Fundamentals of EMC Theory and Principles

Transcription

1 EMC Seminar Series All about EMC Testing and Measurement Seminar 1 Fundamentals of EMC Theory and Principles Dr. LEUNG, Peter Sai Wing 梁世榮 edu hk/ pswleung/ Organized by : Department of Electronic Engineering 1

2 ElectroMagneticl Compatibility bl The ability of an equipment or system to function satisfactorily in its environment without introducing intolerable electromagnetic interference to anything in that environment. EMC = EME + EMI EME=Electromagnetic Emission (Interference) EMI=Electromagnetic Immunity (Susceptibility) 2

3 EMC A complicated and difficult subject!!!!? Talks in Order of Magnitudes Frequency from DC to daylights magnitude µa ka; µv MV works on db for order of magnitude, and log scale in frequency Different types of EMC requirements, methods, measurements Many different standards 3

4 Sources of Emission / Noise Natural / man-made / intended emission! 4

5 Coupling 5

6 Effects of EME/ EM interference Equipment to equipment Loss of data in digital systems or in transmission of data Interference to TV and radio reception Malfunction of medical electronic equipment Malfunction of automotive microprocessor control systems (braking) and navigation equipment Malfunction of critical process control functions (e.g. oil, chemical, airports railways). Equipment to Human (Human Safety) IEEE C95.1 Standard For Safety Levels with Respect to Human Exposure to Radio Frequency Electromagnetic Fields, 3KHz to 300GHz ICNIRP Guidelines limiting exposure to time varying Electric, Magnetic, and Electromagnetic fields (Up to 300 GHz).

7 EME and EMI Testsc 7

8 Different characteristics of emissions Radiated Emission Far field radiation near field radiation E field source H field source Conducted Emission Different paths.dc port, power port, communication port Electromagnetic Coupling 8

9 RE, CE,RI,CI CI 9

10 RE, CE, RI, CI 10

11 RE : 40 dbµv/m ~ 0.01V/m CE : 60 dbµv/m ~ 0.001V/m001V/m Examples of some limits in Radiated Emission from CISPR22 11

12 EMC A reasonable good margin between RE and RI, for general consideration!! RI requirement.3v/m RE : 40 dbµv/m ~ 0.01V/m01V/m CI requirement.3v CE : 60 dbµv/m ~ 0.001V/m Examples of some limits in Radiated Immunity from IEC for RCLI 12

13 ELECTROSTATIC DISCHARGE (ESD) A transfer of electric charge between bodies of different electrostatic potential in proximity or through direct contact. Effect: Cause damage to electronic equipment. 13

14 ELECTROSTATIC DISCHARGE (ESD) Hard failures (irreversibly) Junction burnout IC metal burnout Dielectric breakdown Soft failures ( mainly digital circuits) Transient interference ( eg. Radio) Logic errors, System resets, Lost data, Lost program flow 14

15 HUMAN BODY MODEL R L C V C C = 50 to 250 pf R = 500 to 10k V C = 0 to 30kV ( above 30V will have corona effect ) L = nH First order model, TRIBOELECTRIC EFFECT EN Testing and measurement techniques Electrostatic discharge immunity test 15

16 DISCHARGE INTO AN IDEAL GROUND R=500 L=100nH I 15kV C=300pF I t=0 I pk I pk 15kV A 0 ~ 1ns t 16

17 ESD Tests Direct Application: Air Discharge (sparks) Discharge Electrodes EUT Contact Discharge EUT..different electrostatic potential in proximity or through direct contact. 17

18 ESD Generators Some models can generate airor contact discharge up to 30kV. With different combination of R C value for other applications 18

19 Fast Transient/Burst Electrical Fast Transients caused a spark in air or other gas When a circuit is switched off, the current flowing is interrupted; large di/dt is generated. Arcing between the contacts; first at a low voltage and high frequency; later at a higher voltage and lower frequency. 19

20 Electrical Fast Transient Electrical Fast Transients caused a spark in air or other gas When a circuit is switched hdoff, the current flowing is interrupted; large di/dtd is generated. Arcing between the contacts; first at a low voltage and high frequency; later at a higher h voltage and lower frequency. IEC Electromagnetic Compatibility (EMC) Part 4 4: Testing and measurement techniques Electrical fast transient/burst immunity test. 20

21 Fast Transient/Burst Electrical Fast Transients caused a spark in air or other gas When a circuit is switched hdoff, the current flowing is interrupted; large di/dtd is generated. Arcing between the contacts; first at a low voltage and high frequency; later at a higher h voltage and lower frequency. Coupling of the EFT into electronic products occurs when power cables handling high currents are run in close proximity to power, data, and/or I/O cables. 21

22 Surge Sudden rises in voltage and/or current to a connected load; standard household equipment can be damaged by surges of 500 volts or greater. Indoors, caused by major equipment, such as your air conditioner switching on and off. Outdoors, they can be caused by incidents involving electric lines, power equipment failures. Lightning in seasonal storms. Electromagnetic Compatibility (EMC) Part 4 5: Testing and measurement techniques Surge immunity test 22

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24 Power frequency magnetic field Electrical power lines, wiring, transformers and household h appliances Power stations, tti HV transformer builder, overhead cable, railways system. Electromagnetic compatibility (EMC) Part 4 8: Testing and measurement techniques Power frequency magnetic field immunity test 24

25 H dl I l Ampere' s law; H I 2 r 10 I 2 X1m Electromagnetic compatibility (EMC) Part 4 8: Testing and measurement techniques Power frequency magnetic field immunity test 25

26 Voltage dips, short interruptions and voltage variations Electrical equipment can be affected by voltage dips, short interruptions or voltage variations of the power supply caused by faults in the network, in installations or by a sudden large change of load. Electromagnetic compatibility (EMC) Part 4 11: Testing and measurement techniques Voltage dips, short interruptions and voltage variations immunity tests 26

27 Voltage dips, short interruptions and voltage variations 27

28 Immunity Test results Criterion A B Performance Normal performance, specified by manufacturer Temporary loss of function or performance degradation during test. EUT recovers its performance without t intervention ti C D Temporary loss of function or degradation (requiring intervention) Loss of function or degradation unrecoverable 28

29 Summary Some concept and fundamentals on EMC. RE, RI, CE, DI, ESD, FT & S, H Field, Voltage Dip. Electromagnetic compatibility (EMC) Part 4 11: Testing and measurement techniques Voltage dips, short interruptions and voltage variations immunity tests 29

30 Thank You!! Peter Sai Wing LEUNG, 梁世榮 edu hk/ pswleung/ 30