An extended induction motor model for investigation of faulted machines and fault tolerant variable speed drives

High performance variable speed induction motor drives have been commercially available for industrial applications for many years. More recently they have been proposed for applications such as hybrid automotive drives, and some pump applications on more electric aircraft. These applications will require the drive to operate in the presence of faults i.e. they must be “Fault Tolerant” and be capable of “Fault Ride Through”. The aim of this project was therefore to investigate fault ride through control strategies for induction motor drives, particularly with respect to open circuit winding or power converter faults. Three objectives were identified and addressed to meet this aim. a) A new simulation model for an induction motor was created which reflects both saturation and space harmonics effects within the drive under both symmetric (healthy) and asymmetric (faulted) conditions. The model has a relatively low computational requirement to allow it to be used in conjunction with the simulation of high performance control algorithms and power electronic equipment. For operation in both healthy and faulty conditions, comparisons show that the simulated saturation and space harmonic effects match those obtained from an experiment system. Therefore this model is a very useful tool for the development and optimisation of new control strategies for fault tolerant drive systems. b) A novel on-line fault detection and diagnosis algorithm based on the measurement of the third harmonic component in the motor line currents has been proposed. The location of the open circuit fault is detected based on detecting a magnitude reduction for the third harmonic component of the current flowing to the motor terminals, and can be implemented in real time to give a fast response with little additional computational overhead. c) A new open circuit fault tolerant control strategy has been designed for a delta connected induction machine suddenly affected by an open circuit winding fault. The fault ride through is achieved without any modification to either the power converter or the motor circuit. A novel feedforward compensation algorithm is introduced which considerably reduces the current and the torque ripple in the faulted drive motor. Two methods for controlling the neutral point voltage are also presented so that the available voltage capacity of the inverter is maximised in both normal and fault mode. For high speed operation, two different methods for field weakening control are presented, so that the available voltage capacity is maximized in both normal and fault mode. This thesis describes the theoretical derivation of the new models and algorithms, and presents experimental results from a 4kW laboratory prototype to validate the proposals. The full fault tolerant system is experimentally demonstrated on a delta connected machine which suffers an open circuit winding fault. The improved motor performance under fault conditions is clearly seen

Shortest Route at Dynamic Location with Node Combination-Dijkstra Algorithm

Abstract— Online transportation has become a basic requirement of the general public in support of all activities to go to work, school or vacation to the sights. Public transportation services compete to provide the best service so that consumers feel comfortable using the services offered, so that all activities are noticed, one of them is the search for the shortest route in picking the buyer or delivering to the destination. Node Combination method can minimize memory usage and this methode is more optimal when compared to A* and Ant Colony in the shortest route search like Dijkstra algorithm, but can’t store the history node that has been passed. Therefore, using node combination algorithm is very good in searching the shortest distance is not the shortest route. This paper is structured to modify the node combination algorithm to solve the problem of finding the shortest route at the dynamic location obtained from the transport fleet by displaying the nodes that have the shortest distance and will be implemented in the geographic information system in the form of map to facilitate the use of the system. Keywords— Shortest Path, Algorithm Dijkstra, Node Combination, Dynamic Location (key words

Segmental rotor switched reluctance drives

One of the well-known drawbacks of switched reluctance machines is the relatively high output torque ripple. Techniques aiming to reduce machine torque ripple either compromise the machine performance or the simplicity of the inverter and the controller. The work presented in this thesis shows that low torque ripple over a wide speed range can be achieved without severe penalties in terms of the machine performance and the size, cost and complexity of the power electronics and the controller. This is achieved by designing a 6-phase machine and driving it from a three-phase full bridge circuit. Switched reluctance motors with segmented rotors are a relatively recent advancement in the electromagnetic design of doubly-salient reluctance motors, having only been introduced in 2002. By replacing the conventional toothed rotor with individual segments, it has been proven that higher torque density than conventional switched reluctance machines could be achieved. Early work by Mecrow and El-Kharashi has demonstrated the operation of prototype machines with short-pitched and fully-pitched windings. The machine design work presented here builds on this early work by examining aspects of the machine design and its operation. Two six-phase machines – one with a segmented rotor and the other with a toothed rotor - have been designed. Performance comparisons have been made between the two six-phase machines and a three phase segmented rotor machine that was previously designed at Newcastle University. Additionally, a three phase single tooth winding and a two phase segmented rotor switched reluctance machine have been studied in simulation and experimentally. Detailed comparison of inverter ratings and machine efficiencies are made under equal conditions for a 2-phase machine driven from h-bridge and asymmetric half-bridge inverters. This is achieved with results from a test rig and the use of accurate dynamic simulation. Simulation models for 3-phase and 6-phase machines have also been generated. Detailed comparison of inverter ratings and machine efficiencies are made under equal conditions for the 3-phase and 6-phase drives in the dynamic simulation. Comparisons between simulated and measured results are shown to be very good for all of the drives.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Mejora de las prestaciones de los convertidores de potencia para máquinas de reluctancia conmutada aplicadas a vehículo eléctrico.

326 p.Con unas normativas sobre emisión y consumo energético cada vez más restrictivas y una conciencia social cada vez más implicada en la necesidad de proteger el medio ambiente, los vehículos eléctricos (EVs) están atrayendo cada vez más la atención del sector de la automoción, político y de los consumidores. Los motores síncronos de imanes permanentes (PMSMs), debido a su gran densidad de potencia y eficiencia, han sido la tecnología de tracción dominante desde la década de los años 90. No obstante, estos motores son fabricados a partir de tierras raras. Las reservas de estos recursos son limitadas y su extracción provoca un gran impacto medioambiental. Por otra parte, los costes de los imanes basados en tierras raras han sufrido un incremento significativo en los últimos años. En este sentido, hay que constatar que el de los EVs es un mercado muy sensible con respecto a los costes.En este contexto, la elección de una alternativa de máquina eléctrica libre de tierras raras es una cuestión importante. Esta alternativa debe ser capaz de satisfacer los objetivos de eficiencia, robustez, densidad depotencia, simplicidad de control y costes establecidos por los distintos organismos internacionales. O en su defecto, mostrar un potencial para cumplir a corto/medio plazo.De entre todas las alternativas de máquinas libres de tierras raras, las máquinas de reluctancia conmutada (SRMs) son consideradas las candidatas más prometedoras para la próxima generación de EVs. Ésto es debido, principalmente, a que poseen características tales como una estructura simple, flexibilidad de control, alta eficiencia, bajos costes y robustez para funcionar en condiciones de fallo. Sin embargo, a causa del intercambio de grandes cantidades de energía magnética entre los devanados y la fuente de energía, es necesario incorporar grandes condensadores en el bus DC. Como consecuencia, se produce un aumento tanto del volumen como de los costes de los convertidores de potencia empleados.Ante este problema, es conveniente investigar en soluciones que aborden o que minimicen la estructura del convertidor. En esta tesis se aportan soluciones que van encaminadas a reducir el tamaño del condensador sin tener que acometer cambios estructurales en el convertidor de potencia de la SRM. Para ello, se realiza un análisis exhaustivo del estado de la tecnología SRM para, de esta forma, determinar la opción de topología de convertidor, control/modulación y tecnología de condensador que mejores prestaciones ofrece.A partir del análisis realizado, en esta tesis se presenta y valida un novedoso algoritmo de modulación para resolver la problemática de las altas corrientes en el bus DC del convertidor SRM. A dicho planteamiento se le ha denominado Modulación de Conmutación Sincronizada (Synchronized Switching Modulation, SSM), el cual se vale de un fenómeno de intercambio de energía entre fases para disminuir la dependencia del bus DC.La reducción en la corriente lograda en el bus DC tiene dos consecuencias directas en el condensador. Por un lado, permite disminuir su tamaño, reduciendo, así, los costes y el volumen de los condensadores a incorporar en el bus de continua. Por otro lado, dicha reducción de corriente redunda en un menor estrés térmico, lo cual aumenta la vida útil de los condensadores. Este segundo aspecto es analizado también en la presente tesis al realizarse un estudio sobre modelos de vida útil, modelos de daño acumulado y fiabilidad en los condensadores que conforman el convertidor SRM. Completando, de esta forma, el análisis del algoritmo SSM desarrollado.Los resultados obtenidos por el algoritmo SSM son positivos. Éste muestra una mejora en la corriente del bus DC del convertidor de potencia de hasta un 16 %, permitiendo una reducción del 20.8 % de la capacidad mínima requerida en el punto de operación más adverso, y un incremento de la eficiencia de hasta un 6 %. Asimismo, esa reducción en la corriente es suficiente para lograr un aumento del 13.83 % de la vida útil del condensador del bus de continua.Disponer de un modelo de vida útil fiable es, a la vez, muy importante y complicado. Sin embargo, el funcionamiento real de un EV es dinámico y el efecto de aplicar el algoritmo SSM depende de muchos otros factores (modelo de EV, aplicación de éste, ciclo de conducción, modelo de condensadores, etc.). Por todo esto, finalmente, en la presente tesis se define una metodología para predecir la vida útil de un condensador del bus de continua de un convertidor SRM a partir de la corriente que la atraviesa, es decir, a partir del conjunto de puntos operacionales (o ciclo de conducción) en el que está trabajando el tren de tracción del EV

Power Converters in Power Electronics

In recent years, power converters have played an important role in power electronics technology for different applications, such as renewable energy systems, electric vehicles, pulsed power generation, and biomedical sciences. Power converters, in the realm of power electronics, are becoming essential for generating electrical power energy in various ways. This Special Issue focuses on the development of novel power converter topologies in power electronics. The topics of interest include, but are not limited to: Z-source converters; multilevel power converter topologies; switched-capacitor-based power converters; power converters for battery management systems; power converters in wireless power transfer techniques; the reliability of power conversion systems; and modulation techniques for advanced power converters