| Permanent magnet synchronous motors(PMSM)are widely used in various industrial fields for its simple structure,wide speed range,low-speed performance and high efficiency.China is rich in rare earth resources,so PMSM has become an important direction for the development of energy-efficient motor.In the process of motor operation,rotor eccentricity will produce electromagnetic vibration and noise,which has an important impact on the performance of the motor,so it is necessary to analyze and study it.In this paper,the influence of rotor eccentricity on the dynamic characteristics of three phase AC PMSM is analyzed.The main contents of this paper are as follows.(1)First,the analytical model of air gap magnetic field of motor radial is established according to the theory of electromagnetic field by magnetic potential and permeance method.At the same time,the air gap magnetic field of PMSM is calculated by the finite element method and validated the analytic model by comparison.Then the composition and characteristics of radial electromagnetic force are analyzed by Maxwell stress tensor method.(2)The radial air gap magnetic field is corrected when the rotor is eccentric by using the permeance correction method,then the analytical model of the radial air gap magnetic field with rotor eccentricity is established and the composition and characteristics of radial electromagnetic force are analyzed.Moreover,the unbalanced magnetic pull(UMP),which is the resultant of the electromagnetic force,is analyzed and studied.The study pointed out that the UMP will be produced when the rotor has eccentricity.causing the vibration and noise of the motor.(3)The dynamics model of the rotor system in PMSM is established when considering the rigid support,and the influence on rotor dynamic responses with different eccentric parameters,gravity and gyroscopic moment are analyzed.The results showed that the rotor dynamic responses increase with the displacement and angle eccentricities,and the eccentricities could affect the frequency of rotor dynamic responses.The study pointed out that the influence of gravity on the dynamic responses of the rotor is consistent with the static eccentricity,and it can be considered as a static eccentricity in the analysis process.(4)The dynamic model of the rotor bearing stator system in PMSM is established when considering the influence of elastic support,and the influence on rotor dynamic responses with different eccentric parameters,rotor speed and rotor offset are analyzed.The results showed that the dynamic responses of the rotor and the bearing increased with the eccentricity and rotor speed,but the influence of rotor offset on the dynamic responses of the rotor and the bearings are different.The research indicated that eccentricity parameters,rotor speed and rotor offset also affected the frequency of the rotor and bearing.The rotor frequencies have a greater impact on the bearing frequencies,and the impact of bearing frequencies on the rotor frequencies emerged only when the rotor offset is large. |
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