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Switched reluctance machines have the drawback of a high acoustic excitation. This paper presents an acoustic optimization method that analyzes the signal of a vibration sensor in the control loop and is able to eliminate mode-0 borne vibrations. A search algorithm which determines the optimized control parameters is proposed. The potential of the control concept is described including measurement...
We present a new intuitive and rational model of parametric resonance. In parametric resonators one of the system parameters, usually stiffness, is modulated in time. Due to this time modulation the system may develop a periodic response. It is well known that when this modulation is sufficiently strong and at an appropriate frequency, the periodic response may be unbounded — even though the system...
Gearboxes are important components in industrial applications and its condition monitoring is relevant in industries for reducing costs and minimizing maintenance downtime. Diagnosing wear in gearboxes saves time to prepare appropriate corrective actions, and to ensure that the system does not deteriorate critically. Nowadays, for condition monitoring in gearboxes, vibration analysis is commonly used...
Informative features having important discriminatory power, also called high-level features, for classification of bearings faults can be automatically extracted from the spectrum of the vibration signal envelope without the a prior knowledge of the characteristic bearing frequencies. It was shown in a previous work that the Principal Component Analysis (PCA), when applied on a specific spectral matrix...
In this paper, we show experimental results indicating that tactile mechanoreceptors have non-linear sensitivity to an applied vibration. We focus on the perceptual characteristic of high frequency amplitude-modulated (AM) vibration. It is known that humans can feel AM vibration even when its carrier frequency is higher than the perceivable range. Non-linearity of perception should be taken into consideration...
A wavelength division sensing RF vibrometer which is implemented as a tunable carrier frequency Doppler radar sensor was used for the first time to accurately measure mechanical vibrations of complex patterns. The amplitude ratio of a pair of baseband harmonics under different carrier wavelengths was used to obtain the vibration patterns. A software-controlled PLL was built to generate carrier frequencies...
This paper presents a new control strategy for the reduction of the electromagnetic vibration (and thus the acoustic noise emitted) in the external casing of a three-phase induction machine fed by a three-phase inverter. We compared the measurements of classical technique SPWM (Sinusoidal Pulse Width Modulation) and technical basis of this new strategy (without random parameters) with the new technique...
Induction motor-gearbox group vibrations, caused by bearing defects, result in the modulation of the stator current. In this research, bearing defect is detected using the stator current analysis and mechanical vibration. The advantage of this method is in the detection of incipient faults. Faulty balls in bearing suspension and eccentricity are the relatively common faults in induction motors coupled...
The definition of S transform was respectively deduced from short time Fourier transform and continuous wavelet transform. The simulation experiment indicates that S transform behaves itself with better time-frequency analysis and positioning capability. It is feasible to adopt S transform to investigate the time-frequency characteristics of engine induction noise in acceleration. Engine induction...
Fault detection and diagnosis of asynchronous machine is became a central problem for industrial domain since the past decade. A solution to tackle this problem is to use stator current for a great condition monitoring, as referred to the ldquoMCSArdquo (Motor Current Signal Analysis). Indeed, it is known that due to the motor structure, mechanical spectral signature fault, as for example bearing...
The issue of non-conventional energy sources now is correlated with energy efficiency and clean energy. An application researched by the authors is vibration stress relieving, which consist in vibration of stress reliving piece with electromagnetic or electro-dynamic vibrator to determine frequencies of resonance. Technology is energy efficient and involves a single-phase inverter with variable frequencies,...
The effects of inverter harmonics on motor current fault signatures are studied in detail in this paper. According to theory and experimentation, the fault signatures caused by the inverter harmonics are similar and comparable to those generated by the fundamental harmonic of the line current. Unlike the utility-driven motor, monitoring the current of the inverter-fed motor is considerably noisy,...
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