Magnetic Field Analytical Modeling And Control Strategy Study Of Hybrid Excitation Amorphous Alloy Axial Flux Motor

The axial flux permanent magnet motor has the characteristics of high efficiency,high torque density and high power density,and has a wide range of applications in the fields of wind power,new energy car and aerospace.However,due to the fixed magnetic field of the permanent magnet and the long equivalent air gap of the axial flux permanent magnet motor,it is difficult to adjust the magnetic field of this type of motor,limiting the further application of this type of motor.In order to improve the problems of axial flux permanent magnet motor,the structure of the hybrid excitation axial flux motor can be adopted.Aiming at the uneven distribution of the 3-D magnetic field of the hybrid excitation axial flux motor,an analytical modeling method for the air gap magnetic field based on conformal mapping method is proposed.In order to reasonably configure the armature current and electric excitation current of this type of motor,reduce motor loss and increase torque output,the minimum copper loss control strategy of this type of motor is deduced..First,one topology structure of the hybrid excitation axial flux motor is introduced,and the Structural features,magnetic modulation mechanism and operating principle of this motor are analyzed.The influence of the soft magnetic pole width on its magnetic modulation performance and torque characteristic is studied,and the preliminary design parameters of the motor are given.After that,by the Ansys Maxwell software,the three-dimensional magnetic field distribution is simulated and calculated.Then,based on the conformal mapping method,an quasi 3-D analytical model of the air gap magnetic field of the hybrid-excitation axial flux motor is established,and the effects of stator slotting,rotor salient poles and permanent magnet end effects are considered.The no-load magnetic field,armature reaction magnetic field and electric excitation magnetic field are calculated analytically.The analytical calculation results and the finite element calculation results are compared and analyzed.Based on the solution of the armature reaction magnetic field of the motor,the armature inductance parameters are calculated analytically and compared with the results of the finite element calculation.A prototype experiment is performed on a 7k W axial flux permanent magnet motor at 1000 r/min to verify the accuracy of the magnetic field analytical model.Finally,based on the analysis of the operating principle and the solution of the inductance parameters,the flux equation,voltage equation,torque equation and motion equation of the motor are introduced.The vector control model of the motor was built in Matlab Simulink software.In order to improve the torque output capacity and efficiency of the motor,the minimum copper loss control strategy is proposed.The proposed control strategy is simulated and analyzed in the Matlab Simuink software environment,where the motor current and copper loss is compared with that of i_d=0 control strategy,to prove the effect of this control strategy on the efficiency improve of the motor.