EMI Filter Design  book cover
3rd Edition

EMI Filter Design

ISBN 9781439844755
Published September 23, 2011 by CRC Press
272 Pages 148 B/W Illustrations

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USD $290.00

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Book Description

With today’s electrical and electronics systems requiring increased levels of performance and reliability, the design of robust EMI filters plays a critical role in EMC compliance. Using a mix of practical methods and theoretical analysis, EMI Filter Design, Third Edition presents both a hands-on and academic approach to the design of EMI filters and the selection of components values. The design approaches covered include matrix methods using table data and the use of Fourier analysis, Laplace transforms, and transfer function realization of LC structures. This edition has been fully revised and updated with additional topics and more streamlined content.

New to the Third Edition

  • Analysis techniques necessary for passive filter realization
  • Matrix method and transfer function analysis approaches for LC filter structure design
  • A more hands-on look at EMI filters and the overall design process

Through this bestselling book’s proven design methodology and practical application of formal techniques, readers learn how to develop simple filter solutions. The authors examine the causes of common- and differential-mode noise and methods of elimination, the source and load impedances for various types of input power interfaces, and the load impedance aspect of EMI filter design. After covering EMI filter structures, topologies, and components, they provide insight into the sizing of components and protection from voltage transients, discuss issues that compromise filter performance, and present a goal for a filter design objective. The text also includes a matrix method for filter design, explains the transfer function method of LC structures and their equivalent polynomials, and gives a circuit design example and analysis techniques. The final chapter presents packaging solutions of EMI filters.

Table of Contents

EMI Filters
Technical Challenges
Types of EMI Filters
No Such Thing as Black Magic
It Is All in the Mathematics

Why Call EMI Filters Black Magic?
What Is EMI?
Regular Filters versus EMI Filters
Specifications: Real or Imagined
The Inductive Input for the 220-A Test Method
The 400-Hz Filter Compared with the 50- or 60-Hz Filter

Common Mode and Differential Mode: Definition, Cause, and Elimination
Definition of Common and Differential Modes
The Origin of Common-Mode Noise
Generation of Common-Mode Noise—Load
Elimination of Common-Mode Noise—Line and Load
Generation of Differential-Mode Noise?
Three-Phase Virtual Ground

EMI Filter Source Impedance of Various Power Lines
Skin Effect
Applying Transmission Line Concepts and Impedances
Applying Transmission Line Impedances to Differential and Common Mode
Differences among Power Line Measurements
Simple Methods of Measuring AC and DC Power Lines
Other Source Impedances

The Various AC Load Impedances
The Resistive Load
Off-Line Regulator with Capacitive Load
Off-Line Regulator with an Inductor ahead of the Storage Capacitor
The Power Factor Correction Circuit
Transformer Load
The UPS Load

DC Circuit—Load and Source
Various Source Impedance
Switcher Load
DC Circuit for EMI Solutions or Recommendations
Some Ideas for the Initial Power Supply
Other Parts of the System
Lossy Components
Radiated Emissions

Typical EMI Filters—Pros and Cons
The π Filter
The T Filter
The L Filter
The Typical Commercial Filter
The Cauer Filter
The RC Shunt
The Conventional Filters

Filter Components—the Capacitor
Capacitor Specifications
Capacitor Construction and Self-Resonant Frequency
Veeing the Capacitor
Margins, Creepage, and Corona—Split Foil for High Voltage
Capacitor Design—Wrap-and-Fill Type

Filter Components—the Inductor
Inductor Styles and Specifications
Core Types
High-Current Inductors
Inductor Design
Converting from Unbalanced to Balanced

Common-Mode Components
The Capacitor to Ground
Virtual Ground
Z for Zorro
Common-Mode Inductor
Common-Mode Calculation
Differential Inductance from a Common-Mode Inductor
Common-Mode Currents—Do They All Balance?

The Transformer’s Addition to the EMI Filter
Transformer Advantages
Leakage Current
Common Mode
Voltage Translation—Step Up or Down
The Transformer as a Key Component of the EMI Package
Skin Effect

Electromagnetic Pulse and Voltage Transients
Unidirectional versus Bidirectional
The Three Theories
Initial High-Voltage Inductor
The Arrester Location
How to Calculate the Arrester
The Gas Tube

What Will Compromise the Filter?
Power Supplies—Either as Source or Load
9- and 15-Phase Autotransformers
Neutral Wire Not Part of the Common-Mode Inductor
Two or More Filters in Cascade—the Unknown Capacitor
Poor Filter Grounding
The "Floating" Filter
The Unknown Capacitor in the Following Equipment
Filter Input and Output Too Close Together

Waves as Noise Sources
The Spike
The Pulse
The Power Spectrum—dB μA/MHz
MIL-STD-461 Curve

Initial Filter Design Requirements
Differential-Mode Design Goals
The Differential-Mode Filter Input Impedance
The Differential-Mode Filter Output Impedance
The Input and Output Impedance for a DC Filter
Common-Mode Design Goals
Estimation of the Common-Mode Source Impedance
Methods of Reducing the Inductor Value due to High Current

Matrices, Transfer Functions, and Insertion Loss
Synthesis, Modeling, and Analysis
Review of the A Matrix
Transfer Functions
Review of Matrix Topologies
The π Filter
The L Matrix
The T Filter
The Cauer or Elliptic Matrix
The RC Shunt
Filter Applications and Thoughts
Single-Phase AC Filter
Three-Phase Filters
Low-Current Wye
High-Current Wye
The Single Insert
The Low-Current Delta
High-Current Delta
Telephone and Data Filters
Pulse Requirements—How to Pass the Pulse
The DC-DC Filter
Low-Current Filters

Matrix Applications: A Continuation of Chapter 16
The Impedance of the Source and Load
dB Loss Calculations of a Single π Filter
Example of the Calculations for a Single π Filter
Double π Filter: Equations and dB Loss
Triple π Filter: Equations and dB Loss

Network Analysis of Passive LC Structures
Lossless Networks
Network Impedances Using Z Parameters
Network Admittances Using Y Parameters
Transfer Function Analysis—H(jω)
Transfer Function Analysis—H(s)
Coefficient-Matching Technique
EMI Filter Stability

Filter Design Techniques and Design Examples
Filter Design Requirements
Design Techniques
Filter Design Summary
EMI Filter Design Example
Four-Pole LC Structure

Packaging Information
The Layout
Estimated Volume
Volume-to-Weight Ratio
Potting Compounds

Appendix A: K Values of Different Topologies
Appendix B: LC Passive Filter Design
Appendix C: Conversion Factors


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Richard Lee Ozenbaugh is a consultant of EMI filter design and magnetics engineering for such companies as Hughes Aircraft Corporation, Parker Hannifin Aerospace, Franklin Electric, McDonnell Douglas, and Cirrus Logic. Involved in the electrical and electronics industries since the early 1950s, he has worked as a radar specialist for the U.S. Navy as well as an engineer for Hopkins Engineering and RFI Corporation.

Timothy M. Pullen is a principal electrical engineer at Rockwell Collins. He has over 25 years of experience in the research, design, and development of electronic systems for commercial and military applications, including power electronics, motor control, and full authority digital engine control technology. His areas of expertise include model-based design and control, analog circuit design, and filter design.


"This 3rd edition book is an excellent resource for solving EMI problems. It provides a systematic procedure for identifying noise sources and provides the design tools needed to solve problems. It will be an invaluable reference book for working electrical engineers as well as students who want to learn about EMI filtering and EMI noise problems. ... The book is filled with design equations that can be immediately put to use by the reader. This book can be a guidebook for diagnosing troublesome EMI issues in existing designs, and it can also be used to prevent EMI issues from occurring in the first place because of the information in this book. ... This is a book that should be used by every electrical engineer involved with EMI issues. It is filled with design equations, but more importantly it will provide you with an understanding of EMI issues, thus, making you a better design engineer."
—John J. Shea, IEEE Electrical Insulation Magazine, March/April, Vol. 29, No.2, 2013