Voltage Shape Research Articles

MATHEMATICAL MODEL OF A VOLTAIC SOLAR POWER PLANT

In many countries, including Armenia.Solar power plants, are constructed according to the scheme of voltaic solar power plants that directly convert solar energy into electrical energy. The schemes and methods of research and calculation of such solar power plants are not sufficiently developed. That is solution to these issues is relevant. Mathematical models and software and computing complexes are effective tools for research and calculation. The developed schemes and mathematical model of a voltaic power plant based on a voltage inverter and a resonant parallel-series filter operating in parallel with the network are presented. The intensity of solar radiation is an argument for the processes taking place and, with the existing approach, is expressed by the magnitude of the generated direct current. Voltage and power are considered derived quantities. In the schemes and mathematical model, a transformation is performed in which solar panels are presented as a voltage source, where the independent variable is voltage, which linearly depends on solar radiation, and the function is the generated current and load power. Using the model, the following was studied: ensuring a sinusoidal shape of the output voltage, the frequency spectra and distortion coefficients of the output voltage shape were calculated, the functions of the transient process when connecting a solar power plant to the network, the load characteristics of the generation and transmission of active and reactive power to the network were determined. The developed mathematical model of a voltaic solar power plant is an adequate tool for research and calculation of power plant parameters. Studies conducted on the model confirm the possibility of generating and transmitting active and reactive power to the network, linearly related to the intensity of solar radiation, while ensuring the sinusoidal shape of the output voltage and satisfactory quality of the transient process. To increase the overloadability, stability and controllability of power (both active and reactive) of voltaic solar inverter power plants, it is advisable to use buffer batteries at the inverter input and/or synchronous compensators at the inverter output, as well as parallel operating synchronous generators of traditional power plants with low communication resistances.

ПОВЫШЕНИЕ ЭНЕРГОЭФФЕКТИВНОСТИ АСИНХРОННОЙ ЭЛЕКТРИЧЕСКОЙ МАШИНЫ ЗА СЧЕТ ОПТИМИЗАЦИИ УДЕЛЬНЫХ ПОКАЗАТЕЛЕЙ

The role of the electric motor in industry is clearly high. However, speaking about complex mechanisms, the use of elec-tromechanical converters of a specific series is impractical due to low energy efficiency. In the technical literature, electric drives used the term “registered” electric machines, i.e. machines manufactured for a specific technological mechanism, for example, the nominal motor of the main drive of the 5000 MMK mill (the installed power of one motor is 12 MW). The most common type is asynchronous due to its obvious advantages. The development of semiconductor technology makes it possible to expand the scope of regulation and control of IM, which in turn changes the vector in the production of elec-trical machines. The main idea is to create the most energy-efficient electric motor by changing the geometry of the stator and rotor, voltage shape, number of phases, number of poles, etc. Thus, to implement the existing idea, it is necessary to study the region of magnetic field formation by using parametric optimization and achieving the maximum root-mean-square torque.

МЕТОДИКА ВЫБОРА ПАРАМЕТРОВ ПАССИВНОГО ФИЛЬТРА ДЛЯ ПОВЫШЕНИЯ КАЧЕСТВА ЭЛЕКТРОЭНЕРГИИ В ЭЛЕКТРИЧЕСКИХ СЕТЯХ С АКТИВНЫМИ ВЫПРЯМИТЕЛЯМИ

The relevance Due to the wide spread of compact metallurgical plants, which use powerful drives with frequency converters with active rectifiers (FC-AR), an urgent task has become the fight against resonant phenomena in medium voltage electrical networks, since these converters, despite their significant advantages, have a disadvantage — the deterioration of the quality of electricity in the power supply system 6–35 kV. Existing methods of dealing with resonant phenomena in medium voltage electrical networks, in which non-linear elements are present, such as powerful drives of rolling mills with FC-AR used in power supply systems of metallurgical enterprises, do not always allow changing the situation for the better. One way to solve this problem is to use classic traditional filters. Often, the use of traditional filters to eliminate strong voltage distortions in sections of 6–35 kV does not have the desired effect. The installation of traditional filters is accompanied by additional parasitic current resonances, which amplify the intermediate harmonics. These harmonics multiply the oscillations and strongly distort the voltage shape when the frequency response of the distribution network is superimposed with the region of high-frequency harmonics generated by modern FC-AR. Aim of research The article is devoted to the issues of improving the electromagnetic compatibility (EMC) of FC-AR as part of electric drives of rolling mill stands with an internal power supply system for metallurgical plants in the presence of resonant phenomena through the use of specialized passive filters (SPF). Research methods Methods of theoretical and experimental researches are applied in the work. When studying the causes of the occurrence of resonant phenomena, experimental data obtained in the course of research work at the metallurgical plant JSC Metallurgical Plant Balakovo were used. For the processing of experimental data, mathematical modeling methods were used in the Matlab environment with the Simulink application. Results The significance of the results of the work lies in improving the quality of electricity in the distribution electrical networks of mini-plants with FC-AR in the presence of resonant phenomena in the frequency response of the network through the use of SPF. The implementation of the results of the work is an improvement in quality indicators and, as a result, an increase in the reliability of the operation of all power converters in the internal power supply system and a decrease in emergency situations associated with the failure of power elements. The results of the work were implemented at the metallurgical plant of JSC Metallurgical Plant Balakovo. The quantitative indicator of the technical effect of changing the level of the coefficient of the total harmonic components of the voltage in the general sections of the factory GPP КU is: 1) without the use of SPF КU = 10.26 %; 2) when using SPF КU = 1.42 % (relative change δ КU = –72 %). These results can be used at other compact metallurgical enterprises with extended cable lines of medium voltage 6–35 kV and powerful electric drives with FC-AR.

Application of fuzzy sliding mode control on a single-stage grid-connected PV system based on the voltage-oriented control strategy

Due to the increasing costs of components and the complexity of controlling the production of PV systems on the one hand, and the quality of the energy produced and the connection to the grid on the other. This work describes how the optimal operation and cost minimization of a grid-connected PV system via the single-stage structure (without a DC-DC converter) can be achieved. Through the development of control algorithms, the extraction of the maximum power from the solar panel has been achieved by fuzzy sliding mode control (FSMC). The main development of this proposed technique is to combine the advantages of fuzzy logic and sliding mode in an algorithm that directly controls the inverter to track the maximum power point and to keep good control of the voltage Vmp used as a reference voltage at the input of the inverter control (VOC) for maximum power point extraction and to properly control their switches. Therefore, the latter acts on the voltage and current shapes of the system and allows decreasing the harmonic distortion rate. These current and voltage shapes facilitate the design of a less complex filter, in order to obtain a well-controlled active and reactive power with reduced cost. The simulation results are obtained in the MATLAB-Simulink environment.

Direct comparison of silicon carbide and silicon diode avalanche shaper in multi-pulse applications

This paper compares the pulse shaping characteristics of SiC and Si Diode Avalanche Shaper (DAS) under quasi-uniform triggering with the help of Technology Computer-Aided Design (TCAD) software. Under the same static breakdown voltage (VSB), the opening speed of SiC DAS does not show obvious advantages over that of Si DAS. With the same device structure, SiC DAS has a higher breakdown voltage than Si DAS, so it has a faster dV/dt in the triggering process. In addition, compared to Si, SiC DAS delayed breakdown voltage (VDB) is less affected by the input pulse rise rate. This is because the SiC DAS avalanche generation rate is more sensitive to the device voltage in the vicinity of VDB. Then, the multi-pulse operating characteristics of SiC and Si DAS with the same VSB were compared by continuously triggering the SiC and Si DAS 50 times at the 1 MHz frequency. It is revealed that the VDB of the SiC DAS is low but has excellent multi-pulse consistency. At the same time, under multi-pulse operation, the temperature rise speed of SiC DAS is slow, and the temperature distribution in the device is more uniform. It can be concluded that SiC DAS has significant advantages in high voltage and multi-pulse shaping.

CT scanner-specific organ dose coefficients generated by Monte Carlo calculation for the ICRP adult male and female reference computational phantoms

Objective. Provide analyses of new organ dose coefficients (hereafter also referred to as normalized doses) for CT that have been developed to update the widely-utilized collection of data published 30 years ago in NRPB-SR250. Approach. In order to reflect changes in technology, and also ICRP recommendations concerning use of the computational phantoms adult male (AM) and adult female (AF), 102 series of new Monte Carlo simulations have been performed covering the range of operating conditions for 12 contemporary models of CT scanner from 4 manufacturers. Normalized doses (relative to free air on axis) have been determined for 39 organs, and for every 8 mm or 4.84 mm slab of AM and AF, respectively. Main results. Analyses of results confirm the significant influence (by up to a few tens of percent), on values of normalized organ (or contributions to effective dose (E 103,phan)), for whole body exposure arising from selection of tube voltage and beam shaping filter. Use of partial (when available) rather than a Full fan beam reduced both organ and effective dose by up to 7%. Normalized doses to AF were larger than corresponding figures for AM by up to 30% for organs and by 10% for E 103,phan. Additional simulations for whole body exposure have also demonstrated that: practical simplifications in the main modelling (point source, single slice thickness, neglect of patient couch and immobility of phantom arms) have sufficiently small (<5%) effect on E 103,phan; mis-centring of the phantom away from the axis of rotation by 5 mm (in any direction) leads to changes in normalized organ dose and E 103,phan by up to 20% and 6%, respectively; and angular tube current modulation can result in reductions by up to 35% and <15% in normalized organ dose and E 103,phan, respectively, for 100% cosine variation. Significance. These analyses help advance understanding of the influence of operational scanner settings on organ dose coefficients for contemporary CT, in support of improved patient protection. The results will allow the future development of a new dose estimation tool.

Designing and Manufacturing a Single-Phase Transformer and Analyzing Its Performance

Aims: This work aims to design a single-phase transformer for analyzing its performance based on some requirements.&#x0D; Study Design: At first, requirements are set, then the design was completed using AutoCAD, after that the designed machine was simulated in MATLAB Simulink, manufactured in real-time in the laboratory, tested experimentally, and then the equivalent circuit parameters were computed from the experimental data.&#x0D; Place and Duration of Study: The design, manufacturing, simulation, and performance testing were conducted in the electrical machine 1 laboratory of American International University-Bangladesh (AIUB). It took around four months to complete the whole task.&#x0D; Methodology: This work is a bit expensive and complicated process for students without any funds. So, a group was formed with eight students. The tasks were to design, simulate, implement, and test a single-phase transformer that would step down 220 V (ac) to 110 V (ac) having a 440 VA capacity, and core loss should not exceed 5 W.&#x0D; Results: MATLAB Simulink was used to simulate the designed transformer to get the primary and secondary winding voltage and current wave shapes that were confirmed by the experimental results. Open and short circuit tests indicate that loss is only between 5 W and 8 W respectively. The total design cost is only BDTK1, 270.&#x0D; Conclusion: The results satisfied the design and performance parameter requirements and the designed transformer worked very well. The design cost was also kept minimum.

Control and Performance of 240-Clamped Space Vector PWM in Three-Phase Grid-Connected Photovoltaic Converters Under Adverse Grid Conditions

This article evaluates the performance of a relatively new pulsewidth modulation (PWM) method i.e., 240 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^\circ$</tex-math></inline-formula> -clamped space vector PWM (240CPWM), in three-phase grid-connected photovoltaic (PV) converters under various grid voltage conditions. 240CPWM is a minimum switching loss PWM method that reduces the switching loss by 85% at unity power factor and has better total harmonic distortion (THD) as compared to conventional space vector PWM. A unique six-pulse dynamically varying dc-link voltage is required for 240CPWM. Typically, a three-phase grid-connected PV system consists of a dc–dc stage followed by a dc–ac stage. In this article, the dc–dc stage is operated in closed-loop control to shape the dynamic dc-link voltage required for 240CPWM. The dc–ac stage is operated in the current control mode using a proportional–integral controller along with a harmonic compensator to ensure sinusoidal grid currents along with maximum power point tracking. The modulation index of the dc–ac stage is uncontrolled and fixed at the maximum value, and the primary control mechanism changes the magnitude, phase, and wave shape of the dc-link voltage. The coordinated control of dc–dc and dc–ac stages is ensured for better dynamic performance and grid support functions. Finally, the performance of the grid-connected PV converter with 240CPWM is validated using a three-phase 3-kW 208-V hardware prototype under nonunity power factors, voltage unbalance, and voltage sag/swell conditions for the first time. The implemented control with 240CPWM achieves smooth operation under nonunity power factor and grid voltage disturbance conditions with THD as low as 3.5% and peak combined efficiency of dc–dc and dc–ac stages as 96.4%.

Progress on research of construction of carbon nanotubes/carbon fiber cross-scale interface enhancement systems

<p indent="0mm">Carbon fiber reinforced composites (CFRP) have a broad application prospect in aerospace, military equipment and other fields because of their many excellent properties such as high strength and stability. However, the inert surface structure of carbon fiber (CF) seriously affects the load transfer efficiency with the matrix, which hinders the full play of the excellent performance of the composites. Therefore, the optimization and design of the interfacial structure between the two phases has become a hot research topic. Carbon nanotubes (CNTs) with excellent mechanical properties were deposited on the surface of CF to form a three-dimensional network hybrid structure with multiple orders of magnitude, thereby improving the interfacial bonding ability between the CF and the matrix. This paper introduces four process routes for the construction of cross-scale enhancement systems, including chemical vapor deposition (CVD), electrophoretic deposition (EPD), chemical grafting and dip-coating spraying process. The advantages, limitations and key process parameters of each method are summarized. The study of CVD method focuses on the influence of process parameters such as catalysts (type, morphology, concentration), growth time, treatment temperature, carbon source and carrier gas (type, mixing ratio, inlet speed) on the growth morphology (length, density, thickness) of CNTs. This method achieves the direct directional growth of CNTs on the CF surface, but the CF is affected by the pre-activation treatment, metal catalyst etching, and high-temperature environment, which leads to a significant decrease in its own strength. In the EPD method, the adjustment of key process parameters (applied voltage, energization time, electrode distance, and electrode shape) becomes the key to successful application of the EPD method. Although the EPD method is capable of producing textured CNT coatings or thin films on the CF, the weak van der Waals force bonding form and the “disorder” of deposition are the main pain points of this method. In the chemical grafting process, the reaction between multiple reactive functional groups and the use of macromolecular coupling agents provide a more diversified preparation scheme, and the bonding strength between CNTs and CF is greatly enhanced by chemical bonding. The construction of CNTs/CF interfacially enhanced structures, using two different processes, surface dip coating and spraying, is considered to be simple and effective, and the degree of dispersion of CNTs in sizing agents or different solvents becomes an important consideration for good deposition on the CF surface. Although the combination between CNTs and CF is not strong, the simple operation process and reasonable economic cost show a high suitability for industrialization. In this paper, three different attachment types of CNTs, namely radial embedding, random topology and surface attachment, are proposed in summary to investigate the stress transfer paths between the composite matrix and the form of interfacial enhancement. The three different attachment types contribute to the enhancement of the interface properties in different ways and to different degrees, with radially embedded structures contributing the most to the enhancement of the interface properties, vertically oriented CNTs significantly weakening the radial stresses between the CF and the matrix, and surface-applied CNTs suppressing the shear stresses more significantly than the radial stresses. Finally, the application of the CNTs/CF cross-scale interfacial reinforcement system in composites is explored, resulting in CFRP exhibiting superior properties in a number of ways, but only in terms of the mechanical properties of the system, which are exploited. Therefore, the development and application of multi-functional materials such as heat and electricity, as well as the preparation of high efficiency, high quality and low cost CNTs/CF/matrix three-phase composites will be the main development direction in the field of nano-reinforced CF composites in the future.

An optimal deep learning based Islanding power quality detection technique for distributed generation systems

Power quality disturbance (PQD) defines the presence of inconsistencies that occur in the usual wave shapes of voltage and current signals. Power quality is considered the main challenge for power industry with the increase in dynamic load and highly subtle electronic devices. Besides, the islanding events, particularly unintended islanding, grasp significant challenges and it needs to be identified at the early stage. Islanding is an anomalousstate in the power system, where the distributed generators (DGs) are placed on supplying electrical energy to the local load even after the shortage of the major grid. Therefore, it is essential to identify and differentiate the PQ events and islanding events in ensuring pollution-free power, equipment, and labor safety. With this motivation, this paper presents an automated optimal deep learning based islanding detection (AODL-ID) technique. The proposed AODL-ID technique involves three major stages namely decomposition, classification, and hyperparameter tuning. Firstly, an empirical mode decomposition (EMD) approach is utilized to decompose the basic signals from the polluted signals. In addition, bidirectional gated recurrent neural network (BiGRNN) technique is employed for the classification of islanding and non-islanding PQ events in the wind energy penetrated DG systems by means of features (Voltage and current (RMS, half-cycle, peak and fundamental) Frequency. Power Factor / Cos Phi. Power and energy (active, reactive, harmonic, apparent)). Since the hyperparameters play a significant role in overall classification performance, the hyperparameter tuning of the BiGRNN model takes place using chaotic crow search algorithm (CCSA). To examine the enhanced classification outcome of the AODL-ID technique, a set of experimental analyses is carried out and the outcomes are investigated interms of various evaluation metrics. The simulation outcomes highlighted the supremacy of the AODL-ID technique over the compared techniques.

CONTROL OF WORKING BODY OF AIRBORNE AIRCRAFT POSITIONING MECHANISMS BY MEANS OF STEPPER MOTOR IN STEP CRUSHING MODE

Step splitting control mode of the electric drives stepper motors working bodies of the positioning mechanisms of onboard aviation equipment is carried out by means of programmable controllers. From their output signals, pulse-wide signals are formed by means of drivers that control power transistors, which are included in the windings of a stepper motor.&#x0D; A simpler version of building control systems for stepper motors (SM) involves the use of programmable timers, which requires its reprogramming when changing the step splitting factor.&#x0D; In the process of step splitting the shape of the current in the winding of the SM approaches sinusoidal with an increase in the number of sine discretes stored in the controller's memory. However, in this case, the sine samples must follow at a higher frequency, which difficulties in programming them.&#x0D; There is a problem of finding new ways of programming in the controller's memory information about the changing shape of the supply voltage SM in the process of step splitting in order to ensure the maximum speed of the code and the minimum consumption of the processor time of the microcontroller.&#x0D; To solve this problem, it is proposed to specify information about the changing shape of the SM supply voltage not in the form of sine samples (table method), but the sum of the coefficients of the Walsh-Fourier series, the amplitudes of which depend of value of the step splitting factor.&#x0D; The Walsh-Fourier series is a natural basis for approximating the pulsed supply voltage of a stepper motor. Structural diagrams of digital and analog systems for stepper motors in the step splitting are proposed.&#x0D; In the digital control system, the Walsh matrix is entered into the permanent memory of the controller, the size of which is determined by the value of the minimum step splitting factor, and the column vectors of the coefficients of the amplitudes of the Walsh functions are entered into the random-access memory, each of which corresponds to its step splitting factor.&#x0D; The input controller sets the program for implementing the inverse Walsh transform to the control controller, as a result of which control signals for the driver are generated at the output of the DAC controller. As its output, control signals are generated for power transistors including in the windings of the stepper motor.&#x0D; In the analog control system, the main links are the Walsh functions generator and the block of summing coefficients. In the block of summing coefficients of each Walsh function is assigned an amplitude corresponding to a given step splitting factor, and then they are summed. As a result, a pulsed voltage is formed, which is fed to the input of the driver, as in a digital system. It is shown that an analog control system can be used to form low-frequency quasi- sine signals of high stability. They can be used in precision electric drives with high stability.

An Interleaved PFC Boost Converter With Soft Commutations and Voltage Follower Characteristics

This article presents an interleaved boost rectifier for power factor correction (PFC) that operate in the continuous conduction mode and is grounded on the switching cell with switching frequency modulation. The input current naturally follows the shape of the input voltage, which is a resistive input characteristic (voltage follower). In the proposed converter, only one output voltage control loop is required. Moreover, the proposed topology has a wide range of soft commutation and no reverse recovery when the diodes block. This article presents the operating principle, a mathematical analysis of the converter, and four topological variations. In addition, experimental results of a 1-kW rectifier prototype with four different switch technologies [ <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">MOSFET</small> , high voltage superjunction <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">MOSFET</small> (CoolMOS), silicon carbide (SiC), and insulated gate bipolar transistor (IGBT)], are discussed and their operational characteristics are demonstrated.

Self-Balanced Multilevel Inverter With Hybrid Double- and Half-Mode Switched Capacitor

Two 17-level inverters based on switched capacitor (SC) are presented in this article. Each of them involves two SC units and a neutral-point-piloted unit. A total of four pairs of transistors, a bidirectional switch, two pairs of diodes, and three pairs of capacitors are employed. All of the switching components are controlled by six pulsewidth modulation signals and all capacitors’ voltages are self-balanced. With an improved selective harmonic eliminated modulation strategy, low-order harmonics are effectively suppressed and switches operate in low switching frequency. In addition to the use of fewer components, high-quality output voltage shape is benefited from the unique topology and reduced capacitor voltage ripple accumulation. Experiment results demonstrate the excellent performance of the proposed inverter. High efficiency is also achieved and the maximum value is up to 98.05%.

Sensorless torque and flux control of induction motor fed by photovoltaic system

This paper presents a new direct torque and flux control method for induction motor fed from Photovoltaic (PV) System. The proposed strategy is based on Stator Field Orientation with deadbeat torque and flux control. The deedbeat control approach is based on establishing the voltage vector necessary to supply the motor and reach the electromagnetic torque and flux references at the end of a sampling period T. In order to create the voltage shape and frequency to control the induction motor, the inverter is supplied by a DC voltage extracted from a PV system. Model Reference Adaptive System and Luenberger Observer are designed to determine the stator flux and rotor speed. Extensive simulation work was carried out, which demonstrated that the proposed strategy is capable of reducing the torque and flux ripples and maintaining a constant switching frequency.

Voltage Control of Three-Phase Stand-Alone Photovoltaic System Based on Improved DeadBeat Controller

Stand-Alone Photovoltaic systems (SAP) based on power electronics converters have found high attention, recently. According to the rate of power, three phase inverter is more applicable for high power applications. However, unbalanced loading condition is inevitable condition for these inverters. To prepare a current flow for inevitable fourth wire current, 4-Leg inverter is a beneficial solution. To sinusoidal load voltage shaping, the control method is very important since it must maintain three-phase balanced sinusoidal load voltages. Among different linear and non-linear control methods, deadbeat (DB) method offers high simplicity as well as good accordance for digital implementation. But, it suffers from two sampling period delay which deteriorate the load voltages quality and sometimes, results in instability of the control system. In this paper, new DB control method with delay compensation strategy is proposed which not only have the usual benefits of the DB control method but also, it overcomes the aforementioned weakness. Finally, a 3kW laboratory test bench based on DSP-Based digital control board is provided to consider the result of the proposed control methods. Several tests under various inverter loads such as no load, full linear load and 100% unbalanced load are done to evaluate the benefits of the proposed system.

ЭКСПЕРИМЕНТАЛЬНОЕ ИССЛЕДОВАНИЕ РАБОТОСПОСОБНОСТИ МЕТОДИКИ АДАПТИВНОЙ ИДЕНТИФИКАЦИИ ЭЛЕКТРИЧЕСКИХ ПАРАМЕТРОВ АСИНХРОННОЙ МАШИНЫ С РАЗОМКНУТОЙ ОБМОТКОЙ РОТОРА В УСТАНОВИВШЕМСЯ РЕЖИМЕ НА ОСНОВЕ БАЛАНСА МОЩНОСТЕЙ

Relevance For the operation of a closed-loop sensorless electric drive as part of an electrical complex, it is necessary to ensure adequate restoration of the vector of state variables of an induction motor using a customizable mathematical model in the control system. The accuracy of restoring the state variable vector depends on two factors. The first factor is the mathematical description of the substitution circuit of an asynchronous motor by a system of differential equations with certain assumptions that reliably reflects the physical processes occurring in an asynchronous motor. Used in the electric drive control system, T- and L-shaped equivaent circuits of an asynchronous motor, described by a system of differential equations in a customizable mathematical model, are universal and allow simulating the behavior of an asynchronous motor in all operating modes: «start», «load surge», «load shedding», «reverse», «stop», which is a sufficient condition for their use without modifications within the framework of this article. The second factor — the coefficients in the system of differential equations with some error correspond to the electrical parameters of the equivalent circuit of an asynchronous motor. In turn, the electrical parameters of the equivalent circuit of an asynchronous motor are unique for each motor and cannot be used in a system of differential equations without their refinement, i.e. no identification process. There are several types of identification of the electrical parameters of an induction motor: by the experience of idling and short circuit, by catalog data, by induction motor attenuation with a locked rotor of an induction motor, and others. The described methods for identifying parameters in most cases require the decommissioning of an asynchronous motor and conducting separate experimental studies, after which the electrical parameters in the equivalent circuit are considered constant and unchanged during operation. It is known that when an asynchronous motor is heated during operation, the active resistances of the stator and rotor circuits change. The inductance of the main magnetization circuit, stator and rotor circuits vary depending on the shape of the supply voltage and the operating modes of the asynchronous motor. Changing these parameters means that the restoration of the state variable vector will occur with a larger error. Given the above, the development of a methodology for adaptive identification of the electrical parameters of the equivalent circuit of an asynchronous motor during operation, without decommissioning and shutting down the entire electrical complex, is an urgent scientific and practically significant task. Aim of research Development and experimental study of a method for determining the electrical parameters of the stator winding in steady-state operation modes without decommissioning and stopping the electrical complex. Research methods Systems of nonlinear equations, iterative procedures, Newton's method, numerical methods, state space method, optimization methods. Results A method of adaptive identification of the electrical parameters of the stator winding replacement circuit in steady-state operation based on the power balance has developed and experimentally tested, which allows for accurate estimation of the parameters of the stator winding replacement circuit during induction motor operation. The developed technique in the future, with the expansion of the mathematical apparatus, will allow determining the parameters of both the stator and rotor windings of the induction motor when the electric drive is operating as part of an electrical complex. The practical application of open woundrotor induction motor is not possible, therefore this article is of a research nature and is intended only for experimental confirmation of the operation of the technique.

Управление нелинейными динамическими процессами трехфазных рекуперирующих преобразователей с пространственно-векторной модуляцией

A control system for nonlinear dynamic processes of threephase regenerative converters is considered. The system is built on the basis of the target-oriented control and allows to provide the desired dynamic mode without additional parametric synthesis. It eliminates the contradiction between the requirements for the switching frequency or the parameters of the transient process in the system and the requirements for the desired dynamic mode when the system parameters change over a wide range. A control system for nonlinear dynamic processes based on the method of directing to the purpose is proposed, that allows solving the specified problem. When implementing the system under consideration, it is assumed to evaluate the coordinates of fixed points of the desired mode based on measurements on a real control object with subsequent digital processing of the received signals in order to isolate the main harmonics. The simulation of the considered system and the efficiency of the proposed control system for nonlinear dynamic processes are performed. The proposed approach can be applied in other power conversion systems with low- frequency periodic impacts in conditions of lowfrequency distortion of the shape of currents or voltage as a result of bifurcations.

ИССЛЕДОВАНИЕ ВЛИЯНИЯ ХАРАКТЕРИСТИК ИЗЛУЧАТЕЛЬНЫХ ЭЛЕКТРОТЕХНОЛОГИЧЕСКИХ УСТАНОВОК С ПИТАНИЕМ ТОКОМ СЛОЖНОЙ ФОРМЫНА ТЕХНОЛОГИЧЕСКИЙ ПРОЦЕСС

Using the complex waveform current (CWC) in electrotechnological installations (ETI) with radiators of different types allows improving their energy efficiency. A review of the literature sources revealed the theoretical prerequisites for the use of CWC in ETI with infrared radiators. The research allowed us to obtain the energy characteristics of the ETI and radiators powered by CWC. It suggests the need for further research of the impact on the technological process. The expediency of regulating the shape and amplitude of the supply voltage (current) for ETI with radiators of different types and processed productswere proved. The results of the research allow us to develop recommendations on the choice of an automatic control system for the installation mode.

Определение потерь в стали бесконтактного двигателя постоянного тока с использованием линейной аппроксимации импульсов напряжения

Analysis of iron loss of a BLDC motor is of particular interest at the design stage or when researching methods to improve energy efficiency. Most of the existing methods for determining losses in steel are based on the analysis of losses for individual harmonic components of induction with their subsequent summation. However, the application of these methods for various forms of voltage obtained at the output of the converter is incorrect due to the non-linearity of magnetic circuits. This paper proposes a method for determining steel losses of BLDC motor using a linear approximation of voltage pulses, which makes it possible to take into account the influence of the voltage shape on the magnitude of magnetic induction directly, without expansion into a Fourier series. The dependences of steel losses on the switching frequency for various values of the duty cycle, and on the rise time of voltage pulses are obtained. Comparison of the simulation results of the 5 kW BLDC Motor with the experimental data of the idling mode given by the manufacturer proved the adequacy of the considered method.

Innovative Construction of the AFPM-Type Electric Machine and the Method for Estimation of Its Performance Parameters on the Basis of the Induction Voltage Shape

The article presents an innovative construction of the Axial Flux Permanent Magnet (AFPM) machine designed for generator performance, which provides the shape of induced voltage that enables estimation of the speed and rotational angle of the machine rotor. Design solutions were proposed, the aim of which is to limit energy losses as a result of the occurrence of eddy currents. The method of direct estimation of the value of the rotational speed and rotational angle of the machine rotor was proposed and investigated on the basis of the measurements of induced voltages and machine phase currents. The advantage of the machine is the utilization of simple and easy-to-use computational procedures. The acquired results were compared with the results obtained for estimation performed by using the Unscented Kalman Filter (UKF).