The drive motor has independently developed products that meet all kinds of new energy vehicles, and some main performance indexes have reached the international advanced level, but there is still a certain gap with foreign countries in peak speed, power density and efficiency. Peak speed is an important indicator of motor, and it is also the most obvious indicator of the gap between domestic motor and foreign motor. The peak speed of most permanent magnet synchronous motors in China is below 10000rpm, while it is basically above 10000rpm abroad. Domestic motors can basically reach the international level in power, but there is a weight disadvantage under the same power condition, so there is a big gap in power density. The power density of permanent magnet synchronous motors in China is mostly in the range of (1~2)kw/kg, which is far from the target value of 3.5kw/kg in 2020. In terms of motor efficiency, the highest efficiency of domestic motors has reached 94%~96%, reaching the level of Siemens, Bosch and other enterprises. However, there is still a certain gap in high-efficiency areas, such as the proportion of areas with system efficiency greater than 80%. The high efficiency area of the motor is concentrated in 70%~75%, and the foreign motor basically reaches 80%. In addition, the cooling mode of the motor has gradually developed from natural cooling to water cooling. The domestic motor is mainly water cooling, and the advanced motor abroad has developed into oil-cooled motor.
According to the technical roadmap of energy-saving and new energy vehicles, the main development trends of drive motors are: integration-integration with vehicle electronic controller, electromechanical coupling integration; High efficiency-improve power density and reduce cost; Intelligent-Cooperate with vehicle sensors and controllers to continuously improve the performance of the drive system.
The main classification of 1.2 drive motors has a long history. 1885, nikola tesla of the United States applied for the patent of induction motor, and then various motors were continuously derived, which were widely used in all walks of life. Below, the driving motors are classified according to their power sources: Figure 1 As can be seen from Figure 1, there are many types of motors, each of which has its own characteristics. Combined with the market, the performance of mainstream drive motors is simply compared, as shown in the following table: Table 1. Combined with the analysis of complex working conditions such as frequent start and stop, acceleration and deceleration, load climbing and continuous high-speed and low-speed crawling of new energy vehicles, AC asynchronous motor and permanent magnet synchronous motor have obvious advantages in volume, mass, power density and efficiency, and gradually become the mainstream choice of new energy vehicles.
2 performance requirements of new energy vehicles for drive motors. Cars powered by internal combustion engines and drive motors began to compete as early as19th century. After continuous development, optimization and competition, electric vehicles have become a few models because of their shortcomings such as slow charging and short battery life, while internal combustion engines have finally dominated the world because of their advantages such as stability, reliability and convenient refueling.
(Photo/Text/Photo: Pacific Auto Network Q&A called Beast)