Effects of Material Deformation Due to Aging of Electrical Steel on the Brushless Wound-Field Synchronous Generator

Abstract

This study analyzes the material deformation of electrical steel with aging and its effects on the electromagnetic and thermal characteristics of a Brushless Wound-Field Synchronous Generator (BL-WFSG). First, in order to confirm the material deformation of electrical steel applied to the BL-WFSG, magnetic property tests are performed on the core sheets of the old and new generators. Those two generators are made of the same material, so there was no difference except for their usage time. Based on the results of the magnetic property tests, an electromagnetic field analysis is performed on the old and new generators, and analysis results are compared in order to confirm the effects of material deformation on the electromagnetic characteristics of BL-WFSG. Then, a thermal analysis is performed on the old and new generators using losses calculated by electromagnetic field analysis as heat sources, and analysis results are compared in order to confirm the effects of material deformation on the thermal characteristics of BL-WFSG. Finally, an additional electromagnetic analysis is performed on both the old and new generators, using the exact winding resistances that were calculated in the thermal analysis for each respective generator in order to calculate and compare the efficiency of the old and new generators. Through this process, the authors confirmed the effects of material deformation of the rotor and stator cores due to aging on the electromagnetic and thermal characteristics of the BL-WFSG.