The performance of the brushless doubly-fed machine (BDFM) is analysed using a perphase equivalent circuit. An expression for the rating of the machine as a function of magnetic and electric loadings is developed, and the rating is compared to those of the doubly-fed induction machine and cascaded induction machines. As the magnetic field in a BDFM is complex, the magnetic loading is considered in detail and a new generalised loading is derived. The BDFM suffers a reduction rating of about one-quarter in comparison to comparable conventional machines, arising from penalties in magnetic and electric loadings consequent on the presence of two stator to rotor couplings. The handling of reactive power has an important effect on the machine performance and this point is illustrated with experimental results from a frame size 180 BDFM. The tests were carried out at modest flux densities to avoid the effects of saturation, but the implications of saturation are considered.

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Experimental results from a frame size 180 brushless doubly fed (induction) machine (BDFM) fitted with four rotor designs are presented. The machine is intended for use as a variable speed generator, or drive. A per phase equivalent circuit for the machine has been developed and a method of obtaining parameters for the circuit is described. Expressions for the torque as a function of speed have been derived and predictions of machine performance in both self-cascaded and synchronous (doubly fed) modes have been verified experimentally. The work illustrates the link between rotor equivalent circuit parameters and machine performance and a comparison between rotor designs has been made.

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This study presents the performance analysis and testing of a 250 kW medium-speed brushless doubly-fed induction generator (DFIG), and its associated power electronics and control systems. The experimental tests confirm the design, and show the system's steady-state and dynamic performance and grid low-voltage ride-through capability. The medium-speed brushless DFIG in combination with a simplified two-stage gearbox promises a low-cost low-maintenance and reliable drivetrain for wind turbine applications.

This paper describes the development of a thermal model for flash lamp processing of 3C-SiC on silicon substrates in the millisecond regime, the FLASiC process. The model is a numerical solution of the enthalpy equation, using a modified implicit Crank-Nicholson scheme to combine accurate prediction of melt depths with reasonable computation times. The model has been calibrated against experiments and then used to compute the temperature distribution in the wafer during annealing. The results show the time and extent of melting as a function of layer thickness, wafer preheat temperature, and pulse intensity and duration. The kinetics of melting and regrowth have also been considered.