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A high-frequency modeling of AC motor in a frequency range from 40 Hz to 110 MHz
(Національний технічний університет "Харківський політехнічний інститут", 2022) Miloudi, Houcine; Miloudi, Mohamed; Gourbi, Abdelkader; Bermaki, Mohammed Hamza; Bendaoud, Abdelber; Zeghoudi, Abdelhakim
Most electromagnetic compatibility models developed for the study of three-phase induction machines are generally valid for low and medium frequencies (<< 1 MHz). This frequency limit seems to be too restrictive for the overall study of conducted electromagnetic interference. In this paper, the model is using the proposed model and compared with experimental results in low and medium frequency. And then, the high-frequency modeling of induction motor is presented new method based on transfer function model. The proposed methodology is verified on an experimental and simulation, it’s suitable for prediction of the terminal overvoltage analysis and electromagnetic interference problems and common-mode and differential-mode currents. The novelty of the work consists to develop an improved high-frequency motor model based on transfer function to represent the motor high-frequency behavior for frequency-domain analyses in the frequency range from 40 Hz up to 110 MHz .The purpose of this work is to study the common-mode impedance and the differential-mode impedance of AC motor. The determination of these impedances is done for firstly both common and differential modes at low and medium frequency, and then common-mode and differential-mode characteristics at high frequency. Methods. For the study of the path of common-mode and differential-mode currents in typical AC motor (0.25 kW, 50 Hz) an identification method in high frequency for induction motor has been proposed based on the transfer function in differential-mode and common-mode configuration. The low and medium frequency model were presented in the first time based on equivalent circuit of electrical motor. Then, the common-mode and differential-mode impedances were defined in high frequency using asymptotic approach. This motor was studied by MATLAB Software for simulation and also experimental measurements. Results. All the simulations were performed using the mathematical model and the results obtained are validated by experimental measurements performed in the University of the Federal Armed Forces Hamburg in Germany. The obtained results of common-mode and differential-mode at low frequency, medium and high frequency are compared between simulation and experiment.
Method of coding information distributed by wireless communication lines under conditions of interference
(Національний технічний університет "Харківський політехнічний інститут", 2018) Serkov, A.; Breslavets, Vitaliy; Tolkachov, M.; Kravets, V.
The subject matter of the paper is the processes of analysis and evaluation of the effectiveness of information coding methods in wireless systems. The aim is to improve noise immunity of information messages under conditions of powerful electromagnetic interference, with the help of complex signal-code constructions. The objective is to develop a method for noise-immune encoding in a wireless information transmission system, providing increase ininformation transmission rate. The methods used: Simulation and digital signal coding. The following results have been obtained: A method for encoding information transmitted via wireless communication lines in presence of interference. For signal coding, it is proposed to use Gaussian monocycle with time-dependent position-pulse modulation (PPM). It is shown that for organization of independent channels within a single frequency band, it is practical to use a system of orthogonal codes. Pulses of the useful information signal accumulated in a receiver correlator provide significantly increase in signal-to-noise ratio, allowing transmission of information over a wide frequency range well below the noise level. As a result of encoding information in wireless information transmission systems with the help of ultra-short pulse signals, the effectiveness of the proposed method is aquantitatively and qualitatively evaluated. Using Pulse Position Modulation coding in wireless information transmission systems allows transmitting large volumes of information with high transmission rate and high noise immunity of the communication channel as well as protecting the channel from message interception. Ability to work with low radiating power and high signal capacity to penetrate various obstacles ensure fulfilment of electromagnetic compatibility requirements as well as stable communication in conditions of multipath radio wave propagation. Apossibility that powerful electromagnetic disturbances accompanying a lightning discharge may have catastrophic impact on the information transmission channel is also eliminated.
Electromagnetic terrorism: new hazards
(НТУ "ХПИ", 2005) Gurevich, V. I.
A new kind of terrorism is considered, namely, electromagnetic terrorism. The history of development of this kind of weapon is described, and information on countries, companies, and leading experts in the area is given. It is shown that modern power objects are quite vulnerable to intentional electromagnetic action because of wide application of microprocessor-based protective relays and computers. Accessibility of special equipment allows carrying out successful terrorist attacks on such objects.

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