Magnetic Actuators and Sensors

MAGNETIC ACTUATORS AND SENSORS......Page 3
Contents......Page 7
Preface......Page 13
PART I MAGNETICS......Page 15
1.1 Overview of Magnetic Actuators......Page 17
1.2 Overview of Magnetic Sensors......Page 18
1.3 Actuators and Sensors in Motion Control Systems......Page 19
References......Page 20
2.1.1 Gradient......Page 21
2.1.3 Curl......Page 23
2.2 Ampere’s Law......Page 26
2.3 Magnetic Materials......Page 29
2.4 Faraday’s Law......Page 32
2.5 Potentials......Page 36
2.6 Maxwell’s Equations......Page 38
Problems......Page 40
References......Page 42
3.1 Simplifying Ampere’s Law......Page 43
3.2 Applications......Page 46
3.4 Complex Reluctance......Page 50
References......Page 51
4.1 Energy Conservation and Functional Minimization......Page 53
4.2 Triangular Elements for Magnetostatics......Page 54
4.3 Matrix Equation......Page 56
4.4 Finite-Element Models......Page 58
Problems......Page 62
References......Page 63
5.1 Magnetic Flux Line Plots......Page 65
5.2 Magnetic Energy......Page 70
5.3 Magnetic Force on Steel......Page 71
5.4 Magnetic Pressure on Steel......Page 74
5.6 Permanent Magnets......Page 76
5.7 Magnetic Torque......Page 80
References......Page 81
6.1.1 Definition and Evaluation......Page 83
6.1.2 Relation to Force and Other Parameters......Page 84
6.2.1 Definition and Evaluation......Page 86
6.2.2 Relation to Force and Other Parameters......Page 88
6.3.1 Definition......Page 89
6.3.2 Relation to Energy and Force......Page 90
6.4 Impedance......Page 91
References......Page 94
PART II ACTUATORS......Page 97
7.1.1 Clapper Armature......Page 99
7.1.2 Plunger Armature......Page 105
7.2 Voice Coil Actuators......Page 110
7.3 Other Actuators Using Coils and Permanent Magnets......Page 111
7.4 Proportional Actuators......Page 112
7.5 Rotary Actuators......Page 115
Problems......Page 118
References......Page 119
8.1 Skin Depth......Page 121
8.2.1 Laminated Steel......Page 122
8.2.2 Equivalent Circuit......Page 123
8.2.3 Solid Steel......Page 125
8.3.1 Force with Single AC Coil......Page 127
8.3.2 Force with Added Shading Coil......Page 128
8.4 Cuts In Steel......Page 130
8.4.1 Special Finite-Element Formulation......Page 131
8.4.2 Loss and Reluctance Computations......Page 132
Problems......Page 136
References......Page 137
9.2 Size, Force, and Acceleration......Page 139
9.3.1 Steel Slab Turnon and Turnoff......Page 142
9.3.2 Steel Cylinder......Page 145
9.4.2 Transient Finite-Element Computations for Steel Slabs......Page 146
9.4.3 Simple Equation for Steel Cylinder with “Step” B–H......Page 149
9.4.4 Transient Finite-Element Computations for Steel Cylinders......Page 150
Problems......Page 152
References......Page 156
PART III SENSORS......Page 157
10.1 Simple Hall Voltage Equation......Page 159
10.2 Hall Effect Conductivity Tensor......Page 160
10.3.1 Unsymmetric Matrix Equation......Page 163
10.3.2 2D Results......Page 164
10.3.3 3D Results......Page 170
10.4 Toothed Wheel Hall Sensors for Position......Page 171
10.5.1 Classical Magnetoresistance......Page 173
10.5.3 Newest Forms of Magnetoresistance......Page 174
10.6 Magnetoresistive Heads for Hard-Disk Drives......Page 175
References......Page 176
11.1 Speed Sensors Based on Faraday’s Law......Page 179
11.2 Inductive Recording Heads......Page 181
11.3 Proximity Sensors Using Impedance......Page 183
11.3.1 Stationary Eddy Current Sensors......Page 184
11.3.2 Moving Eddy Current Sensors......Page 187
11.4 Linear Variable Differential Transformers......Page 188
11.5 Magnetostrictive Sensors......Page 191
11.6 Flux Gate Sensors......Page 193
11.7 Magnetometers and Motes......Page 195
References......Page 200
PART IV SYSTEMS......Page 203
12.1 Wire Size Determination for DC Currents......Page 205
12.2 Coil Time Constant and Impedance......Page 208
12.3 Skin Effects and Proximity Effects for AC Currents......Page 209
12.4.1 Thermal Conduction......Page 213
12.4.2 Thermal Convection and Thermal Radiation......Page 215
12.4.3 AC Magnetic Device Cooled by Conduction, Convection, and Radiation......Page 216
References......Page 220
13.1 Signal-to-Noise Ratio......Page 223
13.2 Shields and Apertures......Page 224
13.3.1 TEM Transmission Lines......Page 229
13.3.3 Triplate Cells......Page 231
References......Page 234
14.1 Electromagnetic Finite-Element Matrix Equation......Page 237
14.2 0D and 1D Finite Elements for Coupling Electric Circuits......Page 239
14.3 Structural Finite-Element Matrix Equation......Page 242
14.4 Force and Motion Computation by Timestepping......Page 246
14.5.1 DC Solenoid with Slowly Rising Input Current......Page 248
14.5.2 DC Solenoid with Step Input Voltage......Page 249
14.5.3 AC Clapper Solenoid Motion and Stress......Page 252
Problems......Page 256
References......Page 258
15.1.2 Simple LR Circuits......Page 261
15.1.3 Tables of Nonlinear Flux Linkage and Force......Page 263
15.1.4 Analogies for Rigid Armature Motion......Page 264
15.1.5 Maxwell SPICE Model of Bessho Actuator......Page 265
15.1.6 Simplorer Model of Bessho Actuator......Page 266
15.2.2 Model of Solenoid Actuator......Page 268
15.3.1 Software......Page 272
15.3.2 MATLAB Model of Voice Coil Actuator......Page 273
15.4.1 Resistor for Planar Devices......Page 278
15.4.2 Resistor for Axisymmetric Devices......Page 279
References......Page 282
16.1 Comparing Hydraulics and Magnetics......Page 285
16.2 Hydraulic Basics and Electrical Analogies......Page 286
16.3 Modeling Hydraulic Circuits in SPICE......Page 288
16.4 Electrohydraulic Models in SPICE and Simplorer......Page 291
16.5.1 Valves and Cylinders......Page 297
16.5.2 Use in SPICE Systems Models......Page 300
16.6 Magnetic Diffusion Resistor in Electrohydraulic Models......Page 306
Problems......Page 310
References......Page 311
Appendix: Symbols, Dimensions, and Units......Page 313
Index......Page 315