Introduction to Electromagnetic Interference and Compatibility (EMI/EMC) and Best Practices

Learn about Electromagnetic Interference (EMI) and Electromagnetic Compatibility (EMC), including best practices and a building-block approach with application-specific examples.

• Electrical engineers 
• Mechanical design engineers 
• System engineers 
• Project engineers 
• System integrators 
• Program managers 
• Technical leaders

Introduction – Examples of EMI/EMC Considerations

• Power electronic circuits (inverters and DC/DC converters)
• Hybrid electric vehicles and plug-in electric vehicles
• Appliances and computers

EMI/EMC Background

• Emissions and susceptibility
• Important electromagnetic laws

EMI Specifications and Standards

• Emission regulations (DO 160, FCC, CISPR)
• Susceptibility regulations (DO 160, IEC)

Path of Lowest Impedance

• Examples of high frequency current flow
• Review of current paths

Noise Coupling Mechanisms

• Four types of noise coupling

Common Impedance Coupling

• Circuits sharing electrical connections

Magnetic Coupling

• Meaning of Faraday’s Law
• Understanding magnetic fields
• Equivalent circuit of magnetic coupling

Electric Field Coupling

• Electric and magnetic field comparison
• Equivalent circuit for electric field coupling

System and Board Layout Issues

• Power bus decoupling
• Return (ground) planes
• Board layout priorities and board level concerns
• Common susceptibility problems

Electromagnetic Coupling (Radiation)

• Characteristics of radiation
• Dipole antenna characteristics
• Characteristics of unintentional radiators

Shielding

• H-field shielding and skin depth
• Electric field shielding

Bonding

• Seam bonding and faying surfaces
• Bonding methods

Grounding

• Signal grounds
• Single and multiple point grounds, hybrid grounds
• Signal reference subsystem
• Equipment and facility grounding

Lightning

• Specification
• Test methods
• Indirect and direct effects

Filtering

• Models
• Common mode filtering, differential mode filtering
• Low-pass, high-pass, band-pass filtering
• Signal filter design techniques
• Filter damping

Shielding Practical Considerations

• Cabinet and enclosure design
• Cables and connectors
• EMI gaskets
• Slots and seams

Antennas for EMC

• Antennas for emissions and for susceptibility
• Monopole and biconical antennas for EMI tests

Best Practices to Pass EMI Tests

• Design practices for passing EMI qualification tests
• Conducted and radiated emissions and susceptibility

System Issues Excited by AC Drive CM and DM voltages

• Motor over-voltages
• Bearing damage

Michael Schutten

Michael Schutten is presently self-employed as an EMC consultant, specializing in using novel technologies to ensure EMI compliance for power converters and inverters, ranging from low power up to several megawatts. He has developed many innovative technologies to diagnose, locate, and resolve EMI problems.

He was previously a Principal Engineer at the General Electric Global Research Center in Niskayuna, New York. While there he developed advanced EMC technologies that enabled compact, EMI compliant power electronic systems. He has developed robust and ultra-low noise power converters for military, industrial, and consumer applications.

His areas of expertise include electromagnetic compatibility, power electronics, RF electronics, nonlinear control theory, and analog electronics. He has taught multiple short courses at universities, government laboratories, and at twelve IEEE EMC and power electronics conferences. Mike has 35 issued patents and multiple journal and conference papers.

John Stanford

John Stanford, MSEE is an EMC consultant for Tork Technologies. John earned his MSEE degree from University of Illinois, Urbana–Champaign and his BEE degree from University of Dayton.  John is a iNARTE Certified Design Engineer and has 32 years experience ranging from product design to system level EMC.  John has also designed high-level lightning simulators. His background is military and commercial aerospace EMC and is knowledgeable with MIL-STD-461, 464 and RTCA DO160 standards.

Kenneth Wyatt

Kenneth Wyatt is principal consultant of Wyatt Technical Services LLC and served three years as the senior technical editor for Interference Technology magazine from 2016 through 2018. He has worked in the field of EMC engineering for over 30 years with a specialty in EMI troubleshooting and pre-compliance testing.

He is a co-author of the popular EMC Pocket Guide and RFI Radio Frequency Interference Pocket Guide. He also co-authored the book with Patrick Andre, EMI Troubleshooting Cookbook for Product Designers, with forward by Henry Ott. He recently completed and released a three-volume “EMC Troubleshooting Trilogy”, which is now available through Amazon. See his web site for ordering info.

He is widely published and authors a monthly column, “Practical EMC”, for the Signal Integrity Journal, has blogged for EDN.com or many years, has a monthly column, “Benchtop EMC”, for InCompliance Magazine, writes regularly for EEWorld and continues to write for Interference Technology Magazine. Ken is a senior life member of the IEEE and a longtime member of the EMC Society. To contact Ken, or for more information on technical articles, training schedules and links, check out his web site: emc-seminars.com