Induction motors are commonly used in numerous industrial applications. To maintain a reliable operation of the motor, it is important to identify the potential faults that may cause the motor to fail. Bearing failures are one of the main causes of motor breakdown. The causes of bearing damage have been studied in detail for a long time. In some cases, bearing failed due to the current passing through them. In this thesis, bearing currents in an inverter driven five-phase induction motor are studied and a new solution is proposed. First, theory of shaft voltage and bearing current are presented. The causes are identified and current solutions are discussed. Then, new switching patterns are proposed for the five-phase induction motor. The new schemes apply a modified algorithm for the space vector pulse-width-modulation (SVPWM). The system is simulated and the results of the new switching patterns are compared with the conventional switching pattern. Finally, the new schemes are experimentally tested using a digital signal processor (DSP) to drive the five-phase IGBT inverter. The experimental results verified that the new switching pattern could reduce shaft voltages and bearing current without affecting the performance.

Submitted by Maria Suzana Diniz (msuzanad@hotmail.com) on 2015-11-06T15:48:55Z No. of bitstreams: 1 arquivototal.pdf: 3791340 bytes, checksum: 58dd4dde93f8552a891a0760151a7c10 (MD5) / Made available in DSpace on 2015-11-06T15:48:55Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 3791340 bytes, checksum: 58dd4dde93f8552a891a0760151a7c10 (MD5) Previous issue date: 2015-02-27 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The interest for the study of multiphase (more than three phases) machines and variable speed drives has substantially increased in the last two decades. The advantages presented by the multiphase systems compared to their three-phase counterparts have being the the main effort to increase researches all over the world. Reduction in torque oscillation, lower current ratings, high drive reliability, better fault tolerance and harmonic content reduction in the DC bus are some of these advantages. The additional degrees of freedom due to extra phases make multiphase systems very flexible when it comes to control systems and modulation strategies. Although three-phase systems are predominant in industrial applications, the use of multiphase machines and drives has increased in very specific areas such as locomotive traction, electric ship propulsion, aerospace industry (more electric aircraft), electric and hybrid vehicles and industrial high power systems. Due to high coupling degree between electric variables in multiphase systems, modeling of multiphase machines has been and still is a challenge task in research centers. In this present work, analitic modeling of symmetric and asymmetric nine-phase machines using natural variables and space vector decomposition are presented. The principles used in the study are the same used for three-phase systems. However, multiphase systems are analised in multiple d-q planes. PWM modulation strategies based on space vectors theory (SVPWM) for a voltage source inverter (VSI) are presented. The multiphase drive system presented works in the linear operation region with sinusoidal voltage generation. Results for both machines and drive modeled are verified by simulation programs developed in C programming language an Matlab. / O interesse pelo estudo de máquinas de indução multifases (mais de três fases) e dos seus sistemas de acionamento cresceu substancialmente nas últimas duas décadas. As muitas vantagens apresentadas pelos sistemas multifases, em relação aos sistemas trifásicos convencionais, têm sido fatores motivadores para o aumento de pesquisas em todo o mundo. Redução das oscilações de torque, redução da corrente por fase, maior confiabilidade do acionamento, grande tolerância à faltas e redução no conteúdo harmônico da corrente no barramento CC são algumas destas vantagens. O maior grau de liberdade proporcionado pelas fases extras torna os sistemas multifases bastante flexíveis quanto às estratégias de modulação e de controle. Apesar da atual predominância da utilização das máquinas e acionamentos trifásicos na indústria, as máquinas multifases estão sendo cada vez mais utilizadas em áreas de aplicações específicas tais como tração de locomotivas, propulsão de navios elétricos de grande porte, indústria aeroespacial, tração de veículos híbridos e elétricos e sistemas industriais de alta potência. Devido ao alto grau de acoplamento entre as variáveis elétricas de um sistema multifases, a modelagem e análise desses sistemas tem representado uma tarefa desafiadora nos centros de pesquisa. No presente trabalho são apresentadas as modelagens analíticas de uma máquina de indução de nove fases simétrica e de uma máquina de nove fases assimétrica pelo método de variáveis naturais e pelo método de decomposição vetorial. Os princípios utilizados na modelagem são os mesmos utilizados nos sistemas trifásicos. No entanto, sistemas multifases são analisados em múltiplos planos d-q. Estratégias de modulação PWM baseadas na teoria de vetores espaciais (SVPWM) para um inversor de nove fases tipo VSI (Inversor Fonte de Tensão) são apresentadas para acionamento das máquinas. O sistema de acionamento apresentado trabalha na região linear de operação e gera tensão de saída senoidal. Dados de simulação obtidos a partir de programas desenvolvidos em linguagem C e Matlab são apresentados para ambas as máquinas de nove fases modeladas.

No description available.

This thesis aims to design and build a power electronics system for the rectification and control of magnetization currents in synchronous generators with rotating exciters.The rotating exciter provides three-phase AC while the generator rotor needs DC with a high degree of control. The system needs to be able to rectify the three-phase AC to a stable DC without unwanted harmonic content, neither on the DC or the AC side. For control purposes it is also important that the current in the rotor can be changed very swiftly, preferably by several amperes during a single revolution ofthe machine.The system of choice is a synchronous rectifier bridge consisting of six MOSFET switches operated using the Space vector pulse width modulation (SVPWM) algorithm. This method gives a stable and controllable DC voltage while it keeps the harmonic content of the input currents at a minimum. However the DC voltage will always be higher than the peak line-to-line voltage from the exciter. To be able to lower the voltage below this value a Buck-converter is placed after the rectifier bridge.To gain a higher degree of control of the current density in the rotor windings the windings have been subdivided into three parts. To provide individual control of the current in the three rotor parts each part have been outfitted with a Push and Pull H-bridge.The proposed system has been both simulated using MATLAB Simulink and built and tested in the laboratory with satisfactory results. / I detta examensarbete presenteras ett kraftelektroniksystem för förbättrad kontroll av magnetiseringsstömmar i vattenkraftsgeneratorer som är utrustade med roterande matare.Generatorer används för att konvertera energi från rörelseenergi till elektrisk energi. Detta görs genom att man utsätter spolar för varierande magnetfält; då induceras spänning i spolarna. I vattenkraftsgeneratorer används oftast stora elektromagneter placerade i en rotor för att skapa dessa magnetfält. För att magnetisera elektromagneterna behövs ström som på något sätt måste överföras mellan den statiska och den roterande sidan i generatorn. Traditionellt görs detta med hjälp av släpringar och kolborstar som genom mekanisk kontakt överför elektriciteten. En roterande matare kan beskrivas som en liten generator som har sina elektriska utgångar på den roterande sidan istället för på den statiska sidan. Genom att placera en roterande matare på samma axel som den stora generatorn kan man istället alstra den elektricitet som behövs för att magnetisera generatorn direkt på den roterande sidan. Däregenom undviks många problem som är associerade med lösningen med släpringar.Den roterande mataren ger dock växelström medan magnetiseringsströmmen måste vara likström. Det är här kraftelektroniken kommer in i bilden. Det finns flera sätt att åstadkomma likriktning av ström. I det här projektet har ett fullständigt aktivt system byggts. Systemet är uppbyggt av transistorer av MOSFET typ och kan kontrolleras trådlöst med hjälp av Bluetoothteknik. Systemet ger full kontroll över strömmar och spänningar både på växelströmssidan och på likströmssidan och ska användas till en testgenerator på avdelningen för ellära vid Uppsala Universitet. Där ska den utökade kontroll som systemet ger förutsättningar till användas för att undersöka hur den här typen av system kan optimera de magnetiska krafterna inuti generatorn. En sådan optimering kan minska vibrationerna i generatorn och därigenom minska slitaget på lager och andra delar i maskinen.

A servo system intended to steer antennas on board ships is designed, built and tested. It uses a Brushless Direct Current (BLDC) motor with an encoder to keep track of its position, and Field Oriented Control (FOC) implemented on Toshibas microprocessor TMPM373 in order to control the current flowing to the motor. The servo system will be connected in cascade to another already existing servo system and controlled with two input signals. The first signal determines if the antenna axis should rotate clockwise or counter clockwise. The second signal is a stream of pulses, where each pulse means that the motor should move one encoder point. A printed circuit board is designed and built to complete these tasks. A proportional-integral regulator is used to control the position of the motor, using the position error as the controller input. The servo system is tested. The performance of the resulting servo system is sufficient to satisfy the required position error limit of 0.5 degrees. In order to reduce the periodic disturbances presented in the system in experiments, Iterative Learning Control (ILC) is implemented. It is shown that using ILC further decreases the position error.

No description available.

There are several benets of electrohydraulic power steering systems, as compared to hydraulicpower steering systems where the pump is driven directly by the engine of the vehicle. Someof these benets are increased eciency and improved steering performance. The purpose ofthis project is to create a simulation model of the electrohydraulic power steering system inSimulink, excluding the hydraulic circuit. The model should thus consist of the electric motor,the drive electronics, the control system, the hydraulic pump as well as the communication andinterface to the master simulation system in which the model will be used.As a start a mathematical model of the motor is derived. Then the motor controller includingtwo current controllers and a speed controller is developed. The switching signals for the threephase bridge that drives the motor are calculated using space vector modulation. The motordrives a hydraulic pump, which is modeled using data sheet eciency curves. Finally a thermalmodel of the drive is developed. To fulll real time requirements, a lumped parameter approachis chosen. The nal model is exported as a Functional Mock-up Unit, which is a black-boxencapsulation of the complete simulation model.The simulation model is compared to measurement data to conrm its validity. Thesecomparisons shows that the dynamic response of the motor and its controller are close to themeasured values and that the thermal model adequately corresponds to the thermal tests. Thehydraulic pump model varied from measurements more than the other sub-modules. It was,however, seen as acceptable. Overall the system response was satisfactory, but naturally a lotof future improvements and new features could be made to improve the model. / Det finns flera fördelar med elektrohydraulisk servostyrning, där hydraulpumpen drivs av en el-motor, jämfört med hydraulisk servostyrning, där pumpen drivs direkt av fordonets förbränningsmotor. Några av dessa fördelar är ökad effektivitet och förbättrad styrprestanda. Syftet med detta projekt är att skapa en Simulink-modell av ett elektrohydraulisk system för servostyrning, exklusive hydraulkretsen. Modellen ska alltså bestå av delmodeller för elmotorn, drivelektroniken, styrsystemet, hydraulpumpen samt kommunikation med den övergripande simuleringsplattformen.Inledningsvis beskrivs en matematisk modell av elmotorn och efter det utvecklas motorstyrningen, bestående av två strömregulatorer samt en hastighetsregulator. Spänningen från strömregulatorerna uppnås genom space vector-modulation, som beräknar de pulskvoter som krävs för att uppnå denna spänning. Elmotorn driver en pump. Denna pump modelleras med hjälp av data från pumpens datablad. Slutligen modelleras drivelektronikens termiska egenskaper med ett termiskt nätverk. Den slutliga modellen omsluts av en Functional Mock-up Unit somintegreras i den övergripande simuleringsplattformen.

The original idea of the thesis was realized to control the electric drive of the rotor with a special feature. Without using a complex mechanism, the angle of each blade of the rotor can be controlled individually. The blades are fixed independently to a permanent magnet and the housing encompassing the rotor contains coils. By powering the coils, the whole rotor turns into a permanent magnet motor and by using a control algorithm, each blade can be separately driven. In the first chapter, the introduction to the main idea of the research project is described along with working principle of rotor blade. The basic concept of blade angle is introduced. The second chapter is the state of Technique. In this chapter, the working principle and basics of permanent magnet synchronous machine and brushless motor with mathematical model is described. Also, space vector pulse width modulation and double acting piezoelectric actuator model for helicopter rotor are explained. The third chapter is the overall description of the initial status of the research project. This part includes the basic principle of the control system, sensorless field-oriented control of Permanent Magnet Synchronous Machine (PMSM). Also, the motor parameters calculated from the python script of motor design are listed in tabular form. The fourth chapter focuses on control strategy implementation. First of all, the criteria for selecting the microcontroller are described. After that, the structure of the program with a flow chart was explained. Also, a short description is mentioned of how space vector pulse width modulation is applied. The main function of the position and speed controller with block diagram is explained. Moreover, back-EMF based observer and EKF-based observer are described. In the fourth chapter, the initial problem of the research project is discussed. To overcome this problem, a set of experiments is carried out. In the last chapter, the result of the experiment with proper explanation is summarized. Further on the future work to solve the problem is listed.

No description available.

Fossil-fuel vehicles are one of the main causes of CO2 emissions nowadays. As we are moving toward cleaner environment electrification of vehicles are becoming more and more popular. With the environment in mind, the recent improvement in battery technology and electronics has drawn a lot of attention to Brushless DC or BLDC  motors. Due to their high torque output and robust design, BLDC motors are a popular choice as the main propulsion unit in electric vehicles.  Permanent magnet synchronous motor, PMSM, is also a brushless dc motor with minor changes in design. So the word BLDC and PMSM is used interchangeably. In this thesis, two motor control algorithms were investigated. 6-Step control and Field oriented control or FOC. A three-phase inverter allows these motors to be driven by a battery. But when battery voltage goes down the speed of the motor also goes down. This thesis investigates a method to maintain the same speed at lower dc voltage. Also running of other motors than the control system was designed for. The control system performs well in simulation for two of the motor tested with the FOC algorithm. Simulation results show that the control system can track speed and current references with minimum error. Speed controller and current controllers control each parameter independently to control the motor. Low battery simulations provide useful data that shows how the field weakening technique makes it possible to achieve higher speed at low dc voltages. / Fossildrivna fordon är en av de främsta orsakerna till koldioxidutsläpp i dag. I och med att vi går mot en renare miljö blir elektrifieringen av fordon allt mer populär. Med miljön i åtanke har den senaste tidens förbättring av batteriteknik och elektronik dragit mycket uppmärksamhet till Brushless DC- eller BLDC-motorer som ska användas som huvudframdrivningsenhet. På grund av dess höga vridmomentutgång och robusta design så är BLDC-motorer mer populära. En permanent magnetisk synkronmotor, PMSM, är också en borstlös dc-motor med mindre förändringar i designen. Så orden BLDC och PMSM används omväxlande. I denna avhandling undersöktes två motoriska styralgoritmer. 6-stegskontroll och fältorienterad kontroll eller FOC. En trefas växelriktare gör att dessa motorer kan drivas av ett batteri. Men när batterispänningen går ner går motorns hastighet också ner. Denna avhandling undersöker en metod för att bibehålla samma hastighet vid lägre likspänning, men även drift av andra motorer än vad styrsystemet var konstruerat för. Styrsystemet fungerar bra i simulering för två av de motorer som testas med FOC-algoritmen. Simuleringsresultat visar att styrsystemet kan spåra hastighet och aktuella referenser med minimalt fel. Hastighetsregulator och aktuella styrenheter kontrollerar varje parameter individuellt för att styra motorn. Simuleringar med lågt batteri ger användbara data som visar hur fältförsvagningstekniken gör det möjligt att uppnå högre hastighet vid låg likströmsspänning.