A modified 2-D multislice FEM for computing the airgap flux density of induction motor with skewed slots

To numerically analyze the electromagnetic torque of the induction motor with skewed slots, accurate and timely computation of the airgap flux density (AGFD) is required. Two-dimensional multi-slice finite-element method (2-D multi-slice FEM) is typically used in the computation of the AGFD in the induction motor with skewed slots. However, in order to achieve high accuracy, the number of the slices is generally very high, resulting in high computational costs. In this paper, a new computation method for the AGFD of the induction motor with skewed slots is proposed. In the proposed method, a skewed factor is introduced to the AGFD computed by the 2-D multi-slice FEM. With the proposed method, the number of slices needed of the 2-D multi-slice FE models are dramatically decreased. Then, the effect of the skewed rotor bars on the AGFD waveform of the induction motor under no-load and rated load conditions is analyzed. The influence of the skewed rotor bars on the torque characteristics of a 5.5 kW and a 55kW induction motor with skewed rotor bars are also studied. Finally, the experiment results of both 5.5 kW and 55kW induction motors with skewed rotor slots are obtained to verify the proposed method.