Research On Design Method For Formed Winding Of Permanent Magnet Synchronous Motor

Winding design is one of the key issue in the design of permanent magnet synchronous motors.Permanent magnet synchronous motors mainly have two winding types,namely round wire winding and flat wire winding.Flat wire winding motors are widely used in various high power occasions due to their high slot fill factor and strong heat dissipation ability.However,with the gradual development of aerospace and electric vehicle traction motors in the direction of high frequency and high speed,the problem of large eddy current loss in the existing flat wire windings has become more and more serious.The formed winding consisting of multiple parallel flat strands can effectively reduce the eddy current loss in the existing flat winding.The formed winding is a new winding technology of permanent magnet synchronous motor,which has many advantages,such as high slot fill factor,strong heat dissipation capacity,and low winding eddy current loss.It is of great significance to investigate the formed winding permanent magnet synchronous motors.This dissertation takes a 60 k W permanent magnet synchronous motors as a research object to give the design method of the formed winding.And the arrangement method,the end connection method and the slot strands transposition structure of the formed winding are studied.Firstly,design method of the formed winding in permanent magnet synchronous motor is given,and three winding arrangement types of the formed winding are completed,including double-layered overlapping winding arrangement,double-layer wave winding arrangement and odd-even layered wave winding arrangement.The 2D field-circuit coupled finite element model of the formed winding in the permanent magnet synchronous motor is established.And the magnetic field,electric potential and loss distribution are analyzed respectively,which proves the rationality of the permanent magnet synchronous motor using the formed winding.The results also illustrate the necessity of weakening the circulating current loss in the formed windingSecondly,for the purpose of reducing circulating current losses,the end winding group transposition connection of the formed winding permanent magnet synchronous motor is analyzed,and the RI combined connection is proposed based on the analysis of the existing R connection and I connection.The 2D field-circuit coupling finite element model of the end group transposition winding is established.And the circulating current loss of the end R connection,I connection and the proposed RI combination connection are calculated,respectively.The results show that the RI combined connection has the best effect on reducing the circulating current loss,which verifies the effectiveness of the proposed RI combined connection to reduce the circulating current loss.Finally,in order to further reduce the circulating current loss,the slot strands braided transposition methods of the formed winding in permanent magnet synchronous motors are studied.The 3D field-circuit coupling finite element model of the slot strands braided transposition winding is established.And the circulating current loss distribution of strands with 360° complete transposition and 288°incomplete transposition are calculated,respectively.The results show that the 288°incomplete transposition has a better effect of reducing the circulating current loss.The slot strands braided transposition method to reduce the circulating current loss of the formed winding in permanent magnet synchronous motors is obtained.