Experiment-driven identification approach of anisotropic damping behaviors and theoretical modal dynamic modelling of electric motors

The modal dynamic behavior of the electrical motors (EMs) is a key determinant in accurately predicting vibration and noise. The natural frequency determines the frequency of structural resonance noise, making it a subject of extensive research. Notwithstanding the significant contributions of the damping ratios to the noise amplitude, this factor remains underexplored in the research field. Essentially, the anisotropic material damping of stator cores and windings remains unstudied. To address the existing research deficiency, an experiment-driven approach for calculating the damping ratios is put forward. Firstly, a theoretical modal dynamic model of the coupled structure consisting of the stator core, winding, and casing is developed. In particular, the hysteresis damping theory is employed to take the material damping behavior into account. Accordingly, the effect of anisotropic material damping of the stator core and windings on the structural damping ratios is thoroughly investigated. Subsequently, the anisotropic material parameters (AMPs) and anisotropic damping parameters (ADPs) of stator cores and windings are identified based on the proposed theoretical models and modal experiments. Finally, Natural frequencies and damping ratios are calculated utilizing the identified AMPs and ADPs. The absolute errors of the damping ratios of the stator core and stator assembly are within 0.14%, and the absolute errors of the stator system are within 0.25%. The proposed approach is of great significance for analyzing and controlling structural resonance noise of the EMs.