Research On High Power Density Permanent Magnet Synchronous Motor For All Electric Aircraft

All electric aircraft works at high altitude with complex working environment,low temperature,low pressure,strong light,low humidity,and obvious convection effect.All electric aircraft with limited space and compact aircraft structure.Higher power density is required for permanent magnet synchronous motor used to drive propellers.In addition,there are many special requirements for the propeller driven motor which is suitable for high altitude flight.In the process of designing the motor,it is necessary to make proper adjustment on the structure to meet the performance requirements of the motor.This paper has done some related research of permanent magnet synchronous motor for all electric aircraft:In this paper,the performance index of the motor is combined with the requirement of the power density of the electric machine and the limitation of the size.The magnetic circuit,the structure of the winding,the coordination of the pole slot and the parameters of the motor are designed.The 16 pole 24 slot,20 pole 24 slot and 22 pole 24 slot matching scheme were designed,the basic size parameters of the three schemes are consistent.The power density of the three schemes is no less than 4.59 k W/kg,which meets the requirement of high power density.The electrical load of all electric aircraft high power density permanent magnet synchronous motor is generally larger,armature reaction is obvious,cogging torque and electromagnetic torque ripple of motor are larger.In order to reduce the slot torque of the motor and suppress the electromagnetic torque ripple,the influence of the structural parameters on the cogging torque and electromagnetic torque ripple of the three schemes is analyzed from the angle of the width of the slot,the height of the slot and the shape of the permanent magnet.Considering the direct effect of the magnetization method on the air gap magnetic density,the effects of the parallel magnetization and the Halbach magnetic force line distribution,the air gap magnetic density,the cogging torque and the electromagnetic torque are analyzed in detail with the combination of 16 pole and 24 slot as an example.The larger electric load causes obvious armature reaction,and the magnetic field harmonic produced by armature reaction produces larger eddy currents in the permanent magnet.The larger load current,the more serious loss of drive motor.Theoretical analysis and numerical calculation of loss of iron loss and permanent magnet eddy current loss of motor under rated load condition.The influence of stator slot shape and material on iron loss is analyzed.The influence rule of circumferential subsection and axial section of permanent magnet on eddy current loss is explored,so as to provide reference for restraining eddy current loss of permanent magnet.In this paper,when the motor runs with rated load,the loss of the motor is large,causing the motor temperature to rise greatly.In order to find out whether the internal temperature rise of the motor is within the limit temperature range of the material,the three-dimensional transient temperature field model of the motor is established,the distribution of the heat source of the motor is determined,the basic law of the heat conduction of the motor is analyzed,the calculation method of the equivalent thermal conductivity of each part of the motor and the calculation method of the heat dissipation coefficient at the end surface of the motor is given,and the calculation of the electric power is calculated.The relationship between the transient temperature field and the limit temperature rise is confirmed,so as to ensure the continuous operation of the motor.