Stanimir Valtchev

New University of Lisbon; TU Sofia and BFU Bulgaria

THE PURPOSE. Conduct a study to improve the reliability of forecasting the magnitude of power consumption and power losses at an industrial enterprise. METHODS. Methods are used to determine and predict the parameters of consumption and losses of electricity at industrial facilities. RESULTS. To clarify the magnitude of electricity losses, it is pr...

The world is once again facing massive energy- and environmental challenges, caused by global warming. This time, the situation is complicated by the increase in energy demand after the pandemic years, and the dramatic lack of basic energy supply. The purely “green” energy is still not ready to substitute the fossil energy, but this year the fossil...

THE PURPOSE. Investigation of the control system of the cargo movement mechanism when using different variants of sensorless control. The search for the optimal option, in which the formation of the speed is identical to the data obtained from the speed sensor. Analysis of the results obtained during the study, including the results obtained taking...

A generalized non-affine nonlinear power system model is presented for a single machine bus power system with a Static Var Compensator (SVC) or State Var System (SVS) for hybrid Unmanned Aerial Vehicles (UAVs). The model is constructed by differential algebraic equations on the MATLAB-Simulink platform with the programming technique of its S-Functi...

1 Худжандский политехнический институт таджикского технического Университета имени академика М.С. Осими, г. Худжанд, Таджикистан 2 Казанский государственный энергетический университет, Россия 3 Новый Лиссабонский университет; ТУ София и БФУ Болгария ORCID*: http://orcid.org/0000-0002-2573-759X, shahbozdadoboev@mail.ru Резюме: ЦЕЛЬ. Анализ пусковых...

THE PURPOSE. Investigation of the degree of influence of the characteristics of inplant electrical networks on the reliability of the results in the algorithms for estimating equivalent resistances. METHODS. When solving this problem, a study of the radial power supply scheme of the tool shop section was carried out with the calculation and modelin...

In recent years, the growing concern for air quality has led to the development of sustainable vehicles to replace conventional internal combustion engine (ICE) vehicles. Currently, the most widespread technology in Europe and Portugal is that of Battery Electric Vehicles (BEV) or plug-in HEV (PHEV) electric cars, but hydrogen-based transport has a...

THE PURPOSE. Investigation of the degree of influence of the characteristics of in- plant electrical networks on the reliability of the results in the algorithms for estimating equivalent resistances. METHODS. When solving this problem, a study of the radial power supply scheme of the tool shop section was carried out with the calculation and model...

ТНE PURPOSE. The objective of this study is to investigate the possibilities of longer distance resonant energy transmission applying Wireless Power Transfer (WPT) in the MHz frequency range. The planned final purpose is the energy to be transferred to all types (aerial and terrestrial) of electric vehicles (EV), mainly for the battery charging at...

THE PURPOSE. Investigation of the degree of influence of the characteristics of inplant electrical networks on the reliability of the results in the algorithms for estimating equivalent resistances. METHODS. When solving this problem, a study of the radial power supply scheme of the tool shop section was carried out with the calculation and modelin...

THE PURPOSE. In controlled AC drives used on continuous-action mechanisms, which include conveyors, conveyors, cranes, the most widespread are asynchronous motors with a phase rotor, controlled mainly along the rotor circuit using various regulators with low energy efficiency. To improve the energy efficiency of an electric drive based on ADFR, it...

THE PURPOSE. In controlled AC drives used on continuous-action mechanisms, which include conveyors, conveyors, cranes, the most widespread are asynchronous motors with a phase rotor, controlled mainly along the rotor circuit using various regulators with low energy efficiency. To improve the energy efficiency of an electric drive based on ADFR, it...

The hybrid three-phase rectifiers (HTR) consist of parallel associations of two rectifiers (rectifier 1 and rectifier 2), each one of them with a distinct operation, while the sum of their input currents forms a sinusoidal or multilevel waveform. In general, rectifier 1 is a GRAETZ (full bridge) (can be combined with a BOOST converter) and rectifie...

This work presents a mid-range wireless power transfer (WPT) system that uses a high-temperature superconducting coil in the transmitter circuit to increase the efficiency of the system. The presented system is foreseen to provide energy to superconducting magnetic levitation vehicles and is intended to be implemented in the Brazilian MagLev-Cobra....

ЦЕЛЬ. Практическая реализация плазменной установки с полой цилиндрической камерой и исследование возможности стабилизации и регулирования положения электрической дуги и выхода языка плазмы из рабочей камеры на заданное pасстояние. Проанализировать особенности конструкций электроплазменных установок (плазмотронов), предназначенных для выполнения раз...

Superconductivity is a remarkable state of matter exhibited by some materials, which is characterized by the vanishing of electrical resistivity at cryogenic temperatures, among other phenomena. However, the prospective economical viability of superconducting devices relies heavily on an efficient cooling system to remove the heat generated during...

THE PURPOSE. In controlled AC drives used on continuous-action mechanisms, which include conveyors, conveyors, cranes, the most widespread are asynchronous motors with a phase rotor, controlled mainly along the rotor circuit using various regulators with low energy efficiency. To improve the energy efficiency of an electric drive based on ADFR, it...

It is inevitable that high-intensity, wide-spectrum electromagnetic emissions are generated by the power electronic equipment of the Extra High Voltage (EHV) power converter station. The surveillance flight of Unmanned Aerial Vehicles (UAVs) is thus, situated in a complex electromagnetic environment. The ubiquitous electromagnetic interference dema...

The paper reports a theoretical and experimental study of a novel thermal energy harvester with heat-induced vibrations in an environment with a nonzero temperature gradient. The energy harvester comprises a Shape Memory Alloy wire from Nitinol and two elastic cantilever beams with deposited Lead Zirconium Titanate piezoelectric layers. The Shape M...

The IEEE IES: An Interdisciplinary Family of Mentors, Young Professionals, and Students If we look at the world today, we may wonder how technology is important for us. Is there any discipline that could cover and join with current trends? At the IEEE Industrial Electronics Society (IES) website [1], one can read the following: The Industrial Ele...

In this paper, a new way to mitigate the current interactions is proposed. The problem of current interactions arises when a modular three-phase (3-phase) rectifier (three single-phase modules) with boost converter for power factor correction (PFC) is used. A new differential-mode choke filter is implemented in the developed boost converter. The ch...

THE PURPOSE. To analyze the starting transient processes of an asynchronous motor with a low quality of electricity in the supply network. To consider starting an asynchronous motor at a reduced mains voltage, at a reduced mains frequency, as well as starting with voltage dips in the network. METHODS. Simulation modeling based on computer models wa...

In this paper, an analytical formula for the coupling coefficient (k) was introduced for two inductively coupled coils of ring configuration. The response surface methodology (RSM) was used as a tool to develop this formula. The k was tested as a function of the geometrical parameters which include the followings parameters: an air-gap (d) between...

This study introduces an efficient method to determine the computation mathematical formula of mutual inductance (M) for a pair of ring coils. A design technique called Box-Behnken that based on the response surface methodology (RSM) was utilised to develop such a formula. The M was developed to be a function for the air-gap (d) between the coupled...

The restoration of the materials surface layer can be performed by depositing a metal layer using an electric arc plasmatron. The restoration technology is based on feeding molten metal into the reduction zone, and subsequent additional heating of the reduction zone by plasma. In an electric arc plasmatron, an electric arc is ignited between two el...

This paper discusses the improvement of two-phase motor control systems. In the last 100 years two-phase induction motors have been massively replaced by the three-phase motors, but nevertheless in many industries, they are still good solution. These areas are high-power traction drives with DC motors used in electric vehicles. Or vice versa, low-p...

Real-time systems are confidently used by electric drive developers to test control systems and converters. Such systems are called Hardware-in-the-Loop (HiL) system and Power Hardware-in-the-Loop (PHiL) system. The application options of these systems are presented. Issues connected with HiL and PHiL requiring study and research are discussed.

In this paper, an analytical formula for the coupling coefficient (k) was introduced for two inductively coupled coils of ring configuration. The response surface methodology (RSM) was used as a tool to develop this formula. The k was tested as a function of the geometrical parameters which include the followings parameters: an air-gap (d) between...

Cardiovascular diseases remain the leading cause of morbidity, mortality, early disability and growing health costs worldwide. The difficulty for monitoring the evolution of cardiovascular related diseases can be, partially, attributed to the lack of appropriate indicators for arterial injury and cardiac disfunction during routine clinical practice...

The thesis focuses on the study of the electrical component of the electromagnetic field, radiated by the wireless energy transfer system into the adjacent environment. The wireless energy transfer and the wireless data transfer are studied simultaneously, focusing on the appropriate wireless communication channel between the transmitter and the re...

The modelling of the distribution transformer winding is the starting point and serves as important basis for the transformer characteristics analysis and the lightning pulse response prediction. A distributed parameters model can depict the winding characteristics accurately, but it requires complex calculations. Lumped parameter model requires le...

The modelling of the distribution transformer winding is the starting point and serves as important basis for the transformer characteristics analysis and the lightning pulse response prediction. A distributed parameters model can depict the winding characteristics accurately, but it requires complex calculations. Lumped parameter model requires le...

In this paper, an analytical formula for the coupling coefficient (k) was introduced for two inductively coupled coils of ring configuration. The response surface methodology (RSM) was used as a tool to develop this formula. The k was tested as a function of the geometrical parameters which include the followings parameters: an air-gap (d) between...

In this paper, an analytical formula for the coupling coefficient (k) was introduced for two inductively coupled coils of ring configuration. The response surface methodology (RSM) was used as a tool to develop this formula. The k was tested as a function of the geometrical parameters which include the followings parameters: an air-gap (d) between...

In this paper, an analytical formula for the coupling coefficient (k) was introduced for two inductively coupled coils of ring configuration. The response surface methodology (RSM) was used as a tool to develop this formula. The k was tested as a function of the geometrical parameters which include the followings parameters: an air-gap (d) between...

In the inductive contactless battery charging, the power transfer capability and efficiency are mainly depending on the coupling coefficient (k) between the inductively coupled coils. In this work, the spiral and square coil configurations were experimentally made from litz wire as well as another spiral copper coil. This study investigates the fre...

The paper deals with a novel vibrating energy harvester consisting of a cantilever beam with a spherical inertial mass attached on its free end. The vibration amplitudes of the cantilever are limited by static elastic membranes against which the sphere impacts. Two piezoelectric layers disposed on both sides of the cantilever convert the mechanical...

In this paper, a three-phase hybrid rectifier is proposed, employing a boost converter without the addition of isolation transformer and output voltage control. This topology is usually considered to be not viable due to the current interactions. In order to mitigate those interactions, the boost inductor is replaced by a magnetically coupled induc...

The focus of this chapter is the electromagnetic interference (EMI) and the electromagnetic compatibility (EMC) that the wireless power transfer (WPT) systems reveal as problems. The wireless power transfer (WPT) was introduced by Nikola Tesla more than one hundred years ago, and only recently it attracted the attention of specialists, due to the i...

This chapter focuses on mid-range wireless power transfer (WPT) systems applied to electric vehicle (EV) battery chargers. The WPT is recently considered as an efficient electric energy transfer process between two or more points in space, without wiring. The technology associated with each specific process of WPT differs from case to case dependin...

This book chapter focuses on mid-range Wireless Power Transfer (WPT) systems applied to Electric Vehicle (EV) battery chargers. The WPT is recently considered as an efficient electric energy transfer process between two or more points in space, without wiring. The technology associated with each specific process of WPT, differs from case to case, d...

This paper presents the study of induction motor operation with regulated frequency and voltage while maintaining the absolute slip of the two optimal modes with a minimum of the “stator current / torque” ratio and a minimum of the “winding loss / torque” ratio; the results of experimental studies confirm the validity of the analytical expressions.

This paper discusses the wound rotor induction motor and variable-frequency drive (VFD) that regulates the stator voltage frequency. The stator and rotor windings are connected to a common electrical circuit. The slip energy of the motor goes to the DC link and feeds the stator winding of the motor. The block diagram of the electric drive, the equi...

This chapter presents control methods applied in the operation of the series loaded series resonant (SLSR) power converters in a most efficient operation zone. The choice of the control method is affected by the objective to guarantee suitably the efficiency, being this method in the same time, relatively easy to apply. The first part of the chapte...

Growth of technology leads to an increase in the number of electric vehicles (EV) on the roads in the world. The technologies of rapid battery charging and wireless charging on the parking and on the move are developing for electric vehicles-EV (electric cars, electric buses, mobile robots). At the same time, electric transport can potentially be n...

Growth of technology leads to an increase in the number of electric vehicles (EV) on the roads in the world. The technologies of rapid battery charging and wireless charging on the parking and on the move are developing for electric vehicles-EV (electric cars, electric buses, mobile robots). At the same time, electric transport can potentially be n...

The steel industry has its special requirements tor the metal strip transportation, inside the mill groups. The transportation of the strip, and especially the inter-stand tension, exercised over the metal strip by MW power motors, are important electromechanical systems. In this article, a new type of control is proposed and applied to the electri...

Modular Multilevel Converter (MMC) is one of the most promising topologies for high power- medium voltage application. However, the use of MMC in variable speed drive applications is still limited. This is due to the fact that the fluctuation of the submodules capacitor voltage is large at low speed constant torque operation. This paper proposes an...

Power-Hardware-in-the-Loop (PHiL) system for electric drives application based on power converter with Field Programmable Gate Array (FPGA)-based control system is discussed. PHiL structures are under discussion as well. During the PHiL mathematical model analysis instantaneous current repeating quality is increased. Variable frequency drive (VFD)...