Design of the Brushless Doubly-Fed (Induction) Machine

This paper discusses the design of the brushless doubly-fed (induction) machine (BDFM). It is focused on the evaluation of the electric and magnetic loadings of the machine and their allocation to two stator windings. A method of estimating the back iron flux density is presented. The electric and magnetic loadings are assessed for a prototype BDFM. The limits of back iron flux and the electric & magnetic loadings are treated as constraints in an iterative method of machine design which optimizes the division of electric and magnetic loadings between two stators windings of the BDFM. This method was applied to optimize stator windings of the prototype BDFM for maximum motoring output with constraint on power factor of the power winding. A comparison between the original and redesigned BDFMs is presented with experimental verification.