General pole number model of the brushless doubly-fed machine

The brushless doubly-fed machine is receiving attention as a contender for several niche applications. In some cases the speed ranges of these applications appear to be more readily met by judicious selection of the pole-pair numbers of the stator phase winding. In order to compare different proposed pole-pair configurations and to help in the development of specific designs, a general analytical model, in both dynamic and steady state forms, is presented. This model supersedes previous analyses which are restricted to the 3/1 pole-pair combination or early laboratory machines. The new model is also completely valid for both positive and negative control voltage sequences. The increased modelling flexibility enables sound estimations of the drive power convertor rating, the reduction of which is the key to the economic advantage or these machines. An example of the correlation or the performance predictions and test results encourages use of this new model