A Brushless, Doubly Fed Machine (BDFM) attempts to combine the advantages
of conventional induction and synchronous types of electrical machines by its unique
architecture. The validation of BDFM designs in an actual test environment requires the
estimation of the BDFM model parameters from actual experimentation. Accurate values
for the parameters...
This thesis introduces a Brushless Doubly-Fed Machine (BDFM), stand-alone
generator system. Development of a BDFM current-forced model, along with the
analysis of air gap power distribution between the two stator windings and the rotor
circuit, pave the way for the characterization and analysis of stand-alone generator
systems.
The main disadvantage...
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...
A highly flexible numerical simulation model for the performance
prediction of brushless dc drives is presented, which is capable of
investigating unbalanced and asymmetrical operating conditions as well
as drives with non-ideal parameters. Numerical speed-up procedures
allow for the investigation of pulse-width modulated (PWM) drives using
a personal computer. Experimental...
The brushless doubly fed machine (BDFM), or self-cascade
single-frame machine, can operate asynchronously or
synchronously over a wide speed range. In this sense the
machine becomes an adjustable speed synchronous machine.
Such machines may become unstable in certain regions of
operation. Analyzing its steady-state performance and
determining its stable operating...
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...
The continuing desire of industry to further improve process efficiency,
through tighter control and energy conservation, has prompted users to pay closer
attention to Adjustable Speed Drives (ASDs). The conventional ASDs consist of
induction or synchronous motors controlled by power electronic controllers through
the adjustment of supply frequency and line...
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...
Use of conventional induction machines (IM) in adjustable
speed drives (ASD) has increased in recent years. Electronic
power processing has facilitated this increased use. The IM
is an inexpensive and robust machine, but when used as part of
an ASD, the cost of the system increases due to the inclusion...
This thesis presents the development of a supervisory controller for a pre-commercial
Brushless Doubly-Fed Machine (BDFM) drive system. In addition,
characterizations of new diecast rotors for the BDFM are presented. Using the
characterization results from the new rotors, a control scheme was developed to allow a
BDFM to be packaged...
The exceptional feature of the brushless doubly-fed
machine is the lack of need for frequent replacement of
brushes. The inherent instability of this machine has to be
overcome for its application in adjustable speed drives and
variable speed generation systems.
Specific objectives were:
to study the characteristics of the machine...
The Brushless Doubly-Fed Machine (BDFM) has recently become an
important research topic in the field of variable-speed AC drives. In
recent studies, the BDFM has shown significant potential for improving the
reliability and performance of AC drive systems, as well as reducing total
system cost. While the BDFM offers several...
The alternators in today's automobiles are of the claw-pole or Lundell
construction, which is a readily manufactured, low-cost derivative of the conventional
rotating dc field synchronous generator. The efficiency of the Lundell system is low due
to a complicated magnetic circuit of predominantly solid steel and a high windage rotor...
An AC/AC converter has been designed and implemented for the purpose of
providing a modular drive system with a Brushless Doubly-Fed Machine (BDFM.) This
converter is to be used in laboratory testing and also as part of a demonstration system in
the field.
All hardware needed to start and run...
A brushless doubly-fed machine (BDFM) is a single-frame, self-cascaded
induction machine capable of operating in both the induction
and the synchronous modes. This thesis presents some important
advances concerning dynamic modeling, simulation and analysis of the
BDFM.
Initially, a two-axis model and its associated parameters are developed
and calculated. The...
The Brushless Doubly Fed Machine (BDFM) is receiving attention as a candidate for use in adjustable speed drives (ASDs) and variable speed generators (VSGs). With a large percentage of a drive or generator system's cost due to power electronics content, considerable research has been conducted to find drives in which...
Generation of electricity from the wind is becoming increasing popular as an
environmentally responsible resource. Current methods for generating electricity from
the wind involve the use of fixed-speed generators. However, the use of variable-speed
generators increases the amount of energy that can be extracted from the wind.
Most variable-speed technologies...
The Brush less Doubly-Fed Machine (BDFM) has the potential to be a more cost effective replacement for conventional induction or synchronous machine drives. The BDFM has two stator windings: a power winding and a control winding. An electronic power converter of variable voltage and frequency is connected to the control...
The loads on the electrical systems of automobiles are projected
to increase significantly in the near future. This will result in a
requirement for improved efficiency over the present-day car
alternators. An alternative scheme proposed at Oregon State
University employs a Brushless Doubly-Fed Machine (BDFM) as an
alternator.
This thesis...
The advent of superior power semiconductor devices and converter topologies
has renewed interest in ac drive systems. Although considerable research efforts have
gone into improving power electronic converter devices and topologies, very little has
been reported on the overall performance optimization of induction machine drive
systems. The report of the...
Brushless Doubly Fed Machines (BDFM) have potential advantages in variable
speed generation and adjustable speed drive applications. The most significant of these
advantages is a reduction in the power electronic converter rating, and therefore a
reduction in overall system cost. Presently, efforts are being directed at optimizing the
design of...
Permanent magnet synchronous machines (PMSMs) are widely used in electric vehicles and hybrid electric vehicles to propel the wheels. Various control strategies have been developed for PMSM drive systems to achieve both high efficiency and safe operation. In a PMSM drive system, generally the high voltage battery and the power...
The induction motor in its electromagnetic features
is essentially a transformer, while in its general behavior
it is analogous to the continuous-current shunt wound
motor. In a transformer the primary and secondary members
are both stationary and electrical energy is transformed
from one pressure to another by the ratio of...
Throughout the year the regular design work of the
class room proved so profitable that it was thought that
there was no subject which could be selected for thesis
purposes of greater benefit,or which offered as great a
latitude in the working out of the various problems, than
the one...
The following discussion is confined mostly to
that type of machine in which the squirrel care revolving
secondary it used. In its most primitive form it con -
listed simply of a disk- aramature as described by Baily
in 1870 and due to Tesla (1888), of the fact that two,...
The study, design, construction, operation and care
or synchronous machines forms one of the most important
branches of electrical engineering. The extent to which
they are now being used is a notable feature of recent
electric progress.
The term synchronous machines covers quite a field
and it might be well...
The problem of the economical transmission of power has long been a serious one to the engineer. Formerly the power had to be generated on or near the spot where it was to be used, but now the advance that has been made in Electrical Engineering has largely done away...
In order that the proper motor for a given service
may be chosen it becomes necessary to study and know
the requirements and characteristics of the machine which
may be used for that purpose. When these are known the
selection of that one which is best adapted for the use...
Direct digital control is becoming quite common in the control
of industrial processes. However, due to the relatively high accuracy
of both analog and conventional digital systems for controlling the
speed of a dc motor, there has been a reluctance to try DDC for
this purpose. This thesis describes a...
A model of a squirrel cage induction machine, d.c.-
link power supply and centrifugal pump is developed and
used in the design and evaluation of a perturbation feedback
control system for a sewage pumping station. A comparison
of the simulation model of the induction machine
and a laboratory machine to...
The effect of the mutual inductances between the rotor coils of a synchronous machine on its defined reactances and predicted transients are investigated. Two linearized models of the machine are considered. One uses the Laplace-Transform approach, with minimum number of assumptions on the inter-coil couplings, in developing a model for...
Synchronous machines provide a practical way to control reactive power consumption of a plant. One of the main advantages of using synchronous motors in a plant is their ability to generate reactive power for plant loads. A new control scheme for synchronous motor excitation systems is developed to automate reactive...
A relatively new development in the electric machines field has been the written-pole technology, of which the latest product is the large single-phase electric motor, the single phase Written-Pole Motor (WPM). The WPM is a synchronous, permanent-magnet single-phase motor having a weak rotor cage for start-up which in addition exhibits...
This thesis comprises a series of tests run on a compound direct current generator and an induction motor; separately and combined as a set, with sheets of data; characteristic and efficiency curves and deduction drawn therefrom relative to the two machines.
The three-phase squirrel-cage induction motor is rugged, compact,
inexpensive, can be totally enclosed and requires little maintenance.
Its use as a variable speed drive has been limited, however, by the
state-of-the art of control components.
The advent and continuing development of the silicon controlled
rectifier and associated solid-state components has...
Electromagnetic engines, or motors, are machines in which the motive power is derived from electric currents by means of their electromagnetic action. The following design is for a 1½ K.W. bi-polar motor.
With the development of converters and inverters, it
became possible to control the stator current of an
induction motor. The differential equations which describe
transient behavior of the induction motor are conveniently
expressed by transforming the stator and rotor variables to
d-q axes rotating at synchronous speed. The transient
behavior...
The evaluation of the stray-load losses in induction motors is an important part of the efficiency estimation process. However, stray-load losses have several components which are difficult to isolate and calculate. Consequently, they are more readily determined by test. IEEE Standard 112-1996 recommends the testing of electrical induction motors at...
The detection of motor faults at their incipient stage is of prime importance to any industrial plant. The introduction of adjustable speed drives has improved the control and the efficiency of induction motors, however, this has changed the nature of motor faults and how they can be detected.
Current signature...
A state of the art motor testing facility has been built at Oregon State University.
This is the largest independent testing laboratory of its type in the western United States.
The construction was funded by a consortium of industrial sponsors, with a goal of
becoming financially self-sufficient by charging the...
Declared out of print May 2010. Facts and recommendations in this publication may no longer be valid. Please look for up-to-date information in the OSU Extension Catalog: http://extension.oregonstate.edu/catalog
Adjustable Speed Drive (ASD) systems are widely used in industry to effectively improve process efficiency and control. Typically, an ASD system consists of a motor with its speed controlled by a power electronics converter via varying the amplitude and frequency of the input voltage. However, several abnormal insulation failures of...
Traditionally linear actuator applications are addressed by the use of hydraulic systems. The high maintenance cost and poor reliability will always be the most critical problem in the real applications. Benefited from both the high mechanical advantage of the roll screw and the simple structure of the switched reluctance motor,...
A 300 hp motor and generator testing facility is being completed at Oregon State University. The testing center is the largest independent testing facility west of the Mississippi River. This regional resource center will incorporate state-of-the-art features that set it apart from other testing facilities. An induction machine with a...
The Motor Systems Resource Facility (MSRF) at Oregon State University presently conducts a variety of steady state tests on Motors and Generators, with ratings of upto 300Hp.(225kW), using a dynamometer. The dynamometer consists of an induction motor fed by a power electronic converter. A control computer uses a serial link,...
Environmental concerns have renewed the interest in electric vehicles. To gain
widespread use, electric vehicles will also have to offer good performance and be
reasonably priced. AC drive systems using modern semiconductors can provide
efficient operation at the required power levels, but their cost at present is still too
high....
A project funded by the Southern California Edison (SCE) Company, Research
Center of Irwindale, California, has supported the development of a performance and
parameter prediction software program for use during the refurbishment of large
synchronous machines, turbine generators, and synchronous condensers. The computer
program was developed for SCE to allow...