1. Conducted EMI Filter Design Tool (PREMI-PRO)
Advanced Engineering

2. EMI Filter Design Research
Past activities:
EMI Filter Component Characterization
Impedance testing of DM & CM chokes, X & Y caps
Creation of EMI filter component database for R&D reference
EMI Filter Circuit Modeling & Simulation
Pspice modeling of equivalent circuit (with parasitics)
Simulation of EMI filter transfer function
EMI Filter Circuit Characterization
Gain-phase testing of actual filter assemblies
Correlation of tested & simulated gain-phase waveforms
EMI Filter Attenuation Analysis
Conducted EMI testing of actual SMPS’s w/ & w/o the characterized filters
Extraction of actual EMI filter attenuation curves using MathCAD and comparison with gain-phase plots

3. EMI Filter Design Research
Results:
Understand effects of filter component parasitics
Good correlation between simulated and actual component impedance-phase plots
Good correlation between predicted and actual EMI filter gain-phase plots
Data was obtained using infinite filter input and output impedances
Line impedance
50 or 25
EMI filter
SMPS noise source
Zin = ?

4. EMI Filter Design Research
Problem Encountered:
Lack of Equipment to Measure PSU Input Impedance vs Frequency
Input impedance contributes greatly to overall filter attenuation
Comparison between actual and predicted attenuation plots revealed little correlation due to unknown input impedance
Sample DM attenuation plots
Sample CM attenuation plots

5. PREMI-PRO Interference Source Analyser
Features:
CM-DM Mode Splitter
EMI Impedance Analyser
Filter Design Software
- key feature equivalent to 70 pages of design equations developed by a Ph.D. over a period of 3 years
Can analyze both DM & CM input impedances.

6. PREMI-PRO Interference Source Analyser
Track Record (as claimed by Predictive EMI Ltd.):
Used satisfactorily by TUV Product Services
Near-optimal EMI filter design in one (1) hour from initial test
Initial conducted EMI plot
Conducted EMI plot 1.5 hrs after initial plot

7. PREMI-PRO Interference Source Analyser
Expectations:
Man-hour cost reduction
Will speed up filter design process in all future medium-to-high power PSU models
Parts count / cost reduction
Can be used to optimize existing filter designs of production & proto units based on user-defined constraints: either size (L,W,H) or cost (added feature for Astec)
Technology improvement
Input impedance analysis will allow EMI Filter Design Research to progress to the next level
Ultimate Goal:
Optimal EMI Filter Design Capability
Comprehensive understanding of EMI filter design