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The paper studies problems of stability of synchronization conditions for nonlinear systems, which occur spontaneously during operation of three and more electric motors fixed on one foundation, where their rotors are unbalanced, and conditions excluding synchronization. The paper considers systems of three motors. Necessary and sufficient conditions for synchronization are revealed. Problem of stable...
This work deals with the adaptive imbalance force compensation for a three-pole active magnetic bearing (AMB) system. The adaptive compensation scheme utilizes the method of immersion and invariance (I&I) control. In this study, the stabilized three-pole AMB system with known imbalance is considered as the target system. In practical applications, the imbalance force may be unknown and may be...
This paper investigates the detectability of mechanical unbalance in double cage induction motor load using motor vibration signature analysis technique. Rotor imbalances induce specific harmonic components in electrical, electromagnetical, and mechanical quantities. Harmonic components characteristic of this category of rotor faults, issued from vibration signals analysis, are closely related to...
Vibration suppression is crucial for applications in engineering particularly for aircraft systems. A hybrid control approach comprising a feedforward intelligent command shaping technique inverse-model based PID feedback control is presented in this paper. The proposed augmented control scheme is used to control both the flexible motion and rigid body dynamics of a twin rotor multi-input multi-optput...
Online monitoring of rotary machines, like induction motors, can effectively diagnosis electrical and mechanical faults. The origin of most recurrent faults in rotary machines is in the components: bearings, stator, rotor and others. Different methodologies based on current and vibration monitoring have been proposed using FFT and wavelet analysis for preventive monitoring of induction motors resulting...
Longitudinal-torsional mode converters have greatly simplified the structure of ultrasonic motors using a combined torsional/ longitudinal vibration, making miniaturization more practical. A previous design of this type of motor used a multi-layer piezoelectric actuator. In this paper, we report on the performance of motors using wafer-type actuators. This motor design requires a reduced volume of...
An automatic dynamic balancer is installed on a rotor system in order to reduce radial vibrations caused by eccentricities. However, it is found that due to rolling friction between the balancing balls and race, the ball may not be able to be precisely settled at the desired equilibrium position for each rotor speed-up. This inconsistence of ball mis-positioning results in even larger residual vibrations...
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