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Chapter 1 Magnetic Circuits and Magnetic Materials
Chapter 1 Magnetic Circuits and Magnetic Materials The objective of this course is to study the devices used in the interconversion of electric and mechanical energy, with emphasis placed on electromagnetic rotating machinery. The transformer, although not an electromechanical-energy-conversion device, is an important component of the overall energy-conversion process. Practically all transformers and electric machinery use ferro-magnetic material for shaping and directing the magnetic fields that acts as the medium for transferring and converting energy. Permanent-magnet materials are also widely used. The ability to analyze and describe systems containing magnetic materials is essential for designing and understanding electromechanical-energy-conversion devices. The techniques of magnetic-circuit analysis, which represent algebraic approximations to exact field-theory solutions, are widely used in the study of electromechanical-energy-conversion devices. §1.1 Introduction to Magnetic Circuits Assume the frequencies and sizes involved are such that the displacement-current term in Maxwell’s equations, which accounts for magnetic fields being produced in space by time-varying electric fields and is associated with electromagnetic radiations, can be neglected. Z H : magnetic field intensity, amperes/m, A/m, A-turn/m, A-t/m Z B : magnetic flux density, webers/m2, Wb/m2, tesla (T) Z 1 Wb =108 lines (maxwells); 1 T =104 gauss Z From (1.1), we see that the source of H is the current density J . The line integral of the tangential component of the magnetic field intensity H around a closed contour C is equal to the total current passing through any surface S linking that contour. -
Ch Pter 1 Electricity and Magnetism Fundamentals
CH PTER 1 ELECTRICITY AND MAGNETISM FUNDAMENTALS PART ONE 1. Who discovered the relationship between magnetism and electricity that serves as the foundation for the theory of electromagnetism? A. Luigi Galvani B. Hans Christian Oersted C.Andre Ampere D. Charles Coulomb 2. Who demonstrated the theory of electromagnetic induction in 1831? A. Michael Faraday B.Andre Ampere C.James Clerk Maxwell D. Charles Coulomb 3. Who developed the electromagnetic theory of light in 1862? A. Heinrich Rudolf Hertz B. Wilhelm Rontgen C. James Clerk Maxwell D. Andre Ampere 4. Who discovered that a current-carrying conductor would move when placed in a magnetic field? A. Michael Faraday B.Andre Ampere C.Hans Christian Oersted D. Gustav Robert Kirchhoff 5. Who discovered the most important electrical effects which is the magnetic effect? A. Hans Christian Oersted B. Sir Charles Wheatstone C.Georg Ohm D. James Clerk Maxwell 6. Who demonstrated that there are magnetic effects around every current-carrying conductor and that current-carrying conductors can attract and repel each other just like magnets? A. Luigi Galvani B.Hans Christian Oersted C. Charles Coulomb D. Andre Ampere 7. Who discovered superconductivity in 1911? A. Kamerlingh Onnes B.Alex Muller C.Geory Bednorz D. Charles Coulomb 8. The magnitude of the induced emf in a coil is directly proportional to the rate of change of flux linkages. This is known as A. Joule¶s Law B. Faraday¶s second law of electromagnetic induction C.Faraday¶s first law of electromagnetic induction D. Coulomb¶s Law 9. Whenever a flux inking a coil or current changes, an emf is induced in it. -
Advanced Magnetism and Electromagnetism
ELECTRONIC TECHNOLOGY SERIES ADVANCED MAGNETISM AND ELECTROMAGNETISM i/•. •, / .• ;· ... , -~-> . .... ,•.,'. ·' ,,. • _ , . ,·; . .:~ ~:\ :· ..~: '.· • ' ~. 1. .. • '. ~:;·. · ·!.. ., l• a publication $2 50 ADVANCED MAGNETISM AND ELECTROMAGNETISM Edited by Alexander Schure, Ph.D., Ed. D. - JOHN F. RIDER PUBLISHER, INC., NEW YORK London: CHAPMAN & HALL, LTD. Copyright December, 1959 by JOHN F. RIDER PUBLISHER, INC. All rights reserved. This book or parts thereof may not be reproduced in any form or in any language without permission of the publisher. Library of Congress Catalog Card No. 59-15913 Printed in the United States of America PREFACE The concepts of magnetism and electromagnetism form such an essential part of the study of electronic theory that the serious student of this field must have a complete understanding of these principles. The considerations relating to magnetic theory touch almost every aspect of electronic development. This book is the second of a two-volume treatment of the subject and continues the attention given to the major theoretical con siderations of magnetism, magnetic circuits and electromagnetism presented in the first volume of the series.• The mathematical techniques used in this volume remain rela tively simple but are sufficiently detailed and numerous to permit the interested student or technician extensive experience in typical computations. Greater weight is given to problem solutions. To ensure further a relatively complete coverage of the subject matter, attention is given to the presentation of sufficient information to outline the broad concepts adequately. Rather than attempting to cover a large body of less important material, the selected major topics are treated thoroughly. Attention is given to the typical practical situations and problems which relate to the subject matter being presented, so as to afford the reader an understanding of the applications of the principles he has learned. -
DC Uncontrolled Rectifier by Using Phase- Shifting Transformer
University of Halabja (UoH) College of Science Physics Department Undergraduate’s Last year Project 2020-2021 ‘’Harmonics Cancellation from AC- DC Uncontrolled Rectifier by using Phase- Shifting Transformer.’’ Prepared by: Supervised by: Shilan Ali Faraj Mr .Farhad Muhsin Mahmood Bushra Ahmad Abdulla Nada Jaba Hassan 1 [‘’Harmonics Cancellation from AC- DC Uncontrolled Rectifier by using Phase-Shifting Transformer.’’] By Shilan Ali Faraj Bushra Ahmad Abdulla Nada Jaba Hassan A thesis submitted to the College of Science, University of Halabja In partial fulfillment of the requirements For the degree of Bachelor of Physics Graduate Program in Physics Written under the direction of [Mr. Farhad M. Mahmood] [May, 2021] 2 Contents Abstract ......................................................................................................................................................... 4 Chapter one (History and background) ........................................................................................................ 5 Background and history of Rectifier. ........................................................................................................ 5 1.1 Rectifier : ............................................................................................................................................. 5 1.2. Inverter :............................................................................................................................................. 7 Chapter two (introduction) ........................................................................................................................ -
Chapter 7 Magnetism and Electromagnetism
Chapter 7 Magnetism and Electromagnetism Objectives • Explain the principles of the magnetic field • Explain the principles of electromagnetism • Describe the principle of operation for several types of electromagnetic devices • Explain magnetic hysteresis • Discuss the principle of electromagnetic induction • Describe some applications of electromagnetic induction 1 The Magnetic Field • A permanent magnet has a magnetic field surrounding it • A magnetic field is envisioned to consist of lines of force that radiate from the north pole to the south pole and back to the north pole through the magnetic material Attraction and Repulsion • Unlike magnetic poles have an attractive force between them • Two like poles repel each other 2 Altering a Magnetic Field • When nonmagnetic materials such as paper, glass, wood or plastic are placed in a magnetic field, the lines of force are unaltered • When a magnetic material such as iron is placed in a magnetic field, the lines of force tend to be altered to pass through the magnetic material Magnetic Flux • The force lines going from the north pole to the south pole of a magnet are called magnetic flux (φ); units: weber (Wb) •The magnetic flux density (B) is the amount of flux per unit area perpendicular to the magnetic field; units: tesla (T) 3 Magnetizing Materials • Ferromagnetic materials such as iron, nickel and cobalt have randomly oriented magnetic domains, which become aligned when placed in a magnetic field, thus they effectively become magnets Electromagnetism • Electromagnetism is the production -
Design of Magnetic Circuits
Design of Magnetic Circuits Fundamental Equations Circuit laws similar to those of electric circuits apply in magnetic circuits as well. That is, a magnetic circuit can be replaced by an equivalent electric circuit for Ohm’s Law to be applied. If the magnetomotive force of a magnet is F and the total magnetic flux is Φt, and assuming the magnetic resistance (reluctance) of the circuit is R, then the following equation is valid. (1) Assuming the vacant length of the circuit as ℓg and the vacant cross-sectional area as ag, the magnetic resistance is then given by the following equation. (2) μ is the magnetic permeability of the magnetic path and is equivalent to the magnetic permeability μ0 of a vacuum in the case of air. (μ0=4π×10-7 [H/m]) Yoke 〈Figure 7〉 Although the current in an electric circuit rarely leaks outside the circuit, as the difference in the magnetic permeability between the conductor yoke and insulated area in a magnetic circuit is not very large, leakage of the magnetic flux also becomes large in reality. The amount of the magnetic flux leakage is expressed by the leakage factor σ, which is the ratio of the total magnetic flux Φt generated in the magnetic circuit to the effective magnetic flux Φg of the vacant space. (3) In addition, the loss in the magnetic flux due to the joints in the magnetic circuit must also be taken into consideration. This is represented by the reluctance factor f. Since the leakage factor σ is equivalent to the increase in the vacant space area, and the reluctance factor f refers to the correction coefficient of the vacant space length, the corrected magnetic resistance becomes as follows. -
Electrical Energy Utilisation
Jacek F. Gieras Izabella A.Gieras Electrical Energy Utilisation Wydawnictwo Adam Marszalek Contents Preface ........................................................VII 1 ENERGY AND DRIVES .................................. 1 1.1 Electrical energy . 1 1.2 Conservation of electrical energy . 2 1.3 Classification of electric motors . 4 1.4 Applications of electric motor drives . 5 1.5 Trends in the electric-motor and drives industry . 11 1.6 How many motors are used in affluent homes ? . 11 1.7 Fundamentals of mechanics of machines . 12 1.7.1 Torque and power . 12 1.7.2 Simple gear trains . 12 1.7.3 Efficiency of a gear train . 14 1.7.4 Equivalent moment of inertia . 14 1.8 Torque equation . 18 1.9 Mechanical characteristics of machines . 19 Problems . 21 2 D.C. MOTORS ............................................ 23 2.1 Construction . 23 2.2 Fundamental equations. 24 2.2.1 Terminal voltage . 24 2.2.2 Armature winding EMF . 25 2.2.3 Magnetic flux . 25 2.2.4 Electromagnetic (developed) torque . 25 2.2.5 Electromagnetic power . 26 2.2.6 Rotor and commutator linear speed . 26 2.2.7 Input and output power . 26 2.2.8 Losses . 27 2.2.9 Armature line current density . 28 2.3 D.c. shunt motor . 28 VI Contents 2.4 D.c. series motor . 30 2.5 Compound-wound motor . 31 2.6 Starting . 32 2.7 Speed control of d.c. motors . 34 2.8 Braking . 36 2.8.1 Braking a shunt d.c. motor . 37 2.8.2 Braking a series d.c. motor . 37 2.9 Permanent magnet d.c. -
Lecture 8: Magnets and Magnetism Magnets
Lecture 8: Magnets and Magnetism Magnets •Materials that attract other metals •Three classes: natural, artificial and electromagnets •Permanent or Temporary •CRITICAL to electric systems: – Generation of electricity – Operation of motors – Operation of relays Magnets •Laws of magnetic attraction and repulsion –Like magnetic poles repel each other –Unlike magnetic poles attract each other –Closer together, greater the force Magnetic Fields and Forces •Magnetic lines of force – Lines indicating magnetic field – Direction from N to S – Density indicates strength •Magnetic field is region where force exists Magnetic Theories Molecular theory of magnetism Magnets can be split into two magnets Magnetic Theories Molecular theory of magnetism Split down to molecular level When unmagnetized, randomness, fields cancel When magnetized, order, fields combine Magnetic Theories Electron theory of magnetism •Electrons spin as they orbit (similar to earth) •Spin produces magnetic field •Magnetic direction depends on direction of rotation •Non-magnets → equal number of electrons spinning in opposite direction •Magnets → more spin one way than other Electromagnetism •Movement of electric charge induces magnetic field •Strength of magnetic field increases as current increases and vice versa Right Hand Rule (Conductor) •Determines direction of magnetic field •Imagine grasping conductor with right hand •Thumb in direction of current flow (not electron flow) •Fingers curl in the direction of magnetic field DO NOT USE LEFT HAND RULE IN BOOK Example Draw magnetic field lines around conduction path E (V) R Another Example •Draw magnetic field lines around conductors Conductor Conductor current into page current out of page Conductor coils •Single conductor not very useful •Multiple winds of a conductor required for most applications, – e.g. -
A Mini-Review: Emerging All-Solid-State Energy Storage Electrode Materials for Flexible Devices
Nanoscale A mini-review: Emerging All-Solid-State Energy Storage Electrode Materials for Flexible Devices Journal: Nanoscale Manuscript ID NR-MRV-10-2019-008722.R1 Article Type: Minireview Date Submitted by the 25-Dec-2019 Author: Complete List of Authors: Yang, Yang; University of Central Florida, NanoScience Technology Center Page 1 of 31 Nanoscale A mini-review: Emerging All-Solid-State Energy Storage Electrode Materials for Flexible Devices Yang Yang* NanoScience Technology Center, Department of Materials Science and Engineering, Energy Conversion and Propulsion Cluster, University of Central Florida, 12424 Research Parkway Suite 423, Orlando, Florida 32826, United States *E-mail: [email protected] Abstract: New technologies for future electronics such as personal healthcare devices and foldable smartphones require emerging developments in flexible energy storage devices as power sources. Besides the energy and power densities of the energy device, more attention should be paid to safety, reliability, and compatibility within the highly integrated systems because they are almost in 24-hour real-time operation close to the human body. Thereupon, all-solid-state energy devices become the most promising candidates to meet these requirements. In this mini-review, the most recent research progress in the all-solid-state flexible supercapacitors and batteries will be covered. The main focus of this mini-review is to summarize new materials development for all-solid-state flexible energy devices. The potential issues and perspectives regarding -
Transient Simulation of Magnetic Circuits Using the Permeance-Capacitance Analogy
Transient Simulation of Magnetic Circuits Using the Permeance-Capacitance Analogy Jost Allmeling Wolfgang Hammer John Schonberger¨ Plexim GmbH Plexim GmbH TridonicAtco Schweiz AG Technoparkstrasse 1 Technoparkstrasse 1 Obere Allmeind 2 8005 Zurich, Switzerland 8005 Zurich, Switzerland 8755 Ennenda, Switzerland Email: [email protected] Email: [email protected] Email: [email protected] Abstract—When modeling magnetic components, the R1 Lσ1 Lσ2 R2 permeance-capacitance analogy avoids the drawbacks of traditional equivalent circuits models. The magnetic circuit structure is easily derived from the core geometry, and the Ideal Transformer Lm Rfe energy relationship between electrical and magnetic domain N1:N2 is preserved. Non-linear core materials can be modeled with variable permeances, enabling the implementation of arbitrary saturation and hysteresis functions. Frequency-dependent losses can be realized with resistors in the magnetic circuit. Fig. 1. Transformer implementation with coupled inductors The magnetic domain has been implemented in the simulation software PLECS. To avoid numerical integration errors, Kirch- hoff’s current law must be applied to both the magnetic flux and circuit, in which inductances represent magnetic flux paths the flux-rate when solving the circuit equations. and losses incur at resistors. Magnetic coupling between I. INTRODUCTION windings is realized either with mutual inductances or with ideal transformers. Inductors and transformers are key components in modern power electronic circuits. Compared to other passive com- Using coupled inductors, magnetic components can be ponents they are difficult to model due to the non-linear implemented in any circuit simulator since only electrical behavior of magnetic core materials and the complex structure components are required. -
Magnetism and Magnetic Circuits
UNIVERSITY OF BABYLON BASIC OF ELECTRICAL ENGINEERING LECTURE NOTES Magnetism and Magnetic Circuits The Nature of a Magnetic Field: Magnetism refers to the force that acts between magnets and magnetic materials. We know, for example, that magnets attract pieces of iron, deflect compass needles, attract or repel other magnets, and so on. The region where the force is felt is called the “field of the magnet” or simply, its magnetic field. Thus, a magnetic field is a force field. Using Faraday’s representation, magnetic fields are shown as lines in space. These lines, called flux lines or lines of force, show the direction and intensity of the field at all points. The field is strongest at the poles of the magnet (where flux lines are most dense), its direction is from north (N) to south (S) external to the magnet, and flux lines never cross. The symbol for magnetic flux as shown is the Greek letter (phi). What happens when two magnets are brought close together? If unlike poles attract, and flux lines pass from one magnet to the other. الصفحة 321 Saad Alwash UNIVERSITY OF BABYLON BASIC OF ELECTRICAL ENGINEERING LECTURE NOTES If like poles repel, and the flux lines are pushed back as indicated by the flattening of the field between the two magnets. Ferromagnetic Materials (magnetic materials that are attracted by magnets such as iron, nickel, cobalt, and their alloys) are called ferromagnetic materials. Ferromagnetic materials provide an easy path for magnetic flux. The flux lines take the longer (but easier) path through the soft iron, rather than the shorter path that they would normally take. -
MAGNETISM and Its Practical Applications
Mechanical Engineering Laboratory A short introduction to… MAGNETISM and its practical applications Michele Togno – Technical University of Munich, 28 th March 2014 – 4th April 2014 Mechanical Engineering laboratory - Magnetism - 1 - Magnetism A property of matter A magnet is a material or object that produces a magnetic field. This magnetic field is invisible but it is responsible for the most notable property of a magnet: a force that pulls on ferromagnetic materials, such as iron, and attracts or repels other magnets. History of magnetism Magnetite Fe 3O4 Sushruta, VI cen. BCE (lodestone) (Indian surgeon) J.B. Biot, 1774-1862 A.M. Ampere, 1775-1836 Archimedes (287-212 BCE) William Gilbert, 1544-1603 H.C. Oersted, 1777-1851 (English physician) C.F. Gauss, 1777-1855 F. Savart, 1791-1841 M. Faraday, 1791-1867 J.C. Maxwell, 1831-1879 Shen Kuo, 1031-1095 (Chinese scientist) H. Lorentz, 1853-1928 Mechanical Engineering laboratory - Magnetism - 2 - The Earth magnetic field A sort of cosmic shield Mechanical Engineering laboratory - Magnetism - 3 - Magnetic domains and types of magnetic materials Ferromagnetic : a material that could exhibit spontaneous magnetization, that is a net magnetic moment in the absence of an external magnetic field (iron, nickel, cobalt…). Paramagnetic : material slightly attracted by a magnetic field and which doesn’t retain the magnetic properties when the external field is removed (magnesium, molybdenum, lithium…). Diamagnetic : a material that creates a magnetic field in opposition to an externally applied magnetic field (superconductors…). Mechanical Engineering laboratory - Magnetism - 4 - Magnetic field and Magnetic flux Every magnet is a magnetic dipole (magnetic monopole is an hypothetic particle whose existence is not experimentally proven right now).