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Magnetic Actuators and Sensors

Cover Image Copyright Year: 2014
Author(s): Brauer, J.
Publisher: Wiley-IEEE Press
Content Type : Books & eBooks
Topics: Components, Circuits, Devices & Systems ;  Fields, Waves & Electromagnetics
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Abstract

A fully updated, easy-to-read guide on magnetic actuators and sensorsThe Second Edition of this must-have book for today's engineers includes the latest updates and advances in the field of magnetic actuators and sensors. Magnetic Actuators and Sensors emphasizes computer-aided design techniques—especially magnetic finite element analysis; offers many new sections on topics ranging from magnetic separators to spin valve sensors; and features numerous worked calculations, illustrations, and real-life applications.To aid readers in building solid, fundamental, theoretical background and design know-how, the book provides in-depth coverage in four parts:PART I: MAGNETICS
Introduction
Basic Electromagnetics
Reluctance Method
Finite-Element Method
Magnetic Force
Other Magnetic Performance ParametersPART II: ACTUATORS
Magnetic Actuators Operated by Direct Current
Magnetic Actuators Operated by Alternating Current
Magnetic Actuator Transient OperationPART III: SENSORS
Hall Effect and Magnetoresistive Sensors
Other Magnetic SensorsPART IV: SYSTEMS
Coil Design and Temperature Calculations
Electromagnetic Compatibility
Electromechanical Finite Elements
Electromechanical Analysis Using Systems Models
Coupled Electrohydraulic Analysis Using Systems ModelsWith access to a support website containing downloadable software data files (including MATLAB® data files) for verifying design techniques and analytical methods, Magnetic Actuators and Sensors, Second Edition is an exemplary learning tool for practicing engineers and engineering students involved in the design and application of magnetic actuators and sensors.

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      Front Matter

      Brauer, J.
      Magnetic Actuators and Sensors

      DOI: 10.1002/9781118779262.fmatter
      Copyright Year: 2014

      Wiley-IEEE Press eBook Chapters

      The prelims comprise:
      Half Title
      Editorial Board
      Title
      Copyright
      Contents
      Preface
      Preface to the First Edition
      List of 66 Examples View full abstract»

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      Introduction

      Brauer, J.
      Magnetic Actuators and Sensors

      DOI: 10.1002/9781118779262.ch01
      Copyright Year: 2014

      Wiley-IEEE Press eBook Chapters

      This is the introductory chapter of the book, Magnetic Actuators and Sensors. Magnetic actuators and sensors are energy conversion devices, using the energy stored in static, transient, or low frequency magnetic fields, to produce and sense motion. The chapter presents overviews of magnetic actuators and magnetic sensors, and highlights the applications of actuators/sensors in motion control systems and mechatronics. View full abstract»

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      Basic Electromagnetics

      Brauer, J.
      Magnetic Actuators and Sensors

      DOI: 10.1002/9781118779262.ch02
      Copyright Year: 2014

      Wiley-IEEE Press eBook Chapters

      Study of magnetic fields provides an explanation of how magnetic actuators and sensors work. This chapter presents the basic principles of electromagnetics including magnetic fields. In reviewing electromagnetic theory, the chapter introduces various parameters and their symbols. Magnetic fields are vectors, and thus it is useful to review mathematical operations involving vectors. Separate sections of the chapter are devoted to Ampere's law, Faraday's law and Maxwell's equations. Magnetic materials with high relative permeability are said to be magnetically soft. The reason for the high permeability of certain materials is that they contain many magnetic domains. Potentials are useful in electrical engineering; the most common example of potential is voltage. View full abstract»

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      Reluctance Method

      Brauer, J.
      Magnetic Actuators and Sensors

      DOI: 10.1002/9781118779262.ch03
      Copyright Year: 2014

      Wiley-IEEE Press eBook Chapters

      The reluctance method is a way of using Ampere's law to solve for magnetic fluxes and magnetic fields. For very simple problems, its results are often reasonably accurate, and thus it often serves as a first step in the process of designing magnetic actuators and sensors. This chapter highlights the steps involved in reluctance method, and provides examples for the method for a C steel path with airgap and for a sensor with variable airgap. The chapter provides a brief discussion on the concepts of fringing flux and complex reluctance, and is concluded by highlighting the limitations of reluctance method. View full abstract»

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      Finite-Element Method

      Brauer, J.
      Magnetic Actuators and Sensors

      DOI: 10.1002/9781118779262.ch04
      Copyright Year: 2014

      Wiley-IEEE Press eBook Chapters

      Due to the limitations of the reluctance method, engineers have long sought more accurate ways to calculate magnetic fields. This chapter is devoted to the finite-element method, the most general and accurate method for calculation of magnetic fields. The finite-element method can be derived using the basic principle of conservation of energy. The Law of Energy Conservation requires the functional to be zero. Besides the energy functional, the second main requirement of finite-element analysis is to discretize (break up) the volume analyzed into small pieces called finite elements. The most basic finite element is the triangle. Making a finite-element model consists of four steps; the four steps are often called preprocessing, because they must be accomplished in order for the matrix equation to be set up and solved for the magnetic vector potential distribution throughout an analyzed device. View full abstract»

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      Magnetic Force

      Brauer, J.
      Magnetic Actuators and Sensors

      DOI: 10.1002/9781118779262.ch05
      Copyright Year: 2014

      Wiley-IEEE Press eBook Chapters

      The magnetic vector potential and the magnetic flux density computed by the finite-element method can be used to find magnetic forces of magnetic actuators and sensors. This chapter discusses magnetic flux plots, magnetic energy, magnetic pressure, permanent magnets, and magnetic torque, which are all related to magnetic force; these all are also examples of postprocessing of finite-element solutions. For both 2D and 3D finite-element models, it is vital that flux line plots and/or flux density plots be obtained and examined. The chapter demonstrates a method, other than the method of virtual work, for the computation of Lorentz force. It also demonstrates the calculation of magnetic volume forces on permeable particles. View full abstract»

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      Other Magnetic Performance Parameters

      Brauer, J.
      Magnetic Actuators and Sensors

      DOI: 10.1002/9781118779262.ch06
      Copyright Year: 2014

      Wiley-IEEE Press eBook Chapters

      This chapter discusses a few magnetic performance parameters. After defining these key parameters, they are evaluated using reluctance and finite-element methods. Their relations with energy and force are also explained. The parameters discussed in the chapter are magnetic flux, flux linkage, inductance, capacitance and impedance. View full abstract»

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      Magnetic Actuators Operated by DC

      Brauer, J.
      Magnetic Actuators and Sensors

      DOI: 10.1002/9781118779262.ch07
      Copyright Year: 2014

      Wiley-IEEE Press eBook Chapters

      Magnetic actuators use magnetic fields to transform electrical energy into mechanical energy. Thus they are a type of transducer. This chapter discusses in detail the most common types of magnetic actuators operated by direct current (DC). The magnetic actuators discussed in the chapter are: solenoid actuators, voice coil actuators, other linear actuators using coils and permanent magnets, proportional actuators, rotary actuators, magnetic bearings and couplings, and magnetic separators. View full abstract»

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      Magnetic Actuators Operated by AC

      Brauer, J.
      Magnetic Actuators and Sensors

      DOI: 10.1002/9781118779262.ch08
      Copyright Year: 2014

      Wiley-IEEE Press eBook Chapters

      Since alternating current (AC) voltage is commonly available, many magnetic actuators are designed for AC operation. In most cases, the direct current (DC) actuators must be substantially modified for AC operation. This chapter discusses the issues that are needed to be considered for AC-operated magnetic actuators. Separate sections are devoted to the concepts of skin depth, power losses in laminated steel, equivalent circuit and solid steel, force pulsations, and cuts in steel. View full abstract»

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      Magnetic Actuator Transient Operation

      Brauer, J.
      Magnetic Actuators and Sensors

      DOI: 10.1002/9781118779262.ch09
      Copyright Year: 2014

      Wiley-IEEE Press eBook Chapters

      This chapter discusses the transient effects of turning on (or off) the direct current (DC) and alternating current (AC) currents or voltages. The basic timeline for transient operation of magnetic actuators consists of many steps. For many applications, a time delay slows the speed of response. The steps discussed in the chapter are: (i) the magnetic flux density rises, partly determined by a time constant called the magnetic diffusion time or nonlinear infusion time; (ii) the force rises as the magnetic flux density rises; (iii) the force produces acceleration of the armature and/or attached mass; and (iv) after a certain time, during which the armature may or may not reach the end of its stroke, the energizing circuit may be turned off; if the current suddenly becomes zero, then the magnetic flux density (and related force) falls, partly determined by the magnetic diffusion time or nonlinear effusion time. View full abstract»

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      Hall Effect and Magnetoresistive Sensors

      Brauer, J.
      Magnetic Actuators and Sensors

      DOI: 10.1002/9781118779262.ch10
      Copyright Year: 2014

      Wiley-IEEE Press eBook Chapters

      Usually magnetic sensors output a signal voltage along with little or no current. The magnetic fields sensed may vary over an extremely broad range. Magnetic sensors using the Hall effect are very common, small, and inexpensive. This chapter examines the behavior, accuracy, and construction of typical Hall sensors. Along with the Hall effect, it describes a related parameter called magnetoresistance. The chapter discusses Hall voltage equation, Hall effect conductivity tensor, finite-element computation of Hall fields, position sensors, mangnetoresistive heads, and giant magnetoresistance (GMR) sensors. View full abstract»

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      Other Magnetic Sensors

      Brauer, J.
      Magnetic Actuators and Sensors

      DOI: 10.1002/9781118779262.ch11
      Copyright Year: 2014

      Wiley-IEEE Press eBook Chapters

      Besides the Hall effect and magnetoresistive sensors, many other types of magnetic sensors are commonly used. This chapter examines these major remaining types of magnetic sensors. The sensors covered in the chapter are: speed sensors based on Faraday's law, inductive recording heads, proximity sensors using impedance, linear variable differential transformers (LVDTs), magnetorestrictive (MR) sensors, fluxgate sensors, Chattock coil field and current sensors, squid magnetometers, magnetoimpedance and miniature sensors, and microelectromechanical systems (MEMS) sensors. View full abstract»

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      Coil Design and Temperature Calculations

      Brauer, J.
      Magnetic Actuators and Sensors

      DOI: 10.1002/9781118779262.ch12
      Copyright Year: 2014

      Wiley-IEEE Press eBook Chapters

      Magnetic actuators and sensors are often components of large systems, such as automobiles. The actuators and sensors must perform reliably in the system environment and interface properly with the system. To interface properly with system power supplies, the coils of the magnetic components must be properly designed. As part of the coil design, the temperatures developed by the coils and the components must be predicted. This chapter discusses the coil design and temperature calculations for magnetic actuators and sensors. The concepts discussed in the chapter are wire size determination for direct current (DC) currents, coil time constant and impedance, skin effects and proximity effects for alternating current (AC) currents, and finite-element computation of temperatures. View full abstract»

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      Electromagnetic Compatibility

      Brauer, J.
      Magnetic Actuators and Sensors

      DOI: 10.1002/9781118779262.ch13
      Copyright Year: 2014

      Wiley-IEEE Press eBook Chapters

      Just as the magnetic device design must be compatible with system voltages and temperatures, the device must also possess electromagnetic compatibility (EMC). EMC is related to electromagnetic interference (EMI). Magnetic actuators and sensors must not produce unacceptable EMI, nor have their performance affected adversely by EMI. This chapter discusses the important concepts regarding EMC. The concepts discussed are signal-to-noise ratio, shields and apertures, and test chambers including transverse electromagnetic (TEM) transmission lines, TEM cells and triplate cells. View full abstract»

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      Electromechanical Finite Elements

      Brauer, J.
      Magnetic Actuators and Sensors

      DOI: 10.1002/9781118779262.ch14
      Copyright Year: 2014

      Wiley-IEEE Press eBook Chapters

      For magnetic actuators and sensors, mechanical parameters usually influence performance more than any other nonelectromagnetic parameters. For example, armature mass directly affects the speed of response of a magnetic actuator. This chapter uses electromechanical finite elements to analyze the behavior of magnetic actuators and sensors. An electromagnetic finite-element formulation that is capable of analyzing all types of electromagnetic fields is described in the chapter. To allow nonrigid body motion, that is, deformations and stresses, structural finite elements can be used. Structural finite-element analysis is very commonly used to compute mechanical stresses and other mechanical parameters. The chapter shows examples where the motion is small enough such that no element reconnection is required. All results are obtained by time stepping using both nonlinear electromagnetic and structural-finite elements. View full abstract»

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      Electromechanical Analysis Using Systems Models

      Brauer, J.
      Magnetic Actuators and Sensors

      DOI: 10.1002/9781118779262.ch15
      Copyright Year: 2014

      Wiley-IEEE Press eBook Chapters

      While the finite-element techniques accurately predict electromechanical behavior of magnetic devices, many engineers need systems models instead. Design of such systems is carried out nowadays using systems software such as SPICE, MATLAB, and Simplorer. This chapter discusses how magnetic actuators and sensors can be modeled with such systems software. Since most magnetic devices are connected to electric circuits, electric circuit simulation software is appropriate. If an equivalent electric circuit can be found for the magnetic device, then it can be inserted in the circuit software. The development and simulation of VHDL-AMS models is supported by Simplorer. It contains wizards, importers, exporters, schematics, netlists, digital stimuli, and other VHDL-AMS modeling capabilities. MATLAB performs engineering calculations with and without matrices. Simulink provides efficient graphical way for MATLAB users to model and simulate control systems in block diagram form. The chapter demonstrates a simple way to include eddy current effects in systems models. View full abstract»

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      Coupled Electrohydraulic Analysis Using Systems Models

      Brauer, J.
      Magnetic Actuators and Sensors

      DOI: 10.1002/9781118779262.ch16
      Copyright Year: 2014

      Wiley-IEEE Press eBook Chapters

      In many cases, especially with computer control, the input to the hydraulic system is electrical. The usual coupling devices are magnetic actuators and sensors. The most common way of utilizing electric power as well as optional computer control is through the magnetically operated hydraulic valve. While multistage systems have been common in the past to produce large forces in large aircrafts, the trend today to increase efficiency is toward one stage that uses electrohydraulics. The electric circuits in SPICE can be used to model hydraulic circuits by the analogies; for linear orifices, the ordinary constant resistor suffices. A hydraulics library is available for Simplorer. One of its hydraulic elements, the variable orifice, is used to model a control valve operated by the Bessho magnetic actuator. Digital hydraulics includes digital valves, pumps, and cylinders, and can theoretically unload a railcar full of logs or coal with zero net power consumption. View full abstract»

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      Appendix A: Symbols, Dimensions, and Units

      Brauer, J.
      Magnetic Actuators and Sensors

      DOI: 10.1002/9781118779262.app1
      Copyright Year: 2014

      Wiley-IEEE Press eBook Chapters

      No Abstract. View full abstract»

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      Appendix B: Nonlinear Curves

      Brauer, J.
      Magnetic Actuators and Sensors

      DOI: 10.1002/9781118779262.app2
      Copyright Year: 2014

      Wiley-IEEE Press eBook Chapters

      No Abstract. View full abstract»

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      Appendix C: Final Answers for Odd-Numbered Problems

      Brauer, J.
      Magnetic Actuators and Sensors

      DOI: 10.1002/9781118779262.app3
      Copyright Year: 2014

      Wiley-IEEE Press eBook Chapters

      No Abstract. View full abstract»

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      Index

      Brauer, J.
      Magnetic Actuators and Sensors

      DOI: 10.1002/9781118779262.index
      Copyright Year: 2014

      Wiley-IEEE Press eBook Chapters

      No Abstract. View full abstract»