Space vector theory and control of brushless doubly fed reluctance machines

The advent of power electronics and cost-effective microprocessors has resulted in the revival of interests in brushless doubly fed or self-cascaded machines (BDFMs) over the last decade. A reluctance version of the BDFM, the brushless doubly fed reluctance machine (BDFRM), appears to be more attractive than its counterpart, the brushless doubly fed induction machine (BDFIM). This article presents the basics of the BDFRM's unusual torque producing mechanism, dynamic modeling aspects, issues related to power flow regulation, optimal control properties and associated performance trade-offs. Several control strategies are highlighted, namely, the maximum torque per inverter ampere and the maximum power factor at the mains side.