Research On Transposition Types And End Connection Of Strands In Stator Multi-turn Bars Of AC Electrical Machine

Induction motor is the important equipment in electric power production and industrial production.With the growing capacity of induction motor,the losses of various parts in electrical machine are increasing.In particular,the increased circulating current losses causes the stator bars to be partially overheated,which seriously threaten the safe operation and service life of the motor.Therefore,how to reduce the circulating current losses becomes a key issue in the windings design of induction motor.According to the generation mechanism of the circulating current losses,the paper studies the transposition types and end connection methods of the stator bars.The paper calculates the strand losses of the bow-shaped and the N-shaped transposition types and makes comparison and analysis of two different transposition types according to the calculation results.The paper also calculates the strand current and circulating current losses of R-connection and T-connection by analyzing the connection methods between different groups.By analyzing the effects on the magnetic field of different connection methods between strands groups,the paper proposes a new type of end connection method.As a result,the distribution of strand current in the stator multi-turn bars is more balanced,the circulating current losses of stator multi-turn bars are reduced.Because of the complexity of three-dimensional physical modeling of stator multi-turn bars and the problem on long time of the artificial modeling,low efficiency and poor quality,the paper writes the automatic generation program of 3D physical model,including 360°transposition,inadequate 360°transposition,void transposition and extended transposition.The program greatly shortens the time for 3D modeling,improves the quality of modeling,and creates a parametric modeling method for three-dimensional physical model of stator multi-turn bars.