Research On Magnetic Network Modeling And Torque Of Amorphous Alloy Axial Flux Hybrid Excitation Motor

Permanent magnet motors are widely used in wind power generation,new energy vehicle driving and other fields due to the compact structure,high efficiency,high torque density and power density.However,the magnetic field produced by permanent magnet is fixed,which limits the application of permanent magnet motors.In order to compensate the weakness of permanent magnet motor to expand the speed range,a hybrid excitation motor structure is proposed.Hybrid excitation motor has the advantages of permanent magnet motor and excitation motor,so the structure is complex.Firstly,the hybrid excitation structure and the topological structure are analyzed.A new type of amorphous alloy axial flux hybrid excitation motor is proposed according to the parameters of an axial flux permanent magnet prototype.The motor is divided into permanent magnet region and electric excitation region according to the excitation method.The permanent magnet region is with single stator and double rotors structure,and the electric excitation region is with multi-disk structure,which reduces the amount of amorphous alloy materials and improves the stator cooling conditions.The main structure parameters of the motor are given preliminarily.Secondly,a transient equivalent magnetic network model is established by combining the sub-domain method in the permanent magnet region of the amorphous alloy axial flux hybrid excitation motor.The saturation of the edge position at the top of the stator teeth is considered in the equivalent magnetic network model.The calculation speed is rapid based on the magnetic equivalent network which structure is simple.In the electric region,the complete magnetic equivalent network is established.Based on the models above,the magnetic field distribution and electromagnetic characteristics of hybrid excitation motor is obtained and analyzed.The correctness of the magnetic equivalent network model is verified by the finite element method.Finally,the effects of air gap length,slot width and permanent magnet pole arc coefficient on hybrid excitation motor are calculated and analyzed based on the equivalent magnetic network model.Maxwell tensor method is used to calculate the cogging torque of different slot widths in permanent magnet region.The electromagnetic torque of the motor under load is analyzed by finite element software.To solve the problem of large torque ripple in the excitation region,a double-layer staggered structure is proposed,which reduces the torque ripple in the excitation region and improves the stability of the motor evidently.