EMC in automobiles

Goals

formation-objectifs-seointro EMC in automobiles :

- Design and integrate electronic modules in automobiles, taking into account coupling modes and limiting the effects of different 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 ESAE

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