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- Wavelet-Fourier Analysis of Audible Signals to Characterize the Vibrations in LSRAPublication . Salvado, José António da Costa; Calado, M. Do Rosário; Espírito Santo, AntónioThis paper proposes the analysis tools, the methodology, and the experimental setup to support the characterization of vibrations in linear switched reluctance actuators by analyzing the audio signals emitted. The analysis is performed by using two approaches: the windowed Fourier transform and the joint wavelet-Fourier which leads to a hybrid spectrum representation. The spectrum of the audible noise from the vibrations is characterized for different configurations of the actuator, and the spectral components are presented, analyzed and discussed. To evaluate the responses for these configurations, one uses either its frequency components, the spectral cross-correlation, and the Cross-Power Spectrum Density through the Welch periodogram. The reliability and the suitability of this approach are verified by comparing the experimental data with the outcomes from finite elements simulations. The proposed method enables the experimental identification of the critical vibration frequencies in LSRA.
- Numerical Modal Analysis of Vibrations in a Three-Phase Linear Switched Reluctance ActuatorPublication . Salvado, José; Calado, M. Do Rosário; Espírito Santo, António; Guerman, AnnaThis paper addresses the problem of vibrations produced by switched reluctance actuators, focusing on the linear configuration of this type of machines, aiming at its characterization regarding the structural vibrations. The complexity of the mechanical system and the number of parts used put serious restrictions on the effectiveness of analytical approaches. We build the 3D model of the actuator and use finite element method (FEM) to find its natural frequencies. The focus is on frequencies within the range up to nearly 1.2 kHz which is considered relevant, based on preliminary simulations and experiments. Spectral analysis results of audio signals from experimental modal excitation are also shown and discussed. The obtained data support the characterization of the linear actuator regarding the excited modes, its vibration frequencies, and mode shapes, with high potential of excitation due to the regular operation regimes of the machine. The results reveal abundant modes and harmonics and the symmetry characteristics of the actuator, showing that the vibration modes can be excited for different configurations of the actuator. The identification of the most critical modes is of great significance for the actuator’s control strategies. This analysis also provides significant information to adopt solutions to reduce the vibrations at the design.