technische universität dortmund - home - … of non-symmetrical samples and large connectors Ability to correlate with Antenna measurements with least variation in test setup Capacitive

technische universitätdortmund

Faculty of Electrical Engineering and

Information Technology

On-Board Systems Lab

Comparative Study of Transfer Impedance (ZT) Measurement

Methods and Simulationmodels to Analyze Shielding

Behaviour of High Voltage Cables in Electric VehiclesM.Sc. Abid Mushtaq, Dipl.-Wirt.-Ing. Katharina Hermes,

Prof. Dr. -Ing. Stephan Frei.

technische universität

dortmund

Abid Mushtaq, Katharina Hermes, Stephan Frei – Kleinheubacher Tagung 2015

Comparative Study of Transfer Impedance (ZT) Measurement Methods and Simulation models to Analyze Shielding

Behaviour of High Voltage Cables in Electric Vehicles

Content

Introduction

Measurement methods

Simulation methods

Conclusions

2


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Content

Introduction

Motivation

Basic Terminology

Measurement methods

Simulation methods

Conclusions

3


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Motivation

Problem Overview

In Electrical Vehicles (EV) and Hybrid-Electrical Vehicles (HEV)

Power drive systems, inverters convert and provide PWM signals at high voltage

(Vpeak-to-peak ≥ 300V) to drive the E-motors via HV-cables (shielded power cables)

EMI noise signals from these HV-cables may cause malfunction of LV

electronics devices, MCUs, vehicular communication networks (LIN, CAN,

Flexrays, MOST, etc), AM Radio, etc

4

HV Cable-Connectors

Inverter

HV Cables

EMI Noise

Low Voltage Systems

HV Connectors

3P

MotorBattery

pack

Low Voltage Systems

• Optimum shielding of the HV-cables and HV-connectors

Dummy inverter with HV

Cable-Connectors


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Motivation

Steps:

How to evaluate shielding performance of HV-shielded cables?

Shielding Effectiveness vs. Transfer Impedance

Shielding Effectiveness (SE)

Is a measure for the not just shielded cable, but also depends on external parameters

For the same shield, we can get different SE by varying the external parameters

Good for overall integrated system shielding analysis

Transfer Impedance (ZT)

Is an intrinsic property of the shield, and doesn’t depend on external parameters

For the same shield, ZT is independent of external parameters like termination load,

external layouts, etc.

Good for component level shielding analysis

Main focus of this talk is on ZT:

Predicting Transfer Impedance using simulation and measurement methods

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Motivation

Basic Terminology

Transfer Impedance (ZT)

It is defined as:

6

SHIELDT

SHIELD SHIELD

dVZ

I l

Simulation methods

Based on braid parameters,

dimensions, ZT can be predicted

Based on circuit models

Measurement method

Based on above formula,

various test setup have been proposed (Triaxial Method and

Line Injection Method)


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Content

Introduction

Measurement methods

Existing methods

Ground Plate Method (GPM)

Capacitive Voltage Probe (CVP) Method

Simulation methods

Conclusions

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Measurement methods

Existing methods

ZT measurement methods

Triaxial Method (IEC 62153-4-3)

Complex structure for variable sizes and connectors

Variable size of tubes require for different sizes and shapes, specially for connectors

Line Injection Method (LIM) (IEC 62153-4-6)

For non-symmetrical cables and connector assemblies, different positioning of the

injection wires can cause inaccuracy in measured results

8

Triaxial tube

Triaxial cell

LIM Cable test

LIM Cable-Connector test


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Measurement methods

Use of alternative methods to measure ZT

For shielding analysis of HV-cable-connector systems, it should be

Flexible to measure ZT of non-symmetrical samples

and large connectors

With maximum accuracy and better repeatability/reproducibility

To overcome these issues in HV-cable-connector analysis, following

methods are used:


Overcomes the limitation of the existing methods

Flexible to measure ZT of non-symmetrical samples and large connectors

Ability to correlate with Antenna measurements with least variation in test setup

Capacitive Voltage Probe (CVP) measurement

Direct measurement of Voltage over the shield

Transfer Impedance can be approximated using both voltage and input current

Ability to correlate with Antenna measurements with least variation in test setup

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Measurement methods


Circuit schematics for all three measurement setups are similar

Source circuits are almost same

Receiver circuits are different (physically)

Same GPM test setup for both HV-Cable and HV-Cable-Connector system

10

~R1F

R2P

R2N

U1N

U2,FE

Inner side of shield

Z1,εr1

Z2,εr2

NWA port1:

SourceNWA port 2

Receiver

Source-circuit

Inner-conductor

:

Far-end

ZT

Receiver-circuit:

Cylinder (Triaxial-Method)/

Injection (Parallel) lines (Line Injection Method)/

Copper-plate (Ground-Plate Method)

Near-end

R1P

RDamping

Outerside of shield

U2,NE

SHIELDT

SHIELD SHIELD

dVZ

I l


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Measurement methods


Test setup

11

R2F

R1FLine Injection Method

(Far-end configuration)

R2FR1F

Triaxial Method

RDamping

R1F

IINNER

+

VSHIELD

_ZT = VSHIELD/ (IINNER .lDUT)h= 65 mm

HV-Cable only

Inverted

Connector-box

HV-Cable-

Connector system

RDamping

R1F

lDUT

lBox

h= 65 mm hbox = 100 mm


Alternative

method for

measuring

Transfer

Impedance ZT


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Measurement methods


12

105

106

107

10810

0

101

102

103

Frequency [Hz]

ZT [m

Ohm

/m]

Comparison of LIM, Triaxial and GPM for HV-cables only

LIM

Triaxial TUDO

Triaxial Bedea

GPM

Triaxial tube

Line Injection Method

Ground Plate Method

Matched-Matched

termination

improves range

ZT-cable ≈ RDC-cable-shield


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Measurement methods


13

105

106

107

108

100

101

102

103

104

Frequency [Hz]

ZT [m

Ohm

/m]

ZT comparison of Connectors A,B and Dummy-box (Ideal)

ZT-Connector-A

ZT-Connector-B

ZT-Dummy-box

ZT-Cable

Ref.

Lesser contact-

points improve

shielding


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Measurement methods

Capacitive Voltage Probe (CVP) test

Using basic definition of ZT

14

(Ground) Copper plate

Near-end Far-end

ZLOAD

lbracket-bracket

h Vshield

ISOURCE

CVP

insulator

ISHIELD

SHIELDT

SHIELD SHIELD

dVZ

I l

CVP SHIELDV V

50

SOURCESOURCE

IN

VI

Z

lSHIELD

Contacts are

assumed to be perfect R= 0Ω

For unknown input

impedance/mismatched system, it can be measured using reflection

measurements using NWA

Longer DUT

length will ensure better RDC

measurements


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Measurement methods


15

104

105

106

107

108

10-1

100

101

102

103

Frequency [Hz]

ZT [m

Ohm

/m]

ZT-GPM

ZT-CVP

RG58 (with shield-dia ‘D0’= 4.4mm; braid thickness

‘d’=0.15 mm; No. of braid filaments ‘n’= 5; No. of

carriers ‘N’= 24; Weave angle=21

CVP doesn’t require soldering matched

terminations in complex ways, but has

lesser measurable ZT


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104

105

10610

-2

10-1

100

101

Frequency [Hz]

ZT [m

Ohm

/m]

Semi-rigid cable ZT using CVP

ZT-Semi-Rigid-L25cm

ZT-Semi-Rigid-L50cm

ZT-Semi-Rigid-L75cm

ZT-Semi-Rigid-L75cm-LF

ZT-SIM

Measurement methods


16

Benefit:

For semi-rigid cables, very good shielded

cables CVP measures directly

T-SIM-RG-402

;1

sinh 1DCZ

jR

j


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Content

Introduction

Measurement methods

Simulation methods

Analytical models

Circuit models

Conclusions

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Braid parameters

Diameter of the

braidD0

Diameter of single

braid wired

Number of wires in

carriern

Number of carriers N

Weave angle Ψ

Conductivity σ

Simulation methods

Analytical Model

Using analytical model (Demoulin model) for ZT

18

103

104

105

106

107

108

10-1

100

101

102

103

Frequency [Hz]

ZT [m

Ohm

/m]

Shielded cable ZT model description vs. frequency

ZT = |Z

D|

ZT = |jL|

Zk = |k|

ZT model

ZT measured

_ _T Cable DC shieldZ R

1 2

_ 0

1

sinh 1T Cable

jZ R

j

3

4

_ 0

1*( )

sinh 1

j

T Cable SHIELD CABLE

jZ R j L k e

j

4

_ *( )T Cable shieldZ j L

ZT Dominant parts (1-4) in ZT

4

0

1( );

sinh 1

j

T CABLE HOLE BRAID

jZ R k e j L L

j

Aperture

Carrier N

Weave Angle Ψ

Single Braid-wire ‚n‘


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Simulation methods

Analytical Model

How ZT can be improved based on geometrical parameters of the shield?

19

Inner ConductorBraid Structure

Outer Shield

Insulating Material

d

D0

Aperture

Carrier N

Weave Angle Ψ

Geometrical parameters of shield

Single Braid-wire ‚n‘

103

104

105

106

107

10810

0

101

102

103

Frequency [Hz]

Zt [m

Ohm

/m]

Effect of braid wire thickness on Zt

d = 1.0mm

d = 1.2mm

d = 1.4mm

d = 1.6mm

d = 1.8mm

d = 2.0mm

Braid thickness has major

impact on how ZT behaves at low frequencies as ZT = RDC

103

104

105

106

107

10810

0

101

102

103

Frequency [Hz]

Zt [m

Ohm

/m]

Effect of Weave angle variation on Zt

weave angle 20

weave angle 25

weave angle 30

weave angle 35

weave angle 40

Inductance is directly dependent on weave

angle. Changing weave angle means changing inductance of the shield thus

major impact is at higher frequencies

where inductance are dominant in ZT

Break frequency

decreases with

increasing shield

thickness


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Simulation methods

Circuit models

Combination of analytical

and circuit models

give more realistic

prediction of shielding

behavior

Advantages: Possible to..

Add TL models for

connecting cables, to

predict realistic

measurement results

Add to other modules, for

complex system analysis

20

(LCOAX/2)

CCOAX

(LCOAX/2)(LCC/2)

CCC

(LCC/2)

VSOURCE

~RPORT1

(LCC/2)

CCC

(LCC/2)

R1F

T-cellT-cellSOURCE

PORT

Inner-shield

Inner-

conductor IIN-CCT

ISOURCE

ISHIELD

RPORT2

RECEIVER

PORT

(LSG/2)

CSG

(LSG/2)

~RGND-Contact

RDAMPINGOuter-

shield

Ground plane

_ +

IOUT-CCT

VT

0.1Ω

104

105

106

107

108

109

10-1

100

101

102

103

Frequency [Hz]

ZT [m

Ohm

/m]

Verification of ZT model for HV-cable only

ZT model 25mm

2

ZT QUCS 25mm

2

ZT meas 25mm

2

Circuit model

Demoulin

Measured

VT = ISHIELD.ZT-model


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Content

Introduction

Measurement methods

Simulation methods

Conclusions

21


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Conclusions

Summary

Overview

Comparative study of ZT measurement methods and Simulation methods for

shielding analysis of HV cables used in EVs

Measurement methods

Existing methods like Triaxial and Line Injection Methods


Capacitive Voltage Probe (CVP) Method

Simulation methods

Analytical models

Circuit models

Applications:

Component level shielding analysis of shielded cables and connectors

Further integration of proposed simulation methods into complex system

simulations

Correlation with Antenna measurements

22

Fakultät für Elektrotechnik und Informationstechnik

Arbeitsgebiet Bordsysteme

technische universitätdortmund

Thanks for your attention!

M.Sc. Abid Mushtaq

[email protected]

ACKNOWLEDGMENT

The reported R+D w ork was carried out w ithin the CATRENE project CA310 EM4EM (Electromagnetic Reliability and Electronic Systems for Electro Mobility). This

particular research is supported by the BMBF (Bundesministerium fuer Bildung und Forschung) of the Federal Republic of Germany under grant 16 M3092 I.

Documents

technische universität dortmund - home - … of non-symmetrical samples and large connectors Ability to correlate with Antenna measurements with least variation in test setup Capacitive