A structure excited by a DC motor of limited power supply and controlled by a pendulum like device

In this paper, a mathematical model is derived via Lagrange's Equation for a shear building structure that acts as a foundation of a non-ideal direct current electric motor, controlled by a mass loose inside a circular carving. Non-ideal sources of vibrations of structures are those whose characteristics are coupled to the motion of the structure, not being a function of time only as in the ideal case. Thus, in this case, an additional equation of motion is written, related to the motor rotation, coupled to the equation describing the horizontal motion of the shear building. This kind of problem can lead to the so-called Sommerfeld effect: steady state frequencies of the motor will usually increase as more power (voltage) is given to it in a step-by-step fashion. When a resonance condition with the structure is reached, the better part of this energy is consumed to generate large amplitude vibrations of the foundation without sensible change of the motor frequency as before. If additional increase steps in voltage are made, one may reach a situation where the rotor will jump to higher rotation regimes, no steady states being stable in between. As a device of passive control of both large amplitude vibrations and the Sommerfeld effect, a scheme is proposed using a point mass free to bounce back and forth inside a circular carving in the suspended mass of the structure. Numerical simulations of the model are also presented Copyright © 2007 by ASME.

Analysis of electric torque in single machine-infinite bus system using phase shifters

ResumoThe main idea of this work is based on the analysis of the electric torque through the acting of the PS in the power system, provided of a control for the compensation degree (PSC). A linear model of the single machine-infinite bus system is used with a PS installed (SMIB/PS system). The variable that represents the presence of PS in the net is associated to the phase displacement introduced in the terminal voltage of the synchronous machine by PS. For the input signals of the PSC are evaluated variations of the angular speed of the rotor, the current magnitude and the active power through the line where the PS is located. The simulations are accomplished to analyze the influence of the PS in the torque formation (synchronizing and damping), of the SMIB/PS system. The analysis are developed in the time and frequency domain.

Active control in rotating machinery using magnetic actuators with linear matrix inequalities (LMI) approach

The recent years have seen the appearance of innovative system for acoustic and vibration attenuation, most of them integrating new actuator technologies. In this sense, the study of algorithms for active vibrations control in rotating machinery became an area of enormous interest, mainly due to countless demands of an optimal performance of mechanical systems in aircraft, aerospace and automotive structures. In this way, this paper presents an approach that is numerically verified for active vibration control in a rotor using Active Magnetic Bearings (AMB). The control design in a discrete state-space formulation is carried out through feedback technique and Linear Matrix Inequalities (LMI) approach. LMI is useful for system with uncertainties. The AMB uses electromagnetic forces to support a rotor without mechanical contact. By monitoring the position of the shaft and changing the dynamics of the system accordingly, the AMB keeps the rotor in a desired position. This unique feature has broadened for the applications of AMB and now they can be considered not only as a main support bearing in a machine but also as dampers for vibration control and force actuators. © 2009 Society for Experimental Mechanics Inc.

Estudo dos efeitos da compensação série no desempenho transitório dos sistemas de energia elétrica sob o enfoque da energia

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Deposição e qualidade de sementes de sorgo utilizando um mecanismo dosador de fluxo contínuo

Pós-graduação em Agronomia (Energia na Agricultura) - FCA

Redução de vibrações de rotores utilizando atuadores magnéticos e sistema de controle feedforward

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Mancais magnéticos ativos para atenuação de vibrações em eixos rotativos

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Controle ativo de vibração de rotores com mancais magnéticos: influência da flexibilidade dos rotores

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Controle ativo de vibrações de rotores com mancais magnéticos: influência dos parâmetros do controlador PID

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Detecção de falhas via observadores de estado em sistemas rotativos, considerando-se suas fundações

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Estimação de rigidezes de mancais de rotores por análise de sensibilidade

Pós-graduação em Engenharia Mecânica - FEIS

Demanda de turbinas hidráulicas en algunos países latinoamericanos en centrales que entran en operación en período 1980-1990: clasificadas según diámetros

Complementa la información contenida en el documento E/CEPAL/G.1241

Comportamento dinâmico não-linear de um sistema mecânico com vibrações associadas a uma transição brusca na rigidez

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Estudo da estabilidade a pequenas perturbações do sistema elétrico de potência sob a ação do dispositivo FACTS PHASE SHIFTER - PS

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Análise da viabilidade técnica e econômica de implantação de uma microusina hidrelétrica

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)