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The ways of the improvement of the method for the determination of steel losses in the electrical devices of basic types are substantiated. The method is refined by taking into account the magnetic system properties at high saturation. The presence of the interrelation between the special features of the domain structure movement and the shape of the hysteresis loop is proved for laminated cores....
The methods of the theory of fractional-order calculus are used, which extends the possibilities of differentiation and integration to the operators of an arbitrary order during the synthesis of automatic control systems. The expediency of the use of Grunwald-Letnikov equation for the calculation of the fractional-order derivative and integral under the condition of limited signal sampling is demonstrated...
The paper describes the method for indirect determination of the torque, power and energy indices of an induction motor shaft. A developed research laboratory stand is presented. It enables load testing of an induction motor with a possibility of direct measuring the torque, speed, currents and voltages of the researched motor. The analysis of the experimental research of the method for indirect determination...
It is shown that virtual laboratory complexes identical to real physical stands may provide an alternative in laboratory workshop for students of technical specialties of higher educational establishments. The basic requirements for virtual complexes are formulated and graphic programming medium LabVIEW is proposed as a platform for their creation. An example of a virtual laboratory complex for the...
It is demonstrated that pump complexes pipeline networks are characterized by a high degree of breakdown rate because of leakages accompanied by complicated wave processes in the hydrosystem. It is found out that pipeline network wave processes depend on localization place and amount of the leakage, hydronetwork structural parameters as well as the properties of the transported liquid. Leakage influence...
Operation of a variable-frequency electric drive with damages in power electric circuit of the motor stator results in asymmetry of the motor phase current charge, increase of heating losses in certain phases, occurrence of variable components of electromagnetic torque and consumed power. Such operation modes significantly influence both motor operation and frequency converter operation, as long operation...
A diagnostic coefficient, being the function of the average value of wavelet-decomposition coefficients sum for medium-frequency domain is proposed. A method for its decomposition with the use of the theory of reverse z-transform is worked out. The proposed method made it possible to specify diagnostic signs of IM broken rotor bars in the motor self-running-out mode and determine the degree of the...
A method for identification of induction motor parameters with the use of instantaneous power components balance equations is proposed in the paper. A dependence for nonlinear resistance in the rotor current function is obtained.
A method for provision of operability of a variable-frequency electric drive with vector control in the presence of breakages in the induction motor stator power electric circuit is presented. Analysis of electromagnetic torque orthogonal components in an analytical form has revealed that the influence of breakages, causing induction motor stator circuits asymmetry, on the electric drive operating...
A possibility of application of power harmonic analysis method to an electrohydraulic complex with nonlinear processes in the pipeline system is demonstrated. It is determined that nonlinear processes in a hydraulic network, caused by cavitation self-oscillations, result in periodical stationary oscillations of power, are accompanied by increase of its variable component. To assess the processes of...
One of the reasons for deterioration of the efficiency of operation of a variable-frequency electric drive (VFED) with scalar control consists in occurrence of asymmetry of induction motor (IM) parameters. Apart from appearance of variable components of consumed power and electromagnetic torque, such asymmetry causes deterioration of operating mode of an autonomous voltage inverter (AVI). Assessment...
Operation of an induction motor with electric or magnetic asymmetry of stator windings results in uneven distribution of losses in copper across stator phases and appearance of variable components of electromagnetic torque and consumed power. Such operating modes considerably influence both operation of the motor and operation of the technological mechanism on the whole, as there appears continuous...
An equivalent circuit of an electrohydraulic complex taking into account periodic nonlinear processes in a pipeline network is proposed. It is shown that the use of the method of harmonic analysis of hydraulic power makes it possible to single out variable components generated by cavitation phenomena, to perform frequency analysis of power processes in the hydraulic system. A power model of an electrohydraulic...
In the work it was carried out the research on the processes of compensation for three-phase power-supply system with the use of cross-vector theory of instantaneous power in the frequency domain in an analytical form. The obtained results made it possible to propose a method for improvement the compensation of inactive instantaneous power components under harmonic distortions of the mains supply...
In the article a theoretical basis of induction motor diagnostic methods based on motor current and motor power consumption spectra analysis is presented. Equations, describing current and power curves of motor working with most frequently caused damage types, were shown. A comparison of informative values of these signals has showed that power consumption signal contains greater number of diagnostic...
It has been shown that the analysis of power conversion processes in all the power channel elements, based on instantaneous power harmonic components, underlies the estimation of electromechanical systems power controllability. Presence of additional power variable component reflecting energy exchange processes in the system results in the decrease of the object power controllability. It has been...
In this paper, the theoretical basis and developed hardware and software for an induction motor diagnostic system based on electrical signals analysis is presented. The theoretical principles underlying these methods are based on a spectral analysis of the stator current and motor power consumption signals. The hardware allows data measuring for different operating modes with different range of motor...
The aim of proposed paper is to present the magnetic field calculation in aerial toroidal and poloidal coil systems arrangement. The magnetic system is in principal very similar to the Tokamak configuration. The coil models have been done in 2-D axisymmetry and/or in 3-D, depending on geometric arrangement and excitation of coils. The finite element method (FEM) was used in all analyses. The calculation...
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