Transcript slides
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 Spectrum Analyzer Screen Units: dBuV 50dBuV = 316uV ~15uV Frequency 100kHz – 100MHz EMC in Product Development Typical Development Cycle Outputs Corresponding EMC Outputs • Product Specification • EMC Requirements Analysis • System Architecture • EMC Concept Review • Physical Design • EMC Design Review • Product Qualification • EMC Lessons Learned EMC in Product Development Typical EMC Activities During Product Development Specification: Define the EMC requirements (5 types). Which directives apply? Ensure the standards are understood. What are the implications? Architectural/System Design: 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. Detailed Design: Implement the strategies and concepts. Do pre-screening tests and simulation. Prototype/Qualification: 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 Transients Inductive Load Switching Voltage Sag “Load Dump” RF Immunity On-Board Transmitters Radio Stations Airport Radar Systems Sensors are Most Vulnerable Electrostatic Discharge (ESD) Up to 15kV EMC In The Automotive Environment: Emissions Radiated Emissions Very 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 Pulse Width and the Rise and Fall Times. Example: 20kHz waveform with 10ns rise & fall times. F1 ~ 13kHz F2 ~ 32MHz ELECTRO-HYDRAULIC POWER STEERING SYSTEM Hydraulic Pump Electronic Control Unit • Three-Phase Inverter • Microcontroller & S/W • Sensors • CAN Bus Three-Phase Brushless DC Motor Conducted Emissions Results Test Conditions; Typical Load, PWM @ 20-30A, 1,000RPM PWM Harmonics Power Stage & I/O Load Z Low Frequency; 150kHz - 30MHz Fast Edges & I/O 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 Society Fostering 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 www.irf.com