Electrical Engineering and Power Engineering

Slip modes modeling of electric vehicle asynchronous electric drive

S.O. Senchenko — 2024-04-24

Purpose. Creation a computer model of electric drive of an electric vehicle with the possibility of modeling in slippage modes, as well as the subsequent determination of slippage detection method as early as possible to further reducing or preventing slippage.

Methodology. Mathematical analysis and modeling.

Findings. Mathematical models in the structural form of the control system, power converter and motor are added in a simplified way, as the blocks. For compiling a computer model, the blocks of the control system and the power converter will be assembled using models of elements of power electric circuits. The model allows the ED simulation with a huge number of parameters varying – modeling slipping processes with one or two wheels, a sharp change in engine parameters, failure of one of the components of the power circuit, etc. Using the Simulink and SimPower packages of the Matlab software package, as well as the block diagram of the electric drive, a computer model of the ED was synthesized. Computer simulation of dynamic processes in the electric drive during a collision, as well as pulling away on the road surface with a reduced coefficient of friction, was carried out. The obtained diagrams fully correspond to the real physical processes occurring in the electric vehicle and give reason to believe that the constructed mathematical and computer models are adequate. Proceeding from this, electromechanical transients in the electric drive during acceleration with slipping and one wheel runover a road surface with reduced traction were obtained and analyzed. As a result of this analysis, the most optimal and reliable way to determine the skidding mode for its further elimination was determined.

Originality. Computer model of the asynchronous electric drive of an electric vehicle with a detailed mechanical part, taking into account the mechanical differential gear, was built. The model allows the ED simulation with a huge number of parameters varying – modeling slipping processes with one or two wheels, a sharp change in engine parameters, failure of one of the components of the power circuit, etc.

Practical value. Computer simulation was carried out for two modes: start of electric vehicle movement , when one of the wheels has been of on the road surface with a reduced coefficient of adhesion (0,1) since launch and acceleration with a collision with a surface with a reduced coefficient of adhesion (0,1) with one wheel at the moment of time of 6.3 s.

Investigation of electromagnetic processes in the case of static eccentricity of a two-pole induction motor with a short-circuited rotor

I.M. Kotsur — 2024-04-24

Purpose. Correction of the mathematical model of electromagnetic processes in a two-pole induction motor with a short-circuited rotor, taking into account static rotor eccentricity to identify diagnostic correlations.

Methodology. Analytical modeling using the method of specific magnetic conductivity, mathematical modeling of electromagnetic fields in a three-phase induction motor with a short-circuited rotor using methods of electromagnetic field theory and finite element methods.

Obtained results. The necessity of improving mathematical models for induction motors with short-circuited rotors to establish new or refine connections between diagnostic features and diagnosed defects has been demonstrated. Refined mathematical expressions for calculating the specific conductivity of non-uniform air gaps in induction motors with static eccentricity are provided. Modeling was performed using the FEMM environment for a statically eccentric two-pole induction motor with a short-circuited rotor. It has been proven that the harmonic order values obtained using the numerical-field method are consistent with those obtained analytically.

Findings. Based on the field approach and using the finite elements method, an analysis of the distribution of magnetic field in a two-pole induction motor with a short-circuited rotor was conducted. Harmonic analysis of the magnetic field in the air gap was performed to identify the fundamental harmonic and higher and lower-order harmonics when eccentricity occurs. The influence of static rotor eccentricity on the electromagnetic processes of the induction motor was analyzed.

Practical value. The results of the study can be utilized for functional diagnosis of the rotor winding of induction motors based on the radial component of the magnetic field. This will contribute to enhancing the reliability of induction motors and enable the prevention of failure in induction motors with short-circuited rotors.

To the question of construction of welding inverter sources with a high power factor

O.S. Savenko — 2024-04-24

Purpose. Design a power-factor-corrected, energy- and cost-efficient switchmode power supply for welding.

Methodology. It is proposed to use the principle of direct conversion and to develop the "hybrid" power circuit consisting of a main power path using direct conversion and an auxiliary power path having a converter with an intermediate DC link with relatively low stored energy. Since a load to the welding power supply is the welding arc, its instantaneous power fluctuations during the mains voltage period essentially do not influence the welding process due to the thermal constant of the weld pool molten metal. Effective use of this features of the welding arc allows to optimize the power processing, reduce the amount of energy stored in the reactive elements of the circuit and improve the economical, mass and dimensional parameters of the supplies.

Findings. A new power factor corrected switchmode power supply topology is proposed utilizing beforementioned principles of power processing. The algorithm for calculating the switching frequency of supply power switches is given. To confirm the adequacy of the developed provisions, an experimental sample of the power supply was created. Oscillograms of mains voltage and source current consumption and oscillograms in output current limitation mode are obtained. The results of experiments showed that the supply has a power factor > 0.94 in a wide range of powers.

Originality. A distinctive feature of the supply is the absence of additional inductive components in the power path, a lower capacitance of the DC-link bulk capacitor and a simplified scheme for limiting its inrush current during initial charging. The supply has an increased open circuit voltage, independent of the mains voltage, which allows for easy arc ignition during manual arc welding.

Practical value. Due to the increased power factor, the current drawn from the mains is 30 % to 45 % lower than that of widespread inverter supplies without a power factor corrector. These features allow to simultaneously use more power supply units with the same mains current load, and/or to provide stable welding in conditions of a "weak" mains.

Use of criteria for process optimization elevator complex routing

M.P. Kundenko — 2024-04-24

The goal of the work. The purpose of this work is to describe the optimality criteria for determining the direction of solving the problem of optimizing transport and technological routes of grain products at the elevator complex.

Research methods. An analytical research method was applied to determine the technological characteristics of the elevator complex line and the dependence of the quality of transported products on the constructed transportation route. A mathematical method is applied to describe the constituent elements of the optimization criteria.

Obtained results. One of the directions for increasing and improving the technological process at the elevator was determined, by improving the control algorithms in the direction of optimizing the technological processes of the elevator according to many criteria. According to optimization criteria, to ensure optimal transportation conditions, minimum losses, minimum transportation time, minimum energy consumption, and minimum length of the laid transportation path should be used, therefore, a description of the main criteria that can primarily affect the efficiency of the elevator complex was performed.

Scientific news. The direction of solving the problem of optimization of transport and technological routes is determined. Analytical derivation of the minimum energy consumption criterion and the minimum grain fight criterion.

Practical value. Optimization of the elevator complex to ensure variable transportation of grain masses, which will affect the productivity and quality of the technological process of the elevator complex.

Renewal of the regression model for normalization of specific energy consumption

N.S. Dreshpak — 2024-04-24

Purpose. To develop a method of updating the regression model for the normalization of specific energy consumption in the presence of frequent and significant changes in the energy efficiency of the production process.

Methodology. Analysis of existing methods of updating regression models, comparison of their possibilities, and synthesis of the method of updating the model in conditions of frequent and significant changes in the energy efficiency of the production process.

Findings. It was established that in the presence of a significant number of possible variants of structural and mode changes in the energy consumption of the control object, the introduction of associated variables into the regression model is problematic, as it requires an increase in the number of experimental data in conditions of their expected heterogeneity. The flaw of the well-known regression model for normalizing the power consumption of the object of control is revealed, which consists of the fact that the model does not take into account the last values in the sequence of their appearance of experimental data obtained in the process of energy efficiency control. This reduces the accuracy of predicted energy consumption values. It is proposed to update the regression model every time after performing the energy efficiency control and sample adjustment. Adjustments are implemented by checking the homogeneity of the obtained experimental data, followed by their addition to the elements of the existing sample and removal (if necessary) from the sample of outdated data. The defined sequence of adjustment of the initial data allows timely updating of the model and implementation of the forecast of specific energy consumption, entering data reflecting the latest changes that occurred in the facility's energy supply. The proposed method of updating the model implements the approximation in time of the moment of energy efficiency control to the moment of obtaining experimental data for building a regression dependence for normalizing energy consumption values. This helps to increase the accuracy of the forecast of normalized values. A significant change in the conditions of production of products with a violation of the homogeneity of data is accompanied by a transition to the transitional mode of adjustment, where it is proposed to reduce the number of elements of the existing sample, ensuring the sequential removal of the elements furthest from the next moment of control. Extraction continues until data homogeneity is achieved. During the daily control of the efficiency of electricity consumption, the change in the values of the regression model coefficients in the process of its renewal reflects the changes in the object's electricity consumption that occurred over the last day. This allows you to separate their impact from the impact of changes that occurred earlier and to assess the level of this impact.

Originality. For the first time, the shortcomings of the existing methods of updating regression models in the conditions of frequent and significant changes in the energy efficiency of the production process were identified. A method of updating the model under these conditions has been developed, which involves adjusting the sample of experimental data by changing the number of its elements and checking the homogeneity of the data.

Practical value is that the sequence of actions during the implementation of the developed method of updating the regression model is defined, which allows for an increase in the accuracy of calculating the normalized values of specific energy consumption.

Green energy as a key element of the implementation of the concept of distributed generation

D.O. Danylchenko — 2024-04-24

Purpose. The purpose of this article is to study the role of "Green energy" in the concept of generation distribution, to analyze the contribution of renewable sources to the stability of energy. The main tasks include improving models of electric photo panels and wind generators to achieve environmental and economic efficiency.

Methodology. Mathematical modeling of photovoltaic panels and wind generators, analysis of the effect of the precision factor and the efficiency factor of the inverter on power generation. A comparative analysis of the obtained results with real data is used to validate the models. The aerodynamic characteristics of the wind generator and the influence on the output power are studied. An optimized model for forecasting the efficiency of hybrid systems using green technologies is being developed.

Findings. The obtained research results reveal the key contribution of "Green Energy" to the concept of distributed generation. The methods of mathematical model panels and the use of photovoltaic generators, together with the application of the current coefficient and taking into account the efficiency of the inverter, made it possible to increase the accuracy of forecasting electricity generation. The developed model takes into account the aerodynamic characteristics of the wind generator, emphasizing the realized possibility of exceeding the nominal power in accordance with the real characteristics. The obtained results are compared with real data for validation and confirmation of the effectiveness of the system.

Originality. It consists in improving the model of photovoltaic panels, taking into account the influence of the inverter and the aerodynamic features of the wind generator. The work found that the largest generation of wind generators on earth is from October to February, indicating the advantage of combining solar and wind energy.

Practical value. It consists in optimizing the forecasting of electricity generation in hybrid systems, which determined the increase in accuracy and adaptability to real conditions. Your study represents the potential for the development of "Green Energy" in communities with a large area and medium capacity.