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Investigation, analysis and design of the linear brushless doubly-fed machine

This thesis covers the efforts of the design, analysis,
characteristics, and construction of a Linear Brush less Doubly-Fed
Machine (LBDFM), as well as the results of the investigations and
comparison with its actual prototype.
In recent years, attempts to develop new means of high-speed,
efficient transportation have led to considerable world-wide interest
in high-speed trains. This concern has generated interests in the
linear induction motor which has been considered as one of the more
appropriate propulsion systems for Super-High-Speed Trains (SHST).
Research and experiments on linear induction motors are being
actively pursued in a number of countries. Linear induction motors are
generally applicable for the production of motion in a straight line,
eliminating the need for gears and other mechanisms for conversion
of rotational motion to linear motion.
The idea of investigation and construction of the linear brushless
doubly-fed motor was first propounded at Oregon State University,
because of potential applications as Variable-Speed Transportation
(VST) system. The perceived advantages of a LBDFM over other LIM's
are significant reduction of cost and maintenance requirements.
The cost of this machine itself is expected to be similar to that
of a conventional LIM. However, it is believed that the rating of the
power converter required for control of the traveling magnetic wave
in the air gap is a fraction of the machine rating. The constructional
design of the machine is such that the primary contains two 3-phase
windings. One of these 3-phase systems is connected directly to the
utility grid; the second 3-phase system, with a different number of
poles, is connected to a power electronic converter which has the
capability of providing adjustable frequency and amplitude of voltage
or current. The speed of the traveling magnetic field can be varied
simply by controlling the output frequency of the power electronic
converter. The design of the actual machine is such that the two
3-phase systems laid in the primary of the machine are magnetically
decoupled from each other because of the difference in pole number
of the two systems, (e.g. 6-pole and 2-pole for the test prototype
machine in our research lab). The other degree of freedom that this
machine provides, is the operation of the machine under two distinct
speeds by implementing the pole change technique. This mode of
operation can give only discrete changes in speed, however, it
provides efficient running at those speeds with a minimum of control
mechanism. On the other hand, it is anticipated that the LBDFM with
two actively fed windings will produce a continuously adjustable speed
over a wide range. Hence, LBDFM will be superior if it can be designed
to function effectively. / Graduation date: 1991
Date08 February 1991
CreatorsSeifkhani, Farroh
ContributorsWallace, Alan K.
Source SetsOregon State University
Detected LanguageEnglish

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