Análise da deformação dinâmica de um estator de um motor de indução trifásico empregando sensores de rede de Bragg em fibra óptica

Abstract

A three-phase induction motor in operation, through mechanical and electrical forces, can cause deformation in the stator, which can generate undesirable vibration problems. These problems generate wear on the machines reducing or even jeopardizing their reliability, leading to an increase in maintenance cost. This work shows a way of measuring the dynamic deformation of the stator of a three-phase induction motor with diferent masses fixed to the rotor axis and driven by diferent feed frequencies, using fiber Bragg greating optic sensors installed between the stator teeth. Electromagnetic immunity and reduced size make fiber optics suitable for this application. The frequency components of the induction motor deformation were predicted using a model of the forces present in the air gap, considering the static and dynamic rotor eccentricity. A test bench was made using a 4-pole induction motor operated by a frequency inverter and instrumented with FBG strain sensor. The sensors were positioned between the stator teeth separated by a 150° angle between them. The experimental analysis shows that the components of the spectrum presented by the two sensors are the same as those predicted in theory. The eccentricity of the motor was performed by fixing unbalanced weights on the rotor shaft. The amplitude of the frequency component of the vibration and rotation increased when the unbalanced mass on the rotor axis increased. The tests presented in this paper can be used to determine some parameters or induction motor failures, such as a broken rotor rod, for example.