1 / 24

IEEE Dallas EMC Society

IEEE Dallas EMC Society. System Level EMC Simulation Using the TLM Method. David Johns. What is FLO /EMC …?. The first electromagnetic field simulator developed specifically for system-level EMC design in the electronics industry

khuyen
Download Presentation

IEEE Dallas EMC Society

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. IEEE Dallas EMC Society System Level EMC Simulation Using the TLM Method David Johns

  2. What is FLO/EMC…? • The first electromagnetic field simulator developed specifically for system-level EMC design in the electronics industry • Enables EMC problems to be identified and managed in the early stages of design • Good for investigating radiated & conducted emissions, immunity (susceptibility), ESD and crosstalk problems: • Enclosures & EMI shields • Interfaces between boards and chassis • Cables and EMI filters • Unintentional antennas! (heat sinks etc.) • Based on the 3D Transmission-Line Matrix (TLM) Method

  3. TLM Method V7 V12 V2 Y V6 Z X V10 V9 V5 V1 V3 V4 V8 V11 • 3D space-volume divided into nodes (10th wavelength) • Each node is a 12-port transmission-line junction • Scattering at the nodes models coupling between E and H fields • Transient E and H fields are calculated from combinations of voltages and currents on the transmission lines • Spectrum found by FFT Ey= ½ (V3i + V4i + V8i + V11i ) / DY

  4. TLM Coupling Matrix Incident Pulses Vik Reflected Pulses Vrk+1 S = ½ Ey= ½ (V3i + V4i + V8i + V11i ) / w

  5. Wave Propagation, Time 0 1 1 1 1

  6. Wave Propagation, Time 1 0.5 0.5 0.5 0.5 -0.5 0.5 -0.5 0.5 0.5 -0.5 0.5 0.5 -0.5 0.5 0.5 0.5

  7. Wave Propagation, Time 2 0.25 0.25 0.25 0.5 -0.25 0.5 0.5 0.5 0.25 0.25 -0.5 -0.5 -0.25 0.25 0.25 -0.5 -0.25 0.25 0.25 -0.5 0.5 0.5 0.5 -0.25 0.25 0.25 0.25

  8. Wave Propagation, Time 3 0.25 0.25 -0.25 0.375 0.375 0.375 0.375 0.125 0.125 -0.125 -0.125 0.375 0.375 -0.125 0.375 -0.375 0.375 -0.125 -0.125 -0.375 0.125 0.125 0.125 -0.375 -0.375 0.25 0.25 -0.25 -0.25 -0.125 0.125 0.125 -0.125 0.25 0.25 -0.375 -0.375 0.125 0.125 0.125 0.375 -0.375 0.375 -0.375 -0.125 -0.125 -0.125 0.375 0.375 -0.125 -0.125 0.375 0.125 0.375 0.125 0.375 0.375 -0.25 0.25 0.25

  9. Complexity of EMC Analysis connectors seams air vents • Accurate modeling requires geometric detail • A long narrow seam may be a good antenna! • Meshing the detail is computationally impractical Compact vent model

  10. FLO/EMC Smart Parts • TLM method uses a TL-Matrix to model fields. • Other TL’s & lumped-circuit models can be connected into the matrix. • Arrays of small holes are often necessary to provide adequate thermal ventilation/cooling. • Apertures increase emissions and decrease shielding effectiveness of the box. • Low-frequency fields are evanescent near the apertures. • Extremely fine grid would be required to model the exponential decay. • FLO/EMC overcomes this difficulty by inserting a “smart part” into the grid.

  11. Air vent smart part For a thin panel TEM transmission can be modelled by a shunt inductor. L is like a short at DC, but allows high freq. transmission. TEM For a thick panel the additional electric field inside the aperture can be modelled by a shunt capacitor • L models the current flow along the edges of the apertures • C models the electric field stored inside the apertures.

  12. Transmission dependence on aperture shape and size, coverage and depth – empirical results • Fine TLM mesh of single aperture used to calculate dependence of Transmission on aperture shape and size, coverage and depth • Fit L,C air vent parameters to the Transmission results at two frequencies - 10% and 80% of aperture cut-off frequency

  13. Air Vent Implementation Inductor modelled by short-circuit transmission line Capacitor modelled by open-circuit transmission line

  14. Validation - Plane Wave 1D propagation through an array of circular apertures (depth equal to diameter) The fine TLM mesh and air vent model give the same results at 10% and 80% of aperture cut-off frequency

  15. Validation - Emission [M.Li et al,’EMI…’,IEEE Trans EMC, Vol. 42, No. 3, p265,2000] r =10.0 mm p = 5.0 mm t = 1.65 mm N=252 a =50 mm b = 20 mm c = 40 mm d = 10 mm

  16. Run time on Dual Pentium Xeon with 3 GHz clock rate

  17. Enclosure with thick walls r = 5.08 mm p = 0.69 mm t = 5.20 mm N= 45 a = 100 mm b = 80 mm c = 15 mm

  18. Run time on Dual Xeon with 3 GHz clock rate

  19. Enclosure with vents & slots r = 5.08 mm p = 0.69 mm t = 0.20 mm N= 45 a =50 mm b = 20 mm c = 40 mm l= 94.92 mm w =0.69 mm t = 0.20 mm

  20. Air ventsand slots 3m from air vent 3m from slot Run time on Dual Xeon with 3 GHz clock

  21. Multi-WireSmart Part cable connector pins Compact vent model • Multi-conductor TL models of wires are connected into the TLM grid • Full coupling between wires and fields • Supports splits, bends, multi-way connections, circuit terminations and ports

  22. Near Field Scan Smart Part Emissions • Pre-determined near-field scans over entire boards or regions/components can be imported and applied as distributed frequency-dependent (time-varying) sources • Ideal for PCB with 1 or 2 layers where radiation from “exposed” nets may be important

  23. TLM References • 1. Johns P. B. & Beurle R. L., ‘ Numerical Solution of 2-Dimensional Scattering Problems Using a Transmission-Line Matrix’, Proc. IEE, Vol. 118, No. 9, Sept 1971.  • 2. Akhtarzad, S. and Johns, P. B., ‘The solution of Maxwell’s equations in three space dimensions and time by the TLM method of numerical analysis’, Proceedings IEE 122, 12, p.1344-1348, December 1975.  • 3. Johns P. B., ‘A symmetrical condensed node for the TLM method’, IEEE Trans. Microwave Theory and Techniques, Vol. MTT-35, No. 4, pp. 370-377, 1987. • 4. Christopoulos C., ‘The Transmission-Line Modeling Method: TLM’, IEEE Press and Oxford University Press, 1995. A volume in the IEEE/OUP Series on Electromagnetic Wave Theory ISBN 0-7803-1017-9

  24. If you have any questions or comments, we welcome your feedback ! Please visit the FLO/EMC web site at www.floemc.com and email us at emsupport@flomerics.com Flomerics Inc.257 Turnpike Road, Suite 100Southborough MA 01772 Tel: (508) 357 2012 Flomerics Inc. 4699 Old Ironsides Drive - #390 Santa Clara, CA 95054-1860 Tel:(408) 562-9100 Flomerics Inc. 410 South Melrose Drive, Suite 102, Vista, CA 92083 Tel: (760) 643 4028 Flomerics Inc.1106 Clayton Lane, Suite 525W Austin, TX 78723 Tel: (512) 420 9273

More Related