Harmonic loss and torque analysis of high speed induction motors

In this study, we investigate the harmonic losses and torques of high speed induction motors from both results of measurements and calculations. The calculation method of harmonic core losses and torques has been developed from the viewpoint of practical and useful application to rotating machines. This method is based on the combination of 2-D and 1-D finite element methods with approximated core loss modeling, which requires only few material constants obtained by Epstein-frame tests. The frequency and flux density dependence of the core loss are modeled by the 1-D analysis along the thickness direction of electrical steel sheets. Furthermore, the proposed method can decompose the total loss and torques into harmonic components because of its simple modeling. This decomposition reveals the main loss factors and decrease in the torque of the high speed induction motors due to the harmonic core losses. The validity of the calculation is confirmed by measurements. In addition, useful information for the design of high speed induction motors is obtained by using the proposed method.