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Techniques for parameter determination of induction and doubly fed induction machines are well established. However, these techniques do not apply directly to the brushless doubly fed reluctance machine (BDFRM). Even though the mathematical model for this machine is like that of a double-fed induction machine, the complexity of the machines magnetic fields due to differing winding pole numbers interacting with a reluctance rotor preclude standard testing. Very high leakage inductances affect the use of the normal locked rotor test, and nonsinusoidal air gap fluxes complicate modeling for stand still frequency domain and time domain testing. This paper examines the validity of a combination of testing and analysis techniques, including open circuit and pulse testing, which were eventually used to determine the BDFRM inductance parameters over a range of operating points. The accuracy of the results are validated by machine testing and comparison with the finite element analysis machine design. [ABSTRACT FROM AUTHOR]

The brushless doubly-fed reluctance machine has two sets of stator windings of different pole number linked by a reluctance type of rotor. The rotor modulates the stator MMF from one winding so that flux links the other winding creating mutual coupling. This is still a research machine and the design methodology is under development. Past works indicates that a ducted rotor with radial laminations is best suited to be the reluctance rotor. In this paper the geometry of the rotor is investigated. If the ducts are too thin then the reluctance ratio is low and the coupling is affected. If they are too wide then the reluctance path for the coupling flux is high and the machine will saturate quickly. It is found, using finite element analysis, that the duct ratio should be about 38% from the results in the paper. This is in line with previous work on synchronous reluctance machines that can also use ducted rotors (although they use axial lamination which are inappropriate for this application). [ABSTRACT FROM AUTHOR]

Brushless doubly fed reluctance machines (BDFRMs) are a class of machines that may be controlled using a power converter that has a rating lower than the total power rating of the machine. The attractive properties of these machines have, in the past, been offset by low power density and efficiency when compared to other types of machines. Recent advances have shown that, when well designed, these machines are, in fact, capable of operation at high torque density and efficiency. However, little guidance on how to design these machines is available in the literature. This paper presents analytical approaches to design a BDFRM with desirable qualities and the use of time-stepped finite-element analysis to validate the results of the design process. [ABSTRACT FROM AUTHOR]

The brushless doubly fed reluctance machine consists of a stator containing two winding sets if different pole number linked by a reluctance type of rotor. This paper studies the magnetic performance of machines with different pole combinations aimed for use in a 2 MW wind turbine. This paper investigates the use of high-flux-density steels in order to observe the influence on torque density. An increase of 27% in performance is observed. In the second part of this paper, the unbalanced magnetic pull on the rotor is investigated. It has been suggested that a 4/6 pole may be suitable for this application, but it is illustrated that the rotor experiences high radial forces that may negate the use of this type of machine due to excessive bearing wear over a prolonged period. [ABSTRACT FROM AUTHOR]

Focuses on a study which examined the control strategies and associated machine performance/inverter size tradeoffs for the brushless doubly fed reluctance machine. Utilization of doubly fed reluctance machines in large pumps and wind turbines; Functions and capacity of brushless doubly fed induction machines; Development of reluctance rotor design model; Discussion of the processes of electric machine control and self-cascade machine.