Electromagnetic Design Research On High Power Density Motor In Electric Vehicle

With the large-scale development of the automotive industry, people benefit a lot. While people enjoy the convenience, automotive industry also causes the oil energy crisis and directly pollutes the environment. Under this background, Environmental friendly, high efficiency and energy saving of electric vehicles has received the widespread attention. In the future, the electric vehicles will play more and more important role in the field of automobile. With the development of power electronics technology and maturity of control methods, control effect of asynchronous motor has been able to well meet the demand of driving motor in electric vehicle. Moreover, asynchronous motor has the advantages of simple structure, low cost and easy to realize high speed. So the asynchronous motor has become one of the most important drive motor applied in electric vehicle. The power density of asynchronous motor must be high due to the limitation of space. In China, the power density of asynchronous motor is low and the technology is relatively backward. The common high power density motor(power density is slightly larger than 0.8 kW/kg) is hard to meet the requirements of the driver system. Therefore, the research of higher power induction motor in electric vehicle is very necessary and urgent. The article mainly completed the following research.First, the characteristics of high power density motor were presented. In order to increase the power density, the motor was improved in the aspects of stator and rotor material selection, winding process, ways of motor cooling and lightweight design.Second, the motor parameters were calculated with the equivalent magnetic circuit method, including the size of stator and rotor, performance parameters and winding wire gauge. And the performance curves of the motor was simulated by the motor design software. The effect on the motor performance of different material of stator rotor was simulated by the means of magnetic circuit calculation software.Third, the working characteristic of motor and the flux density distribution were analyzed using the finite element method, verifying the accuracy of the equivalent magnetic circuit method. At the same time, the simulation analysis of the effect of the iron core length, air gap length and the number of rotor slot on the motor performance was completed. In the aspect of lightweight design, without affecting the magnetic case, some holes were dug in the rotor core to reduce the weight of the motor and increase the motor power density. And the method was simulated with the finite element software.Finally, temperature field distribution of the motor without any cooling measures and the motor applied pouring sealant technology were simulated with the electromagnetic-temperature field coupling analysis method. Through the temperature comparison between the two kinds of motor, it verifies that pouring sealant in stator winding end process can speed up the motor cooling and reduce the temperature to an extent.