EMC analysis workflow - 專業三維電磁模擬軟體 - CST · PDF fileVented Panel Optimization Vented Panel Plane wave excitation Parametric Sweep ... Simulation of EMC test setup

EMC analysis workflow

Antonio Ciccomancini Scogna, CST of America –

CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com

Antonio Ciccomancini Scogna, CST of America –

[email protected]

EMC/EMI Applications


Emissions Susceptibility E3

Typical Emissions Issues

1 2

Image courtesy of Johnson Controls Inc.


Coupling between heat sink

and connector bypasses signal

path through PCB

Coupling through

vent in enclosure

1Slots in ground plane

radiate onto cable, DM to

CM current conversion

� EMC design involves minimizing the noise, absorbing the noise, containing the noise (shielding) and diverting/filtering the

noise.

� Stray fields/couplings/radiation are critical in EMC/EMI. Capturing these effects accurately often requires full system-level

simulation.

USB Channel Application


� USB differential pair with intended differential mode

signals and unintended common mode signals

� Several potential coupling paths that may lead to

emissions effects

USB cable

3 meter radiated emissions

results

Emissions Workflow: USB Channel


Import PCB layout into CST PCB STUDIO and run CST BOARDCHECK to identify critical nets

Perform detailed analysis of critical nets using CST Microwave STUDIO and compute transient CM voltage

Use transient CM voltage to simulate radiation from USB

cable

Cascading approach is only valid if the system can be decoupled

CST BOARDCHECK1. Deal with a new PCB layout

2. Analyze PCB in EMC rule checker

5. Obtain EMC rules for layout engineers Design

Cycle

EMC Rules Checking for PCB Designs


3. Decide which structures need simulation

4. Perform simulations and analyze results

EMC Rule Checking Workflow

• Altium (ODB++), Cadence, Mentor Graphics, Zuken

Import PCB Design

• Categories: Signal reference, Wiring/Crosstalk, Decoupling, Placement

Select EMC Rules

Select Nets


• Tag critical nets, differential pairs, or power and ground nets

Select Nets

• Tag ICs, clock drivers, stitching or decoupling capacitors, or connectors

Select Components

• Press one button and wait for the EMC violations to be listed

Start EMC Rule Check

CST BOARDCHECK: Rules

EMC rules SI rules


EMC Rule Check Violations

Critical Net Near Edge of Reference Plane

Critical Net Near I/O NetCritical Differential Net Length Matching and Spacing


Partitioning of the Model / USB Channel

choke to

connector pinsCM

choke


driver to

choke

CM Signals in Channel

11

22

Source of CM voltage at connector?

1. DM to CM coupling in line

2. coupling via neighbouring line

DM to CM coupling


frequency in GHz

DM to CM coupling

S21in dB

in line -25 dB

via neighbouring line -55 dB

CM Signals in Channel

Without CM choke With CM choke

11DM DM ��CMCM


time in ns

CM voltage in V 1.5 V

80 mV

Driver output skew set to 100ps

Non perfect balanced lice increases skew and CM conversion

Radiated Emissions Prediction (I)

Convolution of impulse response with

Without CM choke63 dBµV/m

Cable

shield


Convolution of impulse response with

periodic CM noise

3 meter emissions scan

With CM choke34 dBµV/m

System Assembly and Modeling

Chassis

Schematic View Assembly View


PCB Vented

Panel

Heat sinks

PCB – Near Field Source ModelingPortion of chassis

modeled to capture

reflections


Chassis EmissionsBaseline Case

Heat sinks

Near field source (automatically

positioned based on PCB location)


Heat sinks

Included

Heat sink

Clone block

Vented Panel OptimizationVented Panel Plane wave

excitation

Parametric Sweep

Task to determine

optimum hole

dimensions

Chassis including


Chassis including

Vented Panel Optimized vented panel

positioned behind fans

Vented Panel Optimization

Without Vented Panel With Vented Panel


Surface Current distribution @ 5GHz

CST BOARDCHECK

• Identify critical nets

Integrated workflows

• PCB + connector + cable

Transient co-simulation

Key Features for Emissions Workflows


• Broadband response, field/circuit coupling (CM chokes etc.)

Efficient cable and aperture modeling

• CS complex cable bundles, TLM compact aperture models

Simulation of EMC test setup

• External ground plane, far-field probes, cylinder scan

System Assembly and Modeling (SAM)

• System-level simulation of design variants

Typical Susceptibility Issues

1

3

4

x

5

Source Victim


Power Line (or other interconnecting cables)

235

Failure criteria depends on the testA No degradation in performance, operates as intended at all timesB Degradation allowed during the test, full performance must be restored

following the test, without user interventionC Degradation allowed during the test, and after the test, provided that

full performance can be restored automatically or by user intervention

ESD Generator ModelThe motivation for developing a detailed full

3D model of the generator is to correctly

simulate the asymmetric fields generated by

the discharge and their coupling to the system.

Discharge current

at gun tip


Full wave model for simulating Noiseken ESD Generator

Dazhao Liu; Nandy, A.; Pommerenke, D.; Soon Jae Kwon;

Ki Hyuk Kim; IEEE Symposium on EMC,17-21 Aug. 2009

Induced voltage in

semi-circular loop

Time animation confirms the asymmetric

field distribution. This may affect the

coupling to the system under test

ESD to Enclosure with Cable EntryExternal Cable

Screen Bonded to

Enclosure


Bi-Directional co-simulation

between the 3D field, cable

and circuit simulations allows

the effect of cable entry to

be considered

External

Cable Screen

not Bonded

to Enclosure

ESD Transient co-simulation


Modeling details/ports

Port 1Ports 3,4

(diodes)


Port 2

(diodes)Reader_p

Reader_n

tag_n

tag_p

Results/currents

Reader_n


tag_n

Surface current


Hybrid Cable EMI

Load

SMPS

Sensor


Programmable switch mode power supply driving an intelligent

sensor with high speed RS485 communications

IGBT switching is used to generate Pulse Width Modulation

waveforms to supply the sensor

Interference between Power and Control circuits

Import measured screen

transfer impedance

RS485

screen

Cable Parameter Extraction

C+,- = 0.0021pF/m

Analysis of mutual

capacitance between Vpos

and Vneg phase wires

Vpos


C+,- = 0.0021pF/m Vpos

Vneg

CST EMS can used to design cable cross section and extract parasitic values

CST CS uses an internal 2D field solver to extract parasitic values for TL analysis

New curved tetrahedral elements in EMS electrostatic solver

Interference AnalysisCST CS used to investigate CM noise for

different SMPS waveforms, cable

lengths, cable screens and terminations

Cable/circuit co-simulation


Input SMPS

PWM voltage

CM Current in

RS485 line

Typical E3 Issues

200kA peak

1.5µs rise, 88 µs fall 50 kV/m peak1ns rise, 25 ns fall

I (A) E (V/m)

tt

300 V/m CW field 10 KHz to 40 GHz

EMP


Lightning Strike Electromagnetic Pulse

Lightning and EMP are transient effects: peak fields and dissipated energy are critical

HIRF requires analysis over an extremely wide spectrum (10 KHz to 40 GHz)

Lightning channel

High Intensity Radiated Fields

HIRF

Field/Cable Co-Sim.Plane Wave Transient EMP


Simulation of incident EMP and effect of cable shield connection to enclosure

Good cable screen to chassis connection

Poor cable screen to chassis connection

Internal probe

Rotorcraft EMP SimulationFree standing curves for slots/seams


Huge difference in scale!

500nm ITO thickness vs. airframe dimensions

Rotorcraft EMP Simulation


ITO coated canopy reduces peak electric field inside cockpit from 8 KV/m to 800 V/m

Solve time 200m on 8-core CPU / 4.3 GB RAM

EMP Protection AssessmentTrue transient co-simulationReal world cable modeling


Non-linear transient protection

devices modeled by true transient

co-simulation

Solid and braided screens can be

added to cable model to

investigate shielding

Cosite AnalysisPowerful workflows for antenna co-site and RADHAZ analysis

CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com

Near Field Source

� Model exchange thru S-parameter and

touchstone standard

� Fully automated Saber model export

approach in CST Studio Suite

CST STUDIO to Saber Link

Structural Component Model

S-Parameter Computation

CST Studio Suite


approach in CST Studio Suite

� Easy external model integration in Saber

thru drag & drop

� Full support for transient & frequency

analysis in Saber

Touchstone Exchange Format

S-Parameter Model Block

TR or AC Analysis

CST Studio Suite

Saber

Common Mode Choke Example


Matching the Inductance


Typical mue value for the ferrite was chosenNumber of windings was adjusted to match inductance given in datasheet

Fine tuning - Common Mode Impedance

1e5

Wire Resistance

Inter wire capacitance


1000

2000

Export into Synopsys Saber


Drag and Drop the created files

into the Saber library.

Frequency Analysis in Saber

Place into Saber

Schematic


common mode +1V / +1V

differential mode +1V / -1V

Hybrid Cable Example

Load

SMPS

Sensor


Programmable switch mode power supply driving an intelligent sensor with high speed RS485 communications

Import measured screen

transfer impedance into

CST Cable Studio

RS485

screen

S Parameters for Saber Export

Broadband S parameter output to

cover power harmonic spectrum


Cable screens groundedPorts placed on power and RS485 pins for coupling analysis

Transient Analysis in Saber


Place into Saber

Schematic

Export Circuit to Synopsys Saber

In addition to S parameter link, CABLE STUDIO can directly generate an

equivalent circuit model for Saber…


Equivalent circuit derived from 2D cross section field solver and TL solver

Powerful solutions for analyzing broad range of Emissions Susceptibility and E3problems

� Coupling, shielding, ESD, lightning, EMP, HIRF…

Transient solver� Direct time-domain analysis of transients such as ESD, EMP and lightning

Co-simulation� MWS+CS+DS co-simulation enables coupling between fields, cables and circuits

Conclusions


� MWS+CS+DS co-simulation enables coupling between fields, cables and circuits

Compact models� Thin conducting panels, slots/gaps, joints/seams and ventilation panels

Realistic cable models� Twisted conductors, screens, connections to 3D structure

New links between CST STUDIO SUITE and Synopsys Saber providesmooth workflow for system-level analysis

Documents

EMC analysis workflow - 專業三維電磁模擬軟體 - CST · PDF fileVented Panel Optimization Vented Panel Plane wave excitation Parametric Sweep ... Simulation of EMC test setup