The paper presents the modelling of the unbalanced magnetic pull (UMP) and its experimental validation in a real machine. It is well known that in electrical machines rotor eccentricity causes an imbalance of the electromagnetic forces acting upon rotor and stator surfaces, so that a net radial force is developed. Large generators of power plants operate above their first critical speed behaving like flexible shafts, therefore the eccentricity of the active part of the rotor with respect to the stator is unavoidable. In the first part of the paper, an original model that calculate the UMP force is presented. This model is based on the actual position of the rotor inside the stator, therefore on the air gap distribution, independently of the orbit type. The closed form of the non-linear UMP force components is expressed. In the second part, the experimental validation is presented, by considering a steam turbo-generator of a power plant and by comparing the simulated dynamic behaviour in the time domain of the machine without and with the excitation of the magnetic field in the generator.
Effect of the unbalanced magnetic pull in two-poles slim generators: modelling and experimental validation
FROSINI, LUCIA;
2006-01-01
Abstract
The paper presents the modelling of the unbalanced magnetic pull (UMP) and its experimental validation in a real machine. It is well known that in electrical machines rotor eccentricity causes an imbalance of the electromagnetic forces acting upon rotor and stator surfaces, so that a net radial force is developed. Large generators of power plants operate above their first critical speed behaving like flexible shafts, therefore the eccentricity of the active part of the rotor with respect to the stator is unavoidable. In the first part of the paper, an original model that calculate the UMP force is presented. This model is based on the actual position of the rotor inside the stator, therefore on the air gap distribution, independently of the orbit type. The closed form of the non-linear UMP force components is expressed. In the second part, the experimental validation is presented, by considering a steam turbo-generator of a power plant and by comparing the simulated dynamic behaviour in the time domain of the machine without and with the excitation of the magnetic field in the generator.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
