Neste trabalho desenvolve-se uma análise sobre o estado da arte e tendências para projeto de geradores elétricos em turbinas eólicas offshore. A conjunção dos requerimentos de alta confiabilidade e potência, criam condições adequadas para a aplicação de máquina elétricas multifásicas nesse setor. Desta forma, optou-se por estudar as características e condições de projeto de máquinas elétricas multifásicas, simétricas ou assimétricas. Com esta finalidade, os métodos analíticos de projeto de máquinas elétricas trifásicas são revisitados e estendidos, quando necessário, para diferentes configurações multifásicas. O foco do trabalho, consiste em desenvolver e explorar temas de projeto de geradores elétricos multifásicos, síncronos de imãs permanentes, com enrolamentos distribuídos de dupla camada. Para estudo de caso, realiza-se a comparação entre o projeto de quatro topologias diferentes. Nomeadamente, compara-se o projeto de geradores de três, seis, nove e dezoito fases para turbinas eólicas offshore de 10 MW. A configuração com gerador de nove fases apresenta os melhores resultados, com densidade de torque 10,96% superior à densidade de torque desenvolvida pela máquina trifásica analisada. Por fim, a metodologia analítica desenvolvida para o projeto de máquinas elétricas multifásicas é verificada usando o método de elementos finitos bidimensional, para o gerador síncrono de imãs permanentes de nove fases. / The state of the art and future trends for offshore wind turbines were reviewed. Due to its fault-tolerant characteristic, multiphase electrical generators were identified as strong candidates to meet the power and resilience targets of the offshore wind sector. In this work, the design aspects of three-phase electrical machines are reviewed and extended to different multiphase configurations. The main focus of the work is to develop an analytical design methodology for multiphase, symmetrical and asymmetrical, synchronous generators with double-layer distributed windings. As a case study, the project of a three-phase, six-phase, nine-phase and eighteen-phase permanent magnet synchronous generators were compared for a 10MW offshore wind turbine. The best results were found for the nine-phase topology, with a torque density 10.96% higher than the torque density of the analysed three-phase machine. The developed design methodology was validated with a finite element analysis of the ninephase permanent magnet generator.

Neste trabalho desenvolve-se uma análise sobre o estado da arte e tendências para projeto de geradores elétricos em turbinas eólicas offshore. A conjunção dos requerimentos de alta confiabilidade e potência, criam condições adequadas para a aplicação de máquina elétricas multifásicas nesse setor. Desta forma, optou-se por estudar as características e condições de projeto de máquinas elétricas multifásicas, simétricas ou assimétricas. Com esta finalidade, os métodos analíticos de projeto de máquinas elétricas trifásicas são revisitados e estendidos, quando necessário, para diferentes configurações multifásicas. O foco do trabalho, consiste em desenvolver e explorar temas de projeto de geradores elétricos multifásicos, síncronos de imãs permanentes, com enrolamentos distribuídos de dupla camada. Para estudo de caso, realiza-se a comparação entre o projeto de quatro topologias diferentes. Nomeadamente, compara-se o projeto de geradores de três, seis, nove e dezoito fases para turbinas eólicas offshore de 10 MW. A configuração com gerador de nove fases apresenta os melhores resultados, com densidade de torque 10,96% superior à densidade de torque desenvolvida pela máquina trifásica analisada. Por fim, a metodologia analítica desenvolvida para o projeto de máquinas elétricas multifásicas é verificada usando o método de elementos finitos bidimensional, para o gerador síncrono de imãs permanentes de nove fases. / The state of the art and future trends for offshore wind turbines were reviewed. Due to its fault-tolerant characteristic, multiphase electrical generators were identified as strong candidates to meet the power and resilience targets of the offshore wind sector. In this work, the design aspects of three-phase electrical machines are reviewed and extended to different multiphase configurations. The main focus of the work is to develop an analytical design methodology for multiphase, symmetrical and asymmetrical, synchronous generators with double-layer distributed windings. As a case study, the project of a three-phase, six-phase, nine-phase and eighteen-phase permanent magnet synchronous generators were compared for a 10MW offshore wind turbine. The best results were found for the nine-phase topology, with a torque density 10.96% higher than the torque density of the analysed three-phase machine. The developed design methodology was validated with a finite element analysis of the ninephase permanent magnet generator.

Les entraînements électriques polyphasés ont acquis une importance particulière ces derniers temps pour leur utilisation dans des applications où la fiabilité présente un intérêt pour des raisons économiques et de sécurité. Cette thèse se centre sur le développement de techniques de commande en mode instantané pour contrôler de manière optimale les machines polyphasées, en analysant leur tolérance dans différentes conditions de fonctionnement, telles que lors de l’atteinte de limites électriques (limites de tension, de courant et de niveau maximum de magnétisation) ou de défauts de type phase ouverte. Tout d’abord, la technique DTC est proposée pour gérer le cas de défaut de type phase ouverte dans la machine polyphasée. Une comparaison de la tolérance à la défaillance des commandes de type DTC par rapport à d’autres techniques de commande est réalisée, permettant une conclusion sur les forces et les faiblesses des méthodes analysées. Enfin, un contrôleur de courant optimal est développé utilisant des techniques MPC permettant une utilisation optimale de la capacité de couple du système en cas de limitations électriques. Des résultats de simulation et des validations expérimentales sont effectués pour corroborer les approches initiales, en utilisant des cas particuliers d’entraînements pentaphasés commandés avec différents sous-espaces de commande dans le domaine fréquentiel. / Multiphase drives have gained special relevance in recent times for their use in applications where reliability is of interest for economical and safety reasons. This Thesis focuses on the development of direct control techniques to optimally control multiphase machines, analyzing their tolerance to different limit operating conditions, such as electrical constraints (voltage, current and magnetization level limits) or failure situations such as an open-phase fault. First, the DTC technique is proposed to manage the open-phase fault operation of the multiphase machine. A comparison of the fault-tolerant capability of DTC with other control techniques is carried out, to conclude the strengths and weaknesses of the analyzed methods facing this limit operation. Finally, an optimal current controller is developed using MPC techniques that allows the optimal utilization of the system’s torque capability under electrical limitations. Simulation results and experimental validations are obtained to corroborate the initial approaches, through the use of particular cases of five-phase drives controlled using different frequency-domain control subspaces.

In the recent decades, an increased interest into multiphase machines has developed due to certain beneficial properties they have over the standard three- phase machines. Proper modelling of a multiphase machine allows access to higher degrees of freedom given by the ability to control higher order harmonic frames. This feature is of particular interest in the area of parameter estimation as it may provide an opportunity to implement methods that are not feasible in three- phase machines. Modelling of a real six- phase machine meant for marine application with a functioning control structure is carried out on MATLAB/Simulink; considering nonlinear relations, cross coupling and saturation effects, the model includes the machine’s behavior in the fundamental frame as well as the next two higher order harmonic frames. Stator resistances and permanent magnet flux linkage are estimated online and simultaneously during various operating points. It is shown that stator resistance may be accurately estimated by means of DC test signal injections into the highest order harmonic frame; thus, minimizing torque ripple and additional loss generation. Permanent magnet flux linkage is accurately estimated via reactive power calculations on the fundamental frame which remains undisturbed by the aforementioned test signals. / Under de senaste decennierna har intresset för flerfasmaskiner ökat, på grund av i vissa avseenden, fördelaktiga egenskaper i jämförelse med traditionella trefasmaskiner. En väl genomförd modellering av flerfasmaskiner möjliggör högre grader av frihet givet förmågan att kontrollera frekvensplan av högre ordning. Denna funktion är av särskilt intresse inom parameteruppskattning, då det kan ge möjligheter att implementera metoder som är omöjliga i trefas maskiner. En modell av en verklig sexfasmaskin, byggd för en marin tillämpning och med ett givet styrsystem, har skapats i MATLAB/Simulink. Modellen tar hänsyn till ickelinjära förhållanden, korskopplingar och mättning. Den inkluderar även maskinens egenskaper i det fundamentala frekvensplanet och de två nästkommande frekvensplanen av högre ordning. Statorresistansen och permanentmagneternas sammanlänkade flöden uppskattas i realtid för olika driftsförhållanden. Det visar sig att statorresistansen kan uppskattas noggrant genom inmatning av en DC testsignal i högsta ordningens frekvensplan vilket minimerar momentrippel och extra förluster. Permanentmagneternas flöden kan uppskattas noggrant genom beräkning av den reaktiva effekten i det fundamentala frekvensplanet som är opåverkat av de ovan nämnda testsignalerna.

Electrical machines with more than three phases are usually called multiphase electrical machines and they can have several advantages compared to conventional three-phase electrical machines such as a lower content of space-harmonics, lower torque ripple and better fault tolerance. This degree project involves rewinding of a three-phase induction machine into an asymmetrical six-phase machine. The winding design is based on simulations of a machine model in a finite element method software and the method "the star of the slot" that computes winding layouts. A six-phase drive is developed based on an existing printed circuit board prototype that is not operating according to its original specifications. Debugging of the prototype is performed and solutions to the problems are identified. Design and layout improvements for better electromagnetic compatibility are also implemented. The drive including the electrical machine is tested and confirmed to be working according to the specifications. Speed control based on indirect rotor field orientation is implemented and tested for the six-phase induction machine as well with the machine connected as a standard three-phase induction machine. / Elektriska maskiner med fler än tre faser kallas vanligtvis flerfasiga elektriska maskiner och kan ha flera fördelar jämfört med konventionella trefasiga elektriska maskiner, som lägre innehåll av övervågor, lägre rippel i vridmomentet och bättre feltolerans. Detta examensarbete involverar omlindning av en trefasig asynkronmaskin till en asymmetrisk sexfasig asynkronmaskin. Lindningsdesignen baseras på simuleringar av en maskinmodell i mjukvara baserat på finita element metoden och metoden kallad the star of the slotsom räknar ut lindnings ritningar. En sexfasig drivlina utvecklas baserat på en existerande kretskorts prototyp som inte fungerar enligt dess ursprunliga specifikationer. Felsökning av prototypen utförs och lösningar till problemen identifieras. Design- och layoutförbättringar för bättre elektromagnetisk kompatibilitet implementeras också. Drivlinan med den elektriska maskinen inkluderad testas och bekräftas fungera enligt dess specifikationer. Hastighetsreglering baserad på indirekt rotorfälts orientering implementeras och testas för den sexfasiga asynkronmaskinen samt även med maskinen kopplad som en standard trefas asynkronmaskin.