Analysis of core loss of three-phase induction motors equipped with concentric single-double layer star-delta winding

摘要

Although star-delta winding can improve the efficiency of motors because of a higher fundamental winding coefficient and lower harmonic winding coefficient. The requirement of turns ratio is very strict. If the turns ratio is not ideal, the core loss of the motor cannot be reduced, thus the efficiency will not be improved. In this paper, a design method for converting a star-delta winding of stator in small- and medium-sized motor into the concentric single-double layer star-delta (CSDLSD) winding is introduced and compared with a traditional delta winding and a star-delta winding. Besides, a method is provided to calculate the winding coefficients of the motors with CSDLSD winding according to the turns number per slot. Harmonic component of magnetic flux density in stator tooth and yoke is consequently reduced, combined with partial core loss calculation method, the core loss is decreased. In addition, the core loss in three-phase induction machines equipped with front three winding types is also been estimated and analyzed. To check the analysis validity, two-dimension (2-D) Finite element method (FEM) is applied on three cage induction motors equipped with different winding types but the same prototypes.