Analysis Of Rotor Loss And Stress Field Of Amorphous Alloy High-speed Permanent Magnet Motor

Compared with the traditional motor,the amorphous alloy high-speed permanent magnet motor has many advantages.such as small size.higher power density and higher operating efficiency.As a new type of motor,it has a broad application prospect in many industrial fields.such as flywheel energy storage.micro gas turbine power generation system.precision machining machine.hybrid vehicle and oil and gas exploration.Because high-speed permanent magnet motor needs to work in high speed state for a long time.there are some outstanding problems to be studied and improved.If the air gap flux density harmonics are large,the induced electromotive force waveform of the high-speed motor will be distorted,which will directly affect the output torque and increase the eddy current loss of the rotor.The increase of the eddy current loss of the rotor directly leads to the increase of the temperature rise of the rotor,which will not only lead to the decrease of the magnetic properties of the permanent magnet steel.but also lead to the increase of the stress on the magnetic steel sheath of the rotor,damage the rotor structure and affect the normal operation of the high-speed motor.Based on these problems,this thesis studies and optimizes a 36000r/min,12KW four pole amorphous alloy high-speed permanent magnet motor from electromagnetic field,temperature field to stress field.Firstly,a two-dimensional electromagnetic field model of the amorphous alloy high-speed permanent magnet motor is established in the time-step finite element simulation software.Based on the Halbach array and the combined pole optimization method,the rotor of the motor is optimized.The orthogonal test table is established by Taguchi method to find the optimal combination of the thickness of the magnetic steel,the magnetization angle,the angle of the weak magnetic energy product and the coercive force of the permanent magnet,which effectively improves the efficiency of the design The fundamental amplitude of air gap flux density and the harmonic distortion rate are reduced in the no-load state of the motor,so as to improve the air gap flux density waveform and improve the operation efficiency of the motor,then the optimal scheme is compared with the rotor structure of parallel magnetization and three-stage parallel magnetization of each pole,and the rationality of the optimal method is verified.Secondly,based on the finite element method,the loss of the optimized amorphous alloy high-speed permanent magnet motor model is calculated.The rotor sheath is made of four materials:aluminum alloy,titanium alloy,non magnetic alloy steel and carbon fiber.The results show that the carbon fiber material can effectively reduce the eddy current loss of the rotor.The results of loss calculation and electromagnetic field calculation are introduced into the three-dimensional temperature field of the motor to calculate the temperature distribution of the motor with four kinds of sheath materials,among which the aluminum alloy sheath motor has the highest temperature rise,especially on the contact surface of the rotor magnetic steel sheath.However,the temperature rise of carbon fiber sheath motor is relatively low,especially the temperature rise of rotor part is significantly lower than that of other three kinds of materials,which shows that carbon fiber sheath can effectively reduce the temperature rise of rotor and protect the magnet steel from demagnetization due to the high temperature rise.Finally,the calculation results of electromagnetic field and steady-state thermal module are introduced into the three-dimensional model stress field,and the stress of the contact surface between the magnetic steel of the motor rotor and the sheath of four kinds of materials is analyzed by the magneto thermo solid coupling field,and the calculated contact surface stress is compared with the yield strength of the sheath material,and the stress safety coefficient under the sheath of different materials is obtained.The results show that the stress safety factor of the contact surface between carbon fiber sheath and magnetic steel is the highest,and the influence trend of interference on the rotor stress is analyzed simply.The research of this thesis is of great significance to the optimal design of the rotor,the reduction of the eddy current loss,the temperature rise and the stress of the contact surface of the magnetic steel sheath.