EMC Simulation of Cables Aerospace Automotive Applications

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EMC Simulation of Cables Aerospace and Automotive ApplicationsTim McDonald, PhDEMA President

EMA PROPRIETARY INFORMATION

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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

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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)

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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


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


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


Rooftop Antenna Interference Level


Case 2: EMC performance of

components

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• 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


Plane Wave Source is used to Illuminate the Vehicle


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


Poorly Twisted Cable (1.6 cm Max Separation)


Poorly Twisted Cable (4 cm Max Separation)


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


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


Best Presentation Award, ICOLSE 2019, Wichita, KS


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


Incorporate Harness Details

• Wire/harness diagrams used to create cable packing in MHARNESS


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


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


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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


Open Circuit Pin Voltages, VOC


• 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


• 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

EMC Simulation of Cables Aerospace Automotive Applications

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