Rotational Iron Losses and Their Estimation in Electrical Steel Sheets

Abstract

The rotational iron loss, WR (BL BC), of electrical steel sheets at two-dimensional flux densities BL and BC were compared with the sum of the alternating iron losses WL (BL) and WC (BC) at BL and BC, respectively. In the case of BL+BC<2T, K nearly equals l, where K is the ratio of WR (BL, BC) to WL (BL)+ WC (BC). For BL+BC>2 T, K<1, the value of K is almost independent of the grade of a non-oriented steel sheet. K is higher in a grain-oriented steel sheet than in a non-oriented steel sheet, and is highest in a doubly grain-oriented steel sheet. The rotational iron losses can be approximately estimated from the alternating iron losses and the constant K. In a non-oriented steel sheet, which is polycrystalline, if BL+BC is low, it is assumed that each crystal grain is mainly magnetized along the easy axis, even if the exciting field is rotational, and that the rotational iron loss is almost equal to the sum of the alternating iron losses in two directions.