Vector Potential, Magnetic Field, Mutual Inductance, Magnetic Force, Torque and Stiffness Calculation between Current-Carrying Arc Segments with Inclined Axes in Air

In this paper, the improved and the new analytical and semi-analytical expressions for calculating the magnetic vector potential, magnetic field, magnetic force, mutual inductance, torque, and stiffness between two inclined current-carrying arc segments in air are given. The expressions are obtained either in the analytical form over the incomplete elliptic integrals of the first and the second kind or by the single numerical integration of some elliptical integrals of the first and the second kind. The validity of the presented formulas is proved from the particular cases when the inclined circular loops are addressed. We mention that all formulas are obtained by the integral approach, except the stiffness, which is found by the derivative of the magnetic force. The novelty of this paper is the treatment of the inclined circular carting-current arc segments for which the calculations of the previously mentioned electromagnetic quantities are given.

Matrix Dimensional Analysis for Electromagnetic Quantities

We utilize the electromagnetically-oriented LTI∅ dimensional basis in the matrix solution of dimensional-analysis (DA) problems involving mainly electromagnetic quantities, whether these quantities are lumped or distributed. Representations in the LTI∅ basis (compared with the standard MLTI basis) are more informative and much simpler. Moreover, matrix DA computations employing the LTI∅ basis are more efficient and much less error prone. Extensive discussions of two demonstrative examples expose technical details of a novel DA scheme, and clarify many important facets of modern dimensional analysis.

Analytical calculations of electromagnetic quantities for wound rotor salient-pole synchronous machines

Purpose This paper aims to present an analytical electromagnetic model for wound rotor synchronous machines with a salient-pole rotor structure based on the two-dimensional subdomain technique. Design/methodology/approach The machine is divided into five active sub-regions: stator slots, stator slot openings, air gap, rotor slots and rotor slot openings. For each sub-region, the governing partial differential equations are derived and solved analytically. Findings The magnetic flux density distributions in all active sub-regions are analytically computed and other quantities such as back-emf, inductances, electromagnetic torque and unbalanced magnetic forces are also analytically calculated. The results of the analytical model are compared to those obtained from the finite element analysis to show the accuracy of the proposed model. Originality/value The two-dimensional analytical model of a wound rotor salient-pole synchronous machine using the sub-domain technique is the main contribution of the research.

MODELING OFDISTRIBUTION TRANSFORMERS BY A 3-D NUMERICAL TECHNIQUE

Modeling of electromagnetic quantities (magnetic flux, leakage flux, eddy current loss, and electromagnetic force) in distributed power transformers remarkably plays an essential role for researchers and designers in the calculation and production of electrical equipment in general and transformer designs in particular. In the frame of this research, the distribution of magnetic flux densities along the tank wall and cover plate, the leakage flux in air regions, and the forces for both rated and short circuit modes in the windings of the transformer are computed/simulated via a 3-D numerical method. The method is herein developed with magnetic vector potential formulations and is applied to a practical application of the distributed transformer (630kVA-22/0,4kV).

Real-Time Digital Twin of a Wound Rotor Induction Machine Based on Finite Element Method

Monitoring and early fault prediction of large electrical machines is important to maintain a sustainable and safe power system. With the ever-increasing computational power of modern processors, real-time simulation based monitoring of electrical machines is becoming a topic of interest. This work describes the development of a real-time digital twin (RTDT) of a wound rotor induction machine (WRIM) using a precomputed finite element model fed with online measurements. It computes accurate outputs in real-time of electromagnetic quantities otherwise difficult to measure such as local magnetic flux, current in bars and torque. In addition, it considers space harmonics, magnetic imbalance and fault conditions. The development process of the RTDT is described thoroughly and outputs are compared in real-time to measurements taken from the actual machine in rotation. Results show that they are accurate with harmonic content respected.

Estimation of ice-liquid plasma phase transition using electronic test equipment

One of the most dynamically developing areas of knowledge is modern medicine. In many ways, the pace of development of medicine is determined by technological capabilities. The blood service is one of the most technologically saturated branches of medicine since the quality of the final product and the patient’s health depend on the processing technology of the blood and its components. According to the technical regulations on the safety requirements of blood, its products, blood-substituting solutions and technical means used in transfusion-infusion therapy, approved by the Government of Russia on 01/26/2010: “The components of donated blood must be thawed and heated to the required temperature using specially designed equipment”. Defroster for cryopreserved blood products are specialized technical means used to measure electrical, magnetic and electromagnetic quantities characterizing the temperature parameters of the object to be thawed and heated. In the field of defrosting and heating cryopreserved blood products for transfusion-infusion, the fundamental task is to develop a software solution for simulating defrosting systems, which can make it possible to determine the optimal parameters of defrosting systems at the stage of pre-model modeling. This article describes an experimental study to evaluate the phase transition of an ice-liquid plasma during defrosting using radio measuring equipment. The obtained data will be used to create a mathematical model of the process of defrosting blood products.

3D harmonic modeling of eddy currents in segmented conducting structures

PurposeThe purpose of this paper is to describe a semi-analytical modeling technique to predict eddy currents in three-dimensional (3D) conducting structures with finite dimensions. Using the developed method, power losses and parasitic forces that result from eddy current distributions can be computed.Design/methodology/approachIn conducting regions, the Fourier-based solutions are developed to include a spatially dependent conductivity in the expressions of electromagnetic quantities. To validate the method, it is applied to an electromagnetic configuration and the results are compared to finite element results.FindingsThe method shows good agreement with the finite element method for a large range of frequencies. The convergence of the presented model is analyzed.Research limitations/implicationsBecause of the Fourier series basis of the solution, the results depend on the considered number of harmonics. When conducting structures are small with respect to the spatial period, the number of harmonics has to be relatively large.Practical implicationsBecause of the general form of the solutions, the technique can be applied to a wide range of electromagnetic configurations to predict, e.g. eddy current losses in magnets or wireless energy transfer systems. By adaptation of the conductivity function in conducting regions, eddy current distributions in structures containing holes or slit patterns can be obtained.Originality/valueWith the presented technique, eddy currents in conducting structures of finite dimensions can be modeled. The semi-analytical model is for a relatively low number of harmonics computationally faster than 3D finite element methods. The method has been validated and shown to be computationally accurate.

Экстремальная и топологическая нелинейная оптика открытых систем

A review of results of an investigation of the theory of optical wave packets with extreme properties with respect to a controllable pulse shape or to the complexity of the internal structure of radiation beam pulses is presented. Special attention is paid to the manifestations of dissipative effects of the electromagnetic energy inflow and outflow. Precisely these factors lead to peculiar rules of conservation of purely electromagnetic quantities in dissipative media, in which the electromagnetic energy irreversibly decreases in the case of absorption and increases with gain. These rules impose certain restrictions on the possibility of transformation of the shape of pulses and allow one to qualitative describe their evolution. A higher efficiency of the action of unipolar or quasi-unipolar radiation pulses on classical and quantum microobjects is shown and possible ways of formation of these pulses are discussed. For bulk laser media with saturable absorption, the topological properties of localized radiation structures and their transformations with a smooth change in the parameters of the medium (pump level) are described. The preservation of the topological structure upon changes in parameters within the stability range yields the possibility of their distinguishing when coding information by topological solitons of the considered type.