EMC in automobiles

Goals

The objectives of the training EMC in automobiles :

Design and integrate electronic modules in automobiles, taking into account coupling modes and limiting the effects of various sources, including radio interference.

The aim of this training course is to:

• Know how to assess the EMC environment inside and outside the vehicle


• Be able to identify the EMC risks of ESAEs based on the source of disturbance inside or outside the vehicle


• Know how to choose the EMC shielding and filtering solutions to be implemented


• Be familiar with the regulations in force for a vehicle and an SEEE

Program

1/ Introduction:
• Introduction: EMC in automobiles
• EMC characterisation of automotive equipment
• Internal EMC in vehicles: permanent sources/victims
• Internal EMC and vehicles: confrontation between sources and victims
• The two modes: common/differential
• Reminder: EMC units and terminology
• Narrowband/broadband spectrum
• Time-frequency conversion


2/ EMI environment
• Typical values of fields radiated by common transmitters
• Radio environment on roads (France)
• Strong radio fields generated in a vehicle
• Signatures of disturbers on vehicles
• Static charges in motor vehicles
• Disturbances in the automotive electrical system


3/ Susceptibilities of logic and analogue circuits
• Response of circuits to HF interference
• Static margins of common logic circuits
• Equivalent frequency of common logic circuits
• Transition power consumption
• Binary error rates with/without coding
• Sensors and transducers in automobiles
• Signal-to-noise ratio
• Envelope detection
• Characterisation of OP amplifier inputs and outputs


4/ Interference from ground planes
• Coupling through common impedance (C.I.C.)
• Impedance of a ground plane
• Impedance of copper and steel planes
• HF impedance of printed circuit tracks
• Impedance of circular conductors
• Critical grounding points on vehicles
• Exercise: interference through common impedance
• Analogue/digital comparison
• Calculating power supply noise
• Reducing power supply impedance
• Mesh power supply networks
• Analogue/digital mixing/high currents in ground planes


5/ Ground loops: solutions
• MC-MD conversion
• Capacitive coupling between board and chassis
• Total capacitance between board and ground plane
• Mechanical ground / electrical ground
• Edge effects


6/ Crosstalk
• Capacitive and magnetic crosstalk: analysis
• Track-to-track capacitance
• Wire-to-wire capacitive coupling
• Wire-to-wire inductive coupling
• Crosstalk reduction using ground planes
• Wiring rules for vehicle harnesses


7/ Field-loop coupling / field-wire coupling
• Field propagation
• Loop voltage
• Approximation of induced field-loop voltage
• Twisting of conductors
• Whip and dipole antennas
• Electric field to cable’ coupling
• Field reduction by ground plane


8/ Radiation from electronic devices
• The two types of radiation from electronic devices
• Spectrum of a trapezoidal train
• Radiation from a small loop
• Radiated spectrum in differential mode
• Why be wary of clocks?
• Radiation from a small whip
• Origins of common mode current
• Radiated spectrum in common mode
• Disturbances in an injection system


9/ Shielding
• How does shielding work?
• Near field/far field
• Losses due to reflection/absorption
• Choice of shielding material
• Shielding of conductive treatments
• Attenuation of an opening in a thin wall
• Steps in developing shielding


10/ Conduction protection
• The three methods of MC BF protection
• The three methods of HF common mode protection
• Immunity of vehicle digital connections
• Immunity of the CAN bus
• Envelope detection of optocouplers
• EMC filters in automotive electronics
• Filter circuits and impedances
• Capacitors and filters for printed circuit boards
• Attenuation due to battery impedance
• 12 V filtering problem
• Input/output filtering and protection
• Performance of different EMC ferrites
• Main surge arresters
• Coil interference suppression
• Shielded and coaxial cables
• Connection of shielded cable screens
• Importance of grounding base plates
• Car radios: interference from antenna coaxial cables


11/ Standardisation
• Automotive Directive: references and application
• R10 03 regulation
• Manufacturer specifications
• ISO 7637-X standard
• ISO 11452-X standard