Influence of Airgaps and Rolling Direction Variation Between Grain-Oriented Steel Sheets on Losses in the Magnetic System

This paper presents results of investigations of the influence of air gaps in GO steel sheet inserts on magnetic losses. Classical iron loss measurements were performed using a single strip tester to magnetize material samples at 50 Hz and 400 Hz. The samples included air gaps of various thickness and it is found that their presence led to the increase of losses up to 30% depending on their size. The variation of the rolling direction has also been studied and revealed no significative influence on magnetic performances. It is concluded that if GO steel inserts are to be used in a magnetic system of an electrical machine, the sheets must be properly connected to reduce the effect of air gaps to increase the overall performances of the machine, but the rolling direction variation in the magnetic flux path has a minor impact on the performances.