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Design, control and application of double-stator permanent magnet brushless machinesNiu, Shuangxia., 牛双霞. January 2009 (has links)
published_or_final_version / Electrical and Electronic Engineering / Doctoral / Doctor of Philosophy
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Design, analysis, control and application of permanent-magnet hybrid brushless machinesLiu, Chunhua, 劉春華 January 2009 (has links)
published_or_final_version / Electrical and Electronic Engineering / Doctoral / Doctor of Philosophy
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Hardware design and protection issues in an AC/AC converterFaveluke, Alex 25 August 1997 (has links)
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 the BDFM is now consolidated into a single
NEMA standard frame electrical equipment box. This allows easy transportation and
setup of the drive system, and will enable the BDFM drive system to be directly
compared with existing induction machine based drive systems.
Converter subsystem overviews in the body of the text and comprehensive
schematics in the appendices of this thesis describe all circuitry included in the drive
system. Sufficient construction detail is given to allow for duplication of this converter
by qualified technical personnel. While not tailored for mass production, this converter
may provide a starting point for a commercially viable design. / Graduation date: 1998
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General pole number model for the brushless doubly-fed machineBoger, Michael S. 06 July 1994 (has links)
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 winding and
allows the speed of the machine to be adjusted synchronously. The power winding, by
design, carries the majority of the current needed for operation, the control winding only a
fraction of the current, thus enabling the converter rating to be as low as 25% of the rating
of the machine depending on the speed range of operation.
To date, only one specific stator pole-pair combination has been investigated,
namely the 3/1 combination, where 3 and 1 refer to the power winding pole-pairs and the
control winding pole-pair, respectively. Since the speed of the machine is dependent on
the sum of the pole-pairs of the stator windings, a general pole numbered model is needed
to evaluate the performance of such general machines with other pole-pair number
machines. The BDFM describing system equations are transformed to the two axis (dq)
rotor reference frame using a power invariant transformation. The analysis shows an
additional term involving the common bar impedance which was not present in earlier
analyses.
The dynamic model is simplified to yield a steady state synchronous model. The synchronous frequency of analysis is investigated which results in two equivalent steady state models. The models developed can easily handle excitation of any frequency or sequence on the control winding without the use of an auxiliary model as used in previous analyses. The voltage forced model predictions match data taken for a 5 hp BDFM laboratory prototype, establishing the validity of the analysis. The model is used in illustrating the torque producing capabilities and unity power factor operation of the machine under a variety of inputs. Using the model, predictions are made on a different pole-pair combination machine (4/2 BDFM) for use as a 60 hp pump drive as an alternative to a 3/1 BDFM for the same application. / Graduation date: 1995
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Digital stabilizer for brushless doubly-fed machineKrishnan, Sheela 01 October 1990 (has links)
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
pertinent to its application in adjustable speed
drives and variable speed generation systems,
to develop a stabilizer depending on the nature of
the instability.
The brushless doubly-fed machine was found to be unstable
over much of the useful operating range. A digital feedback
control was implemented using a combination of hardware and
software elements/to stabilize the machine. The feedback
system was a band pass filter. The software was developed with
a processing time fast enough to match the speed of response
required by the stabilizer to overcome the unstable
oscillations.
The performance of the machine was compared with and
without the stabilizer to test its effectiveness. Stable
operation was achieved over the entire operating region. / Graduation date: 1991
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Direct torque control for brushless doubly-fed machinesBrassfield, William R. 31 March 1993 (has links)
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 advantages over existing AC
drives in steady-state operation, it suffers from dynamic instabilities
and slow response times, and a feedback control system is necessary. The
mathematics of the BDFM are much more complicated than those of a singly-fed
machine, and thus traditional control methods can't be applied. In
this thesis, a control method known as "Direct Torque Control" has been
adapted from that of a singly-fed induction machine and successfully
applied to the BDFM.
The thesis begins by discussing the background of the BDFM, its open-loop
operating characteristics, and some of the control considerations.
The reduced-order system differential equations are introduced, and it is
noted that they are coupled and nonlinear. Furthermore, all state
variables are time-varying (but periodic), even in steady-state operation.
In the controller development, it is found that a linear relationship
exists between the desired torque/flux-level change and the d-q voltages
to be applied to the control winding of the machine via the power-electronic
converter. This linear relationship, together with a one-step-ahead
predictor to compensate for computational delay, is successfully
used to control the speed and efficiency of the machine, for a wide range
of speeds and load torques. Numerous open- vs. closed-loop simulations
are compared and summarized, and it is found that the performance of the
BDFM is greatly improved in the closed-loop, with faster response and
reduced oscillation. Further simulations investigating the robustness of
the controller are summarized, and it is found that the controller is
reasonably insensitive to errors in most of the the static machine
parameters. Hardware implementation is briefly discussed but is not
complete; laboratory results are not yet available but should be soon.
Future controller considerations are then discussed; included among the
recommendations are an on-line parameter estimator for use in adaptive
control, and a controller for generator applications of the BDFM. / Graduation date: 1993
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Design and development of a controller for a brushless doubly-fed automotive alternator systemJavadekar, Virendra S. 31 January 1992 (has links)
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 begins with a study and characterization of the
existing car alternator system. The configuration of the proposed
scheme is discussed. In the proposed configuration, the power
winding of the machine generates the bulk of the power and the
control winding provides the excitation. The power winding feeds a
power rectifier, which in turn charges the battery in an automobile.
The control winding is supplied through an inverter. Issues related to
inverter and rectifier design are discussed. A 3-phase pulse width
modulated inverter and a bridge rectifier were developed and tested
for performance. A PSPICE simulation model for the rectifier was
developed and results are compared with laboratory tests. A Voltage
Regulator Circuit (VRC) and an Efficiency Maximizer Unit (EMU) for
the system are designed and developed. A prototype alternator system
is tested and the principle of efficiency maximization is verified.
Finally. the comparative performance of the the existing and the
proposed system is discussed and some recommendations for further
improvements in the prototype system are made. / Graduation date: 1992
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Design, analysis, control and application of permanent magnet brushless dual-memory machinesLi, Fuhua, 李富华 January 2014 (has links)
Conventional PM machines have fixed PM excitation and can only perform flux-weakening by controlling the d-axis current. This current incurs the power dissipation and reduces the efficiency during flux-weakening operations.
Memory machines change this situation by introducing the memory function, namely magnetizing or reversely magnetizing Al-Ni-Co PMs to change the air-gap flux density. This provides another new way to realizing flux-weakening. And the elimination of the flux-weakening d-axis current improves the overall efficiency. But the single-memory machines have lower power density due to the low-energy Al-Ni-Co PMs.
By incorporating the memory concept and with the intention of improving the power density, the DC-excited PMBL dual-memory machines have been proposed and implemented, based on two kinds of PMs which are high-coercivity Nd-Fe-B PMs and low-coercivity Al-Ni-Co PMs. The Nd-Fe-B PMs provide a strong magnetic field to excite high air-gap flux density; while the Al-Ni-Co PMs can be forward magnetized to strengthen the magnetic field produced by Nd-Fe-B PMs or can be reversely magnetized to cancel that field. Consequently the air-gap flux density can be controlled within a wide range.
A series of design principles on such kind of dual-memory machine are devised for guidance. The key design principles involve how to determine the number of salient poles on the stator and rotor, how to choose the surface areas and thicknesses of the two kind of PM pieces and how to size the rotor dimension.
Generally, increase on the proportion of Nd-Fe-B PMs will raise the base field and the load capacity. On the other hand, increment on the proportion of Al-Ni-Co PMs will extend the controllable flux range. Analysis is also carried out on the equivalent magnetic circuit to formulate the magnetizing force exerted on Al-Ni-Co PMs.
The machine model is analyzed by using time-stepping FEM (TS-FEM) and co-simulation of FEM software and Matlab Simulink. The dynamic reverse magnetizing processes are simulated and presented in details under different magnetizing current. In addition the effect of adding iron bridges between the two kinds PMs is also evaluated by simulations.
Furthermore, the control methods are evaluate by simulations and experiments. The direct torque control (DTC) scheme is adapted to this doubly-salient dual-memory machine and a torque estimator is proposed to facilitate the DTC method. Both of the simulation results and the experimental results confirm the validity of the proposed design principles and the effectiveness of the control methods.
Eventually, this dual-memory machine is proposed as a pole-changing wind power generator and a pole-changing EV machine. Simulation and experimental results have verified the validity of the pole-changing scheme and the pole-protection scheme. / published_or_final_version / Electrical and Electronic Engineering / Doctoral / Doctor of Philosophy
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Design studies relating to the brushless doubly-fed automotive alternatorRavi, D. K. 08 June 1992 (has links)
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
structure. As the number of electrical devices in a car increases, so does the demand on
the generator system. The Lundell alternator is not able to meet the demands and
numerous alternative systems are under investigation. This led to the development of the
brushless doubly-fed alternator system with the advantages of regulation over a wide
speed range, competitive system cost based on inexpensive machine construction, low
rating controller, diode rectifier and robust, low maintenance configuration.
The conventional alternator has only one degree of control (de excitation), whereas
the doubly-fed alternator has three control quantities: excitation magnitude, frequency and
phase sequence. Excitation magnitude is used to regulate the output voltage, which leaves
two control parameters to optimize efficiency over the alternator speed range. Simulation
tools were developed for conducting design studies on the BDFM alternator system.
Various stator and rotor configurations were studied through simulation and a few
prototypes were built.
A proof-of-concept prototype built in an existing induction machine frame
achieved comparable efficiency characteristics to the Lundell System and exceeded the
Lundell performance over part of the speed range. Significant performance improvements
are expected for a new, optimized prototype which will not rely on the induction machine
laminations, but will utilize custom components designed for this low voltage, high
frequency application.
Since the increase in automotive power demand is likely to be coupled with an
increase in system voltage, a 24V, 2kW alternator system is investigated and simulation
results are presented. / Graduation date: 1993
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Geometric Design Optimization of Brushless Permanent Magnet MotorsMartin, Benjamin C. January 2009 (has links) (PDF)
No description available.
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