Stray Load Loss Calculation for Induction Motor by Combination of General Airgap Field Modulation Theory and 2D FEA

The accurate calculation of stray load loss has an important contribution to increasing motor efficiency. The stray load loss can be regarded as the difference of the total iron losses and harmonic rotor cage losses between the no load and load conditions. A method combining the general airgap field modulation theory (GAFMT) and 2D finite element analysis (FEA) is proposed for calculating the stray load loss of the squirrel cage induction motor (SCIM). Firstly, the amplitudes and rotation speeds of the main space harmonics of the airgap magnetic flux density are calculated based on the GAFMT. And the relationships between these space harmonics and stray load loss are analyzed. Secondly, these space harmonics are synthesized by the equivalent current layers in the airgap and then are substituted into the 2D FEA models to calculate the losses. At last, the stray load loss calculated by the proposed method is compared with that obtained by practical motor tests.