Paul Roberts

A procedure has been established for obtaining equivalent circuit parameters for the brushless doubly fed machine, also known as the brushless doubly fed induction machine, by transforming a reduced coupled-circuit model into a sequence component form. This approach takes advantage of the model reduction procedure's ability to reduce a complex roto...

A coupled-circuit model for the brushless doubly fed machine (BDFM) has been developed. The transformation of the model into the d-q axis form, ultimately in a synchronous reference frame in which machine currents and voltages have constant values in the steady state, has been carried out. A model-reduction technique is presented, which gives a con...

Rotor bar current measurement is a valuable step in verifying the theory of electrical machines design and control. However, because the rotor is moving, the approach is difficult to implement. This paper presents the design and evaluation of an approach to real-time rotor bar current measurement using the Rogowski coil as a current transducer. Rog...

The brushless doubly fed machine (BDFM) shows economic promise as a variable speed drive or generator. The optimization of the machine and model-based control strategies both rely on machine models, and the experimental verification of these models. To date, dynamic measurements of rotor quantities have not been possible. The authors present a syst...

The brushless doubly fed machine (BDFM) is attractive for variable speed drive (VSD) applications as its use can reduce the cost of the associated power electronics. Using a simple combination of a rectifier and inverter is attractive but this restricts the speed range to natural speed and above if the machine is to be operated efficiently. However...

The Brushless Doubly-Fed Machine (BDFM) is attractive for use in wind turbines, especially offshore, as it offers high reliability by virtue of the absence of brushgear. Critical issues in the use of the BDFM in this role at a system level include the appropriate mode of operation, the sizing of associated converter and the control of the machine....

The performance of the brushless doubly-fed machine (BDFM) is analysed using a per-phase 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 BDF...

This paper presents an iterative method for the stator design optimisation of the Brushless Doubly-Fed Machine (BDFM) based on a per phase equivalent circuit model and a tabu search method. Maximum power output from a frame size 180 BDFM is obtained by optimally dividing the overall electric and magnetic loadings between the stator windings. Parame...

This paper discusses the inverter ratings of Brush-less Doubly-Fed Machine (BDFM) adjustable speed drive (ASD) or generator (ASG) systems. Based on the per phase equivalent circuit model, the ratings of the two inverters in a bidirectional converter are evaluated individually. An approach to minimise the total inverter rating is presented, taking i...

Analysis of the behaviour of the Brushless Doubly Fed Machine (BDFM) has received considerable attention in the literature. The BDFM is typified by its complex airgap flux distribution. This paper will build upon performance-prediction work, concentrating on the design and electromagnetic behaviour of the BDFM rotor, considering 2 different sizes o...

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. Express...

The BDFM shows economic promise as a variable speed drive or generator. One practical obstacle to commercial exploitation is the presence of operating speeds at which BDFM synchronous action cannot be maintained under open loop conditions. In [7] the authors proposed a control strategy using feedback linearization, requiring full state feedback. In...

The paper presents experimental results to assess the performance of a variety of rotors used in a Brushless Doubly Fed Machine (BDFM). In the experiments the torque-speed characteristics were measured on a BDFM fitted with four rotors with five different windings. The measurements were made of the machine excited with just one stator supply with t...

The BDFM shows economic promise as a variable speed drive. One practical obstacle to commercial exploitation is the presence of operating speeds at which BDFM synchronous action cannot be maintained under open loop conditions. Two control strategies are proposed: feedback linearisation and control winding phase angle control which will enable BDFM...