Accurate Magnetic Field Analysis for Estimating Motor Characteristics Considering Deteriorated Magnetic Properties in Magnetic Core Due to Stamping

Abstract

The electrical steel sheets of motors are often stamped with dies in order to raise productivity. The magnetic characteristics of electrical steel sheets under the strained and stressed conditions due to stamping are known to be inferior to those under normal conditions. In this paper, we propose an accurate finite-element analysis for estimating motor characteristics that focuses on elasto-plastic deformation in the magnetic core. The calculated results were compared with observations of a rectangular test piece in order to validate the methods. Based on the results, the method that considers the maximum principal stress is suitable rather than the method that considers the von Mises stress. This is because the maximum principal stress can be used to distinguish the magnetic properties under compressive stress from the properties under tensile stress. In addition, the proposed method is applicable to motor analysis. The cogging torque waveform and iron loss differ depending on the strain and stress distribution in the magnetic core when the stator core of the motor is stamped out from electric steel sheets with a die.