Recently Developed Reduced Switch Multilevel Inverter for Renewable Energy Integration and Drives Application: Topologies, Comprehensive Analysis and Comparative Evaluation

Recently, multilevel inverters (MLIs) have gained lots of interest in industry and academia, as they are changing into a viable technology for numerous applications, such as renewable power conversion system and drives. For these high power and high/medium voltage applications, MLIs are widely used as one of the advanced power converter topologies. To produce high-quality output without the need for a large number of switches, development of reduced switch MLI (RS MLI) topologies has been a major focus of current research. Therefore, this review paper focuses on a number of recently developed MLIs used in various applications. To assist with advanced current research in this field and in the selection of suitable inverter for various applications, significant understanding on these topologies is clearly summarized based on the three categories, i.e., symmetrical, asymmetrical, and modified topologies. This review paper also includes a comparison based on important performance parameters, detailed technical challenges, current focus, and future development trends. By a suitable combination of switches, the MLI produces a staircase output with low harmonic distortion. For a better understanding of the working principle, a single-phase RS MLI topology is experimentally illustrated for different level generation using both fundamental and high switching frequency techniques which will help the readers to gain the utmost knowledge for advance research

Advances in Rotating Electric Machines

It is difficult to imagine a modern society without rotating electric machines. Their use has been increasing not only in the traditional fields of application but also in more contemporary fields, including renewable energy conversion systems, electric aircraft, aerospace, electric vehicles, unmanned propulsion systems, robotics, etc. This has contributed to advances in the materials, design methodologies, modeling tools, and manufacturing processes of current electric machines, which are characterized by high compactness, low weight, high power density, high torque density, and high reliability. On the other hand, the growing use of electric machines and drives in more critical applications has pushed forward the research in the area of condition monitoring and fault tolerance, leading to the development of more reliable diagnostic techniques and more fault-tolerant machines. This book presents and disseminates the most recent advances related to the theory, design, modeling, application, control, and condition monitoring of all types of rotating electric machines

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

A multilevel converter structure for grid-connected PV plants

A new conversion structure for three-phase grid-connected photovoltaic (PV) generation plants is presented and discussed in this Thesis. The conversion scheme is based on two insulated PV arrays, each one feeding the dc bus of a standard 2-level three-phase voltage source inverter (VSI). Inverters are connected to the grid by a traditional three-phase transformer having open-end windings at inverters side and either star or delta connection at the grid side. The resulting conversion structure is able to perform as a multilevel VSI, equivalent to a 3-level inverter, doubling the power capability of a single VSI with given voltage and current ratings. Different modulation schemes able to generate proper multilevel voltage waveforms have been discussed and compared. They include known algorithms, some their developments, and new original approaches. The goal was to share the grid power with a given ratio between the two VSI within each cycle period of the PWM, being the PWM pattern suitable for the implementation in industrial DSPs. It has been shown that an extension of the modulation methods for standard two-level inverter can provide a elegant solution for dual two-level inverter. An original control method has been introduced to regulate the dc-link voltages of each VSI, according to the voltage reference given by a single MPPT controller. A particular MPPT algorithm has been successfully tested, based on the comparison of the operating points of the two PV arrays. The small deliberately introduced difference between two operating dc voltages leads towards the MPP in a fast and accurate manner. Either simulation or experimental tests, or even both, always accompanied theoretical developments. For the simulation, the Simulink tool of Matlab has been adopted, whereas the experiments have been carried out by a full-scale low-voltage prototype of the whole PV generation system. All the research work was done at the Lab of the Department of Electrical Engineering, University of Bologna

Fase Anizdun bihurgailuentzako modulazio berriak

266 p.Los convertidores multifase han adquirido una gran relevancia debido a sus ventajas sobre los convertidores trifásicos convencionales. Debido a estas ventajas, destacando la tolerancia a fallos, los sistemas multifase se emplean cada vez más en aplicaciones donde la fiabilidad es un factor clave. Sin embargo, estos sistemas no son inmunes a las faltas y, por ello, deben tomarse medidas que aumenten su fiabilidad y robustez. En concreto, esta tesis hace frente a dos de los mayores causantes de faltas en los sistemas basados en motores eléctricos (las faltas por circuito abierto y las faltas en los rodamientos debido a la tensión del modo común) mediante el uso de técnicas de modulación. Por un lado, en caso de perder una de las fases, las técnicas de modulación permiten generar tensiones equilibradas a la salida del convertidor, permitiendo a su vez que el convertidor siga funcionando aunque de forma degradada. Por otro lado, la tensión de modo común generada debido a la conmutación de los dispositivos que forman el convertidor daña los rodamientos de la máquina eléctrica. Por ello, siendo los rodamientos una pieza clave del motor, es necesario desarrollar nuevas técnicas de modulación que minimicen los efectos de la tensión de modo común. De esta forma, esta tesis, además de analizar en profundidad las fuentes causantes de las faltas mencionadas, propone nuevas técnicas de modulación capaces de mejorar el comportamiento del convertidor ante dichos problemas, con el fin de mejorar la tolerancia a fallos del convertidor y alargar la vida útil de los rodamientos del motor

Development of pulse-width-modulation techniques for multi-phase and multi-leg voltage source inverters

A huge body of work has been published in recent times in the area of multi-phase machines and drives. Many aspects of these drives have been analysed, such as reduction of torque pulsations, increased reliability and fault tolerance, improved power sharing capabilities and possibilities for realisation of series-connected multi-motor drives with supply coming from a single multi-phase voltage source inverter (VSI). Various pulse width modulation (PWM) schemes have been developed for multi-phase machines with concentrated and distributed windings, utilising both carrier-based PWM and space vector PWM (SVPWM) approaches. However, no systematic analysis has been performed in order to determine properties of multi-phase PWM in general, and to establish close correlation between carrier-based PWM and space vertor PWM, for multi-phase VSIs. This thesis presents an analysis and development of multi-phase PWM schemes for sinusoidal output voltage generation with two-level muhi-phase VSIs, which are suitable for multi-phase machines with distributed windings. Therefore, attention is paid to the elimination of low order harmonics. The scope of the thesis has been narrowed down to the continuous PWM schemes and operation in the linear region of the modulation only. Both multi-phase carrier-based PWM and SVPWM schemes are considered, and, in particular, five-phase, seven-phase e-phase systems are addressed in detail. Thus, a strong link between these two different approaches is established, allowing for an easier comparison of the features offered by each method. All PWM schemes are practically implemented in a DSP and experimentally verified through extensive experimentation on the custom-built multi-phase VSI. In addition to the methods of sinusoidal output voltage generation, achieved by means of the synthesis of the reference in only the first plane of the multi-phase system with simultaneous zeroing of voltages in all the other planes