Calculation Improvement of No-load Stray Losses in Induction Motors with Experimental Validation

Abstract

On the basis of the known fact that all air gap main flux density variations are enclosed by permeance slot harmonics, only one component of stray losses in rotor (stator) iron is considered in the new classification, instead of 2 components: rotor (stator) pulsation iron losses, and rotor (stator) surface iron losses. No-load rotor cage (high-frequency) stray losses are usually calculated. No-load stray losses are caused by the existence of space harmonics: the air-gap slot permeance harmonics and the harmonics produced by no-load MMF harmonics. The second result is the proof that the corresponding components of stray losses can be calculated separately for the mentioned kind of harmonics. Determination of the depth of flux penetration and calculations of high frequency iron losses are improved. On the basis of experimental validation, it is proved that the new classification of no-load stray losses and the proposed method for the calculation of the total value is sufficiently accurate.