ANALYTICAL AND STATISTICAL ASSESSMENTS OF THE METHODOLOGY FOR EVALUATING THE QUALITY OF LAMINATED MAGNETIC CORES

Abstract

The paper solves the relevant issue of improving the reliability of electromechanical converters with a steel laminated magnetic core by implementing effective measures to diagnose the quality of the laminated core. A method for assessing the quality of laminated magnetic cores with insulated sheets is proposed. The method is based on the analysis of the response of electromagnetic interconnected circuits to test transient processes in order to assess the development of defects in the inter-sheet insulation and the concentration of parasitic eddy currents associated with specific losses in the magnetic core which is the normative method of magnetic core evaluation that is closest to the operation of an electric machine under real conditions. Taking into account the complexity and labour intensity of regulated methods of core quality control, a reasonable assessment of the relationship between the eddy current time constant and the specific losses in the magnetic circuit will significantly simplify the test methodology, the implementation of which does not require complex and expensive equipment and high qualification of the service personnel. In addition to the physical connection, the paper shows the statistical relationship between the eddy current time constant and the specific losses in a number of real magnetic circuits and performs statistical processing of the experimental data. A linear regression dependence is obtained and the correlation coefficient is estimated, which confirms a significant relationship between the above components on the example of magnetic cores of different geometries. Confidence intervals for defect-free and defective magnetic cores are estimated, taking into account the geometric dimensions, power, and number of poles of the studied electric motors.