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.

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• 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

Effect of High Frequency CM and DM on Application Hardware

• Sensors
• Plant equipment/protection
• Mitigation

Effect of High Frequency CM and DM on Control/Protection Components

• Drive sensor characteristics
• Current sensing

Influence of High Frequency on Power Device Switching Dynamics

• IGBT behavior and performance
• Voltage measurement/observers
• Mitigation