Generalised theory of the brushless doubly-fed machine. I. Analysis

The authors develop the concept of the brushless doubly-fed machine (BDFM), from consideration of the frequency and distribution of the EMFs induced in bars of a conventional doubly wound cage motor. These considerations lead to the development of a rigorous mathematical model which is suitable for the analysis of BDFM operating in the synchronous mode. Expressions for all impedances and electrical and mechanical quantities are derived from first principles and the concept of load angle is discussed