Thermal Management And Rotor Dynamics Of High Speed Permanent Magnet Motor With Amorphous Alloy

High speed permanent magnet motor has been widely applied in industrial automation,military equipment,aerospace and other related fields.Especially in recent years,the rapid rise of electric vehicles,high speed permanent magnet motor as a key component of vehicle power system has attracted a lot of attention.High speed permanent magnet motor has many advantages such as high power density,small volume and high efficiency.However,its high loss density and high dynamic demand restrict the development of high speed permanent magnet motor.With the continuous emergence of new materials,it is possible to improve the performance of motor greatly.Amorphous alloys as new emerged stator materials have great advantages in motor loss,and there are few researches on amorphous alloy high-speed permanent magnet motors.In this paper,the thermal management and rotor dynamics of a high speed permanent magnet motor for amorphous alloy are discussed:First,based on a 40 kW amorphous alloy high speed permanent magnet motor,the loss of motor is systematically analyzed,including theoretical analysis and simulation research of iron loss,copper loss and eddy current loss.At the same time,the friction loss of the high speed permanent magnet motor can not be ignored.The fluid field simulation of internal ventilation system for high speed permanent magnet motor is carried out,and the cause of fluid field distribution in internal air duct is analyzed.According to the empirical formula,the air friction loss is compared with the simulation results,and the influencing factors of air friction loss are simulated and analyzed.Secondly,amorphous alloy high speed permanent magnet motor has large loss density and poor heat dissipation.This paper adds the dimpled structure to the inside and outside surface of the traditional straight channel to enhance the wall heat transfer.Based on the theory of fluid mechanics and the method of simulation and analysis,the temperature distribution of the water cooling system is studied,and the dimpled water-cooling structure is optimized.Based on tree network theory,a tree-like water cooling system is proposed,and the cooling effect is compared with that of straight channel water cooling system and spiral water cooling system under the same heat dissipation area,and the cooling effect of the system is analyzed.In addition,the rotor magnetic steel of the amorphous alloy high speed permanent magnet motor is easily damaged at high speed.In this paper,an analysis model of the rotor strength is put forward,and the strength of the carbon fiber-reinforced plastics(CFRP)sheath rotor is analyzed.At the same time,the finite element method and analytical method are used to analyze the rotor strength of the high speed permanent magnet motor of amorphous alloy,and the stress contrast is compared with the traditional model which does not consider the filler.Finally,aiming at the dynamic problem of high speed permanent magnet motor rotor under high speed rotation,the modal analysis and critical speed analysis of high speed permanent magnet motor rotor under free state,load state and gyroscopic effect are carried out.Critical speed of motor rotor under different bearing stiffness is analyzed,and motor rotor start-up transient is analyzed.