Inductive Sensors for Industrial Applications

This practical guide provides a comprehensive survey of all relevant inductive sensor classes for industrial applications in a single volume, from automotive use to white goods, covering design, fabrication, implementation, principles and functionality as well as standards and EMC requirements. The book addresses professional engineers and technicians, but is also accessible to students who require a solid basic knowledge of inductive sensors. Each chapter begins with classic, traditional explanations and gradually moves on to state-of- the art analog and digital solutions, including large-scale integrated systems-on-chip, software defined sensors SDS, digital signal synthesis, coils on silicon and active inductors. The book employs three modern analysis methods: analytic computation; popular graphical methods (phasor diagrams, phase plans, Smith charts, etc.) and computer assisted tools, like the electromagnetic field simulator, Maxwell, and the popular Spice simulator for electronic circuits. For traditional solutions, the chapters give overviews in tables with computation formulae (including empirical expressions). Numerical examples help the reader consolidate the theoretical knowledge gained. Concrete examples for currently available commercial parts are provided. Inductive Sensors for Industrial Applications......Page 1 Contents......Page 8 Introduction......Page 16 1.1.1 Sensor or Transducer......Page 18 1.1.2 IEEE Sensor Definition and Block Diagram......Page 19 1.2.1 Contact or Contactless Detection......Page 20 1.2.3 Absolute or Incremental Reading......Page 21 1.3.1 Supply Conditions and Limitations......Page 22 1.3.2 Sensing Range, Zero and Span, and Hysteresis......Page 23 1.3.3 Sensitivity and Nonlinearity, Linearity Error......Page 24 1.3.4 Accuracy, Resolution, and Repeatability: Three Precision Criterions......Page 26 1.3.5 Drift, Temperature Effects, and Temperature Ranges......Page 27 1.3.6 Dynamic Specification, Response Time and Cut-off Frequency, and Turn on and Turn off Times......Page 28 1.3.7 Analog, Binary or Digital, and Voltage or Current Output Types......Page 29 References......Page 33 Chapter 2 Inductive Proximity Sensors: Standards, EMC/EMI, Safety, Reliability, and Availability......Page 36 2.1.1 International Electrotechnical Commission Standard IEC 60947-5-2......Page 37 2.1.2 International Electrotechnical Commission Standard IEC 60947-5-7......Page 49 2.2 Basic and Specific EMC/EMi Standards......Page 52 2.2.2 Resilience Against Radiated Electromagnetic Fields......Page 55 2.2.3 Resilience Against Fast Transients: EFT, Burst......Page 56 2.2.4 Resilience Against Impulse Voltage (Surge)......Page 57 2.2.5 Resilience against Common Mode Conducted Disturbances......Page 58 2.3 Shock and Vibration Requirements......Page 59 2.4 International Protection Classification......Page 62 2.5 Intrinsic Safety, Product Safety Certification......Page 63 2.6.1 Mean Time Between Failures, Mean Time to Failure, and Failure Rate and Availability......Page 64 2.6.2 Highly Accelerated Life Test......Page 66 References......Page 67 3.1 Overview of the Sensor Classification......Page 68 3.2 Specific Embedding of Inductive Sensors......Page 70 3.3.1 Magnetoelastic Systems......Page 71 3.3.2 Electrodynamic Systems......Page 72 3.3.3 Electromagnetic Systems with Closed Magnetic Loop......Page 75 3.3.4 Electromagnetic Systems with Open Magnetic Loop......Page 83 3.3.5 Variable Differential Transformers......Page 89 3.3.6 Systems Based on the Eddy Currents Evaluation......Page 91 3.3.7 Variable Transformers: Microsyn, Synchro, and Resolver......Page 96 3.3.8 Final Considerations of Main Inductive Sensor Categories......Page 104 3.4.2 Global P&D Sensor Market......Page 105 3.4.3 Global IS Market......Page 107 References......Page 110 4.1.1 Inductors: Inductance, Impedance and Admittance......Page 112 4.1.2 Quality Factor of an Inductor......Page 119 4.1.3 Impedance and Q-Factor of a Resonant Circuit......Page 120 4.2 Measuring Methods to Evaluate the ISE......Page 125 4.2.1 Experimental Methods......Page 126 4.2.2 Measuring Methods Suitable to be implemented in ISE......Page 128 4.3.1 The fundamentals of the Computer-Aided Electromagnetic Field Simulation......Page 131 4.3.2 Field Simulation Software Tools......Page 136 4.3.3 Simulation with ANSYS Maxwell Tool......Page 137 4.3.4 Flow Chart of a Maxwell Field-Simulation Project: Concrete Example......Page 139 References......Page 148 5.1.1 The Solenoid......Page 150 5.1.2 The Toroid......Page 152 5.2 Wire-Wound Coils with Air Cores......Page 153 5.3 Wire-Wound Coils with Magnetic Cores......Page 154 5.3.1 Inductance of Wire-Wound Coils with Magnetic Cores......Page 155 5.3.2 Core Factor and Effective Core Parameters......Page 156 5.3.3 Losses Caused by Cores: Total Formula of the Inductor Impedance at Full Length......Page 158 5.4 Printed Flat Spiral Coils......Page 163 5.5 Integrated Coils on Silicon Substrate......Page 172 5.6 Active Inductors, Gyrators......Page 175 References......Page 178 6.1 Ferrites......Page 180 6.1.1 Ferrites: Classification, Definitions, and Properties......Page 181 6.1.3 Ferrites Core Manufacturing Process: Technical Core Types......Page 191 6.2 Permaloy and Mu-Metals......Page 198 6.3 Soft Iron Alloys......Page 202 References......Page 203 7.1 Generic Functional Diagram of the Inductive Sensor’s Evaluation Electronics......Page 204 7.2 Inductive Sensor with Discrete Evaluation Electronics......Page 207 7.3 Inductive Sensor with Integrated Evaluation Electronics......Page 210 7.3.1 Overview of Bipolar Integration Technology......Page 211 7.3.2 Overview of Complementary Metal-Oxide-Semiconductor Processes: Benchmarking CMOS versus Bipolar Technology......Page 222 7.3.3 Evaluation Electronics of Inductive Sensors with Integrated Circuits......Page 224 7.4.1 Single-ASIC Implementations: The Classical Device TCA505......Page 228 7.4.2 Multi-ASIC Versions......Page 235 7.4.3 Systems on Chip SOC......Page 240 7.5 Software-Defined Sensors: Fantasy or the Inductive Sensor of Tomorrow?......Page 248 References......Page 251 8.1 Theory of Resonant LC Circuits: Series versus Parallel......Page 254 8.1.1 Characteristics of the Series Resonant LC Circuit......Page 255 8.1.2 Characteristics of the Parallel Resonant LC Circuit......Page 256 8.2 General Theory of the Oscillator......Page 259 8.2.1 Harmonic Oscillator......Page 260 8.2.2 Linear Oscillator with Losses......Page 265 8.2.3 Oscillators with Loss Cancellation by Positive Feedback Operation......Page 267 8.3 Convenient Types of LC Oscillators for Inductive Sensors......Page 274 8.3.1 Transistor-Based, Positive-Feedback Oscillators......Page 275 8.3.2 Ring-Circuit Oscillators with LC Dipole......Page 282 8.3.3 Differential Amplifier Oscillators with LC Dipole......Page 293 8.3.4 Bridge-Network Oscillators......Page 297 8.3.5 Oscillators with Pulsing DC Current Excitation......Page 300 8.3.6 Negative-Resistance Oscillators......Page 302 8.5 Function Generators......Page 322 8.5.1 Relaxation Oscillators......Page 323 8.5.2 Self-Oscillating Function Generators......Page 324 8.5.3 Timer-Chip NE555......Page 326 8.5.4 Digitally Synthesized Function Generators......Page 329 References......Page 330 9.1 Signal Amplifiers......Page 332 9.1.1 Operational Amplifiers: Definition and Applications......Page 333 9.1.2 Operational Amplifiers: Frequency Response, Stability, and Compensation......Page 337 9.2 Precision AC/DC Signal Converters......Page 346 9.2.1 Precision Rectifiers......Page 347 9.2.2 Peak Detectors......Page 350 9.2.3 Synchronous Rectifiers......Page 354 9.3 Sample-and-Hold Systems......Page 358 9.4 Signal Linearization, Linearization Methods......Page 360 9.4.1 Analog Hardware-Based Linearization......Page 362 9.4.2 Software-Based Linearization......Page 364 9.4.3 Logic Hardware Linearization......Page 366 9.4.4 Hardware-Software Mixed Approaches......Page 367 9.4.5 Artificial Neural Networks Approaches......Page 369 9.5 Comparators, Window Discriminators......Page 370 9.6 Regenerative Comparators (Schmitt Trigger)......Page 372 9.7 Phase-Locked Loop Circuits......Page 374 9.7.2 Analog PLL: Architecture and Operation......Page 376 9.7.3 PLL Linear Analysis, Stability......Page 378 9.7.4 Digital PLLs......Page 379 9.8.1 Digital-to-Analog Converters......Page 382 9.8.2 Analog-to-Digital Converters......Page 385 References......Page 388 10.1.1 Voltage Output Stages......Page 390 10.1.2 Current Telemetry: Current Output Stages......Page 392 10.1.3 Ratiometric Voltage Outputs......Page 397 10.2 Output Drivers for Digital Inductive Sensors......Page 398 10.2.1 Switched Inductive Loads, Voltage Clamps......Page 399 10.2.2 Output Drivers with Commercial Parts......Page 401 10.2.3 Monolithic Integrated Output Drivers in ASICs......Page 405 References......Page 407 11.1 Power Supply Circuits......Page 408 11.1.1 Series Voltage Regulators/References......Page 409 11.1.2 Shunt Voltage Regulators......Page 413 11.2 Standard and Supplimentary Sensor Protection Functions......Page 416 11.2.2 Reversed Polarity Protection......Page 417 11.2.3 Protection against High-Energetic Pulses (Surge)......Page 419 References......Page 423 Chapter 12 Inductive Sensors: Adjustment and Calibration......Page 424 12.1.1 Trimmable Resistors......Page 425 12.1.2 Rejustor......Page 427 12.1.3 Manual Mechanical Potentiometers......Page 428 12.1.4 Digital Potentiometers......Page 430 12.2 Specific Programmable Electronic Devices used to Calibrate Inductive Sensors......Page 433 12.2.1 Established Methods for the Trimming of Inductive Sensors......Page 434 12.2.2 ASIC and ASIC Sections for Trimming of Inductive Sensors.......Page 439 References......Page 450 13.1.1 Passive Temperature Probes......Page 452 13.1.2 Active Temperature-Dependent Circuits......Page 456 13.1.3 Active Temperature-Independent References: Bandgap References......Page 460 13.2 Theoretical Considerations Regarding the Temperature Behavior of ISEs......Page 463 13.3 Improvement of the Temperature Behavior by Passive Temperature Compensations......Page 467 13.4 Active Analog Hardware-Based Temperature Compensation Methods of ISs......Page 468 13.5 Active and Digital Temperature Compensation Methods of ISs......Page 472 References......Page 480 14.1.1 Communication Network Topologies......Page 482 14.1.2 Network Access Procedures......Page 484 14.1.3 Industrial Fieldbuses: Definition and Features......Page 486 14.1.4 ISO/OSI Network Reference Model......Page 488 14.2 Requirement Description for the Sensor and Actuator Communication Level......Page 491 14.3 Intelligent Sensors: Diagnosis Features......Page 492 14.4.1 RS-232......Page 494 14.4.2 RS-422 and RS-485......Page 495 14.5 Synchronous Serial Buses for Sensors......Page 496 14.5.2 2-Wire Interintegrated Interface......Page 497 14.6.1 AS Interface at a Glance......Page 499 14.6.2 AS Interface Slave Specification......Page 501 14.6.3 ISO Reference Model of the AS Interface......Page 502 14.7.1 IO-Link at a Glance......Page 506 14.7.2 ISO Reference Model of the IO-Link Interface......Page 507 14.7.3 IO-Link Communication Flow......Page 512 14.7.4 IO-Link Hardware......Page 513 References......Page 515 Key to the Symbols for Electronic Components......Page 518 Acronyms and Abbreviations......Page 520 Nomenclature of Electromagnetic Quantities......Page 526 About the Author......Page 528 Index......Page 530 Recent Titles in the Artech House Microelectromechanical Systems (MEMS) Series......Page 544