Research On The Electromagnetic And Thermal Performance Of Toothed Winding External Rotor Motor

External rotor toothed winding permanent magnet synchronous motor has the advantages of high power factor,high power density and high efficiency,which makes external rotor permanent magnet synchronous motor is widely used in electric vehicles,aerospace and other fields.But because of the special pole groove fit of the gear winding motor,the gear winding contains a large number of magnetomotive force harmonics.Compared with the asynchronous operation of the rotor,the rich air gap space harmonics will cause motor vibration,and even affect the running performance of the motor.In this paper,a 10-pole 12-slot permanent magnet synchronous motor with rated power of 3k W is taken as the research object,the design method of tooth coil winding is given,and the winding harmonic magnetomotive force,loss and temperature rise of the motor are studied.The design idea and arrangement principle of toothed winding of permanent magnet synchronous motor are put forward,and the design method of toothed winding is given.Three kinds of phase winding of toothed winding are designed,including 60°phase winding,120° phase winding and big or small phase winding.Based on the phase winding,the finite element model of two-dimensional transient field of permanent magnet synchronous motor with external rotor toothed winding is established,and the distribution of magnetic field and electromotive force is analyzed respectively,so as to determine the best arrangement method of permanent magnet synchronous motor toothed winding.According to the actual parameters of the motor,the analytical expression of the harmonic magnetomotive force generated by the armature winding is derived based on the phasor synthesis method,and the distribution law of the harmonic magnetomotive force is summarized.The method of the star-triangle connection double-layer winding structure and the three-layer unequal turns spatial displacement winding structure to weaken the harmonic magnetomotive force is proposed.The principle of the weakening method is analyzed,and the effectiveness of the method is demonstrated by simulation calculation.At the same time,the impact of weakening methods on the no-load and load characteristics of the motor is analyzed.The two-dimensional transient field simulation model of the external rotor permanent magnet synchronous motor with different winding structures is established,and the calculation methods of motor iron loss,winding copper loss and eddy current loss of permanent magnet are studied.The influences of star-star connection doublelayer winding structure,star-triangle connection double-layer winding structure and three-layer unequal turns spatial displacement winding structure on various motor losses are analyzed.On the basis,the three-dimensional temperature field simulation model of the external rotor permanent magnet synchronous motor with different winding structures is established.Heat source settings are determined according to various losses,and the temperature distribution rules of each component of the motor with different winding structures are obtained.