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Doubly fed induction generators (DFIGs) are the most popular configuration met in the wind energy sector occupying approximately 65% of the total market share. Condition monitoring of wind turbine generators is performed based on vibration data collected from accelerometers mounted on the drive end and non-drive end bearings, meeting the requirements of numerous turbine operators for condition based...
Fractional-slot windings is widely used in synchronous machine due to give us more flexibility on selection of the number of slot at design stage. It is also known that fractional-slot windings produces additional harmonics compare to integral-slot windings. These harmonics may cause increasing of stray losses and stator core vibration This paper describes the result of space flux harmonics caused...
In this paper, we describe the design and development of the newly developed 3-DOF inchworm mechanism with 6 contact points on a surface to improve a positioning repeatability. The mechanism consists of a pair of Y-shaped electromagnets and six piezoelectric actuators and moves like an inchworm. We calculate a 3-DOF simple harmonic vibration model to get input signals in any 3-DOF motions. In several...
Industrial applications involving torque BLDC motors require high efficiency over a large speed range. In order to achieve such specifications, the flux weakening is necessary, which could lead to relative high mechanical vibrations and consequently to audible noise. Furthermore, to decrease cogging torque and to satisfy motor manufacturing constraints, concentric windings are usually considered....
The total harmonic distortion (THD) is an important character of vibration transducer calibration system. A new method is proposed in this paper to reduce the THD, which is based on the open-loop frequency response analysis of the vibration transducer calibration system and harmonic compensation. The mathematic model of the motion of electric shaker is described. Results of simulations and experiments...
The radial force density harmonics and vibration characteristics of three-phase modular permanent magnet brushless AC machines, in which the coils that belong to each phase are concentrated and wound on adjacent or alternative teeth, are analysed. It is shown that, due to the presence of a large number of low and high order space harmonic magnetomotive forces, it is more likely that low frequency...
Damage of bearings is the most common cause of failures of squirrel-cage induction motors. A faulty bearing results in additional motor vibrations. They are reflected in the harmonic content of stator currents. In certain operating conditions the current signal is the sole source of information on the state of the motor. The paper presents a mathematical model of the motor, allowing for rotor eccentricities...
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