1. EET 422 EMC & COMPLIANCE ENGINEERING
Prof R T Kennedy
EMC & COMPLIANCE ENGINEERING

2. EMC & COMPLIANCE ENGINEERING
AC SOURCE
FILTER
EUT
FREQUENCY RESPONSE
LOW Frequency
High Frequency
negligible attenuation at line frequency
large attenuation
Low Pass
High Frequency
large attenuation
Prof R T Kennedy
EMC & COMPLIANCE ENGINEERING

3. L presents HIGH impedance EMC & COMPLIANCE ENGINEERING
LISN COMPARISON OPERATION 150 kHz - 30 MHz from EUT
L presents HIGH impedance
EUT
1 k W
0.25 mF
2mF
L or N G
analyser AC
SOURCE
or 50 W load
50 mH
Prof R T Kennedy
EMC & COMPLIANCE ENGINEERING

4. EMC & COMPLIANCE ENGINEERING
LISN OPERATION: 150 kHz - 30 MHz from EUT
LOW impedance path
EUT noise to analyser
via high pass filter
rfi
0. 47mF AC
SOURCE
EUT
1 kW
0.47 mF
Prof R T Kennedy
EMC & COMPLIANCE ENGINEERING

5. EMC & COMPLIANCE ENGINEERING
INSERTION LOSS (I L)
Zload
Zsource
Vnoise
Vn1
Zload
Zsource
Vnoise
FILTER
Vn2
Prof R T Kennedy
EMC & COMPLIANCE ENGINEERING

6. EMC & COMPLIANCE ENGINEERING
SERIES FILTERING
Zload
Zsource
Vnoise
FILTER
Vn2
Zseries
Zseries >> 50 W
IMPEDANCE MISMATCH
Zsource
Zload
50 W
Prof R T Kennedy
EMC & COMPLIANCE ENGINEERING

7. PARALLEL (SHUNT) FILTERING
Zsource
Zload
Vnoise
Zparallel
Vn2
Zparallel << 50 W
IMPEDANCE MISMATCH
Zsource
Zload
50 W
Prof R T Kennedy
EMC & COMPLIANCE ENGINEERING

8. INSERTION LOSS MEASUREMENT
50 W
Vnoise
FILTER
Vn2
1:1
differential mode
Prof R T Kennedy
EMC & COMPLIANCE ENGINEERING

9. INSERTION LOSS MEASUREMENT
50 W
Vnoise
FILTER
Vn2
common mode
Prof R T Kennedy
EMC & COMPLIANCE ENGINEERING

10. INSERTION LOSS MEASUREMENT
50 W
Vnoise
FILTER
Vn2
unsymmetrical mode
Prof R T Kennedy
EMC & COMPLIANCE ENGINEERING

11. POWER LINE FILTER TOPOLOGIES
Zload
or Znoise
LOW
HIGH
HIGH
Zac, line
LOW
Prof R T Kennedy
EMC & COMPLIANCE ENGINEERING

12. POWER LINE FILTER TOPOLOGIES
Zload
or Znoise
LOW
HIGH
HIGH
Zac, line
LOW
Prof R T Kennedy
EMC & COMPLIANCE ENGINEERING

13. EMC & COMPLIANCE ENGINEERING
SELF DESIGN or BUY ?????
SELF DESIGN ADVANTAGES
reduced cost
(don't pay filter manufacturers' overheads and profits)
better performance for a specific application
(design based on known impedances)
easier to add to existing PCB
Prof R T Kennedy
EMC & COMPLIANCE ENGINEERING

14. EMC & COMPLIANCE ENGINEERING
SELF DESIGN or BUY ?????
BUY ADVANTAGES
Power Line Filter design is not an easy exercise!
units are enclosed
minimising radiated interference
and susceptibility
safety regulations are inherently covered
Prof R T Kennedy
EMC & COMPLIANCE ENGINEERING

15. EMC & COMPLIANCE ENGINEERING
INSERTION LOSS
Irated CX CY L
Ileakage
1 A
0.22 mF
2500 pF
18 mH
< 0.5 mA
2 A
0.33 mF
10 mH 4A
0.47 mF
4.7 mH 6A
33 nF
2.2 mH
< 3.5 mA
Prof R T Kennedy
EMC & COMPLIANCE ENGINEERING

16. EMC & COMPLIANCE ENGINEERING
CM inductor
DM inductor L L1 L2 L*
CY2
CM capacitor
cross
coupled
DM capacitor
CX2
CX2
DM cap
CY2
CM capacitor N L1 L2 N*
DM inductor
CM inductor G LG G*
CM inductor
Prof R T Kennedy
EMC & COMPLIANCE ENGINEERING

17. TYPICAL POWER LINE FILTER
CY1
CX1 M
CX2
AC source
CY2
EUT N L
N * G G*
X capacitors connected line – neutral
for
differential mode (symmetrical) interference
Y capacitors connected line-ground neutral-ground
common mode (asymmetrical) interference
Prof R T Kennedy
EMC & COMPLIANCE ENGINEERING

18. differential mode current
COMMON MODE INDUCTOR
differential mode current
CM
common mode current
DM
Prof R T Kennedy
EMC & COMPLIANCE ENGINEERING

19. EMC & COMPLIANCE ENGINEERING
COMMON MODE
L+M
icm M
Prof R T Kennedy
EMC & COMPLIANCE ENGINEERING

20. EMC & COMPLIANCE ENGINEERING
DIFFERENTIAL MODE
L-M
idm M
Prof R T Kennedy
EMC & COMPLIANCE ENGINEERING

21. EMC & COMPLIANCE ENGINEERING
SECTIONAL WINDING
HIGHER LEAKAGE INDUCTANCE
BIFILAR WINDING
Prof R T Kennedy
EMC & COMPLIANCE ENGINEERING

22. EMC & COMPLIANCE ENGINEERING
SINGLE LAYER WINDING
LOWEST PARASITIC CAPACITANCE
INTER-TURN CAPACITANCE
HIGHEST RESONANCE FREQUENCIES
Prof R T Kennedy
EMC & COMPLIANCE ENGINEERING

23. EMC & COMPLIANCE ENGINEERING
MULTI-LAYER WINDING
HIGHEST PARASITIC CAPACITANCE
INTER-TURN + INTER-LAYER CAPACITANCE
LOWEST RESONANCE FREQUENCIES
Prof R T Kennedy
EMC & COMPLIANCE ENGINEERING

24. EMC & COMPLIANCE ENGINEERING
RANDOM WINDING
PARASITIC CAPACITANCE > SINGLE LAYER
HIGHER RESONANCE FREQUENCIES
BETTER INTERFERENCE SUPPRESSION
Prof R T Kennedy
EMC & COMPLIANCE ENGINEERING

25. EMC & COMPLIANCE ENGINEERING
COMMON MODE L L L*
CY2
CX2 M
CX2
CY2
EUT
AC source N L
N * G G* L L L*
CY2
CX2 M
CX2
CY2
EUT
AC source N L
N * G G*
Prof R T Kennedy
EMC & COMPLIANCE ENGINEERING

26. EMC & COMPLIANCE ENGINEERING
COMMON MODE L L L*
CY2
CX2 M
CX2
CY2
EUT
AC source N L
N * G G* L L L*
CY2
CX2 M
CX2
CY2
EUT
AC source N L
N * G G*
Prof R T Kennedy
EMC & COMPLIANCE ENGINEERING

27. EMC & COMPLIANCE ENGINEERING
COMMON MODE L L L*
CY2
CX2 M
CX2
CY2
EUT
AC source N L
N * G G*
CX2 L or N G L* G*
Prof R T Kennedy
EMC & COMPLIANCE ENGINEERING

28. EMC & COMPLIANCE ENGINEERING
DIFFERENTIAL MODE L L L*
CY1
CX1 M
CX2
AC source
CY2
EUT N L
N * G G*
Prof R T Kennedy
EMC & COMPLIANCE ENGINEERING

29. EMC & COMPLIANCE ENGINEERING
DIFFERENTIAL MODE L L L*
CY2
CX2 M
CX2
AC source
CY2
EUT N L
N * G G*
Prof R T Kennedy
EMC & COMPLIANCE ENGINEERING

30. EMC & COMPLIANCE ENGINEERING
DIFFERENTIAL MODE L L L*
CY2
CX2 M
CX2
AC source
CY2
EUT N L
N * G G*
CX2 L N L* N*
Lleakage
Prof R T Kennedy
EMC & COMPLIANCE ENGINEERING