Design And Loss Characteristics Of External Rotor Permanent Magnet Synchronous Motor For All-Electric Aircraft

The development of green aviation strategy has gradually become the consensus of all sectors of society,all-electric aircraft is an inevitable trend in the development of the aviation industry.Motor is a key part to realize the all-electric aircraft,due to the particularity of the working environment of all-electric aircraft,it is required that the drive motor should have high power density,high reliability,high efficiency and other performance.High power density motor will generate a lot of heat during operation,the space for driving the motor in the aircraft is limited,heat dissipation is difficult,local heating is serious,motor efficiency is reduced,and motor reliability is reduced,the key to studying the problem of motor heating is to accurately calculate the loss of the motor.In this thesis,an external rotor permanent magnet synchronous motor with a peak power of 40 k W and a continuous operating power of 10 k W is the research object,the main contents of the research are as follows:Firstly,external rotor permanent magnet synchronous motor is designed,including magnetic circuit structure,main dimensions,the structure parameters,a groove cooperates,permanent magnet stator slot type parameters,combined with the finite element simulation calculation,the electromagnetic field of the motor under the three operating conditions of no-load,continuous power and peak power is simulated and analyzed to verify the rationality of the motor design scheme.Secondly,based on the Epstein square circle method,the magnetic characteristics of three silicon steel sheet materials B35A230,B35A270,and B35A470 were tested,and the magnetization curves and loss curves of the three silicon steel sheets were obtained and compared.At the same time,in order to consider the influence of processing factors on the loss curve of silicon steel sheet,the magnetic characteristics of the B35A230 ferromagnetic material were tested by the ring sample method,and the loss curve at multiple operating frequencies was obtained,the loss curve measured by the ring sample method was carried out,regression analysis yields a set of loss coefficients with the smallest regression deviation ε,which provides support for the loss calculations below.Finally,according to the loss curve of the core test of the ring sample method,a core loss calculation model that can comprehensively consider the processing factors,the alternating and rotating magnetization methods and the harmonic magnetic field is used to calculate the stator core loss of the motor at no load,sinusoidal power supply and PWM power supply mode.According to the distribution law of the magnetic field lines of the stator teeth and yoke,the motor is divided into seven solution regions,considering the influence of two magnetization methods and harmonics at different areas of the stator core,the iron loss of each area can be calculated and superimposed to get the iron loss value of the entire iron core.At the same time,the permanent magnet eddy current loss is calculated,and the influence of permanent magnet axial segmentation,circumferential segmentation,slot width,air gap length and pole arc coefficient on the eddy current loss is analyzed.