Calculation and Analysis of Iron Loss in Doubly Salient Brushless DC Generator

Doubly Salient Electromagnetic Machine (DSEM) is fundamentally a new type of variable reluctance machine, whose operation principle is different from the conventional AC electrical machines. Analysis of operation principle, magnetic field and loss distribution characteristics of DSEM is important and necessary. This paper has analyzed the magnetic field distribution of Doubly Salient Electro-magnetic generator (DSEG) comprehensively and proposed a method separating DSEG into eight parts to describe the distribution characteristics of iron loss. In order to predict the iron loss of DSEG accurately, Fourier Transform is used to analyze the magnetic flux density of each part. A calculation model of iron loss is established, whose coefficients are determined by the measured data of a 24/16-pole DSEG at different speed. The relationship between the eddy-current loss and hysteresis loss is emphasized as well as the distribution of iron loss of each part. Moreover, the influences of speed, air-gap length as well as field current on iron loss are summarized and analyzed. Finally, the calculation and analysis of iron loss are verified through experiment results.