Unit 5
1.How can you avoid EMI issues due to signal routing?
•Routing & Impedance: Minimize trace width, impedance mismatch, and crosstalk.
Use controlled impedance for high-speed signals.
•Signal Layers: Place high-speed signal layers next to the ground plane for a proper
return path.
•Compliance Testing: Regularly test for EMC compliance to reduce unwanted
emissions.
•Analog & Digital Separation: Keep digital and analog circuits separate to prevent
interference and ground loops.
•Signal Traces: Keep traces short and use differential signaling for high-speed data to
reduce EMI.
•EMI Control: Use proper PCB design techniques to avoid excessive radiated
emissions. Shield sensitive digital components.
•Ground Loop Management: Prevent unintended current paths by designing a solid
grounding system.
•High-Frequency Signals: Use proper PCB layout and filtering to control
electromagnetic radiation.
2.Mention the major causes of EMC problems in PCB Design.
•High-Speed Signals: Can emit EMI, affecting PCB components and external devices.
•Ground & Power Planes: Poor design may transmit noise and act as antennas.
•Clock Signals: Generate EMI; use guard and shunt traces for protection.
•EMI Filters: Improper design may amplify noise instead of reducing it.
3.What do you mean by ground loop in PCB Design?
•A ground loop in PCB design refers to an unintended current path formed between
different ground points on a circuit board.
•Prevent ground loops by carefully designing the grounding system and minimizing
ground inductance.
4.State the needs of emission test in Electric vehicles.
•To ensure compliance with EMC regulations like ECE R10-5.
•To prevent interference with vehicle electronics, power grids, and external devices.
•To check radiated and conducted emissions from high-voltage systems, on-board
chargers, and telecommunication interfaces.
•To ensure compatibility with residential, commercial, and industrial environments.
5.What are the precautionary procedures followed during harmonic and flicker tests of
Electric vehicles?
•Conduct tests in a controlled lab environment using standard methods.
•Ensure the vehicle is immobilized with the engine off.
•Set the vehicle’s charging state between 20% and 80%.
•Perform tests with artificial networks or impedance stabilization networks.
•Apply voltage fluctuations and harmonic measurements per IEC 61000-3-2 and IEC
61000-3-3.
6.What kinds of disturbances are followed during conducted immunity test of Electric
vehicles?
•Electrical fast transients/bursts applied to power lines to test immunity to rapid
switching events.
•Surge voltages (±500V for DC lines, ±1000V for AC line-to-line, and ±2000V for AC
line-to-ground) to check robustness against sudden voltage spikes.
•Common-mode disturbances applied to power lines using a coupling decoupling
network (CDN).