EMF Calculations Research Articles

Бездатчиковая система управления высокочастотным синхронным двигателем с инкорпорированными магнитами на основе комбинированного способа оценки положения

The known methods to estimate the position in drives based on synchronous motors with incorporated magnets have significant limitations in accuracy and noise immunity at high frequencies of the main voltage harmonic. Due to the requirements to improve the weight, size, and cost indicators of electric drives, it is relevant to design a sensorless synchronous drive operating with frequencies from 0 to 1000 Hz and more in the presence of a wide 5…10:1 speed control zone with a constant nominal power. The results of the study are based on the analysis of theoretical and experimental data obtained by other authors, as well as computer modeling in the Delphi software environment. The initial information for the simulation is obtained from the technical description guide and data of a full-scale experiment on a real-life object. A vector control system has been developed for a high-frequency synchronous motor with incorporated magnets without a mechanical coordinate sensor based on a combination of speed and position estimation methods by means of high-frequency injection and EMF calculation. The study of the developed system is carried out by means of modeling, considering the influence of interference in the measuring channels and the effect of cross-saturation of the magnetic circuit. The proposed structure and control algorithms have provided operability and high-quality control indicators sufficient to design a traction drive with a maximum frequency of 800 Hz or more and an area of operation in a constant rated power mode of at least 8:1 with a signal-to-noise ratio characteristic of typical current sensors.

Устройство компенсации провалов напряжения с накопителем энергии и функцией безударного перевода нагрузки

This work is devoted to the development of a simulation model of a voltage drop compensation device containing an electric energy storage device. The proposed control algorithm makes it possible to minimize the shock moment and the current surge of the motor when transferring the load in the event of an emergency. The control system considered in the work implements an algorithm for automatic phase matching of the EMF of the motor and the voltage of the inverter, which allows soft switching function transferring the load from one power source to another. In this case, the electric voltage angle of the inverter is phase-consistent with the decrease EMF of the motor. The calculation of EMF with the allocation of amplitude, phase and frequency is carried out with the help of an observer developed by the authors. As a result, a workable simulation model of a high-speed automatic reserve input device with an energy storage device was obtained. In conclusion, the authors cite transients that confirm the operability of the proposed approaches.

Fuzzy logic based dynamic performance enhancement of five phase induction motor under arbitrary open phase fault for electric vehicle

Abstract The multiphase induction motor can be a highly preferable choice for the EV application, where the reliability and safety of passengers are one of the major concerns. The main objective of this article is to design high performance fault tolerant control of five phase induction motor (FPIM) drive to enhance the dynamic performance under healthy, faulty and fault tolerant modes of operation under arbitrary open phase fault condition. First, a simple method of modeling open phase fault in any phase of the FPIM drive is proposed. The most frequently occurring open phase faults due to the power electronics switch failure in the inverters are considered for the analysis. A generalized method of modeling arbitrary open phase fault in FPIM drive using back EMF calculations in faulty phase is suggested. The developed method utilizes the same transformation matrix for any open phase fault such that the minimum modification in control strategy is required under fault condition. Thereafter, the control technique is detailed. The rotor field oriented control (RFOC) of FPIM with fuzzy logic speed controller is developed to generate optimal torque reference. The design of FLC is detailed with fine-tuned scaling factor, rule base and membership function to obtain robust performance of the drive under healthy and fault tolerant modes of operation. The complete RFOC scheme for 2 HP FPIM drive is built in MATLAB/SIMULINK incorporating fuzzy logic based controller to verify its performance. The comparison of transient and steady state response and robustness (to the load disturbance as well as fault) obtained using developed fuzzy logic based controller with those using conventional PI controller is presented to prove the efficiency of the suggested controller under various speed torque profiles. The effectiveness of the proposed fuzzy based fault tolerant controller for FPIM drive is validated using OP4510 controller based real time HIL simulator.

Comparison of electromagnetic fields emitted by typical overhead power line towers

The problem of electromagnetic fields produced by overhead power lines is still a widely discussed topic. These concerns itself are coming not only from the power line designers, but also from general public sector. Therefore, the topic can be separated into two different areas of interest: health concerns and technical problems. Conducted discussion and research regarding electromagnetic field’s health risks to general public led to creation of legislative time restrictions and absolute value limits for low-frequency electromagnetic fields. On the other hand, technical side of problem is mostly connected with electromagnetic induction in connection with surrounding objects around power lines. Still, precise calculations are needed for both of these areas of interest. The aim of this article is to carry an analysis comparing various electromagnetic fields emitted from basic types of power lines in 2D space. Comparison is made for the worst-case scenarios and for different sets of boundary conditions. The paper also shows the marginal difference of EMF generally emitted by EHV and HV systems. To achieve the most precise results, an integral–differential EMF calculation methodology is introduced and implemented into software interface. Final results are applicable in overhead lines design and planning process and are also suitable for future research of overhead power lines.

South African twelfth grade students’ conceptions regarding Electrochemistry

This current study explored twelfth-grade students' conceptions regarding electrochemistry in the Ximhungwe circuit of the Bohlabela district in the Mpumalanga province of South Africa. The sequential explanatory design was used to gather and analyse quantitative data first before gathering and analysing qualitative data for the current study. In the 2015 academic year, a sample of 10 twelfth-grade physical sciences students from four intact science public high schools was conveniently selected to participate in the current study after analysing the results of the quantitative data. Thirteen questions in which at least 30% of students showed misconceptions were selected for the interview. The result of the interviews indicated that students in the experimental group (EG) had more accurate concepts related to the function of the salt bridge in galvanic cells and the concept of electrical neutrality of anodes and cathodes compared to the control group (CG). Both the EG and the CG had the same viewpoints related to oxidation numbers, electrode potential, Emf calculations, and the identity of electrodes in galvanic cells and electrolytic cells when the placement of the electrodes was altered. However, students in both groups had limited knowledge about electrolytic cells, although the CG had more limited comprehension. It was recommended that educators teach concepts as much as they teach algorithms.

Permanent magnet brushless DC machines (PMBLDC) for general purpose - part II, results of laboratory measurements

The paper presents research on properties of the low power PMBLDC motor, designed to drive a bicycle. In the first part of the study the conditions of the torque generation were analyzed. The purpose of the article is to provide new information about PMBLDC motors and their properties. In the first part of the article the motor construction and torque generation in it were studied. Also the methodology of analysis were presented. The second part of the article will treat on the measurements and calculations of EMF, currents, voltages, and electromagnetic torque.

Permanent magnet brushless DC machines (PMBLDC) for general purpose – part I, the specificity of construction, methods of analysis

The paper presents research on properties of the low power PMBLDC motor, designed to drive a bicycle. In the first part of the study the conditions of the torque generation were analyzed. The purpose of the article is to provide new information about PMBLDC motors and their properties. In the first part of the article the motor construction and torque generation in it were studied. Also the methodology of analysis were presented. The second part of the article will treat on the measurements and calculations of EMF, currents, voltages, and electromagnetic torque.

The Influence of Downtilt of Antennae Directional Diagrams on the Formation of Mobile Network Cells and Estimation of Electromagnetic Field Intensity

The possibility of making use of antennas with continually adjustable mechanical and electrical downtilt of directional diagrams in the formation of mobile network cells has been presented in the paper. The quantitative evaluation of the changes in the intensity parameters of the electromagnetic fields generated by the antenna in the near environment has been made using mechanical and electrical downtilt of directional diagrams. Analytical EMF calculation method errors occurring due to inaccurate evaluation of antennas diagrams and their tilting on the vertical plane have been analysed. Ill.7, bibl.6 (in Lithuanian; summaries in Lithuanian, English and Russian).

Performance evaluation of Halbach magnetized linear generator for mobile apparatus

In this paper, the Halbach magnetized linear generator for charging the battery of a mobile apparatus is proposed and characteristics of the generator are investigated. Magnetic characteristics are analyzed by modified Space Harmonic Method and EMF calculation result is also included.

An approach to the shape optimum design of superconducting synchronous generator

A superconducting synchronous generator (SSG) is characterized by an air-cored machine with its rotor iron and stator iron teeth removed. For this reason, in the case of the shape optimum design of SSG, other design variables different from an iron-cored machine should be considered, which will lead to substantial improvement on the performance. The major design variables that are considered by using 3D finite element method (FEM) in this paper are: (1) field coil width; (2) axial length of magnetic shield; and (3) armature winding method. The end-ring of the armature winding is considered in the calculation of EMF. When it comes to field coil width, as the field coil width enlarges, its effective field increases but the maximum field on the superconductor decreases. This determines the critical current density. This study presents an effective field coil width, axial length of magnetic shield, and armature winding method, and also the analysis is verified by experimental results.

Obtaining High Output in an Electromagnetic Tachometer

Electromagnetic tachometers (EMTs) are used with products from many different industries. Evaluation of their performance requires magnetic field analysis. We simulated the electromotive force (emf) dependence on the yoke in circular cone shape and the thickness of the cylindrical permanent magnet, using the simpler emf calculation method with the finite element method. As a result, the value of emf/ (coil turns) in this simulation was 380% of that for the current yoke shape. Next, we compared the emf of an Al-Ni-Co magnet with that of a Sm-Co magnet. For the current magnet thickness (12 mm), the emf values of the magnets were close. For smaller magnet thicknesses, (3-9 mm), however the emf of the Sm-Co magnet was higher than that of the Al-Ni-Co magnet Therefore, EMTs can be made smaller and with higher emf than current models.

Consideration of emf calculation method on an electromagnetic tachometer.

Consideration of emf calculation method on an electromagnetic tachometer.

An alternative approach to electrochemistry

The concepts used conventionally in electrochemistry, single-ion chemical potential and electrostatic potential difference, are not obtainable from measurements in an inhomogeneous system. The use of nonoperational and mutually dependent forces in flux equations has impeded our understanding of electrochemical processes, and has led to wrong conclusions. The equation for entropy production is derived using only operationally defined quantities, chemical potentials of neutral components and the electric potential measured with reversible electrodes. The electric potential enters calculations as external electric work in the first law of thermodynamics. From entropy production, flux equations are obtained where the forces are operationally defined, measurable quantities. Three different problems from electrochemistry are discussed, the liquid junction potential, the Donnan potential, and energy coversion in mitochondria. The conventional method of calculations and the operational method are compared. The operational method permits more detailed calculations of emf, and an understanding of the process from a different approach.

Solute transport process in intestinal epithelial cells.

In rat small intestine, the active transport of organic solutes results in significant depolarization of the membrane potential measured in an epithelial cell with respect to a grounded mucosal solution and in an increase in the transepithelial potential difference. According to the analysis with an equivalent circuit model for the epithelium, the changes in emf's of mucosal and serosal membranes induced by active solute transport were calculated using the measured conductive parameters. The result indicates that the mucosal cell membrane depolarizes while the serosal cell membrane remarkably hyperpolarizes on the active solute transport. Corresponding results are derived from the calculations of emf's in a variety of intestines, using the data that have hitherto been reported. The hyperpolarization of serosal membrane induced by the active solute transport might be ascribed to activation of the serosal electrogenic sodium pump. In an attempt to determine the causative factors in mucosal membrane depolarization during active solute transport, cell water contents and ion concentrations were measured. The cell water content remarkably increased and, at the same time, intracellular monovalent ion concentrations significantly decreased with glucose transport. Net gain of glucose within the cell was estimated from the restraint of osmotic balance between intracellular and extracellular fluids. In contrast to the apparent decreases in intracellular Na+ and K+ concentrations, significant gains of Na+ and K+ occurred with glucose transport. The quantitative relationships among net gains of Na+, K+ and glucose during active glucose transport suggest that the coupling ratio between glucose and Na+ entry by the carrier mechanism on the mucosal membrane is approximately 1:1 and the coupling ratio between Na+-efflux and K+-influx of the serosal electrogenic sodium pump is approximately 4:3 in rat small intestine. In addition to the electrogenic ternary complex inflow across the mucosal cell membrane, the decreases in intracellular monovalent ion concentrations, the temporary formation of an osmotic pressure gradient across the cell membrane and the streaming potential induced by water inflow through negatively charged pores of the cell membrane in the course of an active solute transport in intestinal epithelial cells are apparently all possible causes of mucosal membrane depolarization.

The Speed of Response of Solid Electrolyte Galvanic Cells for Gas Sensing

The factors affecting the speed of response of solid electrolyte gas sensors are considered. The uptake or release of sample material (gas) by such cells is the main reason for sluggishness in response and for variation with time in the emf developed. Special attention is given to the effect on the emf caused by the presence of a second phase with electrical properties different from those of the main material. For a model cell, consisting of a solid electrolyte containing an intergrain phase with mixed conductor properties, the diffusion equation is solved numerically. The ambipolar diffusion coefficient is used in the calculations. The numerical parameters required for the calculation of concentration profiles and emf as a function of time are those of a typical calcia‐stabilized zirconia. The results have a more general validity.

Discussion of “Unified Approach to Cell EMF Calculations” [D. Gray (pp. 75–76, Vol. 122, No. 1)

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Closure to “Discussion of ‘Unified Approach to Cell EMF Calculations’ [D. Gray (pp. 75–76, Vol. 122, No. 1)

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Closure to “Discussion of ‘Unified Approach to Cell EMF Calculations’ [D. Gray (pp. 75–76, Vol. 122, No. 1)

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Discussion of “Unified Approach to Cell EMF Calculations” [D. Gray (pp. 75–76, Vol. 122, No. 1)

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Unified Approach to Cell EMF Calculations

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