Analysis of Copper Loss of Permanent Magnet Synchronous Motor With Formed Transposition Winding

In recent years, the hairpin winding flat wire motor has received more and more attention because of its high power density and high torque, but the problem of increased AC copper loss caused by the increase of its wire diameter has restricted the use of the motor. Aiming at the problem of large AC copper loss in hairpin winding flat wire motors, this paper introduces the use of formed transposition windings into permanent magnet synchronous motors. Through analysis and comparison, the transposition bar suitable for permanent magnet synchronous motor is determined, and a method of inter-turn transposition that can improve the slot full rate of the motor is proposed. Taking a 223kW permanent magnet synchronous motor as an example, the transient field of the stator bar under 360° transposition was calculated by using the field-circuit combined three-dimensional(3-D) finite element method. By calculating the data, combined with the AC copper loss calculation method of the formed transposition winding given in the article, the distribution of the DC copper loss, eddy current copper loss and circulating copper loss of the motor is obtained. Compared with hairpin windings, the use of formed transposition windings can reduce the AC copper loss of the motor to a certain extent, the feasibility of using the formed transposition winding in the permanent magnet synchronous motor is verified.