| The energy consumption of the vehicle is proportional to its inherent mass,so the lightweight and miniaturization of the driving system is one of the key points of the vehicle lightweight.As one of the core components of the drive system,the motor needs to meet the power requirements of the vehicle under different working conditions in a limited space.With the gradual acceptance of the technical route of compact deceleration motor drive system,the high-speed and high-power density motors matched with it will occupy an obvious advantage in the electric vehicle market.Compared with permanent magnet motor,cage induction motor has more stable electromagnetic performance,simpler and more reliable rotor structure,and is very suitable for high-speed operation.Moreover,it has the advantages of low material and manufacturing costs,wide speed range and simple control device.In this paper,several ways of increasing power density of motor were put forward,and the main characteristics of high power density motor were summarized,then a design scheme of high power density cage asynchronous motor was presented for some electric vehicle drive motor system,with the problem of low power density,which limits the power performance of the whole vehicle.The electromagnetic and working performance of the motor were analyzed,the loss density of each part of the motor and the electromagnetic force in air gap under rated load,and the loss density of each part of the motor under different working conditions were obtained by calculating the transient electromagnetic field.Loss density based on the results of electromagnetic field was coupled to the 3D temperature field model as heat sources.The distribution laws of slender water-cooled motor temperature were obtained by calculating the temperature field on the rated load and other different electric vehicle conditions.The results show that the heat dissipation ability of the motor is good,and the temperature rise under each working condition is within a reasonable range,it can be operated for a long time.The characteristic frequencies and orders of electromagnetic force wave were deduced by analytic method.The space electromagnetic force and time-varying electromagnetic force were calculated by finite element method,and the harmonic analysis and frequency spectrum analysis were carried out respectively.The three-dimensional finite element model was established,the modal analysis and the rotor static analysis of the motor were carried out.Then the time-varying electromagnetic force at rated load was loaded on the three-dimensional model as excitation.The electromagnetic vibration of the motor was calculated,and the vibration displacement curve and its spectrum were obtained.The characteristic frequencies of electromagnetic force and vibration displacement were compared and analyzed with the natural frequencies of the motor,and the rationality of the motor design is verified. |
