Due to the fast-rising voltage pulses of pulse width modulated drives, the generated shaft voltage of electrical motors causes electrical discharge currents in bearings. These discharges can cause bearing failure leading to costly maintenance and unexpected production stops. To eliminate the raised shaft voltage, several techniques are used such as shaft grounding brushes, insulated bearings and conductive grease. The possibility to measure discharge activity on a PWM driven induction motor offers a tool for researchers to test different bearings in electric motors. In order to measure the shaft voltages and bearing currents, modifications of an induction motor are made firstly using 3D software and then on the physical motor. By insulating the bearing from the frame and attaching a copper ring to the bearings outer race bearing currents can be measured. The combined measurements of shaft voltage, bearing currents and frame currents shows the bearings conductive states at low speed, and insulated state at higher speed. Electrical discharge activity (DA) is observed as shaft voltage raises, resulting in a bearing current spike and shaft voltage drops rapidly while stator current is unaffected. Experimental tests were performed with a sample bearing at different operating conditions, such as operating speed, temperature, motor load, etc., to determine the effect of the common mode voltages on bearing currents and shaft voltages. At low temperatures between 23-26 ˚C and motor speeds above 1000 rpm EDM currents were observed. On temperatures above 40 ˚C no major EDM currents were observed regardless of rpm due to the bearing remaining in an ohmic conductive state. The modifications of the motor have shown to give reliable bearing current and shaft voltage measurements that can help in future research in this area.

Orientador: Jose Antonio Siqueira Dias / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação / Made available in DSpace on 2018-08-08T10:27:05Z (GMT). No. of bitstreams: 1 Moraes_LucianoCamaraBuenode_M.pdf: 4566206 bytes, checksum: 004300417197b06c786d6cac40898584 (MD5) Previous issue date: 2007 / Resumo: Este trabalho tem como objetivo propor um sistema de baixo custo para conversão de veículos urbanos convencionais para propulsão elétrica. Serão abordadas também, técnicas, de paralelismo de dispositivos semicondutores para altas demandas de potência, motores elétricos, baterias, e sistemas de recarga. De uma maneira geral o projeto apresenta a viabilização de uni kit prático de conversão que permite a Substituição do sistema de tração original (gasolina ou álcool) para o sistema de tração elétrica movido à bateria interna recarregável, para uso urbano que, futuramente, possa ser produzido em larga escala. Os resultados dos modelos teóricos são confrontados com os testes práticos. É apresentado, ao final, um veículo completo, que opera apenas com propulsão elétrica, bem como os íesíes realizados neste veículo / Abstract: The objective of the dissertation is to present a low cost system for the utilization of electric propulsion in urban vehicles powered with internal combustion engines, ft will be discussed semiconductor devices parallelism techniques for high demands of power, electric engines, batteries, and re-charge- systems. In a general way. the project has as objective the design of a conversion kit that allows the substitution of the of original traction of the vehicle by an electric traction system with rechargeable interna! batteries, and that can be produced in large scale. The results of the theoretical models are compared with the practical evaluation tests. The experimental results measured in a complete vehicle assembled using the developed kit are presented / Mestrado / Eletrônica, Microeletrônica e Optoeletrônica / Mestre em Engenharia Elétrica

<p>This thesis work contains a litterature study about electrical motors in general and how PWM-patterns for brushless DC-motors can be made. A suitable method has been implemented as a simulation model in VHDL. A simulation model of a brushless DC-motor which describes the phasecurrents, torque and angular velocity has also been made. The motor model made simulations easier for the complete PWM-system. </p><p>The design was synthesised and tested with a prototypeboard including a SPARTAN II FPGA. In order to test the design, a powerstage and a motor was included. The tests showed that the design was working as expected according to the previous simulations. </p><p>A study about an alternative way to control a brushless DC-motor has also been made. This alternative is best suited when the generated back-EMK for the motor is sinusoidal. A simulation model for a part of a system like this has been made, and it has been synthesised in order to examine if it is possible to implement using a FPGA availible today.</p>

This thesis work contains a litterature study about electrical motors in general and how PWM-patterns for brushless DC-motors can be made. A suitable method has been implemented as a simulation model in VHDL. A simulation model of a brushless DC-motor which describes the phasecurrents, torque and angular velocity has also been made. The motor model made simulations easier for the complete PWM-system. The design was synthesised and tested with a prototypeboard including a SPARTAN II FPGA. In order to test the design, a powerstage and a motor was included. The tests showed that the design was working as expected according to the previous simulations. A study about an alternative way to control a brushless DC-motor has also been made. This alternative is best suited when the generated back-EMK for the motor is sinusoidal. A simulation model for a part of a system like this has been made, and it has been synthesised in order to examine if it is possible to implement using a FPGA availible today.

The main purpose of this thesis is to develop an efficient and safe lifting device that can make the manufacturing process of electrical motors efficient but also make the work environment safer. The process of the product development has been following steps taught at Universities around the world. These steps go from identifying the problem and making requirements to generating concepts and developing the most suitable one. In order to learn the operators’ opinions, a survey for choosing the right concept was applied at the production line that will use the lifting tool. A choice of concepts and a lifting tool was developed based on the survey results. This development includes calculations of forces, strength of materials simulations and detailed design of the different subfunctions. The result is a developed concept consisting of a physical prototype and drawings for manufacturing.

O acionamento das máquinas de fluxo, sobretudo as bombas e ventiladores centrífugos, têm no motor elétrico seu principal meio de força motriz. O motor assíncrono, também denominado de motor de indução, é o mais utilizado para esse tipo de acionamento. O presente trabalho mostra as diversas alternativas para avaliar a viabilidade de utilização, em alguns casos, do motor de combustão interna substituindo o motor elétrico para acionamento de algumas máquinas de fluxo. As vantagens na utilização do gás natural como energia final, aliada a evolução tecnológica do motor de combustão interna para uso desse combustível, podem fornecer boas condições na escolha alternativa de acionamento. Certos fatores, tais como razão entre o preço do gás natural e o preço da energia elétrica para cada setor de consumo; o alto investimento para a aquisição do motor de combustão interna a gás natural e o aproveitamento para cogeração, são levados em consideração nas análises do presente trabalho. O aproveitamento do rejeito térmico dos gases de combustão do motor e da água de refrigeração do mesmo contribui favoravelmente para a utilização do motor de combustão interna a gás natural. A análise econômica, que permite a comparação entre os dois sistemas de acionamento de cada caso estudado, é também apoiada com a utilização da termoeconomia. / The driving of flow machines, above all centrifugal pumps and fans, have in electrical motor its main resource of driving power. Asynchrony motor, also called induction motor is the most used for that driving type. The present work shows the several ways for measuring the viability of the replacement of electric motor, in some cases, by the natural gas internal combustion engines driving flow machines. The advantages of employing natural gas, allied to the technological evolution of the internal combustion engine for use of that fuel, can produce good conditions for that drive alternative. Certain factors, such as the ratio between the current price of natural gas and the price of the electric power for each consumption sector; the high investment for the acquisition of natural gas internal combustion engine, as well as the use of this gas for cogeneration are factors to be considered in the analysis performed in this work. The reuse of combustion engines exhaust gas and of cooling system waters may successfully contribute for the choice of natural gas internal combustion engine. Economical analysis, which provides a comparison between the two kinds of driving systems investigate here, can also be supported by employing thermoeconomics tools.

O acionamento das máquinas de fluxo, sobretudo as bombas e ventiladores centrífugos, têm no motor elétrico seu principal meio de força motriz. O motor assíncrono, também denominado de motor de indução, é o mais utilizado para esse tipo de acionamento. O presente trabalho mostra as diversas alternativas para avaliar a viabilidade de utilização, em alguns casos, do motor de combustão interna substituindo o motor elétrico para acionamento de algumas máquinas de fluxo. As vantagens na utilização do gás natural como energia final, aliada a evolução tecnológica do motor de combustão interna para uso desse combustível, podem fornecer boas condições na escolha alternativa de acionamento. Certos fatores, tais como razão entre o preço do gás natural e o preço da energia elétrica para cada setor de consumo; o alto investimento para a aquisição do motor de combustão interna a gás natural e o aproveitamento para cogeração, são levados em consideração nas análises do presente trabalho. O aproveitamento do rejeito térmico dos gases de combustão do motor e da água de refrigeração do mesmo contribui favoravelmente para a utilização do motor de combustão interna a gás natural. A análise econômica, que permite a comparação entre os dois sistemas de acionamento de cada caso estudado, é também apoiada com a utilização da termoeconomia. / The driving of flow machines, above all centrifugal pumps and fans, have in electrical motor its main resource of driving power. Asynchrony motor, also called induction motor is the most used for that driving type. The present work shows the several ways for measuring the viability of the replacement of electric motor, in some cases, by the natural gas internal combustion engines driving flow machines. The advantages of employing natural gas, allied to the technological evolution of the internal combustion engine for use of that fuel, can produce good conditions for that drive alternative. Certain factors, such as the ratio between the current price of natural gas and the price of the electric power for each consumption sector; the high investment for the acquisition of natural gas internal combustion engine, as well as the use of this gas for cogeneration are factors to be considered in the analysis performed in this work. The reuse of combustion engines exhaust gas and of cooling system waters may successfully contribute for the choice of natural gas internal combustion engine. Economical analysis, which provides a comparison between the two kinds of driving systems investigate here, can also be supported by employing thermoeconomics tools.

Cette thèse étudie la problématique du fonctionnement sans capteur et à basse vitesse des moteurs synchrones à aimant permanent par l'injection des signaux. Nous nous focalisons sur les effets de la saturation magnétique car leur compensation est primordiale pour résoudre cette problématique. Nous proposons une méthode originale pour modéliser la saturation magnétique en utilisant une approche énergétique (les formulations Lagrangienne et Hamiltonienne), où les symétries physiques sont exploitées pour simplifier l'expression de l'énergie magnétique. Les données expérimentales montrent qu'un polynôme de degré 4 est suffisant pour décrire avec précision les effets de la saturation. Ensuite, nous proposons une analyse claire et originale basée sur la moyennisation de second ordre et qui explique comment obtenir l'information de position à partir de l'injection des signaux (en utilisant le modèle proposé). Nous donnons une relation explicite entre les oscillations des courants statoriques et la position du rotor; cette relation est utilisée en temps réel. Ce modèle de saturation magnétique ainsi que la procédure d'estimation de position ont été testés et validés sur deux types de moteurs : avec des aimants permanents à l'intérieur ou sur la surface du rotor. Les résultats expérimentaux obtenus sur un banc de test montrent que les erreurs d'estimation de la position du rotor n'excèdent pas quelques degrés électriques dans la zone d'opération à basse vitesse. / This thesis addresses the problematic of sensorless low speed operation of permanent magnet synchronous motors (PMSM) by signal injection. We focus on the effects of magnetic and cross saturations because their compensation is paramount to solve this problematic. We propose an original way of modeling magnetic saturation using an energy approach (Lagrangian and Hamiltonian formulations), where the physical symmetries are exploited to simplify the expression of the magnetic energy. Experimental data show that a simple polynomial of degree 4 is sufficient to describe accurately magnetic saturation effects. Then we propose a clear and original analysis based on second-order averaging of how to recover the position information from signal injection (using the proposed model). We give an explicit relation between stator current ripples and rotor position; this relation is used in real time operation. Such magnetic saturation model and the resulting position estimates were tested and validated on two types of motors: with interior and surface permanent magnets (IPM and SPM). Experimental results obtained on a test bench show that estimation errors of the rotor position do not exceed few electrical degrees in the low speed operating domain.

<p>A power assisted wheelchair combines human power, which is delivered by the arms through the pushrims, with electrical motors, which are powered by a battery. Today’s electric power assisted wheelchairs use force sensors to measure the torque exerted on the pushrims by the user. The force sensors in the pushrims are rather expensive and this approach also makes the wheels a little bit clumsy. The objective with this project is to find a new, better and cheaper solution that does not use expensive force sensors in the pushrims. The new power assisted wheelchair will instead only rely on its velocity, which is measured with rotational encoders, as feedback signal and thereby the project name “Torque Sensor Free Power Assisted Wheelchair”. </p><p> </p><p>The project consisted of two main parts; an extensive construction part, where an ordinary joystick controlled motorized wheelchair has been rebuild to the new power assisted wheelchair without torque sensors and a development part, where different torque sensor free controllers has been designed, simulated, programmed and tested.</p><p>The project resulted in a torque sensor free power assisted wheelchair, where the final implemented design is a proportional derivative controller, which gives a very good assisting system that is robust and insensitive to measurement noise. The proportional derivative control design gives two adjustable parameters, which can be tuned to fit a certain user; one parameter is used to adjust the amplification of the user’s force and the other one is used to change the lasting time of the propulsion influence.</p><p>Since the new assisting control system only relies on the velocity, the torque sensor free power assisted wheelchair will besides giving the user assisting power also give an assistant, which pushes the wheelchair, additional power. This is a big advantage compared to the pushrim activated one, where this benefit for the assistant is not possible.</p>

Energy efficiency and renewable energy use are two main priorities leading to industrial sustainability nowadays according to European Steel Technology Platform (ESTP). Modernization efforts can be done by industries to improve energy consumptions of the production lines. These days, steel making industrial applications are energy and emission intensive. It was estimated that over the past years, energy consumption and corresponding CO2 generation has increased steadily reaching approximately 338.15 parts per million in august 2010 [1]. These kinds of facts and statistics have introduced a lot of room for improvement in energy efficiency for industrial applications through modernization and use of renewable energy sources such as solar Photovoltaic Systems (PV).The purpose of this thesis work is to make a preliminary design and simulation of the solar photovoltaic system which would attempt to cover the energy demand of the initial part of the pickling line hydraulic system at the SSAB steel plant. For this purpose, the energy consumptions of this hydraulic system would be studied and evaluated and a general analysis of the hydraulic and control components performance would be done which would yield a proper set of guidelines contributing towards future energy savings. The results of the energy efficiency analysis showed that the initial part of the pickling line hydraulic system worked with a low efficiency of 3.3%. Results of general analysis showed that hydraulic accumulators of 650 liter size should be used by the initial part pickling line system in combination with a one pump delivery of 100 l/min. Based on this, one PV system can deliver energy to an AC motor-pump set covering 17.6% of total energy and another PV system can supply a DC hydraulic pump substituting 26.7% of the demand. The first system used 290 m2 area of the roof and was sized as 40 kWp, the second used 109 m2 and was sized as 15.2 kWp. It was concluded that the reason for the low efficiency was the oversized design of the system. Incremental modernization efforts could help to improve the hydraulic system energy efficiency and make the design of the solar photovoltaic system realistically possible. Two types of PV systems where analyzed in the thesis work. A method was found calculating the load simulation sequence based on the energy efficiency studies to help in the PV system simulations. Hydraulic accumulators integrated into the pickling line worked as energy storage when being charged by the PV system as well.