Comparison of induction motor characteristics calculated from electromagnetic field and equivalent circuit determined by 3D FEM

This paper investigates the correspondence between the equivalent circuit modeling and the electromagnetic field distribution in induction motors using 3D finite element method. The parameters of the equivalent circuit are calculated by the 3D analysis considering end-rings and coil-ends. The torque of the motor is obtained from both the equivalent circuit and the Maxwell stress tensor that is given by the field distribution directly. The differences between the results and the effects of the magnetic saturation are discussed to clarify breakpoints of the approximation of the equivalent circuit. It is clarified that the space harmonics of the magnetic motive force in the motor is one of the reasons that cause the differences of the characteristics calculated by the equivalent circuit and the electromagnetic field.