10 research outputs found
Applications of Power Electronics
Power electronics technology is still an emerging technology, and it has found its way into many applications, from renewable energy generation (i.e., wind power and solar power) to electrical vehicles (EVs), biomedical devices, and small appliances, such as laptop chargers. In the near future, electrical energy will be provided and handled by power electronics and consumed through power electronics; this not only will intensify the role of power electronics technology in power conversion processes, but also implies that power systems are undergoing a paradigm shift, from centralized distribution to distributed generation. Today, more than 1000 GW of renewable energy generation sources (photovoltaic (PV) and wind) have been installed, all of which are handled by power electronics technology. The main aim of this book is to highlight and address recent breakthroughs in the range of emerging applications in power electronics and in harmonic and electromagnetic interference (EMI) issues at device and system levels as discussed in ?robust and reliable power electronics technologies, including fault prognosis and diagnosis technique stability of grid-connected converters and ?smart control of power electronics in devices, microgrids, and at system levels
Lead pursuit control of multiphase drives
Los accionamientos multifásicos, compuestos por una máquina eléctrica de más de tres
fases alimentada por un convertidor de potencia, han atraÃdo recientemente un importante
interés en la comunidad investigadora debido a las ventajas que presentan frente a las
máquinas trifásicas convencionales. Este es el caso de la mejor distribución de potencia
por fase, la menor producción de armónicos en el convertidor de potencia y, la más
importante, la tolerancia a fallos, lo cual significa que la máquina multifásica puede seguir
funcionando cuando una o varias fases se pierden, siempre que el número restante de fases
sea igual o mayor que tres. Debido a esta alta fiabilidad, los accionamientos multifásicos
son especialmente adecuados para aplicaciones relacionadas con los vehÃculos eléctricos
(terrestres, marÃtimos y aéreos) y las energÃas renovables por razones de seguridad y/o
económicas.
El uso de controladores avanzados y de alto rendimiento en accionamientos multifásicos
es particularmente relevante, ya que las estrategias de control convencionalmente aplicadas
a los accionamientos trifásicos no terminan de alcanzar un estándar en su extensión al caso
multifásico. La razón es la mayor complejidad y número de variables a controlar. En este
contexto, los controladores predictivos han encontrado un interesante nicho de aplicación
en convertidores de potencia y accionamientos multifásicos debido a su formulación
intuitiva y flexible: un modelo del sistema es usado para calcular las predicciones de las
variables controladas, que luego se comparan con las referencias impuestas dentro de
una función de coste. Esta estrategia permite incorporar varios objetivos de control y
restricciones en el proceso de control a través de la función de coste. Sin embargo, es
bien sabido que este tipo de controlador sufre de un alto coste computacional y contenido
armónico de corriente que limita su aplicación en los accionamientos multifásicos.
La investigación desarrollada en esta Tesis se centra en la mitigación de las limitaciones
citadas siguiendo dos objetivos principales:
• La incorporación de observadores de corrientes rotóricas en el controlador predictivo
para mejorar asà la precisión del modelo predictivo y, consecuentemente,
el rendimiento del sistema de control, principalmente en términos de contenido
armónico y pérdidas por conmutación en el convertidor de potencia. Un observador de Luenberger es construido para este propósito utilizando una estrategia innovadora
de posicionamiento de polos en su diseño.
• La introducción de un grado de libertad adicional en el controlador predictivo
basado en tiempos de muestreo variables e implementado usando el concepto de
lead pursuit. El resultado es un controlador novedoso que conduce a una resolución
en los tiempos de conmutación más fina en comparación con las técnicas predictivas
más convencionales, lo que proporciona una reducción importante en el contenido
armónico.
Las estrategias de control propuestas son validadas mediante simulación y experimentación
utilizando un accionamiento compuesto por una máquina de inducción de cinco
fases como caso de ejemplo. Los resultados y conclusiones derivadas de esta investigación
han sido presentados en cinco trabajos principales publicados en revistas internacionales
de alto impacto, los cuales constituyen las contribuciones de esta Tesis por compendio de
artÃculos. Sin embargo, otros trabajos relacionados con la lÃnea de investigación han sido
también publicados en artÃculos de revista y conferencia y en un capÃtulo de libro.Multiphase drives, constituted by an electric machine with more than three phases
fed by a power converter, have recently attracted an important interest in the research
community due to the advantages that they present over the conventional three-phase ones.
This is the case of the better power distribution per phase, the lower harmonic production
in the power converter, and the most important one, the fault-tolerant capability, which
means that the multiphase machine can still be operated when one or several phases are
missing, provided that the number of remaining phases is equal or greater than three. Due
to this high reliability, multiphase drives are specially well suited for applications related
to electric vehicles (terrestrial, maritime and aerial) and renewable energies for safety
and/or economical reasons.
The use of advanced and high-performance controllers in multiphase drives is particularly
relevant, since the control strategies conventionally applied to three-phase drives do
not reach a standard in their extension to the multiphase case. The reason is the greater
complexity and number of variables that must be controlled. In this context, predictive
controllers have found an interesting niche of application in power converters and multiphase
drives due to their intuitive and flexible formulation: a model of the system is
used to compute predictions of the controlled variables, which are later compared with the
imposed references in a cost function. This strategy permits incorporating several control
objectives and constraints in the control process through the cost function. However, it is
well known that this type of controller suffers from a high computational cost and current
harmonic content that limit its application in multiphase drives.
The research developed in this Thesis work is focused on the mitigation of the cited
limitations following two main goals:
• The incorporation of rotor current observers in the predictive controller in order to
improve the accuracy of the predictive model and, consequently, the control system
performance, principally in terms of harmonic content and commutation losses in
the power converter. A Luenberger observer is constructed for that purpose using
an innovative pole-placement strategy in its design.
• The introduction of an additional degree of freedom in the predictive controller
based on variable sampling times and implemented using the lead-pursuit concept. The result is a novel controller that leads to a finer resolution in the commuting
times in comparison with more conventional predictive techniques, which provides
an important reduction in the harmonic content.
The proposed control strategies are validated by simulation and experimentation using a
five-phase induction machine drive as case example. The results and conclusions derived
from this research have been presented in five main works published in high-impact
international journals, which constitute the contributions of this article compendium Thesis.
Nevertheless, other related works have also been published in journal and conference papers
and a book chapter
Aeronautical engineering: A continuing bibliography with indexes (supplement 202)
This bibliography lists 447 reports, articles and other documents introduced into the NASA scientific and technical information system in June 1986
Industrial and Technological Applications of Power Electronics Systems
The Special Issue "Industrial and Technological Applications of Power Electronics Systems" focuses on: - new strategies of control for electric machines, including sensorless control and fault diagnosis; - existing and emerging industrial applications of GaN and SiC-based converters; - modern methods for electromagnetic compatibility. The book covers topics such as control systems, fault diagnosis, converters, inverters, and electromagnetic interference in power electronics systems. The Special Issue includes 19 scientific papers by industry experts and worldwide professors in the area of electrical engineering
Aeronautical Engineering, a continuing bibliography with indexes, supplement 173
This bibliography lists 704 reports, articles and other documents introduced into the NASA scientific and technical information system in March 1984
A synchronised multi-motor control system using hybrid sensorless induction motor drives
The main aim of this project was to research, develop and test an induction motor drive not requiring a speed encoder, but which could be considered commercially viable by motor drives manufacturers, and which should aim to meet the follow requirements:
• Dynamic torque performance and steady state speed-holding accuracy to be comparable with encodered vector controlled drives
• Extensive and highly accurate knowledge of electrical and mechanical parameters of the motor and load not to be required
• Extensive commissioning from an expert engineer not to be necessary
• Algorithm not to rely on excessive computational capability being available
The drive was to operate, in a stable manner, over speed and load ranges at least comparable with commercially available sensorless induction motor drives. The above requirements were set such that the developed sensorless technique may be considered for synchronised multi-motor process applications, where the advantages of a sensorless system could be exploited for hazardous, damp and hot conditions.
The solution developed consists of a leading model-based sensorless method augmented with a speed estimator that tracks harmonics, seen in the stator terminal quantities, due to rotor slotting. The model-based scheme facilitates field-orientated control for dynamic performance. The slot harmonic speed estimator tunes the model for speed accuracy. Slot harmonics are identified using a recursive signal processing method termed the Recursive Maximum Likelihood - Adaptive Tracking Filter. This work is the first example of the method being developed into a practical sensorless drive system and the complete speed identifier is described, including set-up, pre-filtering and the minimal parameter considerations. Being recursive the method is computationally efficient, yet has accuracy comparable with that of FFT identifiers used in other work.
The developed sensorless strategy was implemented practically on two motor drive systems. The performance of the scheme is shown to give encoder like speed holding accuracy and field-orientated dynamic performance. The two drives were also configured and tested as a speed synchronised pair, using applicable multi-motor control techniques, themselves compared and contrasted. The sensorless performance is demonstrated, alongside an encodered version acting as a benchmark, and the performance of the two schemes is shown to be highly comparable. The author has found no other example of sensorless techniques considered for use in multi-motor applications. The use of such a technique brings established advantages associated with encoder removal and allows multi-axis electronic synchronisation to be considered for parts of a process where an encoder may not be appropriate
A synchronised multi-motor control system using hybrid sensorless induction motor drives
The main aim of this project was to research, develop and test an induction motor drive not requiring a speed encoder, but which could be considered commercially viable by motor drives manufacturers, and which should aim to meet the follow requirements:
• Dynamic torque performance and steady state speed-holding accuracy to be comparable with encodered vector controlled drives
• Extensive and highly accurate knowledge of electrical and mechanical parameters of the motor and load not to be required
• Extensive commissioning from an expert engineer not to be necessary
• Algorithm not to rely on excessive computational capability being available
The drive was to operate, in a stable manner, over speed and load ranges at least comparable with commercially available sensorless induction motor drives. The above requirements were set such that the developed sensorless technique may be considered for synchronised multi-motor process applications, where the advantages of a sensorless system could be exploited for hazardous, damp and hot conditions.
The solution developed consists of a leading model-based sensorless method augmented with a speed estimator that tracks harmonics, seen in the stator terminal quantities, due to rotor slotting. The model-based scheme facilitates field-orientated control for dynamic performance. The slot harmonic speed estimator tunes the model for speed accuracy. Slot harmonics are identified using a recursive signal processing method termed the Recursive Maximum Likelihood - Adaptive Tracking Filter. This work is the first example of the method being developed into a practical sensorless drive system and the complete speed identifier is described, including set-up, pre-filtering and the minimal parameter considerations. Being recursive the method is computationally efficient, yet has accuracy comparable with that of FFT identifiers used in other work.
The developed sensorless strategy was implemented practically on two motor drive systems. The performance of the scheme is shown to give encoder like speed holding accuracy and field-orientated dynamic performance. The two drives were also configured and tested as a speed synchronised pair, using applicable multi-motor control techniques, themselves compared and contrasted. The sensorless performance is demonstrated, alongside an encodered version acting as a benchmark, and the performance of the two schemes is shown to be highly comparable. The author has found no other example of sensorless techniques considered for use in multi-motor applications. The use of such a technique brings established advantages associated with encoder removal and allows multi-axis electronic synchronisation to be considered for parts of a process where an encoder may not be appropriate