Direct power control of brushless doubly-fed reluctance machines

A new algorithm for independent shaft position sensor-less control of real and reactive power (and therefore power factor) of the Brushless Doubly-Fed Reluctance Machine (BDFRM), a promising cost-effective candidate for applications with limited variable speed capability (e.g. pumps or wind turbines), has been proposed in this paper. The algorithm is inspired by the fundamental dynamic and magnetising principles of the machine and does not require knowledge of any parameters. As such, it should be more robust than model-based control approaches which often suffer from sensitivity issues and performance trade-offs associated with machine parameter variations or their inaccurate identification. In turn, the proposed control method (termed as 'Direct Power Control' due to conceptual similarities with traditional 'Direct Torque Control') merely relies on the grid-connected winding voltage and current information. Simulation studies have demonstrated excellent potential of the DPC scheme for generating operating mode of the custom designed BDFRM at maximum power factor.