Dynamic modelling and control schemes for current-source resonant converters

Versió amb diverses seccions retallades, per drets de l'editorThis thesis focuses on the control methods applied to current source resonant converters, especially in two different applications of switching power supplies and wire-less power transfer systems. In fact, the existing applications are mostly working with voltage source resonant converters. For voltage-source resonant converters, many control strategies have been analyzed and investigated, turning this into a mature technology nowadays. The current-source resonant converter is an alternative solution as they offer well-known advantages such as non-pulsating input current, low stress for switches, simple driving circuitry, and short circuit protection capabilities. However, there is an obvious lack of control methods applicable to current-source resonant converters. In addition, obtaining an appropriate dynamic model to be used in control design is the other challenging issue in this field. Hence, the objectives of this thesis are used to fill these gaps. The proposed control schemes are: - Frequency modulation control scheme applied to a DC/DC current-source parallel resonant converter. - Sliding mode control scheme with amplitude modulation applied to a DC/DC current-source parallel resonant converter. - A control scheme for a multiple-output DC/DC current-source parallel resonant converter. - A communication-less control scheme for a variable air-gap wireless energy transfer system using a current-source resonant converter.Esta tesis doctoral está centrada en los métodos de control aplicados a los convertidores resonantes con fuente de corriente, especialmente en dos aplicaciones distintas como son fuentes de alimentación conmutadas y sistemas de transferencia de energía sin hilos. De hecho, las aplicaciones existentes trabajan principalmente con convertidores alimentados mediante fuentes de tensión. Para los convertidores resonantes con fuente de tensión, se han analizado muchas estrategias de control en la literatura, lo que hace hoy en día que esta sea una tecnología madura. El convertidor resonante con fuente de corriente es una solución alternativa, que ofrece ventajas conocidas como corriente de entrada no pulsante, baja tensión para interruptores, circuitos de conducción sencillos y capacidades de protección contra cortocircuitos. Sin embargo, existe una falta evidente de métodos de control aplicables a los convertidores resonantes con fuente de corriente. Además, otro desafío en este tema es la obtención de modelos dinámicos apropiados para el diseño del control. Por lo tanto, los objetivos de esta tesis se utilizan para llenar estos vacíos. Los esquemas de control propuestos son: - Esquema de control en frecuencia aplicado a un convertidor resonante paralelo con fuente de corriente para reguladores de tensión en continua - Esquema de control en modo de deslizamiento con modulación de amplitud aplicado a un convertidor resonante paralelo con fuente de corriente para reguladores de tensión en continua. - Esquema de control para un convertidor resonante paralelo con fuente de corriente para la regulación de tensión en continua de varias salidas. - Esquema de control sin comunicaciones para un sistema de transferencia de energía sin hilos con un transformador con entrehierro variable basado en un convertidor resonante con fuente de corriente.Postprint (published version

Microbiological and molecular assessment of interactions among the major Fusarium head blight pathogens on wheat ears

Investigations on putative interactions among Fusarium species colonizing wheat ears were carried out to understand the high frequency of species with low virulence in the presence of more virulent ones. To determine inter-species interactions among the major Fusarium head blight pathogens, wheat ears were inoculated at mid flowering either with F. graminearum, F. culmorum, F. avenaceum and F. poae alone or in combinations of two, three or four isolates under field and greenhouse conditions. The isolates and the composition of inoculum significantly affected FHB severity, kernel weight, number of Fusarium-infected kernels, fungal biomass and mycotoxin production. In single or mixed inoculations, F. graminearum resulted in the highest disease ratings, frequency and intensity of kernel colonization and mycotoxin production, followed by F. culmorum, F. avenaceum and F. poae, respectively. In mixtures, the frequency of F. culmorum, F. avenaceum and F. poae infected kernels and fungal biomass in most cases was lower than in single inoculations, while the mycotoxin productivity significantly increased. The study demonstrated that significant interactions exist between or among Fusarium isolates during kernel colonization, such as competition and amensalism. These interactions were disadvantageous to less-virulent isolates, although to different degrees, no additive effects were detected. Competitiveness and virulence of isolates varied as quantified by the different parameters; they decreased in the order Fusarium graminearum, F. culmorum, F. avenaceum and F. poae, respectively. The frequency of infected spikelets increased with sampling time either in inoculation alone or in mixtures. For F. graminearum, the increase in the percentage of infected spikelets was unaffected by the presence of other isolates, while the other isolates were inhibited by its presence in mixed inoculations. The frequency of infection of wheat flower parts by Fusarium isolates decreased in the order lemma, palea, glume and developing kernel. One to three weeks after mixed inoculations, a high number of spikelets (10-20%) were infected by more than 1 isolate. In contrast, there was relatively low percentage of kernels bearing two Fusarium isolates at harvest (2% ≥). The highest levels of infection with two Fusarium isolates were observed in mixtures including F. avenaceum and F. culmorum. In contrast, infection frequencies were lowest in co-inoculations with F. poae. The comparison of frequency and intensity of kernel colonization proved differences in virulence and development of the isolates in the kernels. Only for the most virulent isolate, application of microbiological and real-time PCR assays gave similar results. For the other species, the intensity of kernel colonization was lower than expected from the frequency of infection. The high frequency of low-virulent Fusarium isolates in a FHB complex has to be attributed to others factors than direct interactions with highly virulent isolates during establishment on the wheat ears. The investigations indicated the biological complexity of multiple Fusarium-infections, head-Scab development and mycotoxin contamination of cereals.Untersuchung von Wechselwirkungen zwischen Fusarium spp., den Erregern der Partiellen Taubährigkeit im Weizen, unter Verwendung mikrobiologischer und molekularbiologischer Methoden Die durchgeführten Untersuchungen bezüglich mutmaßlicher Wechselwirkungen von Fusarium- Arten in infizierten Weizen-Ähren sollen dazu beitragen, das häufige Auftreten weniger aggressiver Arten bei gleichzeitigem Vorhandensein von aggressiven Fusarium-Arten zu verstehen. Zur Bestimmung inter-spezifischer Wechselwirkungen zwischen bedeutenden Erregern der Partiellen Taubährigkeit im Weizen wurden Ähren zum Zeitpunkt der Blüte entweder einzeln mit F. graminearum, F. culmorum, F. avenaceum und F. poae oder durch die Kombination von zwei, drei oder vier Arten im Gewächshaus und in Feldversuchen inokuliert. Die einzelnen Isolate als auch deren Kombination im Inokulum beeinflussten signifikant das symptomatische Auftreten der Partiellen Taubährigkeit, die Tausendkornmasse, die Häufigkeit infizierter Körner, die pilzliche Biomasse und die Mykotoxin-Bildung. Bei Einzeinokulation oder Kombinationsinokulation mit mehreren Isolate zeigte F. graminearum die höchste Pathogenität, die größte Häufigkeit und Intensität infizierter Körner sowie die stärkste Mykotoxin-Bildung, gefolgt von F. culmorum, F. avenaceum und F. poae. Im Vergleich zur Einzelinolukation von F. culmorum, F. avenaceum und F. poae führte Inokulation in Kombinationen einerseits zu einer Reduktion der Häufigkeit infizierter Körner sowie der pilzlichen Biomasse, andererseits jedoch zu einer signifikant höheren Mykotoxinproduktion. Die Ergebnisse aus den Untersuchungen verdeutlichen, dass während der Infektion und Ausbreitung von Fusarium spp. im Korn zwischen den beteiligten Fusarium-Isolaten signifikante Wechselwirkungen wie Konkurrenz und Amensalismus vorkommen. Diese Wechselwirkungen benachteiligten die weniger aggressiven Isolate, wenn auch zu einem unterschiedlichen Grad. Es wurden hier keine additiven Effekte nachgewiesen. Die Häufigkeit infizierter Ährchen stieg mit dem Zeitpunkt der Probennahme, sowohl bei Einzel- als auch Kombinationsinokulationen. Bei F. graminearum wurde der Anstieg der Häufigkeit infizierter Ährchen durch das Vorkommen anderer Isolate nicht beeinflusst, hingegen wurden die weiteren Isolate durch ihre Präsenz in Kombinations-Inokulationen gehemmt. Die Infektionshäufigkeit der Blütensegmente durch Fusarium spp. verringerte sich absteigend von Deckspelze, Vorspelze und Hüllspelze zu dem sich entwickelnden Korn. Ein bis drei Wochen nach Kombinationsinokulationen waren eine hohe Anzahl von Ährchen (10-20%) von mehr als einem Isolat besiedelt. Es wurde aber nur von einem geringen Prozentsatz der geernteten Körner zwei oder mehr verschiedene Fusarium-Isolate isoliert (2% ≥). Der Vergleich von Häufigkeit und Intensität des Fusarium-Befalls infizierter Körner zeigt, dass es Unterschiede hinsichtlich Virulenz und Entwicklung der Fusarium-Isolate in den Körnern gibt. Nur bei dem Isolat mit der höchsten Virulenz kam es zu einem übereinstimmenden Ergebnissen bei der mikrobiologischen und der Real-Time PCR-Untersuchung. Bei den anderen Arten war die war die Intensität der Besiedlung der Körner geringer als die Infektionshäufigkeit vermuten lies. Die große Häufigkeit von Fusarium-Isolaten mit geringer Virulenz muss auf andere Faktoren als die direkte Wechselwirkung mit hoch virulenten Isolaten währen der Entwicklung auf den Weizenähren zurückgeführt werden. Die Untersuchungen zeigten die biologische Komplexität von multiplen Fusarium-Infektionen, Krankheitsentwicklung und Mykotoxin-Belastung von Weizen

Dynamic modelling and control schemes for current-source resonant converters

This thesis focuses on the control methods applied to current source resonant converters, especially in two different applications of switching power supplies and wire-less power transfer systems. In fact, the existing applications are mostly working with voltage source resonant converters. For voltage-source resonant converters, many control strategies have been analyzed and investigated, turning this into a mature technology nowadays. The current-source resonant converter is an alternative solution as they offer well-known advantages such as non-pulsating input current, low stress for switches, simple driving circuitry, and short circuit protection capabilities. However, there is an obvious lack of control methods applicable to current-source resonant converters. In addition, obtaining an appropriate dynamic model to be used in control design is the other challenging issue in this field. Hence, the objectives of this thesis are used to fill these gaps. The proposed control schemes are: - Frequency modulation control scheme applied to a DC/DC current-source parallel resonant converter. - Sliding mode control scheme with amplitude modulation applied to a DC/DC current-source parallel resonant converter. - A control scheme for a multiple-output DC/DC current-source parallel resonant converter. - A communication-less control scheme for a variable air-gap wireless energy transfer system using a current-source resonant converter.Esta tesis doctoral está centrada en los métodos de control aplicados a los convertidores resonantes con fuente de corriente, especialmente en dos aplicaciones distintas como son fuentes de alimentación conmutadas y sistemas de transferencia de energía sin hilos. De hecho, las aplicaciones existentes trabajan principalmente con convertidores alimentados mediante fuentes de tensión. Para los convertidores resonantes con fuente de tensión, se han analizado muchas estrategias de control en la literatura, lo que hace hoy en día que esta sea una tecnología madura. El convertidor resonante con fuente de corriente es una solución alternativa, que ofrece ventajas conocidas como corriente de entrada no pulsante, baja tensión para interruptores, circuitos de conducción sencillos y capacidades de protección contra cortocircuitos. Sin embargo, existe una falta evidente de métodos de control aplicables a los convertidores resonantes con fuente de corriente. Además, otro desafío en este tema es la obtención de modelos dinámicos apropiados para el diseño del control. Por lo tanto, los objetivos de esta tesis se utilizan para llenar estos vacíos. Los esquemas de control propuestos son: - Esquema de control en frecuencia aplicado a un convertidor resonante paralelo con fuente de corriente para reguladores de tensión en continua - Esquema de control en modo de deslizamiento con modulación de amplitud aplicado a un convertidor resonante paralelo con fuente de corriente para reguladores de tensión en continua. - Esquema de control para un convertidor resonante paralelo con fuente de corriente para la regulación de tensión en continua de varias salidas. - Esquema de control sin comunicaciones para un sistema de transferencia de energía sin hilos con un transformador con entrehierro variable basado en un convertidor resonante con fuente de corriente

Robust and fast sliding-mode control for a DC-DC current-source parallel-resonant converter

Modern DC-DC resonant converters are normally built around a voltage-source series-resonant converter. This study aims to facilitate the practical use of current-source parallel-resonant converters due to their outstanding properties. To this end, this study presents a sliding-mode control scheme, which provides the following features to the closed-loop system: (i) high robustness to external disturbances and parameter variations and (ii) fast transient response during large and abrupt load changes. In addition, a design procedure for determining the values of the control parameters is presented. The theoretical contributions of this study are experimentally validated by selected tests on a laboratory prototype.Peer ReviewedPreprin

Imbalance-voltage mitigation in an inverter-based distributed generation system using a minimum current-based control strategy

©2020 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes,creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.Voltage imbalances are one of the most severe challenges in electrical networks, which negatively affect their loads and other connected equipment. This paper proposes a voltage support control strategy to mitigate the voltage imbalance in inverter-based low voltage distribution networks. The control scheme is derived taking in mind the following control objectives: a) to increase the positive sequence voltage as much as possible, b) to decrease the negative sequence voltage as much as possible, c) to inject the power generated by the primary source, and d) to minimize the output current of the inverter. The innovative contribution of the proposed solution is based on the design of a control algorithm that meets the aforementioned objectives without resorting to communications with other grid components. The theoretical results are experimentally validated by selected tests on a laboratory setup with X/R ratio close to one.This work was supported in part by the Ministry of Economy and Competitiveness of Spain and in part by the European Regional Development Fund under Project RTI2018-100732-B-C22.Peer ReviewedPostprint (author's final draft

Frequency-modulation control of a DC/DC current-source parallel-resonant converter

This paper proposes a frequency-modulation control scheme for a dc/dc current-source parallel-resonant converter with two possible configurations. The basic configuration comprises an external voltage loop, an internal current loop, and a frequency modulator: the voltage loop is responsible for regulating the output voltage, the current loop makes the system controllable and limits the input current, and the modulator provides robustness against variations in resonant component values. The enhanced configuration introduces the output inductor current as a feed-forward term and clearly improves the transient response to fast load changes. The theoretical design of these control schemes is performed systematically by first deriving their small-signal models and second using Bode diagram analysis. The actual performance of the proposed control schemes is experimentally validated by testing on a laboratory prototype.Peer ReviewedPostprint (author's final draft

Analysis, design and implementation of a residential inductive contactless energy transfer system with multiple mobile clamps

This study presents the analysis, design and implementation of a simple and cost-effective residential inductive contactless energy transfer system with multiple mobile clamps. The topology is based on the cascaded connection of a buck converter and a high-frequency resonant inverter loaded by several output passive rectifiers. The proposed system includes a sliding transformer to supply the mobile loads, leading to a safe and flexible location of loads. The theoretical analysis and design of the proposed system is based on a mathematical model derived using the first harmonic approximation. Selected experimental results are included to verify the system features. In comparison with conventional topology, the proposed system significantly improves efficiency, complexity and cost.Peer ReviewedPostprint (author's final draft

A flexible experimental laboratory for distributed generation networks based on power inverters

In the recently deregulated electricity market, distributed generation based on renewable sources is becoming more and more relevant. In this area, two main distributed scenarios are focusing the attention of recent research: grid-connected mode, where the generation sources are connected to a grid mainly supplied by big power plants, and islanded mode, where the distributed sources, energy storage devices, and loads compose an autonomous entity that in its general form can be named a microgrid. To conduct a successful research in these two scenarios, it is essential to have a flexible experimental setup. This work deals with the description of a real laboratory setup composed of four nodes that can emulate both scenarios of a distributed generation network. A comprehensive description of the hardware and software setup will be done, focusing especially in the dual-core DSP used for control purposes, which is next to the industry standards and able to emulate real complexities. A complete experimental section will show the main features of the system.Peer ReviewedPostprint (published version

Dynamic modelling and control schemes for current-source resonant converters

Versió amb diverses seccions retallades, per drets de l'editorThis thesis focuses on the control methods applied to current source resonant converters, especially in two different applications of switching power supplies and wire-less power transfer systems. In fact, the existing applications are mostly working with voltage source resonant converters. For voltage-source resonant converters, many control strategies have been analyzed and investigated, turning this into a mature technology nowadays. The current-source resonant converter is an alternative solution as they offer well-known advantages such as non-pulsating input current, low stress for switches, simple driving circuitry, and short circuit protection capabilities. However, there is an obvious lack of control methods applicable to current-source resonant converters. In addition, obtaining an appropriate dynamic model to be used in control design is the other challenging issue in this field. Hence, the objectives of this thesis are used to fill these gaps. The proposed control schemes are: - Frequency modulation control scheme applied to a DC/DC current-source parallel resonant converter. - Sliding mode control scheme with amplitude modulation applied to a DC/DC current-source parallel resonant converter. - A control scheme for a multiple-output DC/DC current-source parallel resonant converter. - A communication-less control scheme for a variable air-gap wireless energy transfer system using a current-source resonant converter.Esta tesis doctoral está centrada en los métodos de control aplicados a los convertidores resonantes con fuente de corriente, especialmente en dos aplicaciones distintas como son fuentes de alimentación conmutadas y sistemas de transferencia de energía sin hilos. De hecho, las aplicaciones existentes trabajan principalmente con convertidores alimentados mediante fuentes de tensión. Para los convertidores resonantes con fuente de tensión, se han analizado muchas estrategias de control en la literatura, lo que hace hoy en día que esta sea una tecnología madura. El convertidor resonante con fuente de corriente es una solución alternativa, que ofrece ventajas conocidas como corriente de entrada no pulsante, baja tensión para interruptores, circuitos de conducción sencillos y capacidades de protección contra cortocircuitos. Sin embargo, existe una falta evidente de métodos de control aplicables a los convertidores resonantes con fuente de corriente. Además, otro desafío en este tema es la obtención de modelos dinámicos apropiados para el diseño del control. Por lo tanto, los objetivos de esta tesis se utilizan para llenar estos vacíos. Los esquemas de control propuestos son: - Esquema de control en frecuencia aplicado a un convertidor resonante paralelo con fuente de corriente para reguladores de tensión en continua - Esquema de control en modo de deslizamiento con modulación de amplitud aplicado a un convertidor resonante paralelo con fuente de corriente para reguladores de tensión en continua. - Esquema de control para un convertidor resonante paralelo con fuente de corriente para la regulación de tensión en continua de varias salidas. - Esquema de control sin comunicaciones para un sistema de transferencia de energía sin hilos con un transformador con entrehierro variable basado en un convertidor resonante con fuente de corriente

Dynamic modelling and control schemes for current-source resonant converters

This thesis focuses on the control methods applied to current source resonant converters, especially in two different applications of switching power supplies and wire-less power transfer systems. In fact, the existing applications are mostly working with voltage source resonant converters. For voltage-source resonant converters, many control strategies have been analyzed and investigated, turning this into a mature technology nowadays. The current-source resonant converter is an alternative solution as they offer well-known advantages such as non-pulsating input current, low stress for switches, simple driving circuitry, and short circuit protection capabilities. However, there is an obvious lack of control methods applicable to current-source resonant converters. In addition, obtaining an appropriate dynamic model to be used in control design is the other challenging issue in this field. Hence, the objectives of this thesis are used to fill these gaps. The proposed control schemes are: - Frequency modulation control scheme applied to a DC/DC current-source parallel resonant converter. - Sliding mode control scheme with amplitude modulation applied to a DC/DC current-source parallel resonant converter. - A control scheme for a multiple-output DC/DC current-source parallel resonant converter. - A communication-less control scheme for a variable air-gap wireless energy transfer system using a current-source resonant converter.Esta tesis doctoral está centrada en los métodos de control aplicados a los convertidores resonantes con fuente de corriente, especialmente en dos aplicaciones distintas como son fuentes de alimentación conmutadas y sistemas de transferencia de energía sin hilos. De hecho, las aplicaciones existentes trabajan principalmente con convertidores alimentados mediante fuentes de tensión. Para los convertidores resonantes con fuente de tensión, se han analizado muchas estrategias de control en la literatura, lo que hace hoy en día que esta sea una tecnología madura. El convertidor resonante con fuente de corriente es una solución alternativa, que ofrece ventajas conocidas como corriente de entrada no pulsante, baja tensión para interruptores, circuitos de conducción sencillos y capacidades de protección contra cortocircuitos. Sin embargo, existe una falta evidente de métodos de control aplicables a los convertidores resonantes con fuente de corriente. Además, otro desafío en este tema es la obtención de modelos dinámicos apropiados para el diseño del control. Por lo tanto, los objetivos de esta tesis se utilizan para llenar estos vacíos. Los esquemas de control propuestos son: - Esquema de control en frecuencia aplicado a un convertidor resonante paralelo con fuente de corriente para reguladores de tensión en continua - Esquema de control en modo de deslizamiento con modulación de amplitud aplicado a un convertidor resonante paralelo con fuente de corriente para reguladores de tensión en continua. - Esquema de control para un convertidor resonante paralelo con fuente de corriente para la regulación de tensión en continua de varias salidas. - Esquema de control sin comunicaciones para un sistema de transferencia de energía sin hilos con un transformador con entrehierro variable basado en un convertidor resonante con fuente de corriente