Analysis And Calculation On AC Loss And Temperature Rise For Stator Winding Of Permanent Magnet Synchronous Motor

In order to overcome the eddy current loss and proximity effects caused by the hairpin winding,each layer of stator winding consists of multiple rectangular copper strands.However,because multiple rectangular strands are located in different magnetic leakage fields,there is an induced electromotive force difference between strands,and the resulting circulating current loss problem cannot be ignored.Therefore,this thesis conducts research work on the calculation of AC loss,grouping connection method,strand transposition,and transposition winding temperature rise for permanent magnet synchronous motor.Analyze and calculate the losses of permanent magnet synchronous motor,and a two-dimensional field circuit coupling model of the permanent magnet synchronous motor is established.A calculation method for the AC loss of the stator winding is gived.The DC copper loss,eddy current loss,and circulating current loss are analyzed and calculated,and the results provide a basis of weakening the AC loss of the winding.Further calculation of the stator iron loss and permanent magnet eddy current loss,two important heat sources,establish the foundation for the study of permanent magnet synchronous temperature rise.Methods for reducing AC loss in winding are studied,and a new TI-type connection scheme is proposed for end-winding.Two-dimensional field circuit coupling model are established for traditional grouping connection and new TI-type connection,and finite element method is used to analyze and calculate the strands current,circulating current loss,and AC loss values when the winding use different grouping connection.The variation law of stator winding AC loss for different connection are compared and analyzed,which verifies the effectiveness of the new TI-type connection method.Further exploration is conducted on the stator winding transposition method.By establishing three-dimensional numerical simulation models for 360° transposition,empty 0.5 strand transposition,and empty 1 strand transposition.The circulating current loss and AC loss of the winding are analyzed and calculated for three transposition structures,and the influence of strand transposition on the AC loss of the winding is obtained,and the optimal transposition method of the winding is determined.The temperature field models of no transposition,360° transposition,empty 0.5strand transposition,and empty 1 strand transposition are established,and the temperature field calculation under natural cooling is performed to obtain the temperature rise distribution laws of the stator and rotor core,stator winding,and permanent magnet under different transposition structures of the permanent magnet synchronous motor.By comparing and analyzing the temperature distribution of the axial section of the winding before and after the strand transposition,the influence of transposition structures on the temperature distribution of the winding is revealed.