Determination of Losses in Adjustable Electric Drive Steel

Operation of induction motors in modern practice is inseparably linked with the use of power semiconductor converters. Specific features of frequency converters and voltage regulators supply require improvement of the methods of determining the characteristics of the induction motor as a part of frequency regulated electric drive. Determination of losses in the steel of an induction motor as one of main factors of formation of an electric machine thermal field is of interest. The impossibility of direct measurement of steel losses and magnetic system saturation level influence on its value complicates the analysis of energy conditions determining the reliability of induction motors. The paper presents materials confirming the fact that the existence of harmonic components of the supply voltage leads to increased losses in AC motors steel. In addition, the steel losses dependence on additional EMF for various forms of supply voltage signal, which is straightforward and does not depend on its form, is obtained.