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Introduction to Electrical & Computer Engineering Inductors Dr. Cynthia Furse University of Utah Dr. Cynthia Furse University of Utah 1 Inductors • What is Inductance ? • How does it relate to magnetic field & Current? • Explain the effect of µ, N, S, l • What does it do to a voltage and current? 2 All rights reserved. Do not copy or distribute. © 2013 National Technology and Science Press Inductors Passive element that stores energy in magnetic field Solenoid Wound Inductor N S L l 2 Henries Magnetic permeability µ=µo µr µo = 1.26 x 10(-6) H Circuits, Second Edition by Fawwaz T. Ulaby and Michel M. Maharbiz, © NTS Press, Used with Permission by the Publisher Current and Magnetic field 4 Wire Wound Inductor http://www.murata.com/products/emicon_fun/2011/03/inductor_en14.html 5 Multilayer Inductor http://www.murata.com/products/emicon_fun/2011/03/inductor_en14.html 6 Thin Film Inductor http://www.murata.com/products/emicon_fun/2011/03/inductor_en14.html 7 Electrical Properties of Inductors • Inductance – current, charge, voltage, power, energy • What happens at DC? • Series and Parallel 8 All rights reserved. Do not copy or distribute. © 2013 National Technology and Science Press Inductors Passive element that stores energy in magnetic field Solenoid Wound Inductor 1 t i vt dt i t0 L to • At dc, inductor looks like a short circuit • Current through inductor must be continuous (no abrupt change) N 2 A L l Circuits, Second Edition by Fawwaz T. Ulaby and Michel M. Maharbiz, © NTS Press, Used with Permission by the Publisher 10 http://hyperphysics.phy-astr.gsu.edu/hbase/electric/indtra.html Inductors: Current & B Field Current = begins to flow and starts to create magnetic field Circuits, Second Edition by Fawwaz T. Ulaby and Michel M. Maharbiz, © NTS Press, Used with Permission by the Publisher Inductors: Current & B Field Current = begins to flow in and starts to create magnetic field At t=0, this acts like an OPEN circuit Voltage is high, current is low Circuits, Second Edition by Fawwaz T. Ulaby and Michel M. Maharbiz, © NTS Press, Used with Permission by the Publisher Inductors: Current & B Field When magnetic field is established, current flows freely At t=∞, this acts like a SHORTcircuit Voltage is low, current is high Circuits, Second Edition by Fawwaz T. Ulaby and Michel M. Maharbiz, © NTS Press, Used with Permission by the Publisher What does an inductor do to the current ? 14 What does an inductor do to the current ? Vs/R 66% at t=L/R t 15 What does an inductor do to the voltage ? Vs 36% at t=L/R t 16 What does an inductor do to a voltage and current? Voltage changes Instantly At ‘steady state’ Voltage =0 At ‘steady state’ Current is Vs/R Current changes slowly • t=0: OPEN CIRCUIT • t=∞: SHORT CIRCUIT 17 http://macao.communications.museum/eng /exhibition/secondfloor/moreinfo/2_3_6_Re sistanceInductance.html 18 Inductors in Series & Parallel 19 How can we use Inductors? • • • • • Resonators (synthesizers) Matching Impedances AC Choke Transformers Inductive coupling 20 http://www.murata.com/products/emicon_fun/2011/03/inductor_en14.html Inductive Coupling http://www.ferroxtag.com/RFID/CP.LFHFUHF.htm 21 Inductive Coupling: Electric Wave Buses (UofU) 22 Blackrock Microsystems http://www.blackrockmicro.com/content.asp x?id=60 23 Passive RFID 24 Transformers 25 Transformers 26 Low Pass filter Noise Filter / Integrator 27 High Pass Filter DC Block / Differentiator 28 White Canyon, American Fork Dr. Cynthia Furse University of Utah Dr. Cynthia Furse University of Utah 29
