Current Overload Research Articles

The involvement of TRPV4 on the hypoxia-induced oxidative neurotoxicity and apoptosis in a neuronal cell line: Protective role of melatonin

The hypoxia (HYPX)-mediated excessive generation of mitochondrial free reactive oxygen species (mROS) and the overload Ca2+ influx via the inhibition of TRPV4 are controlled by the treatment of antioxidants. However, the molecular mechanisms underlying melatonin (MLT)'s neuroprotection remains elusive. We investigated the role of MLT via modulation of TRPV4 on oxidative neurodegeneration and death in SH-SY5Y neuronal cells. The SH-SY5Y cells were divided into five groups as follows: control, MLT (1 mM for 2 h), HYPX (200 μM CoCl2 for 24 h), HYPX + MLT, and HYPX + TRPV4 blockers (ruthenium red-1 μM for 30 min). The HYPX caused to the increase of TRPV4 current density and overload Ca2+ influx with an increase of mitochondrial membrane potential and mROS generation. The changes were not observed in the absence of TRPV4. When HYPX exposure and TRPV4 agonist (GSK1016790A)-induced TRPV4 activity were inhibited by the treatment of ruthenium red or MLT, the increase of mROS, lipid peroxidation, apoptosis, Zn2+ concentrations, TRPV4, caspase -3, caspase -9, Bax, and Bcl-2 expressions were restored via upregulation of reduced glutathione, glutathione peroxidase, and total antioxidant status. The levels of apoptosis and cell death in the cells were enriched with increases of caspase -3 and -9 activations, although they were decreased by MLT treatment. In conclusion, the treatment of MLT modulates HYPX-mediated mROS, apoptosis, and TRPV4-mediated overload Ca2+ influx and may provide an avenue for protecting HYPX-mediated neurological diseases associated with the increase of mROS, Ca2+, and Zn2+ concentration.

Electric resistance measurement–based structural health monitoring with multifunctional carbon fibers: Predicting, sensing, and measuring overload

Polymer matrix composites that also contain carbon fiber reinforcement can be given a secondary function in addition to load bearing due to the electrical conductivity of the reinforcing fiber. We investigated how to measure the deformation of a composite by measuring the resistance of the carbon fiber and indicate its current or previous overload. We found that the resistance of the carbon fiber bundle initially increases linearly and then progressively during the testing of the specimens, and finally, when the fiber bundle snaps, the circuit breaks. We have shown by cyclic testing that overload exceeding reversible deformation can be detected and measured by examining the first derivative of the resistance change with respect to deformation. Based on our results, electric measurements of either an only carbon fiber-reinforced composite or a hybrid composite can be used to detect a possible previous overload of a component with an unknown load history.

Analysis of heat transfer during flame spread over energized-wire under high currents

Electrical wire is one of the primary causes of electrical fires because of short circuiting or overload current. Experiments were carried out to characterize the influence of high currents on flame spread and dripping behaviors over wires. Two samples of polyethylene (PE)-insulated copper wires with different sizes (dc/do = 0.9 mm/3.0 mm for wire #1 and 1.3 mm/4.2 mm for wire #2) were electrified with current, ranging from 10 A to 50 A, to conduct experimental study. Results show that the dripping becomes faster as the current increases and the continuous dripping occurs under high current (I > 40 A for wire #1 and I > 30 A for wire #2), causing the flame to be narrower and shorter. The heat transfer by different passages (radiation, convection, conduction through core and the joule heat) were quantitatively analyzed. The heat feedback from core to the insulation (q˙cp) were the dominant heat transfer mode during flame spread over energized wire. Heat required for flame spread (q˙req) is mainly supplied from the core, nearly 80%, including the joule heat (q˙joule) and the heat conduction through the core from the burning zone (q˙cc). The proportions q˙cp/q˙req decreased with the increasing current, and has a sharp decent to 70% or 50% at I = 50 A or 35 A for wire #1 or wire #2, respectively. In addition, the proportion of q˙cp to the sum of q˙joule and q˙cc drops obviously under high current, which means the dominated role of core heat feedback in heat transfer mode is weakened under high current. A flame spread model for energized wire based on the quantitative analysis of controlling heat transfer mechanism was proposed, and it predicted the flame spread rate well within error of ±20%. The findings of the presented study will be essential for simulation study of flame spread behavior over energized wires with high current and may guide the design of future electric fire safety.

Use of a phase-shifting transformer for increasing the power transmission capacity, taking into account the mode of the adjacent network

In this research, we develop measures aimed at improving the efficiency of power systems by increasing their transmission capacity. To this end, a FACTS system based on the phase-shifting transformer with a thyristor switch developed at the Power Engineering Institute named after G.M. Krzhizhanovsky was used. The efficiency of the phaseshifting transformer under study for increasing the transmission capacity of power systems was determined by the maximum permissible cross-section flows of the Barnaul-Biysk node-2. The calculations were performed for normal and various post-accident schemes using the RastrWin3 software package. Such factors as the regulation of the taps of the phase-shifting transformer and various places of its installation were considered. For the section under consideration, the phase-shifting transformer increased the maximum permissible flow by 4–12%. The determining factor limiting the maximum permissible flow in the Barnaul-Biysk node-2 was found to be the current overload of the 110 kV lines of the adjacent network. The greatest effect of increasing the maximum permissible overflow was noted when the phase-shifting transformer was installed on the 220 kV line adjacent to the section, parallel to the 110 kV lines (which were overloaded when the mode became heavier), rather than on the 220 kV line included in the section. Similar calculations were performed for normal and post-accident schemes of an alternative option, which involved replacing wires and installing automatic equipment for limiting equipment overload on overloaded 110 kV lines. The obtained results show that the effect of increasing the transmission capacity for this option comprised 4%.

Thermal modes of the automated electric drive system during burning under load

Purpose. Conducting experimental studies of temperature regimes of an induction motor during start-up on a laboratory complex. Obtaining real characteristics of the heating process during the start of the start, assessing its impact on the insulation state of the induction motor, confirming the adequacy of the indirect method of determining the heating temperature of the induction motor windings during the formation of the cyclic starting torque during the start.
 Methodology. To solve these problems, we used mathematical modeling based on the first mathematical expressions that calculate the temperature of the stator winding during start-up, taking into account the influence of the frequency of the supply voltage on the parameters of the induction motor. Physical modeling on the developed laboratory stand of modes of movement on fixing of temperature during each stage of experiment for confirmation of theoretical researches of movement at pulse character of the starting moment.
 Findings. The use of different methods of constructing equivalent thermal circuits (ETS) to calculate the temperature of an induction motor requires significant resource consumption, which is unprofitable when the rotor of the machine is stationary as in the case of failure. Using the method of determining losses in steel in the deep saturation mode, the mathematical dependences of the calculation of the temperature regime during the algorithm, taking into account the change in the properties of the stator winding during heating, calculated the allowable current overload parameters taking into account the allowable heating of stator windings. The paper obtains mathematical dependences for calculating the temperature regimes of the stator windings during the formation of the cyclic starting torque for the movement, taking into account the change of the initial conditions of the movement for each cycle and the change in the properties of the stator windings during heating. The developed laboratory complex allows to carry out research of temperature modes of a stator winding at movement of the induction motor with the braked rotor, at assignment of various values ​​of amplitude and frequency of supply voltage. The results of research indicate that the mathematical dependences derived in the work allow to control the heating temperature by the analytical method. Analysis of the modes of operation of the induction motor during the execution of the movement confirmed the need to control the temperature of the stator windings to prevent accidents. In general, when starting with a step-by-step supply of low frequency supply voltage to obtain increased starting torque, the heating of the stator windings is slower compared to heating during prolonged operation of an induction motor with a braked rotor, which allows multiple attempts to move at low frequency. nutrition.
 Originality. For the first time, mathematical dependences for calculating the temperature of stator windings during start-up with a braked rotor of an asynchronous machine are obtained and experimentally confirmed, which take into account the change in stator winding properties during heating and the influence of supply voltage frequency.
 Practical value. For the first time, an indirect method of controlling the heating temperature of the stator windings of an asynchronous machine during start-up is proposed to prevent emergencies on process equipment that is started under load.

CT-Based COVID-19 triage: Deep multitask learning improves joint identification and severity quantification.

The current COVID-19 pandemic overloads healthcare systems, including radiology departments. Though several deep learning approaches were developed to assist in CT analysis, nobody considered study triage directly as a computer science problem. We describe two basic setups: Identification of COVID-19 to prioritize studies of potentially infected patients to isolate them as early as possible; Severity quantification to highlight patients with severe COVID-19, thus direct them to a hospital or provide emergency medical care. We formalize these tasks as binary classification and estimation of affected lung percentage. Though similar problems were well-studied separately, we show that existing methods could provide reasonable quality only for one of these setups. We employ a multitask approach to consolidate both triage approaches and propose a convolutional neural network to leverage all available labels within a single model. In contrast with the related multitask approaches, we show the benefit from applying the classification layers to the most spatially detailed feature map at the upper part of U-Net instead of the less detailed latent representation at the bottom. We train our model on approximately 1500 publicly available CT studies and test it on the holdout dataset that consists of 123 chest CT studies of patients drawn from the same healthcare system, specifically 32 COVID-19 and 30 bacterial pneumonia cases, 30 cases with cancerous nodules, and 31 healthy controls. The proposed multitask model outperforms the other approaches and achieves ROC AUC scores of 0.87±0.01 vs.bacterial pneumonia, 0.93±0.01 vs.cancerous nodules, and 0.97±0.01 vs.healthy controls in Identification of COVID-19, and achieves 0.97±0.01 Spearman Correlation in Severity quantification. We have released our code and shared the annotated lesions masks for 32 CT images of patients with COVID-19 from the test dataset.

Do You Buy or Not? The Effect of Recommender Slogans on Retail Sites

Recommender systems solve the current information overload problem in the online world. By predicting and presenting relevant information, web users do not need to waste time searching and browsing for contents that they are interested in. However, in addition to the accurate contents, slogans associated catching the customers’ eyes are worthy of exploration. This study aims to discover the effects of various recommender slogans. Two categories of slogans were designed in the study: slogans associated with customer inputs and slogans associated with price promotion. Actual customers’ webpage clickstreams and purchase decisions were collected from a Taiwanese retail shopping Website. The effects of recommender slogans on product categories are different. Customers generally were drawn by the slogans associated with price promotion. This study brought to light the effects of different slogans on online shoppers. With the empirical findings, this study provides online retailers important guidelines regarding online customers’ behaviors towards the employment of recommender slogans.

Hybrid Modular Multilevel Converter Design and Control for Variable Speed Pumped Hydro Storage Plants

Hybrid modular multilevel converter control and design for pumped hydro storage plants is presented, addressing application-specific shortcoming of conventional back-to-back half-bridge modular multilevel converter: high common-mode-voltage machine stress. Common-mode-voltage-free operation in the entire or partial frequency range is enabled by variable DC link voltage control, through introduction of minimal full-bridge submodule share in hybrid active front-end converter stage. The developed generalized converter design approach for arbitrary DC link voltage range operation and additional internal energy balancing control layers enable down-to-zero DC voltage control. The results are verified through high-fidelity switched-model simulations of 6 kV converter, with 10/6 ratio of full-bridge to half-bridge submodules in active front-end. The analyzed hybrid active front-end stage benefits from lower converter losses for equal machine operation flexibility compared to full-bridge design, while trade-off between grid-side power factor range and full-bridge submodule share is offered within the design stage. Compared to the state-of-the-art, zero-to-rated DC link voltage operation is possible at lower full-bridge submodule share (62% against 75 %), at the penalty of reduced grid-side power factor. Alternatively, operation at higher full-bridge submodule share (62% against 50% existing solution) enables grid-side reactive power support over wide speed range, without branch current overload.

ОБЗОР МЕТОДОВ ОЦЕНИВАНИЯ ПАРАМЕТРОВ СХЕМЫ ЗАМЕЩЕНИЯ АСИНХРОННОЙ ЭЛЕКТРИЧЕСКОЙ МАШИНЫ ДЛЯ ОРГАНИЗАЦИИ ВЕКТОРНОЙ СИСТЕМЫ УПРАВЛЕНИЯ

Relevance Today, due to the well-known and proven by many years of positive qualities of successful operation, induction machines (IM) have found wide application in various industries [1, 2], as part of motor [3–5] and generator sets [6–8]. The main advantages of an IM include simplicity of design, relatively low cost, the ability to withstand short-term current overloads, the absence of a brush-collector unit and expensive rare-earth magnets [9–14]. The relevance of the use of IM, which has not lost over the years, is confirmed, in particular, by modern manufacturers of electric vehicles [15], for which the issue of the most rational use of electricity is in the first place. The development of the principles of the theory of control of asynchronous controlled electric drives led to the emergence of various IM control methods, implemented in modern microprocessor-based frequency converters. These control methods include U/f control, field oriented control and direct torque control in various modifications and combinations [16–18]. The listed control methods have their own areas of application and are, to varying degrees, demanding on the availability of the parameters of the IM equivalent circuit used as part of the electric drive [19, 20]. Setting incorrect settings of the control system, based to the greatest extent on the parameters of the IM equivalent circuit, can lead to deterioration in the quality of regulation, as well as to a decrease in the energy efficiency of the electric drive [21–24]. It should be noted that the most acute problem with the availability of correct estimates of IM parameters arises when constructing sensorless control systems for electric drives [25]. Aim of research Review and compare the main methods estimation of induction motor equivalent circuit parameters used to organize a closed-loop control system of an electric drive. Research methods In this study, the following methods were used: study of scientific literature, study and generalization of information, comparison. Results The need to find estimations of IM equivalent circuit parameters for organizing a field oriented control system for an electric drive. A comparative analysis is carried out, the advantages and disadvantages of the main groups of methods for finding estimates of the parameters of an IM are described.

Research on the Working Mechanism of Melt Metallurgical Effect

This paper takes rectangular tinned silver flake as the research object to explore the working mechanism of melt metallurgical effect. Firstly, the paper designs and processes rectangular tinned silver flake through the electroplating technology, then conducts low-overload pre-arc experiment with the metallurgical samples. According to the experiment results, it is proposed that “Under low overload current, the formation of silver-tin alloy leads to the increase of current density of the metallic silver layer, which significantly advances the break time of the silver flake. At the same time, the silver-tin interpenetration speed is a linear function of the temperature.” Finally, the self-programming software is used to establish the transient electric heating field model of the metallurgical tinned silver flake. By comparing simulation and experiment, the results verify the accuracy of the hypothesis, and obtain the working mechanism of the melt metallurgical effect, which provides a reliable theoretical basis for the design and application of the metallurgical trigger.

Adaptive Bidirectional Inductive Power and Data Transmission System

For the research of wireless power transfer, loosely coupled inductive power transfer (LCIPT) is one of the widely adopted technologies. There are already various researches focusing on development of high-efficiency LCIPT. However, when the transmission and receiver coils are misaligned, the power transfer efficiency will be significantly dropped. This article considers the change of mutual inductance when two induction coils are misaligned. A fuzzy control approach to solve for this problem by adaptively adjusting operational frequency is introduced. Experiments show that it can reduce the power transferring efficiency drop by 11% when two conduction coils are misaligned up to 50 mm. This research also supports adaptive maximum power transfer using tracking mechanism. Before conducting power transmission, the system can choose G2V or V2G according to the vehicle battery capacity via handshaking communication without the need of radio frequency links. In addition, the phase shift pulsewidth modulation technique is proposed for simultaneous data transmission enabling binary quadrature amplitude modulation for digital signal transmission. Fast over current protection is incorporated for power transfer safety when current overload happens. The transmission frequency of this article is controlled to meet the frequency specified by SAE TIR J2954.

Analysis of electric drive systems for performance of driving and starting under load

Purpose. Perform an analysis of existing automated control systems of the electric drive and methods of forming the starting torque to determine the compliance of the selected system and method to the requirements for trouble-free mode of start and start of the technological mechanism in difficult conditions or breakaway and start under load..
 Methodology. Comparison of energy performance and capabilities of control systems and methods for the formation of starting torque, mathematical calculations, analysis of the properties of systems and methods in accordance with the requirements of technological operations during the start.
 Findings. To obtain the results of the analysis of the current methods of starting induction motors, autotransformer start was considered, which can significantly reduce the starting current, and also connect a capacitor with a reactance to reduce the current and increase the starting torque; the use of soft start with amplitude-phase control allows you to reduce the starting current and reached the absence of its impulses. The vector-pulse method of controlling the converting device increases the starting torque in the absence of an increase in starting current, such advantages have a quasi-frequency starting mode, but the application is limited by special technological equipment. Thyristor voltage regulator using the phase control method, despite its widespread use in control systems, has a low value of the starting torque. To carry out starting in difficult conditions, according to the results of the analysis of existing systems of controlled starting, it was found that a rational electric drive system for hoisting-and-transport mechanisms is a frequency-controlled electric drive system according to the "frequency converter - asynchronous motor" (FC - IM) scheme.
 Originality. For the first time it is proposed to improve the existing control systems of hoisting and transport mechanisms that perform start-up in difficult conditions when using the modes of movement to form the starting torque that exceeds the passport value by 3-4 times. Increasing energy efficiency based on increasing their efficiency, information content and data reliability. For the first time, the reasons for the shortcomings of existing control systems during start-up under load in modern production are analyzed.
 Practical value. The choice of a rational electric drive system for lifting and transport mechanisms is substantiated when starting in difficult conditions, which will provide maximum efforts in the transmission of a technological mechanism with permissible current and thermal overloads of asynchronous machines.

Preventive Control Policy Construction in Active Distribution Network of Cyber-Physical System with Reinforcement Learning

Once an active distribution network of a cyber-physical system is in alert state, it is vulnerable to cross-domain cascading failures. It is necessary to transit the state of an active distribution network of cyber-physical system from an alert state to a normal state using a preventive control policy against cross-domain cascading failures. In fact, it is difficult to construct and analyze a preventive control policy via theoretical analysis methods or physical experimental methods. The theoretical analysis methods may not be accurate due to approximated models, and the physical experimental methods are expensive and time consuming for building prototypes. This paper presents a preventive control policy construction method based on a deep deterministic policy gradient idea (shorted as PCMD) to generate and optimize a preventive control policy with Artificial Intelligence (AI) technologies. It adopts the reinforcement learning technique to make full use of the available historical data to overcome the problems of high cost and low accuracy. Firstly, a preventive control model is designed based on the finite automaton theory, which can guide the data collection and learning policy selection. The control model considers the voltage stability, frequency stability, current overload prevention, and the control cost reduction as a feedback variable, without the specific power flow equations and differential equations. Then, after enough training, a local optimal preventive control policy can be constructed under the comparability condition among a fitted action-value function and a fitted policy function. The constructed preventive control policy contains some control actions to achieve a low cost and in accord with the principle of shortening a cross-domain cascading failures propagation sequence as far as possible. The PCMD is more flexible and closer to reality than the theoretical analysis methods and has a lower cost than the physical experimental methods. To evaluate the performance of the proposed method, an experimental case study, China Electric Power Research-Cyber-Physical System (shorted as CEPR-CPS), which comes from China Electric Power Research Institute, is carried out. The result shows that the effectiveness of preventive control policy construction with the PCMD is better than most current methods, such as the multi-agent method in terms of reducing the number of failure nodes and avoiding the state space explosion.

"DIFFERENCES OF AC AND DC DRIVES OF VARIOUS TRAMCARS MODELS"

The article discusses the schematic diagram of the tram KTM-5M3. Moreover, describes comparative description of the technical properties of tram engines. The limitations and advantages of using mixed excitation motors for urban electric transport are shown. Keywords: tramcar, schematic diagram, current, voltage, current overload, short circuit, engine, trolley

Influence of heating dynamics of polymer insulation of medium voltage power cables on their performance

Currently, global trends in the development of medium voltage cable networks are aimed at the introduction of cables with cross-linked polyethylene insulation. Such cables are innovative products of domestic cable manufacturers. Most often, single-core cables are laid in parallel in one plane. The article analyzes a number of significant features of cables with cross-linked polyethylene insulation, which affect the thermal regime both in working condition and in emergency operation, among which - the dependence of thermal conductivity and heat capacity of polymer insulation on temperature. Cable throughput, which is determined by regulatory models and average environmental parameters, provides only preliminary information about its heating, useful for comparing its throughput with other cables of the same type. For certain requirements and for innovative cable designs, it is necessary to determine the capacity according to thermal constraints in specific operating conditions. Thermal and electrical asymmetry must also be taken into account in the test conditions of cables intended for laying three single-core cables in the plane. The heating of medium voltage cables with crosslinked polyethylene insulation was studied [1], an experimental assessment of the influence of the distance between the cables on the asymmetry of currents and temperatures was performed using three single-phase single-core cables АПвЭгаПу 1х70/16–35with the same current direction. It is established that in the absence of longitudinal currents in electrically conductive screens, the current in the middle core can be practically taken as a basis. It is proposed to use the method of concentrated heat capacities for the analysis of cable heating by overload current, which allows to significantly reduce the test time in production conditions. The study aims to create a method for determining the allowable current of medium voltage cables in specific operating conditions.

Study on the rule of blister formation and identification technology of multi-cores copper wires in fire

The common presence of the wire blisters in fire indicates that the wire was exposed to fire. Yet current overload happening before fire also causes some wire blisters. Most trace evidences on the wire from fire are required to examine melted blisters marks of the wire. Thus, it is critical to clearly identify and determine the differences between blisters merely exposure to fire and current overload for fire investigators. Two fire scenarios, fire heating and overcurrent, and 2.5 mm2 multi-cores copper wires were selected by this paper to make blisters. Then, the identification technology of blisters was studied. The experimental results suggested that the external appearance and metallographic structure taken on by blisters were not the precise evidences to identify whether blisters are merely exposed to fire or overcurrent. Therefore, the metallographical method of polarized light was used to analyse Cu2O content in blisters. Besides, such content was used to accurately identify two kinds of blisters. The content of Cu2O of the overcurrent blisters was larger than that of the fire heating blisters notably.

Increased Alexithymia But No Profound Emotion Processing Disorder in Burnout Syndrome.

Our objectives were to investigate alexithymia in burnout patients while controlling for depression and anxiety, as well as to evaluate whether alexithymia may be part of a profound emotional processing disorder or of a mentalization deficit. Alexithymia, depressive, and anxious feelings were compared in patients with burnout, depression, and healthy controls using an age-, sex-, and education-matched cross-sectional design (n = 60). A facial emotion recognition task and an emotional mentalizing performance test as well as physical and emotional violation experiences were conducted. Alexithymia was significantly increased in burnout patients, mediated by negative affect in this group. No impairment of facial emotion recognition or mental attribution could be shown. Burnout patients demonstrated slightly increased emotional abuse experiences in early childhood. The present results corroborate the supposition that alexithymia in burnout primarily depends on affect and may rise due to current strain and overload experience, rather than based on a profound developmental disorder in emotion processing.

Experimental study of flame spread over PE‐insulated single copper core wire under varying pressure and electric current

SummaryIn this study, the flame spread over a thin wire with overload current (0‐16 A) has been experimentally investigated at both normal pressure (Hefei: altitude 50 m, 100 kPa) and reduced pressure (Lijiang: altitude 2400 m, 76 kPa; Lhasa: altitude 3650 m, 64 kPa). Polyethylene‐insulated single‐core wires, comprising Cu as the inner core of diameter 0.30, 0.50, and 0.80 mm and insulation thickness 0.15 and 0.30 mm, are used as samples. The experimental results clearly indicate that the height of the flame increases with the electric current and ambient pressure, but the flame width changes only slightly. At identical conditions, the finer the wire, the faster the flame spreads. The flame spread rate increases with the electric current and ambient pressure. A simplified thermal balance analysis concerning the load current is developed to calculate the flame spread rate, and the calculated flame spread rates are shown to be fairly consistent with the experimental values at different electric currents for different wires at both ambient pressures. In addition, the coupled effect of electric current and ambient pressure on the flame spread is discussed. These results may be meaningful for promoting the research process of wire fire safety.

ПРИМЕНЕНИЕ САМОВОССТАНАВЛИВАЮЩИХСЯ ПРЕДОХРАНИТЕЛЕЙ «POLYSWITCH» ДЛЯ ПРЕДОТВРАЩЕНИЯ ТОКОВЫХ ПЕРЕГРУЗОК В ФОТО-ЭЛЕКТРИЧЕСКИХ СИСТЕМАХ

Актуальность. Имеющиеся на настоящий момент результаты моделирования и экспериментальные данные свидетельствуют, что обводные диоды в подпанельных строках фотоэлектрических элементов не полностью защищают от появления «горячих пятен». Обводные диоды более эффективны для предотвращения «горячих пятен» при очень коротких длинах строк ФЭП, что не применяется в современной конструкции панелей из экономических соображений. Поэтому необходимо повышения надежности солнечных батарей, включая устранение нештатных (пожароопасных) ситуаций на основе разработки методов и средств предотвращения токовых перегрузок в их фотоэлектрических системах на основе новых подходов.
 Цель. Разработка универсального подхода для минимизации токовых перегрузок в фотоэлектрических системах солнечных батарей путем применения недорогостоящих элементов функциональной электроники, в частности, относительно новых и, получивших широкое распространение, самовосстанавливающихся предохранителей типа “Polyswith”.
 Метод. Предложено схемное решение и методом моделирования обоснованы возможности использования предохранителей типа Polyswitch для предотвращения и минимизации токовых перегрузок в фотоэлектрических системах солнечных батарей. 
 Результаты. Проанализировано влияние величины сопротивления в проводящем состоянии и тока срабатывания предохранителей на вольт-амперные и вольт-ваттные характеристики параллельных соединений фотоэлектрических преобразователей и их модулей.
 Разработана математическая модель схемного решения и проведено моделирование его основных характеристик при использовании типичных параметров фотоэлектрических преобразователей на основе монокристаллического кремния и коммерческих самовосстанавливающихся предохранителей. Проанализировано влияние величины сопротивления в проводящем состоянии и тока срабатывания СВП на ВАХ и ВВХ параллельного соединения фотоэлектрических компонентов солнечных батарей.
 Выводы. Показано, что эффективное ограничение тока при наличии короткого замыкания при таком соединении фотоэлектрических компонент может быть реализовано при выполнении следующих условий:
 – сопротивление предохранителя в проводящем состоянии значительно меньше параллельного соединения последовательных сопротивлений фотоэлектрических компонент;
 – ток срабатывания предохранителя должен быть больше тока короткого замыкания отдельного фотоэлектрического компонента и меньше тока их параллельного соединения. Библ. 26, рис. 5, табл. 1.

Cпособ двухзонного регулирования скорости вентильного двигателя

The aim of the study involved the development of a dual-zone speed control method for a permanent magnet inverted motor applied as a drive for various machines and mechanisms of cyclic action or positional type. In the study, modelling methods were applied based on the contemporary theory of electric drives (using Gorev-Park equations) accompanied by methods derived from classic control theory. As a result, the dual-zone speed control method for an inverted motor was developed based on a previously tested single-circuit control system applicable for speed values below synchronous with full compensation of the stator current along the d longitudinal axis. A method is described for controlling the speed of the value of the stator current superior to synchronous due to incomplete compensation (specified by the coefficient) along the longitudinal axis. A nonlinear model of an inverted motor (based on the Gorev-Park equations) was developed to support a study of its functioning modes at speeds both higher and lower than synchronous. For an engine with specified parameters, the modelling included starting and braking modes, smooth transitions from one speed to another (by selecting the setpoint changing speed), as well as abrupt drops and increases in the load. For the control, a single-circuit control system with a proportional integral differential controller was used. The developed model ensures the selection of the necessary pattern for voltage change along the q transverse axis of the studied motor stator, thus preventing the current overload of the frequency converter during the motor operation both above and below the synchronous speed. Dynamic modes of the "frequency converter - inverted motor" closed-loop system were investigated in the Simulink environment of the Matlab package. The obtained equations of static modes support a determination of the restrictions on speed and torque for two versions of the drive. Thus, the developed inverted motor control system is simpler than the classic dual-circuit system that lacks frequency converter disconnection during overloads.