Analysis of Electric Motor Magnetic Core Loss under Axial Mechanical Stress.

L Ashok Kumar,Bagianathan Madhan Raj,Vairavasundaram Indragandhi,Kalyana C Veluvolu,Varadarajan Vijayakumar,Hamid R Karimi,Vairavasundaram Subramaniyaswamy

doi:10.3390/s20236818

Abstract

The electrical machine core is subjected to mechanical stresses during manufacturing processes. These stresses include radial, circumferential and axial components that may have significant influence on the magnetic properties and it further leads to increase in iron loss and permeability in the stator core. In this research work, analysis of magnetic core iron loss under axial mechanical stress is investigated. The magnetic core is designed with Magnetic Flux Density (MF) ranging from 1.0 T to 1.5 T with estimated dimensions under various input voltages from 5 V to 85 V. Iron losses are predicted by the axial pressure created manually wherever required and is further applied to the designed magnetic core in the range of 5 MPa to 50 MPa. Finite element analysis is employed to estimate the magnetic core parameters and the magnetic core dimensions. A ring core is designed with the selected dimensions for the experimental evaluation. The analysis of iron loss at 50 Hz frequency for non-oriented electrical steel of M400-50A is tested experimentally using the Epstein frame test and force-fit setup test. Experimental evaluation concludes that the magnetic core saturates when it reaches its knee point of the B-H curve of the chosen material and also reveals that the axial pressure has a high impact on the magnetic properties of the material.

Highlights

Iron loss is often considered as the main source of error in the prediction of the motor efficiency.During the manufacturing of an electrical motor, some mechanical stress are often produced due to stamping, punching and stacking in axial or radial directions
Detailed analysis and simulation results are presented for both rectangular and ring cores, the experimental evaluation is only limited to ring core
The input voltage ranges from 5 V to 75 V at 50 Hz for the non-oriented electrical steel of M400-50A

Summary

Introduction

Iron loss is often considered as the main source of error in the prediction of the motor efficiency. During the manufacturing of an electrical motor, some mechanical stress are often produced due to stamping, punching and stacking in axial or radial directions. It leads to deterioration of the magnetic properties in the core materials and leads to iron loss in the core thereby decreasing the efficiency of the electrical machine [1,2,3,4]. The main causes of stress are the stamping of the laminations, the clamping of the laminated core, and the shrink or press fitting of the core into a frame. Even for classical ac sinusoidal flux machines, the difference between iron loss predictions based on specific iron loss density values supplied by lamination steel manufacturers and the measured iron loss cannot be attributed solely

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Conclusion