Basic operation, as well as successful development, of the Brush less Doubly-fed Machine (BDFM) has been documented, and research has turned from proof of concept and early development to the more practical direction of increased manufacturability to prove industrial viability. Previous research centered on using standard induction motor stators along with a manufactured BDFM rotor. The more recent efforts center around a ground up design of an optimized BDFM prototype system including a custom converter, a custom die-cast rotor, and a custom stator, all designed specifically for a BDFM system. This paper presents the design process involved in the development of the rotor and stator of a pre-production optimized 5 hp BDFM with a die-cast rotor, from the initial evaluation of the desired specifications to design, simulation, construction, and finally to testing. Using the results of the 5 hp BDFM design, a 15 hp BDFM was designed and manufactured, and the results of that effort are included in this paper as well. This complete process, from design to testing, enables a closed loop analysis of the design techniques and tools used; the successes of the design can be affirmed and the shortcomings identified and corrected. While the primary goal of this paper is to produce two successful BDFM prototypes, the secondary goal is to improve the BDFM design process. / Graduation date: 1998

This thesis presents the development of dynamic control strategies for the brushless doubly-fed machine (BDFM). A simple open-loop scalar controller is first investigated and its response is found to be oscillatory. Using the speed feedback signal, an improved closed loop scalar control algorithm is designed. Steady state performance is controlled by the magnitude of the BDFM control winding current. Simulation and experimental results demonstrate that the closed loop algorithm has a slow response and is suitable for low performance drive applications. A model reference adaptive control algorithm is investigated in simulation, attempting to improve the BDFM dynamic response and assure its robustness against system parameter variations. Further investigations reveal that the field orientation principle for conventional induction machines can be adapted for the BDFM. This enables the design of a rotor flux oriented control algorithm, based on a newly established synchronous reference frame model. Simulation results illustrate the algorithm's fast dynamic response and robustness against parameter variations. The verification of various control algorithms is carried out on a laboratory system consisting of an experimental BDFM, a power converter and associated control hardware. An Intel 80196Kr microprocessor is used to implement inverter switching and current regulation for the BDFM control winding. The rotor flux oriented control algorithm is implemented using an Intel 80960KB floating point microprocessor, achieving a control bandwidth in the kHz-order. Evaluation of a BDFM synchronous angle shows its significance in control design, and it is incorporated into the later control algorithm development in order to eliminate electric torque estimation. This simplifies control algorithm design and is verified experimentally. Consequently, the control algorithm for the BDFM can approach the simplicity of equivalent induction machine control techniques. / Graduation date: 1996

Thesis (M.S.)--West Virginia University, 2002. / Title from document title page. Document formatted into pages; contains viii, 112 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 110-112).

Thesis (M. Sc.)--University of Hong Kong, 1964. / Mimeographed.

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The travelling magnetic wave of a linear induction motor induces eddy currents in a secondary circuit (usually a sheet consisting at least partly of a non-magnetic metal, often aluminium), which cause the unrestrained member to move linearly in the direction of the travelling wave. A linear motor can also transport ferromagnetic powder, although this travels in the opposite direction to the travelling magnetic field. The motion is therefore due to a mechanism other than the eddy currents flowing in the sheet secondary. Expressions for the forces acting on an iron particle due to a travelling magnetic field are derived in the thesis. Preliminary experiments support the assumptions made in the derivations of the force expressions and lead to the formation of an hypothesis. This is shown to be capable of predicting both linear and rotational particle speeds and, with greater accuracy, the distance travelled and the rotation experienced by the particles. Experiments conducted on tubular and transverse flux motors have enabled different linear motors to be identified as suitable for a number of powder transportation applications. The results obtained show also the importance of large flux density values, the tangential to normal flux density ratio and large pole-pitch winding arrangements, with the latter lending support to the original hypothesis. The results of a finite element investigation of the tubular motor did not closely agree with the results from the experimental motor although similar trends were evident. Flux density values within particles were found to be considerably greater than those outside, as assumed in the hypothesis.

Thesis (M Eng) -- University of South Australia, 1991

Thesis (Ph. D.)--Ohio University, June, 1987. / Title from PDF t.p.