Slip power recovery systems based on brushless doubly fed reluctance machines

The brushless doubly-fed reluctance machine (BDFRM) allows the use of a partially rated converter and therefore reduces cost of a variable speed drive system. The absence of brush gear is undoubtedly its main advantage over the closely related double-excited slip ring induction machine. When compared to its cage counterpart, the brushless doubly-fed induction machine, the BDFRM appears to be more efficient and much easier to control since it has a cageless rotor which can be similar to that of the synchronous reluctance machine. A relatively limited amount of work to date has been published on the BDFRM. This paper attempts to fill this void by presenting a detailed analysis of some of the important vector control strategies for this machine and aspects of their implementation. The target applications to be considered are large pumps and wind turbines.