ELECTROMAGNETIC COMPATIBILITY Dr. Donald Church Senior Staff Engineer International Rectifier Automotive Systems November 17, 2005
Mar 27, 2015
ELECTROMAGNETIC COMPATIBILITY
Dr. Donald Church
Senior Staff Engineer
International Rectifier Automotive Systems
November 17, 2005
Electromagnetic Compatibility Outline
• Introduction: Terms & Definitions
• EMC in Product Development: Activities & Outputs
• EMC in the Automotive Environment: Challenges
• Example: Electro-Hydraulic Power Steering System
• EMC and the IEEE: Education
• Questions
ELECTROMAGNETIC COMPATIBILITY(EMC)
1. Electromagnetic Emissions
Your System Cannot Interfere With Other Systems or Subsystems in the Vehicle
(e.g., FM Radio).
2. Electromagnetic Susceptibility
Your System Must Continue to Operate Correctly
in the Presence of Interference From Others or
Transient Disturbances.
ELECTROMAGNETIC INTERFERENCE (EMI)
• Conducted Interference
Enters/Exits on Wires for Power or Control
• Radiated Interference
Enters/Exits Through the Air
Emissions Must be Controlled to Protect:
AM & FM Radio Stations
Aircraft Communications & Navigation
Emergency Services Land Communications
EMI MEASUREMENT
Units: dBuV
50dBuV = 316uV
Frequency100kHz – 100MHz
Spectrum Analyzer Screen
~15uV
EMC in Product Development
Typical Development Cycle Outputs
• Product Specification
• System Architecture
• Physical Design
• Product Qualification
Corresponding EMC Outputs
• EMC Requirements Analysis
• EMC Concept Review
• EMC Design Review
• EMC Lessons Learned
EMC in Product Development
Typical EMC Activities During Product Development
Specification:
Architectural/System Design:
Detailed Design:
Prototype/Qualification:
Define the EMC requirements (5 types).Which directives apply? Ensure the standards are understood.What are the implications?
Propose preliminary EMC design concepts.Create the EMC test plan.Propose PCB design strategies.Review Power Stage Concept for EMC.Do an EMC risk analysis.
Implement the strategies and concepts.Do pre-screening tests and simulation.
Do formal certification testing.Re-design & Re-test? Failures here are expensive!
EMC In The Automotive Environment
• Harsh Environment
Power Line Transients
RF Interference
Electrostatic Discharge
Power Line Electric & Magnetic Fields
• High Reliability
1 ppm Goal
“Fail Safe” is Critical
• Extreme Cost Sensitivity
EMC In The Automotive Environment:Susceptibility
Power TransientsInductive Load SwitchingVoltage Sag“Load Dump”
RF ImmunityOn-Board TransmittersRadio StationsAirport Radar SystemsSensors are Most Vulnerable
Electrostatic Discharge (ESD)Up to 15kV
EMC In The Automotive Environment:Emissions
Radiated EmissionsVery Sensitive Receivers
Distance to the Antenna
50dB Lower Than Commercial Limits
Cables Are Unintended Antennas
PCB Traces Also Radiate
Digital Circuits Are The Main Source
EMI Lesson #1: Remember Fourier!
The Energy in a Trapezoidal Waveform is a Function of the PulseWidth and the Rise and Fall Times.
Example: 20kHz waveform with 10ns rise & fall times.
F1 ~ 13kHz F2 ~ 32MHz
ELECTRO-HYDRAULICPOWER STEERING SYSTEM
Hydraulic Pump
Electronic Control Unit• Three-Phase Inverter• Microcontroller & S/W• Sensors• CAN Bus
Three-Phase BrushlessDC Motor
Conducted Emissions Results
Test Conditions; Typical Load, PWM @ 20-30A, 1,000RPM
PWMHarmonics
Power Stage & I/O
Load Z Fast Edges & I/O
Low Frequency; 150kHz - 30MHz High Frequency; 30MHz – 100MHz
EMC AND THE IEEE
• Ancora Imparo – “I Am Still Learning”Michelangelo at Age 87
• IEEE EMC Society
• IEEE Annual EMC Symposium
• NARTE & The IEEE EMC SocietyFostering and promoting Technical Awareness,Education and Achievement in EMC
EMC Summary
• What it is and why it is important
• Designing Early for EMC
• EMC Challenges in the Automotive Environment
• Example of a Certified Automotive Component
• Continuing Education Through NARTE & IEEE
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