Accurate active power flow diagrams of Brushless doubly-fed induction machine in motoring and generating modes

The brushless doubly-fed induction machine (BDFIM) shows interesting features for incorporating as wind generator or variable speed drive. The BDFIM operation is based on magnetic flow modulation of two stator winding fields through a special squirrel cage rotor. Hence, the power flow is very different from that of a regular induction machine. Taking into account, accurate analysis of the power flow is very valuable for the comprehension and design of BDFIM as well as the selection of converter capacity. In this paper, the power balance for BDFIM is discussed in the motoring and the generating modes and for both super- and sub-synchronous speed intervals. For this purpose, the power flow equations are extracted and power flow diagrams taking into account all the power loss components are presented. The accuracy of the proposed power flow diagrams is verified by comparing the obtained results with the experimental and finite element ones.