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Due to the expected growth of their market, permanent magnet materials have very favorable future prospects for their development. This is linked to the increasing use of connected devices and electric vehicles, as well as the growing importance of renewable energies in energy production.Ferrite magnets, which account for the largest share of the permanent magnet market revenue, are mainly used in commercial or industrial motors. Nd-Fe-B magnets are seeing their application expand due to their growing use in electric vehicles, hybrid vehicles and wind turbines. Alnico, Sm-Co and Sm-Fe-N magnets are used for specific applications.
The aim of the first part of this article is to define the various elements that make up an electrical network, and the models that represent them. Each model involves the current i(t) flowing through the element under consideration and the voltage v(t) (or potential difference) across its terminals, both functions of an independent variable: time t. Even though each model must remain independent of the actual size of the physical component, it must be borne in mind that the quantities v(t) and i(t) are always assumed to be below their limit values, depending in particular on the component manufacturing method, the material used and the intended field of application.
In this dossier, we look at the main industrial AC electrical machines: Vertical-axis hydraulic alternators, hydrogen-powered turboalternators and special-purpose machines not widely used today are not covered here (see "Hydraulic alternators and compensators" , "Turboalternators" ). This dossier is part of a series on "Rotating machine construction":
The concept of flux vector control, which emerged in the mid-1980s, revolutionized the field of variable speed drives, which were in constant need of performance enhancement. This paved the way for researchers and engineers in various disciplines (automation, electrical engineering, power electronics, industrial computing, microelectronics, instrumentation, etc.) to develop several variants of control algorithms emerging from the concept of flux vector control of asynchronous machines. The natural independence between flux creation and torque generation is clearly the fundamental intrinsic property of a separately excited DC machine. The aim of vector control of an asynchronous cage machine is to reproduce the quadrature between the current and flux vectors.
Turboalternators are alternators driven at high rotating speed by a vapor turbine or a gas turbine. The unit power of turbogenerators and the structure of the networks and power stations have considerably evolved since the beginnings of electrification. This article firstly presents the main parts of a turboalternator (stator, rotor, bearings and auxiliary bearings) before focusing on its functioning and in particular on its types of cooling. The vapor turbine remains the most common driving system for high powers and the combustion turbine has undergone a significant progression over the last few years due to its easy implementation and low investment costs.
Knowledge of leakage inductances is essential for predetermining the electromechanical characteristics of electrical machines. These leakage inductances are used in equivalent diagrams, and are indispensable in the study of the association between the machine and the power source. The latter is not simply the mains, with its practically infinite power and constant frequency; it is often a variable-frequency source, driven by control laws imposed by the structure of the machine and the nature of the load. These few considerations demonstrate the importance of properly predetermining leakage in electrical machines. Before moving on to the actual calculation, we need to define the notion of leakage flux.
This article focuses on electrical resistors that dissipate high power through the Joule effect. Operating at high temperatures (over 400°C), they are made of refractory materials. They are a key component in Joule-effect heating systems (electric furnaces, hot-forming devices, etc.). Electric motor starting and braking rheostats also use the same refractory materials. For other resistors, please refer to the articles Resistors. Potentiometers , Semiconductor ceramics and Varistors, in the Electronics section, and, for ceramic varistors, to the Specific components for protection against interference sections in this section.
Device reliability in electrical engineering is largely determined by the durability of insulation properties. Failures in electrical equipment are often due to dielectric breakdown of the insulators. These phenomena occur at electric fields much lower than the breakdown fields measured in the laboratory on the insulators themselves or on system models. This is largely due to the electrical ageing of insulating materials, a generic term that covers all the mechanisms by which the electrical characteristics of materials evolve over time under the action of system operating stresses. In fact, it can be assumed that the insulation's breaking range decreases with the duration of the stresses applied.
This article extends a previous one devoted to an elementary approach of the transmission lines theory. This novel article composed of three main sections deal firstly with the behavior of propagation phenomena on the line terminated by various types of non linear loads. Second section will be targeted about the study of the propagation occurring on two coupled lines. The problem will be solved by means of the eigenvalues leading to the concept of modes expressed in terms of amplitudes and propagation constants. To conclude, the third section will be focused toward the crosstalk coupling happening between two lines. Analytical formula of crosstalk voltages appearing at both ends of the receiving line will be established.
The purpose of this paper is to provide a comprehensive review of methodologies for electromagnetic compatibility (EMC) in system development. The proposed approach is structured around key steps that enable the identification of EMC risks through preventive analysis and their systematic mitigation throughout the development lifecycle.Established design best practices, particularly regarding interactions with mechanical constraints and PCB layout are examined, with the objective of minimizing the likelihood of critical design errors.
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