Inductor Examples

4 Key excerpts on "Inductor Examples"

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  eBook - PDF

  Handbook of Power Management Circuits

  • Haruo Kobayashi, Takashi Nabeshima, Haruo Kobayashi, Takashi Nabeshima(Authors)
  • 2016(Publication Date)
  • Jenny Stanford Publishing

    (Publisher)

  6.1 Inductors and Transformers 6.1.1 Inductors 6.1.1.1 Definition of an inductor An inductor is a circuit element that is widely used in electronic circuits. Current flow through a conductive wire produces magnetic flux around the wire, following the Maxwell corkscrew (right-handed screw) rule. The main characteristic of an inductor is the magnetic flux that it produces when a current is passed through it. Although wire conductors also possess inductance components, the value is negligibly small. Chapter 6 Passive Components Yuya Tamai a and Yoshiyuki Ishihara b a Solution R & D Department, R & D Headquarters, Nippon Chemi-Con Corporation, 6-4, Osaki 5-Chome, Shinagawa-ku, Tokyo 141-8605, Japan b Electrical Engineering Department, Faculty of Science and Engineering, Doshisha University, Kyotanabe 610-0321, Japan [email protected], [email protected] Handbook of Power Management Circuits Edited by Haruo Kobayashi and Takashi Nabeshima Copyright © 2016 Pan Stanford Publishing Pte. Ltd. ISBN 978-981-4613-15-6 (Hardcover), 978-981-4613-16-3 (eBook) www.panstanford.com 136 Passive Components Inductance L (H) is the proportionality constant between the current flow I (A) through the wire and the linkage flux Φ , and the relation is expressed as follows: Φ = LI (Wb) (6.1) Here L is the value of inductance. When an inductor is used as a circuit component, it is usually constructed by winding a wire into a coil. This case, inductance is expressed as follows: L = n / R m (H) (6.2) Here, n is the number of turns and R m is the magnetic reluctance (A/Wb). Magnetic reluctance, R m , is given by R m = l /( μS ) (A/Wb) (6.3) Here, l is the average magnetic path length (m), μ is the permeability (H/m), and S is the cross-sectional area of the magnetic path (m 2 ).

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  eBook - ePub

  Basic AC Circuits

  • Clay Rawlins(Author)
  • 2000(Publication Date)
  • Newnes

    (Publisher)

  9. Given a circuit of series-connected inductors, the applied voltage, and frequency of the applied voltage, determine the inductive reactance of each inductor, the total inductance, the total current, the voltage across each inductor, the reactive power of each inductor, and the total reactive power in the circuit.

  10. Given a circuit of parallel-connected inductors, the applied voltage, and frequency of the applied voltage, determine the inductive reactance of each inductor, the total inductive reactance, the total inductance, each inductive branch current, the total current, the reactive power of each inductor, and the total reactive power in the circuit.

  INTRODUCTION

  In the last two chapters, discussion concerned the capacitor and how to analyze circuits composed of only capacitors or capacitors and resistors. This chapter is about the remaining passive circuit element — the inductor.

  Figure 8.1 some types of inductors. Basically, any inductor is a coil of thin wire wrapped on a cylinder called the core. The core may be hollow, of laminated paper — an air core — or made of some type of iron — an iron core. Often an inductor is also called a choke or coil. The turns of wire of the inductor are electrically insulated from each other by a thin, non–conductive coating.

  Figure 8.1 Typical Inductors

  As shown in Figure 8.2 the schematic symbol used to represent the inductor resembles what it is — wire wrapped on a core. The inductor’s letter symbol is a capital L which represents linkages — flux linkages.

  Figure 8.2 Schematic Symbol for an Inductor

  An inductor has magnetic properties. Therefore, a brief review of the subject of magnetism should help you understand better the electrical properties of an inductor.

  ELECTROMAGNETIC PROPERTIES

  Faraday’s Discovery

  Recall that in 1831, Michael Faraday showed that when a conductor connected in a closed circuit is moved through a magnetic field, an electron current flows as a result of a voltage induced in the conductor. (In this chapter, like in all other chapters in this book, current flow refers to electron current flow.)

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  Passive Components for Circuit Design

  • Ian Sinclair(Author)
  • 2000(Publication Date)
  • Newnes

    (Publisher)

  Chapter 5

  Inductors and inductive components

  Induction and inductance

  Electromagnetic induction was discovered by Michael Faraday in 1831. The principle is that an EMF (a voltage) is generated in a conductor when the magnetic field across the conductor changes. In the early experiments, the change of magnetic field was accomplished by moving either the wire or a magnet, and this is the principle of the alternator and dynamo. An EMF can also be induced without mechanical movement, when the strength or direction of a magnetic field across a wire is altered, and even the presence of a wire is not necessary, because the alteration in a magnetic field can produce an electric field in the absence of any conductor. Inductive components in electronics make use of the EMF that is generated when a field changes either in the same piece of wire (self-induction ) or in another piece of wire (mutual induction ).

  The amount of EMF that is generated in a wire can be greatly increased if the wire is wound into a coil, and as much as possible of the magnetic field is guided through the coil. Figure 5.1 shows the flux path in a solenoidal winding for a steady current. Concentration and guidance of the magnetic field is achieved by using a magnetic core, for which the traditional material was annealed ‘soft’ iron. One way of looking at a soft iron core is as a conductor for magnetism, using the idea of magnetic flux. It is possible to think of magnetic circuits in which magnetic flux (φ) is the counterpart of current, in a path which has reluctance (analogous to resistance), and in which the amount of flux is produced by a magnetomotive force (MMF). The equation that is the magnetic equivalent of V = R × I

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  Electrical Principles and Technology for Engineering

  • John Bird(Author)
  • 2013(Publication Date)
  • Butterworth-Heinemann

    (Publisher)

  Two examples of practical inductors are shown in Fig. 9.6, and the standard electrical circuit diagram symbols for air-cored and iron-cored inductors are shown in Fig. 9.7. An iron-cored inductor is often called a choke since, when used in a.c. circuits, it has a choking effect, limiting the current flowing through it. Inductance is often undesirable in a circuit. To Iron core -Wire (a) Coil of w.re ( b) Figure 9.6 Air-cored inductor E = 40 V, L = 150 mH = 0.15 H; change in current, 1=6-(-6) = 12 A (since the current is reversed). Since E = L(A//f), Iron cored inductor Figure 9.7 88 ELECTROMAGNETIC INDUCTION Insulator Wire Figure 9.8 reduce inductance to a minimum the wire may be bent back on itself, as shown in Fig. 9.8, so that the magnetizing effect of one conductor is neutralized by that of the adjacent conductor. The wire may be coiled around an insulator, as shown, without increasing the inductance. Standard resistors may be non-inductively wound in this manner. Problem 12. Calculate the coil inductance when a current of 4 A in a coil of 800 turns produces a flux of 5 mWb linking with the coil. For a coil, τ ΝΦ (800)(5 X 10 3 ) Λ ¥¥ inductance L = —— = - ^—- = 1H Problem 13. A flux of 25 mWb links with a 1500 turn coil when a current of 3 A passes through the coil. Calculate (a) the inductance of the coil, (b) the energy stored in the magnetic field, and (c) the average e.m.f. induced if the current falls to zero in 150 ms. (a) Inductance, L = ΝΦ I 9.5 Energy stored An inductor possesses an ability to store energy. The energy stored, W, in the magnetic field of an inductor is given by: W = LI 1 joules Problem 11. An 8 H inductor has a current of 3 A flowing through it. How much energy is stored in the magnetic field of the inductor? Energy stored, W = y LI 2 = -(8)(3) 2 = 36 joules 9.6 Inductance of a coil If a current changing from 0 to / amperes, produces a flux change from 0 to webers, then ΔΙ = I and = .

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