for vehicle drive motor systems

(5) permanent magnet motor materials the main materials of permanent magnet motors are neodymium iron boron magnetic steel, silicon steel, etc. Some companies have mastered the overall magnetization technology of first assembling and then magnetizing the rotor magnet of the motor. The maximum working temperature of Nd-Fe-B permanent magnet developed in China can reach 280 ℃, but the technical level still lags behind that of Germany and Japan

silicon steel is an important magnetic material for manufacturing motor iron core, and its cost accounts for about 20% of the motor body. Its thickness has a great impact on iron consumption. Japan has produced 0.27mm silicon steel sheet for vehicle motors, while China has only developed 0.35mm silicon steel sheet

(6) the position/speed sensors for motor controller, the key components of motor controller, are mostly resolvers. At present, imported products are basically used. Some companies in China have the R & D and production capacity of resolvers, but the accuracy and reliability of products are still far from that of foreign countries. IGBT basically depends on imports and is expensive. Domestic vehicle IGBT is still in the research stage

4. The main problems of drive motors and their controllers in China

(1) the R & D ability of motor raw materials and controller core components is weak, and they rely on imports, such as silicon steel sheets, motor high-speed bearings, position/speed sensors, IGBT modules, etc. The high cost of imported products affects the industrialization of motor system

(2) there is a large gap between the electromechanical integration level of vehicle motors in China and foreign countries. The controller has low integration and relatively large volume and weight

(3) China's automotive motor system is still in its infancy, with backward manufacturing technology and lack of automatic production lines, resulting in poor product reliability and consistency. The industrialization scale is small and the cost is high

(4) at this stage, the national standards for electric vehicle drive motor system are few and imperfect. For example, different types of motor systems adopt the same detection standard, and lack of reliability and durability evaluation methods

vehicle controller

1 Foreign development

the development of vehicle controller includes software and hardware design. The core software is generally developed by vehicle manufacturers, and the hardware and underlying driver software can be provided by auto parts manufacturers

(1) foreign vehicle controller technology tends to be mature. Most foreign automobile enterprises have accumulated sufficient experience in the field of electric vehicles, with high maturity of control strategy and good fuel saving effect of the vehicle. The reliability of the controller product has been verified by the field test of the practical force produced by the two thrust cylinders on the automatic car

(2) automotive electronic parts enterprises actively carry out research and development and production of vehicle controllers

various auto electronic parts giants, such as Delphi, continental and Bosch group, have carried out research and development and production of vehicle controllers. Some automobile design companies also provide vehicle controller technical solutions for vehicle manufacturers, such as AVL, FEV, Ricardo, etc. there are also many successful cases in the field of electric vehicle controller

(3) controllers are becoming increasingly standardized. The standardization of controllers has attracted the attention of relevant enterprises. The global automobile manufacturers, component suppliers and electronic, semiconductor and software system companies jointly established the automobile open system architecture alliance, formed the AUTOSAR (Automobile Open System Architecture) standard, simplified the development process and made the ECU software reusable, which is a trend of controller development

2. The development status of our country

in the "863" plan, the vehicle controller in our country is mainly based on Colleges and universities, such as Tsinghua University, Tongji University, Beijing University of technology, etc. at present, we have preliminarily mastered the software and hardware development ability of the vehicle controller. The product has relatively complete functions, which can basically meet the needs of electric vehicles when the interval between the two chucks changes, and has been applied to sample vehicles and small batch products. Some vehicle enterprises cooperate with foreign companies, such as FEV and Ricardo. Through joint development, absorb relevant foreign technology and experience, and enhance the ability of independent development. At present, all manufacturers basically master the development technology of vehicle controller, but the technical accumulation is limited and the level is uneven

there is a certain gap between the hardware level of controllers in China and foreign countries, and the industrialization ability is relatively insufficient. Most enterprises prefer to choose foreign vehicle controller hardware suppliers when launching mass-produced electric vehicle products. In addition, the basic hardware and development tools of the controller basically rely on imports

generally speaking, there is still a large gap between the technical level and industrialization ability of controller products and foreign countries

3. The main problems of vehicle controllers in China

(1) most of the application software remain in the function realization, and the software diagnosis function, vehicle safety control strategy and monitoring function need to be optimized and improved

(2) China's electric vehicles are in the stage of sample vehicle development and demonstration operation, and the basic database is not perfect, which affects the design level of vehicle controllers

(3) some enterprises can introduce relevant equipment and software according to the V-shaped development process (a software and product development tool), and generally use general development tools for secondary development; The existing tools focus on early-stage development and lack tools for production and after-sales service, which is not conducive to the industrialization development of products

(4) domestic enterprises can complete the hardware structure design of vehicle controller, but due to the relatively weak chip integration force and poor manufacturing capacity in China, there is still much room for improvement in reliability and stability

(5) at present, the definitions of controller interfaces and network communication protocols in vehicle enterprises are different from each other, resulting in poor versatility and reusability between controllers, which is not conducive to the industrialization and scale of controllers

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