Influence Of Rotor Faults On Electromagnetic Vibration Of IPMSM Stator

Interior permanent magnet synchronous motor(IPMSM) is characterized by high efficiency, high energy density, reliable operation, simple structure, etc. In recent years, IPMSM is widely applied in air conditioning drives, hybrid cars, ships and aerospace and other fields, where high-power and high-speed is required. Rotor mechanical structure of IPMSM is very complex. Permanent magnet, which is placed inside the rotor, is protected. But the bridge on the edge of the rotor bears high stress, which requires to analyze the strength. Rotor fault will affect the electromagnetic vibration of the stator, providing the basis for detection of fault diagnosis, which makes the electromagnetic vibration of IPMSM in rotor fault gradually become a focus of the research. The research work of this thesis is a fundamental part of the project “Research on electric and demagnetization faults diagnosis method in permanent magnet synchronous motors based on stator electromagnetic”, which is supported by the National Natural Science Foundation of China.This thesis mainly analyzes the electromagnetic vibration of the stator in IPMSM with rotor fault. Because of the rotor's complex mechanical structure, the first step is to analyze the rotor's structural strength, and the second step is to analysis the effect of the rotor fault(including demagnetization and eccentricity) on the stator's electromagnetic vibration.Firstly, based on the introduction of the fundamental theory of elastic mechanics, structural dynamics and basic electromagnetic, this thesis builds two rotor models, one with epoxy resin, the other one without epoxy resin. At the same time, a unique rotor fault model of PMSM has been built, which includes demagnetization and eccentricity.Then, this thesis calculates the critical speed of the rotor and analyses the change of the rotor maximum stress under different magnet installation crafts. In particular, the thesis gained the results of the maximum stress when the epoxy resin is destroyed so to check the rotor strength of permanent-magnet motor. The results show that, if the rotor filled with epoxy resin, not only the structure of the rotor can be strengthened, but also the stress that the rotor suffered can be reduced. Even if the epoxy resin is destroyed, it is still able to reduce the stress that the rotor suffered.Then, this thesis concentrates on the vibration of the motor at different demagnetization, and compared it with the vibration in healthy motor. The results show that, when demagnetization happened in a single pole, the low frequency harmonic will increase, which causes intense stator vibration. When the uniform demagnetization happened in a single pole, the stator vibration is worse compared with that when the partial demagnetization happened in a single pole. When the loss of the permanent magnet is more than some a certain value, vibration of the stator will not increase. If the demagnetization happens in all poles, its vibration will not have big change.Finally, the motor's electromagnetic vibration caused by eccentricity has been calculated, and compared it with the vibration in healthy motor. Analysis shows that if the motor is under static eccentricity, the deformation of the stator which is no longer central symmetry but axial symmetry. The axis is defined by the center of the stator and the center of rotation. Vibration of the stator will increase, as more serious static eccentricity happened. If the motor is under dynamic eccentricity, low-frequency component will increase significantly. As more serious dynamic eccentricity happened, integer harmonics and fractional harmonics component will also increase significantly.