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Projeto de um travão com máquina elétrica
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| 4.71 MB | Adobe PDF |
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Abstract(s)
Atualmente é cada vez mais necessária uma utilização racional da energia. A
utilização de sistemas que possibilitam a sua recuperação, permite tornar os sistemas
globalmente mais eficientes.
As máquinas elétricas mais utilizadas são as de indução pois estas apresentam um
design simples e robusto, apresentando ainda um baixo custo. As máquinas com rotor em
gaiola de esquilo apresentam menor desgaste pois não utilizam escovas.
Neste trabalho estudaram-se as diferentes formas em que uma máquina elétrica de
indução pode ser utilizada de modo a gerar um binário resistente, obtendo o efeito de
travagem, sendo que, existem três técnicas principais para aplicar travagem com recurso
a este tipo de máquinas: contra corrente, dinâmica e regenerativa.
Para esse fim, estudou-se o conversor Back-to-back com armazenamento de
tensão, pois este conversor permite a implementação dos três diferentes métodos de
travagem utilizando máquinas de indução.
O estudo do conversor Back-to-Back foi realizado em duas partes uma vez que o
barramento DC permite o desacoplamento do sistema de controlo entre o conversor ACDC e o conversor DC-AC pelos quais este é constituído.
Desenvolveu-se um sistema de controlo para o conversor AC-DC de modo a que
a tensão no barramento DC fosse mantida constante independentemente do sentido do
fluxo de energia que atravessa o conversor. O controlo do conversor DC-AC foi realizado
para que este criasse a forma de onda que permite aplicar travagem, respeitando os limites
de corrente e frequência da máquina.
Nas simulações em MATLAB/Simulink, verificou-se que os modelos teóricos
desenvolvidos e as técnicas de controlo desenvolvidas foram capazes de manter a tensão
estável no barramento DC e gerar binário resistente, travagem.
Experimentalmente contruiu-se o conversor Back-to-back e implementou-se o
controlo desenvolvido, verificando assim experimentalmente a geração de binário
resistente e a bidireccionalidade do fluxo de energia no conversor.
Nowadays, the smart use of energy is increasingly necessary. The use of systems that enable energy recovery allows systems to be more globally efficient. The most commonly used electric machines are the induction ones, because they have a simple and robust design with associated low cost. Furthermore, machines with a squirrel cage induction motor have less wear as they do not use brushes. This work studied the different ways in which an induction electric machine can be used to generate a resistant torque, obtaining the braking system effect. There are three main techniques for applying braking using this type of machine: counter current, dynamic and regenerative. The Back-to-back converter with voltage storage was studied, as this converter allows the implementation of the three different braking methods using induction machines. The Back-to-Back converter was carried out in two parts as the DC bus allows the decoupling of the control system between the AC-DC converter and the DC-AC converter. A control system for the AC-DC converter was developed so that the voltage on the DC bus is kept constant regardless of the direction of the power flow through the converter. The control of the DC-AC converter was made to create the waveform that allows the application of braking, respecting the current and frequency limits of the machine. In the simulations in MATLAB Simulink, it was found that the developed theoretical models and the developed control techniques allowed the maintain of the stable voltage on the DC bus and the generation of resistant braking torque. Experimentally the Back-to-back converter was built, and the developed control was implemented, thus verifying experimentally the generation of resistant torque and the bidirectionality of the energy flow in the converter.
Nowadays, the smart use of energy is increasingly necessary. The use of systems that enable energy recovery allows systems to be more globally efficient. The most commonly used electric machines are the induction ones, because they have a simple and robust design with associated low cost. Furthermore, machines with a squirrel cage induction motor have less wear as they do not use brushes. This work studied the different ways in which an induction electric machine can be used to generate a resistant torque, obtaining the braking system effect. There are three main techniques for applying braking using this type of machine: counter current, dynamic and regenerative. The Back-to-back converter with voltage storage was studied, as this converter allows the implementation of the three different braking methods using induction machines. The Back-to-Back converter was carried out in two parts as the DC bus allows the decoupling of the control system between the AC-DC converter and the DC-AC converter. A control system for the AC-DC converter was developed so that the voltage on the DC bus is kept constant regardless of the direction of the power flow through the converter. The control of the DC-AC converter was made to create the waveform that allows the application of braking, respecting the current and frequency limits of the machine. In the simulations in MATLAB Simulink, it was found that the developed theoretical models and the developed control techniques allowed the maintain of the stable voltage on the DC bus and the generation of resistant braking torque. Experimentally the Back-to-back converter was built, and the developed control was implemented, thus verifying experimentally the generation of resistant torque and the bidirectionality of the energy flow in the converter.
Description
Keywords
Máquina indução Back-to-back converter Travagem Transformada Clarke-Park Induction machine Braking Transformed Clarke-Park . Mestrado em Engenharia Eletrotécnica-Telecomunicações Faculdade de Ciências Exatas e da Engenharia