Study On Eddy Current Loss Of Ironless Stator Axial Field Permanent Motor

The coreless magnetic field permanent magnet motor is a new type of motor with short axial dimension,high power density and easy assembly.The stator core structure reduces the overall quality of the motor and eliminates the traditional motor stator.In the hysteresis loss and eddy current loss,while reducing the cogging effect caused by the electromagnetic torque ripple;the use of high coercivity of NdFeB as permanent magnet material,making the motor compact,low speed operation smooth,high efficiency and vibration and noise significantly reduced;with the computers,CNC machine tools,industrial robots and other high-tech products and the rise of some special application system needs,the traditional motor performance has been unable to meet the requirements,coreless AFPM with its excellent characteristics began to gradually replace the traditional motors.But the motor's special structure and complex magnetic field make the problem of high temperature rise in the process of high-speed operation,so as to reduce the motor efficiency and affect the motor performance.Therefore,the electromagnetic field distribution and eddy current loss of the motor are analyzed and calculated as very necessary.In this paper,the electromagnetic field distribution of the coreless AFPM,the eddy current loss of the motor parts and the method of reducing the armature winding and the rotor eddy current loss are systematically analyzed by theoretical analysis,3D finite element simulation and 3D analytic method analysis.Firstly,the finite element model of 3D electromagnetic field of coreless AFPM is established,analyzing the distribution of electromagnetic field and air gap in the case of no-load and load,and the variation law of the back EMF with the increase of the rotational speed is simulated to provide the theoretical basis for calculating the eddy current loss of the motor.The 3D analytic method analysis is used to calculate the accuracy and correctness of the 3D model.Finally,the method to reduce eddy current loss of armature windings and rotors is put forward,and the conclusion is drawn based on the simulation results.In this paper,the eddy current loss of the coreless AFPM is analyzed,and the motor speed has a significant effect on the eddy current loss.In order to reduce the eddy current loss of the motor,the armature winding is multi-stranded and wound,and the rotor adopts the method of blocking and electroplating.When using the method of blocking structure of permanent magnets,the effect of reducing the eddy current loss by the horizontal block and the vertical block is analyzed,thus draw a better horizontal segmentation effect;When using the method of electroplating,the method is verified firstly,and creatively proposed "block + electroplating" to reduce the eddy current loss of the rotor,and finally study the thickness of the plating layer on the eddy current loss.