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Abstract

Abstract The paper treats the thermooptical sound generation in the magnetoactive two-layered medium on the condition of tunnel interference of electromagnetic waves. It were studied the conditions of complete suppression of the photoacoustic signal amplitude in response to the polarization type of oppositely interacting waves, the difference in their initial phases as well as the intensities of one of the oppositely interacted beams. The given paper provides an effective method of managing the thermooptical sound generation in the magnetoactive structural element during the tunnel electromagnetic interference of electromagnetic waves.
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Abstract

With the continuous increase of output power ratings, multi-phase (multichannel) interleaved power factor corrector (IPFC) is gradually employed in domestic and commercial inverter air-conditioners. IPFC can solve several main problems, such as power rating increase, power device selection, input current ripple reduction as well as inductor on-board mounting. But for a multi-phase IPFC, the key problem is that it should show rapid dynamic responds and good current sharing capability, so in this paper the aim is to improve the dynamic performance and current sharing capability by means of passivity control theory. Considering the power circuit topology of a four-phase IPFC, an EL (Euler-Lagrange) mathematical model is established when the IPFC operates in continuous conduction mode (CCM). Then the passivity of the four-phase IPFC is proved, and the passivity-based controller using the state variables feedback and damping injection method is designed. The proposed control scheme, which is easy to control and needs no proportion integral controller, has strong robustness on disturbance from singlephase AC input voltage, the load as well as the parameters of the employed devices. Even in wide-range load condition, the mains current has a fast dynamic response and the average output voltage almost keep unchanged. As a result, the main functions of the four-phase IPFC are implemented including nearly unitary power factor and constant DC output voltage. Meanwhile, the four-phase IPFC acquires an excellent current sparing effect after using passivity-based controller. The above analysis has been proved with simulated results by means of MATLAB/SIMULINK and experimental results, showing that the passivity-based IPFC controller has superior performances and feasibility.
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Abstract

This work presents the co-simulation approach to the analysis of control systems containing detailed models of electromagnetic and electromechanical converters. In this method of analysis the attention is paid to the whole system and not only to its electromagnetic part. The latter is described by equations resulted from the two-dimensional finite element discretisation of the Maxwell equations, and is coupled weakly with the remaining part of the system. The simulation is carried out in Matlab/Simulink environment wherein the coupling is realised through the S-function. Example results regarding simulation of the operation of the control system of an electrical machine and the operation of a power electronic converter are presented and compared with available reference data.
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Abstract

The concept of inverse systems for standard and positive linear systems is introduced. Necessary and sufficient conditions for the existence of the positive inverse system for continuous-time and discrete-time linear systems are established. It is shown that: 1) The inverse system of continuous-time linear system is asymptotically stable if and only if the standard system is asymptotically stable. 2) The inverse system of discrete-time linear system is asymptotically stable if and only if the standard system is unstable. 3) The inverse system of continuous-time and discrete-time linear systems are reachable if and only if the standard systems are reachable. The considerations are illustrated by numerical examples.
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Abstract

Description of program tools simplifying simulation applications building for physical phenomenons described by differential equations in state equations form modeling is presented in the paper. A method for using prepared libraries for squirrel-cage motors including any motor damages modeling had been described. For that purpose, squirrel-cage motor mathematical model in natural coordinates system had been presented. Presented solutions provide also supply sources (inverters) modeling, including their microprocessor implementation and other phenomenons, that assume state equation structure step changes, depending on variable limitations and time value.
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Abstract

The article describes a shock safety modeling method for low-voltage electric devices, based on using a Bayesian network. This method allows for taking into account all possible combinations of the reliability and unreliability states for the shock protection elements under concern. The developed method allows for investigating electric shock incidents, analysing and assessing shock risks, as well as for determining criteria of dimensioning shock protection means, also with respect to reliability of the particular shock protection elements. Dependencies for determining and analysing the probability of appearance of reliability states of protection as well as an electric shock risk are presented in the article.
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Abstract

Author presents an analytical method of calculation of unit power losses in magnetic laminations used in electrical machines and transformers. The idea of this method, based on the solution of Maxwell's equations in the lamination material, was described by the author in the previous work [3], taking into account approximation of constitutive static hysteresis loop by elliptic form of the function B = f(H) depending on magnetic saturation. In the previous formula for new isotropic and anisotropic materials it is needed to introduce so called "anomaly coefficient" deduced from the comparison of measured and calculated value of power losses in arbitrary excitation frequency for assumed induction. The method was tested by comparison with the results of experiments presented in commercial catalogues [1, 2]. Assuming superposition of harmonic power losses it is possible to enlarge this method for the estimation of overloss coefficient in dynamo sheet during axial magnetization with nonsinusoidal flux generated e.g. by PWM voltage supply.
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Abstract

A role of radial corona current in a lightning discharge is discussed in the paper. It is shown that the corona current concept previously introduced by Cooray for lightning return stroke models of distributed-current-source (DCS) type, and later, by Maslowski and Rakov for lumped-current-source (LCS) type models enables to show duality between these two types of models. Further, it is demonstrated that the corona current is useful during consideration of dynamics of the lightning-channel corona sheath. As an example of application of presented approach a relaxation model of charge motion in the corona sheath is analysed together with plots which show the rate of expansion and shrinkage of the lightning corona sheath on both microsecond and millisecond time scales.
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Abstract

This paper addresses the state-variable stabilising control of the power system using such series FACTS devices as TCPAR installed in the tie-line connecting control areas in an interconnected power system. This stabilising control is activated in the transient state and is supplementary with respect to the main steady-state control designed for power flow regulation. Stabilising control laws, proposed in this paper, have been derived for a linear multi-machine system model using direct Lyapunov method with the aim to maximise the rate of energy dissipation during power swings and therefore maximisation their damping. The proposed control strategy is executed by a multi-loop controller with frequency deviations in all control areas used as the input signals. Validity of the proposed state-variable control has been confirmed by modal analysis and by computer simulation for a multi-machine test system.
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Abstract

In this paper, the power factor correction system consisted of: bridge converter, parallel resonant circuit, high frequency transformer, diode rectifier and LFCF filter is presented. This system is controlled by a pulse density modulation method and the principle of its operation is based on the boost technique. The modeling approach is illustrated by an example using AC/HF/DC converter. Verification of the derived model is provided, which demonstrated the validity of the proposed approach.
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