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EMC Simulation of Cables Aerospace and Automotive ApplicationsTim McDonald, PhDEMA President
EMA PROPRIETARY INFORMATION
2
From ICE
Historical Development of Automotive Systems
• Technical development has turned automotive systems into electrical devices
• Increasing levels of autonomy will only increase electrical system complexity
• Inclusion of new technologies has opened the door to EMC issues from LF to EHF!
To EV
Problem Overview
• There are new electromagnetic interference sources and victims on modern and future automobile platforms• Increasing electrification of cars creates new
electromagnetic interferences sources• Autonomous capabilities multiply the number of
antennas, RF systems and optical sensors on the platform
• Program impact• Interference problems occur late in the program phase
and can be costly• Reliance on RF and electronic systems for safety
increases the impact of interference problems• Role of simulation
• Find problems early• Demonstrate ways to fix problems• Increase safety and reliability
EMA PROPRIETARY INFORMATION 3
4
Grounding, Bonding, and Shielding
• Automotive shielding methodology: – HV/HC cables are generally shielded and
terminated with 360° connections to mitigate inverter switching emissions, dV/dt = 5kV/us!• Honda: aluminum pipe to house HV cables
that traversed vehicle length – HS communication cables (e.g. Ethernet) and
safety critical systems (e.g. electronic brakes) are generally shielded: braid + foil construction
• Simulation for HV distribution system prioritized for many e-vehicle manufacturers
• Assessment of EV powertrain emissions to human safety limits (H-field exposure)
4
Magnetic Field Simulation for HV TP Cable
Honda’s Al pipe
EMA3D and MHARNESS
• Vehicle structures solved using full-wave methods in the time domain (FDTD)
• Hybrid simulation with a transmission line solver for general cable harnesses
• EMC simulation across a wide frequency range with fidelity down to the individual conductor level
• EMA3D can accommodate fully customized cables such that any cable configuration can be investigated for potential EMI impacts
Case 1: Power cables interfere with antennas
• Power cables are a source of EMI, especially when high currents are switched on and off
• Hybrid and electric drive-trains increase this interference level
• Antennas are a possible victim for interference in this case
EMA PROPRIETARY INFORMATION 6
Current on Unshielded Power Cable
0 0.2 0.4 0.6 0.8 1
Time (s) 10 -6
0
0.05
0.1
0.15
0.2
0.25
Cur
rent
(A)
Source on Cable Source
EMA PROPRIETARY INFORMATION 7
Rear Window Antenna Interference Level
200 400 600 800 1000 1200 1400 1600 1800 2000
f (MHz)
-160
-140
-120
-100
-80
-60
dBm
Rear Window Antenna
0 0.2 0.4 0.6 0.8 1
Time (s) 10 -6
-1.5
-1
-0.5
0
0.5
1
Cur
rent
(A)
10 -5 Rear Window Antenna
EMA PROPRIETARY INFORMATION 8
Rooftop Antenna Interference Level
EMA PROPRIETARY INFORMATION 9
Case 2: EMC performance of
components
10
• As part of EMC acceptance testing, vehicles are illuminated with an external antenna across a broad frequency range
• Electromagnetic interference couples to cables and vehicle structure, which may cause device failure
• Poor EMC practices may result in increased coupling
• This model shows a method to determine the impact of EMC practices through simulation prior to system or module testing
EMA PROPRIETARY INFORMATION
Exterior Illumination onto a Poorly Twisted Cable
EMA PROPRIETARY INFORMATION 11
Plane Wave Source is used to Illuminate the Vehicle
EMA PROPRIETARY INFORMATION 12
0 0.2 0.4 0.6 0.8 1
Time (s) 10 -8
0
0.5
1
1.5
2
2.5
3
E-Fi
eld
(V/m
)
10 5 Plane Wave Source
10 1 10 2 10 3
f (MHz)
80
85
90
95
100
E - f
ield
(V/m
)
Plane Wave Source
Twisted Cable
EMA PROPRIETARY INFORMATION 13
Poorly Twisted Cable (1.6 cm Max Separation)
EMA PROPRIETARY INFORMATION 14
Poorly Twisted Cable (4 cm Max Separation)
EMA PROPRIETARY INFORMATION 15
Voltage on Cables
10 1 10 2 10 3
Freqency (MHz)
0
0.5
1
1.5
2
2.5
3
Volta
ge (V
)
Induced Differential Mode Voltage
4 cm Separation
10 1 10 2 10 3
Freqency (MHz)
0
0.2
0.4
0.6
0.8
1
Volta
ge (m
V)
Induced Differential Mode Voltage
1.6 cm Separation
No Separation
EMA PROPRIETARY INFORMATION 16
Summary• EMA3D simulation can be used to predict EM
coupling from cables to various antennas on the vehicle platform
• EMA3D simulation reveals the impacts of EMC practices on the interference at cable interfaces from external EMI sources
EMA PROPRIETARY INFORMATION 17
Best Presentation Award, ICOLSE 2019, Wichita, KS
EMA PROPRIETARY INFORMATION 18
Introduction
• Transport category aircraft must show compliance to 14 CFR 25.1316 for electrical and electronic system lightning protection
• Actual Transient Levels (ATLs) need to be determined to verify vehicle/system functionality and safety
• AC 20-136 and ARP 5415 provide guidance on IEL and recognize analysis as a method to determine ATLs
ICOLSE Wichita, Kansas 2019 19
Full aircraft simulations were compared to full aircraft LTA tests to
validate a numerical approach
Import Model and Capture EM Details
• Aircraft model imported for indirect effects of lightning (IEL) simulations
ICOLSE Wichita, Kansas 2019 20
Incorporate Harness Details
• Wire/harness diagrams used to create cable packing in MHARNESS
ICOLSE Wichita, Kansas 2019 21
Wire/Harness Diagram
Match Test Configuration
• Model was initially prepared for inflight configuration
• Adjustments were made to the inflight model to match test configuration– Include RCS – Adjust control surfaces– Adjust harness configurations including pin
breakouts, shield terminations– Capture probe locations
ICOLSE Wichita, Kansas 2019 22
Entry/Exit Configurations
• How many cases are necessary for validation?
• 3 cases were deemed sufficient for this validation effort1. Nose Entry – LH Wingtip Exit2. Nose Entry – LH Stabilizer Exit3. Nose Entry – LH Engine Exhaust Exit
• Areas of highest coupling: wing, LG, engine, Stabilizers
ICOLSE Wichita, Kansas 2019 23
13
2
Indirect Effects of Lightning Transients• Validation probes chosen for critical equipment
and locations throughout the aircraft• Actual Transient Levels (ATLs)
– 32 x Open circuit voltage: Voc
– 25 x Short circuit current: Isc
– 20 x Bundle current: IB
ICOLSE Wichita, Kansas 2019 24
Open Circuit Pin Voltages, VOC
ICOLSE Wichita, Kansas 2019 25
• All simulated pin voltages are more severe or within 6 dB of experimental values
• Majority of results are in Level 1 category
• Simulated Voltages above 50 V are all within 3 dB of experimental value or more severe
Bundle Currents, IB
ICOLSE Wichita, Kansas 2019 26
• All simulated bundle currents are more severe or within 7 dB of experimental values
• Majority of results are in Level 1 category
• Simulated Currents above 125 A are all within 3 dB of experimental value or more severe
EMA PROPRIETARY INFORMATION 28
EMA PROPRIETARY INFORMATION 29
Property of EMA. All rights reserved. 30