| Popis: |
Unbalanced magnetic pull (UMP) effect in a permanent magnet synchronous machine (PMSM) is investigated. The force model is established analytically based on previously studied model by modulating the fundamental magnetomotive force (MMF) wave by air gap permeance and the corresponding force components are evaluated via Maxwell stress tensor method. For considering real rotor dynamic condition, mixed (i.e. static and dynamic) and axial-varying eccentricity are modeled. The rotor bearing system including this UMP model is established by two methods. In the first method, UMP is included as a linear negative spring in the rotor model, while in the second method, the UMP is added as an external force. Rotor dynamics of a centrifugal pump driven by integrated PMSM is modeled using beam elements and different modeling approaches for UMP are applied. From the results, vibration effect of UMP is investigated and difference between two methods is interpreted. For verifying the analysis results, experimental work is conducted for the pump test rig, where the eccentricity condition are produced and the frequency spectra result are obtained. Through these analysis and experimental work, negative stiffness effect and additional vibration excitation by UMP are observed and interpreted. |
