High Voltage Automotive EMC Component Measurements Using and

High Voltage Automotive EMC
Component Measurements Using an
Artificial Network
October 18, 2007
Jody J. Nelson (Daimler AG)
William Goodwin, Mark Steffka, William Ivan (GM)
Markus Kopp (Ansoft)

High Voltage Artificial Network Summary
�� Based on experimental and simulation results:
�� It is not recommended to use an AN as defined by
CISPR for HV conducted emissions voltage
validation.
�� It is not recommended to use an AN as defined by
CISPR during current probe measurements on HV
lines.
�� HV AN can be useful for development and simulations.
�� A new AN for HV applications should be defined if HV
conducted emissions voltage validation is required.
2

Functions of an Artificial Network
1. Provide a defined
impedance over a
given frequency range
at the power terminals
of the equipment under
test (EUT)
2. Allow for the disturbed
voltage to be measured
3. Isolate the EUT from
undesired power supply
disturbances
CISPR 16-1: “Specification for radio disturbance and immunity
measuring apparatus and methods – Part 1: Radio disturbance and
immunity measuring apparatus”, Second edition 1999-10, IEC.
CISPR 25: 0.1 to 100 MHz
3

Early Studies of Artificial Networks
Presented in 1983 IEEE Transactions Paper:
• Impedance measurements of the electrical
network for 6 different vehicles.
• At most 8 electrical components were on
vehicles: horn & light control circuits, ignition
coil, alternator, windshield washer & wiper
motors, EFI, and radio
Example measurements of one vehicle.
S. Yamamoto and O. Ozeki, “RF Conducted Noise
Measurements of Automotive Electrical and
Electronic Devices Using Artificial Network,” IEEE
Trans. Veh. Technol., vol. VT-32, no. 4, pp. 247–
253, Nov. 1983.
4

Early Studies of Artificial Networks – Cont.
Experimental Results:
• Battery cables were < 0.3 Ω.
• From 150 kHz to several MHz, the inductance
range from 1.1 – 6.4 µH
• From several MHz to 60 MHz the inductive
and capacitive impedance ranged from 20 to
740 Ω
Based on empirical
measurements an AN was
developed from 150 kHz to 60
MHz with a 2.85 µH inductor
and 10 µF capacitor.
5

Comparison – AN 1983 vs. AN Today
CISPR 25: Characteristic impedance
Capacitance
Inductance
DC Blocking
Resistance
Frequency
1983
10 µF
2.85 µH
2 µF
0.1 Ω
0.15 – 60
MHz
Today
1 µF
5 µH
0.1 µF
0 Ω
0.1 –
100
MHz
6

Early Studies Using HV Artificial Networks
A number of papers exist using an AN for higher than 12 V automotive applications,
but none question its functionality:
Refer to paper for references.
7

Typical Automotive AN Setup Comparison
Standard 12 V Automotive AN Setup Example HV Automotive AN Setup
Ground Plane
12 V
1 uF
1 uF
5 uH
5 uH
0.1 uF
1 kOhm
1 kOhm
0.1 uF
EUT
• Measures DM voltage:
150 kHz < V out < 100-200 MHz
• 1 µF on return generally shorted
• AN defined to represent system
impedances
• Generally no shielding
High Voltage
Ground Plane
1 uF
1 uF
5 uH
5 uH
0.1 uF
1 kOhm
1 kOhm
0.1 uF
EUT
Ground Plane
• Measures CM voltage, generally
between inner conductor and shield
• 1 µF generally much larger than
HV cable shield capacitance
• 5 µH generally much larger than
coaxial cable inductance
• Shielding termination not defined
8

Common Hybrid Electric Vehicle Layout
2004 Toyota Prius HV Layout
1 2004 Toyota Prius Emergency Response Guide
1

Consequences of HV Shielded Cables
• Shield current is dependant upon the amount of
intercable coupling and electrical terminations of
shield at the ends of the cable.
• Utilization of different geometries for cables will
also affect current path characteristics; shield
diameter vs. inner conductor diameter, different
dielectrics of isolation material

Impedance [Ω]
Phase [°]
HV Shielded Cable Example
5 m long HV shielded cables measured with Network Analyzer and first
resonance calculated with transmission line equations.
10 2
10 0
50
0
-50
Measurement
10 0
Transmission Line Calculation
10 0
Frequency [MHz]
10 1
10 1
10 2
10 2
Per unit calculations for a coaxial
transmission line:
μ0
⎛ D ⎞
l = ln⎜
⎟
2 ⋅π
⎝ d ⎠
700 mΩ
Factor of 500
0.19 μH
2⋅ π ⋅ εr
⋅ε
0
c =
⎛ D ⎞
ln⎜
⎟
⎝ d ⎠
2.0 nF
Factor of 26
11

Ansoft HFSS HV Cable Simulation
If it is desired to
simulate the system to
several MHz, a better
cable model than
transmission line is
required.
HFSS simulation, based
on Finite Element
Method (FEM) with
adaptive meshing, was
used to create HV
shielded cable
simulation model.
Impedance [Ω]
Phase [°]
10 2
10 0
50
0
-50
10 0
Measurement
HFSS Simulation
10 0
Frequency [MHz]
10 1
10 1
10 2
10 2
12

HV Cable Simulation – E & H-Fields
HFSS simulation calculates the simulated near fields within the boundaries of
the HV coaxial shielded cable.
Model was created assuming a perfectly shielded coaxial cable - No fields
outside of shield
E-Field H-Field
13

HV Cable Simulation – Wave Impedance
Ansoft Corporation HFSSDesign3
Characteristic Cable Impedance (ohms)
15.00
14.50
14.00
13.50
13.00
η = 13.2 Ω
Cable Impedance
3D Simulation Model
Curve Inf o
Setup1 : Sw eep1
0.00 20.00 40.00 60.00 80.00 100.00 120.00
Freq [MHz]
14

HFSS Simulation to Simplorer Model
HV Batt HV
Shielded
DC
Cables
E5
EMF := 150 V
EMF := 150 V
E6
C30
C31
HVCableWCG9MBKv1_lfws
HVCableWCG9MBKv1_lfws
C41
C42
HV AN
L19
L18
C43
R12
R13
C44
HFSS simulation
converted to 4port
Simplorer
model
Peak [dBμA]
140
120
100
80
60
40
20
0
10 -2
10 -1
Frequency [MHz]
Higher frequency
content realizable
with HFSS model
1 st resonance of
cable seen
Peak [dBμA]
Unshielded Cable
HFSS Shielded Cable
40
30
20
10
0
-10
-20
10 0
10 0
Improvement
due to
impedance of
shielded cable
realized;
shielding
effectiveness not
part of simulation
10 1
Frequency [MHz]
HFSS Shielded Cable
Unshielded Cable

Benefits of Simulation for this Work
Complex physics of this need to be understood, such
as the frequency dependent characteristics unique to
this type of problem.
Simulation could be used to provide insight into the
physical behavior without affecting system operation
due to testing with standard methods.

HV AN Experimental Test Setup
An experimental test setup was created to
demonstrate the effects of the HV AN
• Mounted on real vehicle chassis
• Routing similar to actual HEV
• Maintained CISPR setup requirements
• All tests performed at 500 rpm, 5 N·m
• Current probe measurements taken 50
mm from EUT (CM)
• Voltage measurements measured from
output of HV AN
To E-machine Load
Current Probe 50 mm from EUT
Power Inverter
(EUT)
Ground Plane
300
mm
Ground Plane
HV AN
HV AN
1750
mm
HV DC Battery
17

HV AN Test Configurations*
HV AN
HV Battery 10 cm 10 cm
10 cm
Ground Plane
HV AN
Test 1
HV AN
HV Battery 10 cm 10 cm
10 cm
HV AN
Test 2
HV AN
HV Battery 10 cm
HV AN
Test 3
HV EUT
HV EUT
HV EUT
HV Battery
HV Battery
HV Battery 10 cm
Ground Plane
HV AN
HV AN
Test 4
Test 5
Test 6
HV EUT
HV EUT
HV EUT
*HV Battery and HV EUT grounded in all tests.
18

HV AN Test Configurations Example
Test 1

HV AN Test Configurations Example
Test 2 & 3

HV AN Test Configurations Example
Test 1, 2, & 3 Test 4

Current Probe vs. HV AN Voltage
Current probe
(+34 dB shift)
and HV AN
produce similar
waveforms
Peak [dBμ]
100
90
80
70
60
50
40
30
20
10
0
Test 4 (Unshielded Cables)
10 0
Frequency [MHz]
Test 4 - Current Probe
Test 4 - Voltage
10 1
Created by
power switch
slew rate of
approximately
1500 V/µs
22

Current Probe – HV AN Influence
Increased
noise due to
AN 1 µF
capacitance
connection to
ground plane
which
completes CM
path from
inverters
through motor
stray
capacitance
Test 4 (Unshielded with AN) vs. Test 5 (Unshielded without AN)
Peak [dBμA]
60
50
40
30
20
10
0
-10
-20
-30
-40
10 0
Frequency [MHz]
10 1
Ambient
Test 5
Test 4
Limit
Noise path is
through HV
battery Ycapacitance
(stray or
intentional)
Reduction due
to additional
capacitance on
HV battery side,
AN with ground
connection, or
shielding.
23

HV Batt
E9
EMF := 150 V
EMF := 150 V
C58
E10
Simulation of 1 µF Effects
Test 4
C59
HV
Shielded
DC
Cables
L24
L25
C69
C70
HV AN
L27
L26
R20
R21
C71
C72
A
A
C61
A
A
1 Inverter
Simulation of I CM
C62
C60
IGBT25
IGBT26 IGBT27
D25 D26 D27
C63
C64
IGBT28 IGBT29 IGBT30
D28 D29 D30
C66 C67
C65
Peak [dBμA]
C68
140
120
100
80
60
40
20
0
+
V
HV
Shielded
3-phase
Cables
A
A
A
Electric Machine
Inside Transmission
-20
0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 0.2
Frequency [MHz]
68u H
L21
L22
L23 68u H
R17
R18
R19
Test 5
Test 4
C57

Current Probe – HV AN Influence
Same as
previous,
increased noise
due to AN 1 µF
capacitance
connection to
ground plane
(through
shielding
connections to
HV battery and
HV DUT which
are grounded)
Test 2 (Shielded with AN) vs. Test 6 (Shielded without AN)
Peak [dBμA]
40
30
20
10
0
-10
-20
-30
-40
10 0
Frequency [MHz]
10 1
Ambient
Test 2
Test 6
Limit
Noise appears
due to non-ideal
shielding
terminations
25

Peak [dBμA]
HV Battery Shield
60
50
40
30
20
10
0
-10
-20
-30
Test 2 (With Batt Cable Shield) vs. Test 3 (Without Batt Cable Shield)
Current Probe HV AN Voltage
10 0
Frequency [MHz]
Same since path between motor
stray capacitance is same
10 1
Test 3
Test 2
Limit
Peak [dBμV]
100
90
80
70
60
50
40
30
20
10
0
10 0
Frequency [MHz]
10 1
Ambient
Test 3
Test 2
Attenuation due to cable shield and Y-capacitance
between HV battery and AN
Limit
26

Peak [dBμV]
HV AN and Shielding Influence
100
90
80
70
60
50
40
30
20
10
0
Test 4 (No Shield, AN GND) vs. Test 1 (Full Shield, AN GND)
Test 4 (No Shield, AN GND) vs. Test 3 (Partial Shield, AN ISO)
10 0
Frequency [MHz]
10 1
Ambient
Test 4
Test 1
Limit
Attenuation due to cable shield
between HV battery and AN
Peak [dBμV]
100
90
80
70
60
50
40
30
20
10
0
10 0
Frequency [MHz]
10 1
Ambient
Test 3
Test 4
Limit
Noise reduction due to grounding of
AN which provides additional Ycapacitance
to HV battery side
27

Summary of Experimental HV AN Tests
• “Grounded” HV AN affects results:
• The 1 µF capacitor creates a current loop from electric machine
stray capacitance
• The 1 µF capacitor creates a current loop from HV battery Ycapacitance
• Cable shields and their connections impact the results
• AN inductance has smaller impact than the AN capacitance
• Most comparable to real vehicle configuration (Test 6 with shielded
cables) is configuration with AN isolated and shielding on both sides
(Test 2); however, shielding terminations are critical for higher
frequency and 1 µF negatively impacts lower frequency band.
28

Comments for New HV AN
1. Provide a defined
impedance over a
given frequency range
at the power terminals
of the equipment under
test (EUT)
2. Allow for the disturbed
voltage to be measured
3. Isolate the EUT from
undesired power supply
disturbances
• Impedance of shielded cable and
HV battery should be considered.
• Shielding connections should be
same as for vehicle.
• Need to protect test equipment
from potentially high CM voltage
pulses. Depending on configuration,
can be 100’s of Volts DC.
• Use actual battery or build HV
battery pack from series Lead-acid
batteries. Then isolating power
supply is not required.
29

Items for Future Study
Consists of both testing and simulation:
• Construct matrix of different shield termination
methods and impact upon CE measurements.
• Measure common mode current on external surface
of shield due to non-ideal shield coverage.
• Analysis of effects due to complex impedance of
sources and loads.

Conclusion of Study
�� Based on experimental and simulation results:
�� It is not recommended to use an AN as defined by
CISPR for HV conducted emissions voltage
validation.
�� It is not recommended to use an AN as defined by
CISPR during current probe measurements on HV
lines.
�� HV AN can be useful for development and simulations.
�� A new AN for HV applications should be defined if HV
conducted emissions voltage validation is required.
31

Final Remarks: New Systems – New
Questions !
Can measurement of CE be used for these
types of systems?
Are there other EMC test methods that need to
be reviewed for HV systems of the new
generation of vehicles?
Should a new standard be created for HV CE
measurement methods and required
performance levels?