Study On The Loss Of The Rare-earth Coreless Permanent Magnet Motor

The rare-earth coreless permanent magnet(PM)motor is a highly efficient novel motor,It has been used to chang the conventional structure of silicon steel sheet andwound stator,Because the inductor of the coreless armature is small,the core of hysteresis loss and eddy current loss is eliminated.Cogging effect is avoided because of the brushless?undamped?non-alveolar.Due to restriction on craft of the rare-earth coreless PM motor.In most cases,the rare-earth coreless PM motor is manufactured into the flat plane,no iron core and axial magnetic field permanent magnet motor(SCAFPM),and because of the compact structure,short axial size,high power density and considerable operating efficiency,the motor is widely used in various fields including electrical vehicle,CNC machine,marine propulsion system and so on.But there exists to be overheating trouble,which decreases the operating efficiency.Therefore,it takes important significance and application value to study on both calculation and suppression method on eddy current loss of motor for the rare-earth coreless PM motor.In this paper,it conducts systematic research on the distribution of electromagnetic field,eddy current loss of the motor and the methods of reducing the eddy current loss for SCAFPM through theoretical analysis,finite-element analysis(FEA)and experimental verification.Firstly,the experimental results of electromagnetic distributions is acquired to provides the basis for calculation of the eddy current,which gets from the transient electromagnetic field analysis by establishing the 3-D electromagnetic finite element model.Then,the change rule of the eddy current loss on armature winding and PM are obtained by simulating on the eddy current loss in different conditions for the motor.In the end,the methods of reducing the eddy current loss of PM can be found out,the results can be given through simulation.By studying the electromagnetic distributions and the eddy current loss for SCAFPM,we conclude that different driving methods and working condition have a significant impact on the eddy current loss of the motor.The results show that PM segments and shielding layer make SCAFPM?s eddy current loss of PM can effectively reduce its eddy current loss.?PM segments plus shielding layer? is presented,according to simulation calculation and analysis,the method has certain feasibility.