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2004 | Buch

Automotive Electromagnetic Compatibility (EMC)

herausgegeben von: Terence Rybak, Mark Steffka

Verlag: Springer US

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SUCHEN

Über dieses Buch

Anyone who has operated, serviced, or designed an automobile or truck in the last few years has most certainly noticed that the age of electronics in our vehicles is here! Electronic components and systems are used for everything from the traditional entertainment system to the latest in “drive by wire”, to two-way communication and navigation. The interesting fact is that the automotive industry has been based upon mechanical and materials engineering for much of its history without many of the techniques of electrical and electronic engineering. The emissions controls requirements of the 1970’s are generally recognized as the time when electronics started to make their way into the previous mechanically based systems and functions. While this revolution was going on, the electronics industry developed issues and concepts that were addressed to allow interoperation of the systems in the presence of each other and with the external environment. This included the study of electromagnetic compatibility, as systems and components started to have influence upon each other just due to their operation. EMC developed over the years, and has become a specialized area of engineering applicable to any area of systems that included electronics. Many well-understood aspects of EMC have been developed, just as many aspects of automotive systems have been developed. We are now at a point where the issues of EMC are becoming more and more integrated into the automotive industry.

Inhaltsverzeichnis

Frontmatter
Chapter 1. What is EMC?
Abstract
This book is a study of the issues, experiences, and trends in automotive system electromagnetic compatibility (EMC). EMC and automotive systems is an area evolving from the early days of few electrical devices to the highly complex electronic components in vehicles. This book will look at how the EMC of automotive systems has become a major issue, and describe the tools and techniques of automotive systems EMC. We will look at various system components architectures and EMC issues that are associated with those systems.
Chapter 2. System Level Issues
Abstract
The study of EMC is required only when systems are involved. There are no EMC issues inherently associated with a switch, a spark plug, or even a microprocessor. These are components. EMC issues occur when components are operating and interface with the external environment. This will be explained in the following text.
Chapter 3. Power and Signal Return
Abstract
Many automotive EMC problems are attributed to “bad ground” connections. Bad ground seems to be the cause of many problems in all types of electrical circuits. The reason that there are bad ground connections is simple. There is not a “ground” anywhere on a vehicle! The reason there is no ground connection is also simple. The vehicle is intended to travel on the ground, not attached to it. Actually, the one time when there can be a ground connection on a vehicle this is shown in Figure 3.1:
Chapter 4. Basic Concepts Used in EMC
Abstract
Many EMC issues result from energy that is transferred by radiation from a source. In order to understand this radiation of energy, it is useful to refer to some basic electromagnetic principles. One of these principles is the “isotropic point radiator” of energy. As this point source has zero radius and radiates equally well in all directions. This is shown in Figure 4.1.
Chapter 5. Electromagnetic Fields
Abstract
Electromagnetic energy is transferred through propagation of waves. These waves can be described by their frequency, direction of propagation, and amplitude. When working with electromagnetic energy and physical devices, one of the fundamental concepts is that of “wavelength”. Wavelength is often expressed in metric units. The definition of wavelength is the speed of the propagation of energy divided by the frequency of that energy, expressed in Equation 5.1. Wavelength is determined by dividing the propagation velocity (in meters per second), by the frequency. Radio frequency energy propagates at about the speed of light, 186,000 miles per second or 300 million meters per second. The unit of frequency is Hertz (Hz.), formerly called “cycles per second” (cps). For example, if we want to determine the wavelength of a 100-MHz signal, the wavelength would be calculated from Equation 5.1 as 300/100 MHz or 3 meters.
Chapter 6. EMC Testing
Abstract
Why is understanding all the EMC disciplines important? The typical EMC problems can involve any combination of the disciplines, as well as combinations of frequencies, dimensions of components, wiring harnesses, and assemblies. This can make problem solving a challenge, requiring seemingly contradictory approaches for solutions at different frequencies or under different conditions.
Chapter 7. EMC Modeling
Abstract
Performing EMC tests is a time-consuming, resource-demanding process. Unfortunately, these tests are often conducted late in a developmental stage, when correcting an EMC problem can be even more difficult and expensive. Validated analytical and numerical methods have the potential to become increasingly important as a process to determine effects of external fields on a car’s electronic systems, or anticipating how emissions will develop.
Chapter 8. Effects of Cabling and Harnesses
Abstract
We have discussed one of the items of an EMC model that consists of the coupling path being radiated through the air or the vacuum of space. This chapter will discuss the fact that is important to remember that emissions and immunity problems can also result from being conducted along some type of wire, cabling, or even conductive portions of a vehicle or system assembly.
Chapter 9. Automobile Electrical/Electronics Systems
Abstract
Automotive systems can be sources of radiated emissions that may affect on-board electronics, or interfere with electronic systems on adjacent vehicles or devices along the roadside, such as televisions, radios, etc. Active electronic devices generate radiated emissions during their normal operation because of switching operations, logic gates, PWM (pulse-width-modulated) control signals, etc. Even the non-solid-state components, such as mechanical switches, horns, relays, other inductive devices, and spark plugs can also radiate. Many of these devices have been used since the early days of the automotive industry, and still require attention to ensure that measures are taken to prevent problems.
Chapter 10. EMC Regulation of Automotive Systems
Abstract
This chapter can be considered a “good news / bad news” chapter! The good news is that for the most part, automotive systems are not directly regulated by governmental legislation, unlike most other consumer electronic devices. The bad news is that the industry (especially in the United States) has a responsibility to “self-police” itself in order to maintain it’s relatively regulation-free status! Even in those countries that governmental regulations do apply, this is the exception rather than the rule and typically the regulations are at a value that if only met, would be at a severe customer dissatisfaction.
Chapter 11. Vehicle System Electrical Transients
Abstract
Automotive systems operate in demanding environmental conditions, have exacting requirements for performance, and are expected to provide years of trouble free operation. They are also expected to be inexpensive and easy to assemble into a vehicle. These systems employ electrical, electro-mechanical, and electronic component technologies that are not used together in other applications. The combination of high voltage and current requirements for some devices can cause problems with the low-level signal or power characteristics of other devices, if precautions have not been taken to isolate these systems.
Chapter 12. Electrostatic Discharge
Abstract
A discussion of electrostatic discharge (ESD) is typically introduced later in the study of most texts on EMC, and this one is no exception. This is because to understand ESD, we need to know the characteristics of both conducted and radiated phenomena discussed in earlier portions of the material. ESD can have emissions that affect devices or components that do not have sufficient immunity.
Backmatter
Metadaten
Titel
Automotive Electromagnetic Compatibility (EMC)
herausgegeben von
Terence Rybak
Mark Steffka
Copyright-Jahr
2004
Verlag
Springer US
Electronic ISBN
978-1-4020-7783-8
Print ISBN
978-1-4020-7713-5
DOI
https://doi.org/10.1007/b101849