Date post: | 22-Jan-2018 |
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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
EMI Analyst™EMI Analyst™
What does CE Analyst™ do?
Calculates RF current and voltage induced on cables and circuitry by active circuits
EMI Analyst™EMI Analyst™
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
EMI Analyst™EMI Analyst™
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
EMI Analyst™EMI Analyst™
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
EMI Analyst™EMI Analyst™
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
EMI Analyst™EMI Analyst™
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
EMI Analyst™EMI Analyst™
SMPS Interference Noise Source
Input DM Current
Input CM Current
FET SwitchingVoltage
Stray C
EMI Analyst™EMI Analyst™
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
EMI Analyst™EMI Analyst™
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
EMI Analyst™EMI Analyst™
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
EMI Analyst™EMI Analyst™
Right-End Circuit: LISN and DC Power Supply
LISN schematic
EMI Analyst™ LISN schematicand power supply impedance
EMI Analyst™EMI Analyst™
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.
EMI Analyst™EMI Analyst™
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
EMI Analyst™EMI Analyst™
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
EMI Analyst™EMI Analyst™
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/