emv-fachtagung – 21. januar...
TRANSCRIPT
GROUNDING DESIGN
GENERATION AND SUPPRESSION
EMV-FACHTAGUNG – 21. JANUAR 2015
GENERATION AND SUPPRESSION
OF COMMON MODE NOISE
Itaru Matsuda
Senior Staff EMC Engineering
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Yukio Kajita
Itaru Matsuda*
Kitagawa Industries Co., Ltd.http://www.kitagawa.de/
http://www.kitagawa-ind.com/
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Electronics life is filled with EM energy.
InterferenceMalfunction
Transmitter /Receptor
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Capacitive coupling
Heat-sink
Radiation of noise
High frequency RF current
(Floating metal)
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LSI
High speed signal
Common mode current is generated by mismatch of balancing which is
caused by different width of ground patterns on PC board.
The other example is between PCB trace and cable connected to the PCB.
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When transient current at switching flows into ground inductance, C.M. is caused.
dmG
dm
G ILjdt
dIL
cycle wave of signal is generated double
frequency noise wave.
Even times “f” noise wave will be generated.
Noise voltage fluctuations in a ground
plane sharing common-inductance return
from PCB.
2/1
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How to consider about
Grounding
At Higher Frequency
•It is not “0V”.
•It is influenced by disturbance
noise.
•It is not stabilized.
Common mode noise is mainly generated
by ground-related phenomena.
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Grounding Design with On-board contact
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Emission Level is improved
Large suppression is obtained
by multi point FG connection.
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Advantage
Suitable for surface mount process.
Small footprint for enhanced grounding.
Grounding placement near noise source.
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Without on board contact
With on board contact
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3 points GND
7 points GND
Connecting points to metal plate is varied.
On-board contact placed on PCB.
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Grounding Design
Current Driven Model & Return Path
Signal current
Return current
Separate return path results increasing GND inductance.
Return current
Return current
Signal current
Power plane
plane
GND plane
Increase GND inductance.
dt
diLL
dt
diLV MGG )(
Split aperture in GND plane Signal jumps over V-G planes
Pattern design with self and mutual inductance control is necessary.
Noise suppression by .
Reduce Increase
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Grounding Design
Multi point connection to Ground
It is necessary to make multi point grounding to GND plane.
Unbalanced GND potential is not accepted.
GND plane
Signal/GND plane
Signal/GND plane
Power/GND plane
To be enlarged ground area.
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Conducted emission from
power line is measured.
How to measure CE?
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Differential Mode Current ID)
Common Mode Current (IC)
)(50
)(50
DCN
DCL
IIV
IIV
Measurement system
Measuring total value of ID and IC
It is hard to separately observe DM current and CM current.
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Initial State
Power line: L,N,G
L+N+G--All lines are tuned around GRFC-13.
GRFC-13: KGS product
Initial level Initial level
Nothing changed. Why?
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LISN
Current Flow
EUT
DM current
CM current “1”
CM Current “2”
Insertion loss is effected against CM Current “2” only.
L
N
G
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Separately Measuring by Current Probe
CM Current 2 is observed. CM Current 1 is observed.
Both of DM and CM current are observed. CM Current “1” is observed.
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CM Current Measurement DM Current Measurement
Emission mode can be identified by Current Probe.
Current Probe Current ProbeCM Current
DM Current CM Current
DM Current
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EUTLISN
L
N
G
DM Current
CM Current “1”
Initial level Initial level
Initial level
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Recommendable Ferrite material is identified by disturbance frequency.
L N L N
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Materials
1
10
100
1000
0.01 0.1 1 10 100 1000
Imp
edan
ce (
)
Frequency (MHz)
Impedance vs Frequency
Suppression performance in Equipment
Initial level
Mg
1
10
100
1000
0.01 0.1 1 10 100 1000
Imp
edance
()
Frequency (MHz)
0.1
1
10
100
1000
0.01 0.1 1 10 100 1000
Imp
edan
ce (
)
Frequency (MHz)
Features
High impedance at lower frequency (kHz - 2 MHz)
'Cable guide'' contribute to workability when increasing
number of turns
RFCK2-M20 is designed to install by using screw
Applications
Inverter, Low frequency noise current from Motors
=> Air-conditioners, Washing machines, machine tools,
Medical equipment etc etc
Specification
AC-DCL.I.S.N
TRMH Low-cut High Ferrite
Present goods
TRM Low-cut Ferrite
GTR Soft ferrite
AC power cable(5T)
AWG14
Compressor cable(6T)
AWG16
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1. Grounding
It is measure to eliminate the noise source and
suppress the radiation.
2. Filtering
Suppression and Isolation of noise source
3. Shielding
Shielding barrier of noise
Front loading design
Engineering after
sample assembled
EMC technique to suppress noise
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Low-cut Core
Shielding Gasket Engineering
Support
Wire Mesh Gasket
Ferrite Clamp
Flat Cable Shield
On-board Clip
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Ferrite Clamp
MAGNEFILM
REMILESS
Shielding Gasket
MIC-HOLDER
LOSTOMER AG
On-board Clip
On-board Contact Cool Provide
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On-board Clamp
On-board Contact
On-board Plate
Cool Provide
REMILESS
SMARTPLY
MIC-DAMPER
On-board Clip MAGNEFILM
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Low cut Core
Ferrite Clamp
Shielding Gasket
Cable Shield
Cable Clamp
Dust Proof Bushing
MEFS
Click
Adjustable Clamp
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On-board Contact
Ferrite Clamp
On-board Terminal
MG Absorption Sheet
KG GEL
Fan Holder
Cool Provide
Re-use Clamp
Connector Clamp
• Automotive electronics
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Kitagawa Industries Co., Ltd.
http://www.kitagawa-ind.com/
Kitagawa GmbH
http://www.kitagawa.de/
Ihr KITAGAWA Vertragspartner für die Schweiz
VIELEN DANK FÜR IHRE AUFMERKSAMKEIT
AWAG Elektrotechnik AG
Sandbüelstrasse 2
CH-8604 Volketswil
www.awag.ch