ce analyst overview | conducted emissions analysis overview

EMI Analyst™

EMI ANALYST™ Software SuiteI n t u i t i v e A c c u r a t e E f f e c t i v e

Conducted emissions analysisoverview

EMI Analyst™EMI Analyst™

EMI Analyst™ is a 4-in-1 EMI Analysis Tool

EMI Analyst™ calculates electromagnetic interference for cable-connected circuits

• Conducted Emissions – CE Analyst™– Audio and radio frequency noise emitted on cables

• Conducted Susceptibility – CS Analyst™– Interference induced by noise on cabling

• Radiated Emissions – RE Analyst™– Electric and magnetic fields emitted by cables

• Radiated Susceptibility – RS Analyst™– Noise induced by electromagnetic fields on cables


What does CE Analyst™ do?

Calculates RF current and voltage induced on cables and circuitry by active circuits


EMI Analyst™ Covers All Frequency Domain Conducted Emissions (CE) Specifications

• All industries

– Consumer and Industrial

– Aviation

– Automotive

– Military and Space

• All frequency ranges

– Audio Frequency, 10 Hz – 150 kHz and up

– Radio Frequency, 10 kHz – 152 MHz and up

EMI Analyst™

Typical Audio Frequency CE Setup

• Military and Space

– CE101, MIL-STD-461G/F/E/D

– CE01, MIL-STD-461C

• Automotive

– CISPR 25

• Aviation

– DO-160G/F/E/D/C, Section 21

• Consumer and Industrial

– IEC EN 55011 and EN 55022

EMI Analyst™

Typical Radio Frequency CE Setup

• Military and Space

– CE102, MIL-STD-461G/F/E/D

– CE03, MIL-STD-461C/B/A

• Automotive

– CISPR 25

• Aviation

– DO-160G/F/E/D/C, Section 21

• Consumer and Industrial

– IEC EN 55011, EN 55022


What Information is Needed?

Before you start the analysis, collect:

– Frequency range of the analysis

– CE test limit

– Active circuit waveforms

– EMI filter schematic

– Cabling configuration

– End circuit schematic


Switch Mode Power Supply (SMPS)For this example, MIL-STD-461F method CE102

Conducted Emissions Example

BlockDiagram

Circuit Schematic

Switch Mode Power

ConverterEMI Filter Cable Conductors

LISNsand

DC Power Supply

Stray C

4.7uH

1uF 3.3uF

0.1uF

0.1uF

10 uH

10 uH

330 nF

10 nF

10 nF

100 uH

PS

Power Converter EMI Filter Cable Conductors LISNs and DC PS

Frequency Range10 kHz – 10 MHz

CE102 Limit94 – 60 dBV

EMI FilterLow pass, T-section

Cabling configurationShielded wire pair over ground plane, conductive fabric tape shield

End CircuitLISN & Power Supply

Pass/Fail CriteriaConducted emissions must be less than CE limit


Frequency Range

• Start & Stop frequencies• Log or Linear scale• Resolution

– Pts / Decade for Log Scale– Hz for Linear Scale

• Example: MIL-STD-461F, CE102– Range: 10 kHz – 10 MHz– Scale: Log– Resolution: 90 pts / decade

• 10 kHz – 150 kHz in 1 kHz steps• 150 kHz – 10 MHz in 10 kHz steps


CE102 SMPS Noise Source

• Switching power supply produces– Differential mode current

– Common mode voltage

• EMI Analyst needs only circuit waveforms from– Datasheets

– Circuit analysis output

– Oscilloscope measurements


SMPS Interference Noise Source

Input DM Current

Input CM Current

FET SwitchingVoltage

Stray C


Cabling Configuration

• 8 built-in templates– 4 shielded, 4 unshielded

• Enter– Physical dimensions

– Conductor and dielectric materials

• Computes– Characteristic impedance

– R, L, C values

EMI Analyst™

Cabling Configuration

• Shielded Wire Pair Over Ground Plane for this example

– #18 AWG wires

– Twisted, shielded pair

– 5 cm above aluminum ground plane per MIL-STD-461F

– Fabric tape shield. Properties are defined on Transfer Impedance form

EMI Analyst™

Conductive Fabric Tape Shield

• Laird 86203 Nickel/Copper Black Fabric Tape

Metalized Fabric

Conductive Adhesive

Release Paper

EMI Analyst™

Conductive Fabric Tape Properties

• Conductive Layer– Nickel over Copper-plated polyester fabric

• Adhesive Layer– Acrylic, conductive

Metalized Fabric

Conductive Adhesive

Release Paper

0.13 mm

Metalized Fabric

Conductive Adhesive

Non-Conductive Surface

I

VRX-Y = 0.06 Ω / sq.

ASTM F390

Metalized Fabric

Conductive Adhesive

Metal Plate

Metal Plate

VI

1 square-inch areaMIL-STD-202 Method 303, 5 psi

RZ = 0.04 Ω / sq.-in. = 25.8 µΩ / sq.-m

EMI Analyst™

Fabric Resistivity and Adhesive Resistivity

• Thickness of metalized fabric is not specified– Fabric + Adhesive = 0.13 mm– Assume fabric is 0.065 mm (half)

• Surface Resistivity

– 𝑅𝑆 =𝜌

𝑡

Ω

𝑠𝑞𝑢𝑎𝑟𝑒

– 𝜌𝑓𝑎𝑏𝑟𝑖𝑐 = 𝑡𝑅𝑆 = 0.065 𝑚𝑚 𝑥 0.06Ω

𝑠𝑞𝑢𝑎𝑟𝑒=

3.9 𝑥 10−6 Ω −𝑚

– 𝜌𝑐𝑢 = 1.68 𝑥 10−8Ω −𝑚

– 𝜌𝑟 𝑓𝑎𝑏𝑟𝑖𝑐𝜌𝑓𝑎𝑏𝑟𝑖𝑐

𝜌𝑐𝑢=232.14

• Adhesive Resistivity

– 𝜌𝑎𝑑ℎ𝑒𝑠𝑖𝑣𝑒 = 25.8Ω

𝑠𝑞.−𝑚,

assuming metallized fabric is much more conductive than adhesive


End Circuits

• Schematic capture

– Ladder network

– Passive components (R, L, C, and magnetically coupled)

• Left-End of cable

– EMI filter for PS circuit

• Right-End of cable

– LISN circuit


Left-End Circuit: EMI Filter

Input Power Filter Schematic

EMI Analyst™ Filter Schematic

10uF

1uF

1uF

25 uH

25 uH

330 nF

10 nF

10 nF

100 uH


Right-End Circuit: LISN and DC Power Supply

LISN schematic

EMI Analyst™ LISN schematicand power supply impedance


Analysis ResultsCE102 Voltage at LISNs

CM and DM Cable Current

View current and voltage at all points in the circuit and anywhere along the length of the cable.


Analysis Results – Animated

• Cable Input Impedance, 10 kHz to 10 MHz– Wire1-to-Shield (blue)

– Shield-to-Ground (orange)

– Wire1-to-Wire2 (green)

• Animate any cable current, voltage, or impedance over frequency or cable length

Click graph to play


Analysis Results – 3D

• View cable current, voltage, or impedance versus frequency and position on cable– Rotate – Click + drag

– Zoom – Ctrl + drag

– Move – Shift + drag

Shown: Common Mode Current


Summary

• The preceding example computes conducted emissions produced by a switching power supply and compares results to the MIL-STD-461F, CE102 limit.

• Conducted emissions are one of four applications in the EMI Analyst Suite– CE Analyst™– RE Analyst™– CS Analyst™– RS Analyst™

• Recommended links:– https://www.emisoftware.com/blogs/emi-analysis-tool-emi-analyst-overview/– https://www.emisoftware.com/blogs/what-else-can-emi-analyst-do/– https://www.emisoftware.com/blogs/right-blend-electromagnetic-interference-analysis/– https://www.emisoftware.com/blogs/6-qualities-to-look-for-in-emi-software/

https://www.emisoftware.com/blogs/emi-analysis-tool-emi-analyst-overview/

https://www.emisoftware.com/blogs/what-else-can-emi-analyst-do/

https://www.emisoftware.com/blogs/right-blend-electromagnetic-interference-analysis/

https://www.emisoftware.com/blogs/6-qualities-to-look-for-in-emi-software/

ce analyst overview | conducted emissions analysis overview

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