MAGNETIC COMPONENTS FOR POWER ELECTRONICS

MAGNETIC COMPONENTS FOR POWER ELECTRONICS

MAGNETIC COMPONENTS FOR POWER ELECTRONICS by Alex Goldman Ferrite Technology Worldwide, US.A. SPRINGER SCIENCE+BUSINESS MEDIA, LLC

ISBN 978-1-4613-5280-8 ISBN 978-1-4615-0871-7 (ebook) DOI 10.1007/978-1-4615-0871-7 Library of Congress Cataloging-in-Publication Data A c.i.p. Catalogue record for this book is available from the Library of Congress. Copyright 2002 by Springer Science+Business Media New York Originally published by Kluwer Academic Publishers in 2002 Softcover reprint ofthe hardcover lst edition 2002 AII rights reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means, mechanical, photocopying, record ing, or otherwise, without the prior written permission of the publisher, Springer Science+Business Media, LLC. Printed on acid-free paper.

TABLE OF CONTENTS Preface Acknowledgements xi xiii Chapter I-Applications and Topologies for Power Electronic Systems 1 Introduction-History of Power Electronics 1 1.1- Applications for Power Electronics 2 1.2- Power Converters 3 1.3- Basic Topologies for Power Converters 4 1.4- Practical Converter Topologies 8 1.4.1- Flyback Converter 8 1.4.2- Forward Converter 9 1.4.3- Push Pull Converter 10 1.5- Converter Strengths and Weaknesses 10 1.6- The Hysteresis Loop for Power Materials 11 1.7- Switching Power Supplies 13 1.8- Ferroresonant Converters 15 1.9- Soft Switching in Common Topologies 19 Summary 20 Chapter 2- Main Considerations for Magnetic Component Choice 25 Introduction 25 2.1- Considerations Based on Component Function 25 2.2- Magnetic Component Choices 26 2.3- Components for Power Transformers 26 2.4- Ferrite Power Transformers 27 2.4.1- Frequency-Voltage Considerations 28 2.4.2- Frequency-Loss Considerations 30 2.4.3- Choosing the Best Ferrite Power Transformer Material 32 2.4.4- Power Ferrite Core Shapes 33 2.4.5- Component Processing after Assembly 34 2.4.6- High Frequency Applications 34 2.5- Metal Strip Power Transformers 35 2.6- Amorphous Metal Strip Cores 35 2.7- Nanocrystalline-Based Power Transformers 37 2.8- Cost Considerations for Magnetic Components 37 2.9- Competitive High Frequency Power Materials 38 2.10- Design Considerations in Component Choice 38 2.11- Ferrites Versus Metallic Magnetic Materials 39 2.12- Output Power Inductors 41 2.12.1- Ferrite Versus Metallic Power Inductors 41 2.13- Power Factor Correction Cores 46

vi MAGNETIC COMPONENTS FOR POWER ELECTRONICS 2.14- Magnetic Amplifier Cores 46 2.15- Pulse Transformers 48 2.16- Components for EMI Suppression 49 2.16.1- Materials for EMI suppression 50 2.16.2- Amorphous and Nanocrystalline Materials for EMISuppression 50 2.17- Common-Mode Filters 51 Summary 53 Chapter 3- Magnetic Materials for Power Electronics 55 Introduction 55 3.1- Soft Ferrites for Power Electronics 55 3.1.1- Ferrite Material Permeabilities 56 3.1.1.1- Initial Permeabilities 57 3.1.1.2- Amplitude Permeability 58 3.1.1.3- Maximum Permeability 59 3.1.1.4- Permeability-Temperature Dependence 59 3.1.1.5- Complex Permeability 61 3.1.2- Saturation Induction for Ferrite Materials 61 3. 1.2. I-Temperature Dependence of Saturation 61 3.1.3-Core Losses 64 3.1.4- Output Power Considerations-Performance Factor 66 3.1.5- Curie Temperature 67 3.1.6- Resistivity 68 3. 1. 7- Density 69 3.1.8- Remanence and Squareness 69 3.1.9- Coercive Force 69 3.1.1 0- Ferrite Power Inductor Materials 69 3.1.11-Magnetic Properties-Ferrite Common-Mode Materials 70 3.1.l2- Magnetic Properties of Ferrite EMI Materials 71 3.1.13- Frequency Characteristics of EM I Materials 75 3.2- Magnetic Properties of Metallic Strip Materials 76 3.2.1- Permeabilities-Metallic Magnetic Strip Materials 76 3.3- Amorphous Metal Magnetic Materials 76 3.3. I-Advantages of Amorphous Magnetic Metals 79 3.3.2- Disadvantages ofiron-based Amorphous Alloys 79 3.3.3- Processing of Amorphous Metals 81 3.3.4- Amorphous Metals- High Perm-High Frequency 81 3.4- Nanocrystalline Materials 86 3.4.1- Nanocrystalline Materials-High Frequency Power 86 3.4.2-Amorphous-Nanocrystalline Materials for EMI 90 3.5- Powder Core Materials-Output Chokes, EMI and PFC 91 3.5.1- Iron Powder Cores 93 3.5.2- NiFe Powder Core Materials 97 3.5.3- Sen dust Powder Material 100

TABLE OF CONTENTS vii Chapter 4- Core Shapes for Power Electronics 105 Introduction 105 4.1- Ferrite Core Shapes 105 4.1.1- Pot Cores 105 4.1.2- Doube-Slab Cores 106 4.l.3- RM Cores and PM Cores 107 4.1.4-ECores 108 4.1.5- E-C Cores 109 4.1.6- ETD Cores 110 4.1.7-E-RCores III 4.1.8- EP Cores III 4.1.9- PQ Cores 112 4.1.10- Toroids 112 4.1.11- EFD Cores 113 4.2- Effective Core Properties of Power Core Shapes 114 4.2.1- Measurement of Effective Permeability 116 4.2.2- Inductance Factor, AL 116 4.3- Gapped Cores 116 4.3.1- Pre-polarized Cores 117 4.4- Low Profile Ferrite Power Cores 119 4.5- Surface-Mount Design in Power Ferrites 119 4.6- Planar Technology 119 4.7- Integrated Magnetics 124 4.8- Core Shapes for Metal Strip Materials 125 4.9- Core Shapes for Metal Powder Components 125 S ~ m ~ 1 ~ Chapter 5- Core Sizes-Design Considerations in Power Electronics 127 Introduction 127 5.1- Determining the Size of the Transformer Core 127 5.1.1- Initial Considerations -Designing Transformer Core 128 5.1.2- Other Area Product Relationships 131 5.1.3- Voltage Regulation in Transformers 132 5.1.4- Other Transformer Design Techniques 134 5.1.4.1- Winding Loss-Limited Design 134 5.1.4.2- Regulated Limited Design 135 5.1.4.3- Saturation Limited Design 135 5.1.4.4- Core Loss-Limited Design 136 5.1.5- Power ferrite Limited Design from Vendors' Catalogs 138 5.1.5.1- Philips(Yageo) 138 5.1.5.2- Epcos (Siemens) 138 5.1.5.3-A VX (Thomson) 141 5.1.5.4- TDK 141 5.1.6- Ferrite Component Design-Power Transformers 142 5.1.6.1- Creepage Allowance 142 5.1.6.2-Effect of Core Size-Dimensional Resonance 144

viii MAGNETIC COMPONENTS FOR POWER ELECTRONICS 5.2-Thennal Characterization-Power Ferrite Cores 145 5.3-Winding Losses 146 5.4- Completing Transformer Design-Winding Data 146 5.5- Very High Frequency Power Ferrite Operation 147 5.6- Ferroresonant Transformers 150 5.7- Design of Power Inductors 151 5.7.1- Design of an Inductor for a Switching Regulator 152 5.7.2- McLyman Treatment ofinductor Design 155 5.7.3- Flyback Converter Design 156 5.8- Swinging Choke 160 5.9- Magnetic Amplifier-Multi-Output Design 161 Appendix 5.1- Design Example-McLyman Kg Approach 161 Appendix 5.2- Magnetics Inductor Design Method-Hanna Curves 164 Appendix 5.3- Magnetics Inductor Design for Switching Regulators 165 Appendix 5.4- McLyman Design-Switching Inductor- Kg Approach 168 Appendix 5.5- Output Inductor Design-Metglas R Amorphous Core 171 Appendix 5.6- Output Inductor-LPT E2000Q Nanocrystalline Core 173 Chapter 6-Commercially-Available Components for Power Electronics 181 Introduction 181 6.1- TDK Ferrite Power Electronics components 181 6.1.1- TDK Power Ferrite Materials 181 6.2- Philips (Yageo) Power Ferrite Components 182 6.3-Epcos (Siemens) Power Ferrite Components 185 6.4- Magnetics Power Ferrite Components 189 6.5- Tokin Power Ferrite Components 191 6.6- Fair-Rite Power Electronic Components 192 6.7- Ferronics Power Ferrite Components 192 6.8- FDK Power Ferrite Components 193 6.9- AVX (Thomson) Power Ferrite Components 193 6.10- MMG (Neosid) Power Ferrite Materials 193 6.11- Kaschke Power Ferrite Materials 194 6.12- Vogt Power Ferrite Materials 194 6.13- Samwha Power Ferrite Materials 194 6.14- Steward Power Ferrite Materials 195 6.15- Ferrite International (TSC) Power Ferrite Materials 195 6.16- Ceramic Magnetics Power Ferrite Materials 196 6.17- Tomita Power Ferrite Materials 196 6.18- Iskra Power Ferrite Materials 196 6.19- Domen Power Ferrite Materials 196 6.20- Hitachi power Ferrite Materials 197 6.21- Cosmo Power Ferrite Materials 197 6.22- Acme Power Ferrite Materials 197 6.23- Hinoday Power Ferrite Materials 198 6.24-Isu Power Ferrite Materials 198 6.25- Mianyang Power ferrite Materials 198 6.26- Hebei Power Ferrite Materials 198 Appendix 6. I-Listing of Catalog Data for Ferrite Suppliers 198

TABLE OF CONTENTS ix 6.27- Magnetics Metallic Magnetic Strio Materials 228 6.28- Arnold Metallic Magnetic Strip Materials 228 6.29- Honeywell (Metglas) Amorphous Metal Materials 228 6.30- Vacuumschmelze Amorphous and Nanocrystalline Alloys 229 6.31- Toshiba Amorphous Alloys 229 6.32- TDK Amorphous Metal Cores 229 6.33- CoreMaster Amorphous and Nanocrystaline Cores 229 6.34- Magnetec Nanocrystalline Cores 229 6.35 -Magnetics Powder Core Materials 229 6.36- Arnold Engineering Powder Core Materials 229 6.37- Micrometals Powdered Iron Cores 230 6.38- Pyroferric Powdered Iron Cores 230 Appendix 6.2-Listing of Catalog Data for Suppliers of Metallic Strip and Powder Cores 230 Summary 250 Chapter 7- Design Aids in Magnetic Component Choice for Power Electronics 251 Introduction 251 7.1- Books on Power Electronics 251 7.2- Power Electronics Magazines 252 7.3- Power Electronics Organizations 253 7.4- Power electronics Web Sites 254 7. 5- Power Electronics Conferences 254 7.6- Power Electronics at Universities and Research Labs 255 7.7- Power Electronics Web Tutorials 255 7.8- Power Electronics Software 255 7.9- Power Electronics Short Courses 256 7.10- Component Vendors' CDROM and Diskettes 256 7.11- Internet Web Sites 256 7.12- Magnetic Component Standards 256 Appendix 7. I-Recent Power Electronic on Specific Power Electronic Subjects 257 Appendix 7.2-IEC and ASTM Standards 260 Bibliography 265 Appendix I-Abbreviations and Symbols 269 Appendix 2-Addresses of Major Suppliers Power Electronic Components 275 Appendix 3-Units Conversion from CGS to MKS Systems 283 Index 285

Preface Power electronics is a rapidly-growing technology encompassing a large variety of applications including automotive, telecommunications, computers and alternative-energy systems. While the origin of modem power electronics was stimulated by the development of power semiconductor devices for high frequency switching purposes, other important and necessary accompanying component have been magnetic cores for transformers and inductors. This need has been especially true for the square wave features produced by solid-state switches that yield a plethora of higher harmonics. The heart of the new circuitry was the switched mode power supply (SMPS). As this new technology developed, there was an increased demand for miniaturization. Magnetic cores were traditionally the largest component in a solidstate circuit. Operation at higher frequencies was seen as a possible solution, As power semiconductors were designed for higher frequencies, the magnetic component suppliers were able to develop new materials and shapes that were optimized for the new conditions. Ferrites were found to be the most suitable materials for the low to medium wattage power supplies. In my fltst book, Modem Ferrite Technology, I said that "ferrites were the new kids on the block". While ferrites still maintain their dominance as power magnetic materials, "there are newer kids on the block ", namely amorphous and nanocrystalline materials. Although these materials are still in their infancy, they require more than a glancing look. My purpose in writing this book was to review the many changes that have taken place in the past 5-10 years in power magnetic components. Some ofthese changes are; 1. Changes in the management of several of the major magnetic component suppliers. These suppliers included Siemens, Philips, Thomson and Allied- Signal (Metglas ). 2. Changes in the available power magnetic materials to operate at higher frequencies and higher DC bias. 3. Greater use of low-profile and planar core shapes 4. The use of Power Function Correction (PFC), Resonant Converter and Soft-Switching Circuits 5. Greater emphasis on EMI requirements in Power electronic cir cuits. 6. The development of cores using amorphous and nanocrystalline materials. This book will discuss these changes and show how it affects power electronic component choice.

xii MAGNETIC COMPONENTS FOR POWER ELECTRONICS The main intent of this book is to advise power electronic design engineers and other magnetic component users as to the considerations that should be made in the choice of an optimum magnetic component for a particular application. This book was not intended to be a manual for the complete circuit design of a power electronic system. There are many other fine books that deal with this subject and some of the are listed in this book under the topic of design aids. Also missing from this book are the sections on basic magnetic theory and the physical, chemical and manufacturing aspects of ferrites. These are found in the author's book, Handbook of Modem Ferromagnetic Materials. There is, however, material-oriented information on the new amorphous and nanocrystalline materials since power components of these materials were not covered elsewhere. Aside from these new materials and ferrites, other metal strip materials and metal powder cores are also discussed. Suppliers of magnetic components may find this book useful as a guide to what properties are desired by the device or system engineer. The frrst chapter deals with the various power electronic topologies including those involved with switched mode power supplies and resonant converters. The second chapter list the considerations encountered in the choice of a magnetic component including the material and shape. The third chapter expands on the material properties while the fourth chapter is involved with component shape including low-profile, planar cores and integrated magnetics. Chapter 5 is involved with the final choice of the size of the core and the windings needed. Included are some examples including the steps in determining the optimum size. These examples include applications for ferrites, amorphous cores and nanocrystalline cores. The sixth chapter contains a compendium of catalog data from the major magnetic component manufacturers in the World. While the data for each individual core are not included (the book would be voluminous), the material parameters and core shapes available are included. The final chapter includes aids for magnetic component design including books, articles, manufacturers CD-ROM's or diskettes and Web sites. Appendices include Tables of Units Conversion, Symbols, IEC and ASTM Standards and Addresses of Major Magnetic Component Suppliers. Alex Goldman

ACKNOWLEDGEMENTS I would like to thank Professor Robert W. Erickson for permission to use some material from his recent book, Fundamentals of Power Electronics, 2 nd Edition. I would also like to thank Gordon "Ed" Bloom for permission to use some figures from his book, Modern DC-To-DC Switchmode Power Converter Circuits" and for discussions about this book. Thanks also are due to Colonel Wm. McLyman, a friend of many years for his useful design notes. Joe Huth III provided some photos of ferrite cores. I could not have written this book without the loving understanding of my wife, Adele, and the encouragement of my children, Mark, Beth and Karen.