3D FEA Software Solves Tough Inductive Noise Problems

Focus:

Switched-mode power supplies are notorious for hard-to-eliminate noise problems simply because we cannot completely avoid proximity of high-power switching circuits and sensitive controls. Good engineering practices such as minimizing high-frequency current loops and voltage surfaces, perpendicular arrangement of potential source-target sets and using large copper planes for shielding are naturally a must. But without any way of quantifying problematic phenomena it is impossible to know if we are pushing our luck and if we did the best we could within the given constraints. However, as the author explains here, dangerous noise can be reduced and many layout re-spins avoided if we model potential trouble spots using the latest-generation 3D finite element analysis (FEA) software, which has the necessary modeling power and user friendliness to be applied in power supply design. After identifying the types of noise problems that can be modeled and minimized with 3D FEA software, the author explains the basic mechanisms of inductive noise coupling and why this problem calls for 3D FEA. Next, five simple cases studies are used to demonstrate the effects of layout and shielding on inductive noise coupling through simulation using EMS software from EMworks. Then a practical methodology for modeling inductively coupled noise is presented.

What you’ll learn:

• How to identify and correct inductively coupled noise problems in switched-mode power supply designs using 3D FEA software
• How to analyze effectiveness of shielding and layout techniques in power supplies using 3D FEA software
• How to improve one’s understanding of inductively coupled noise problems and proper shielding and layout techniques through EM simulation

Notes:

The author notes several benefits of 3D FEA software. Running 3D FEA may simply confirm that there is no real noise problem or identify problems for which the solution is obvious. In rare cases, very detailed FEA will be needed, but in these cases FEA will be extremely valuable. But the use of 3D FEA is also instructive, as author explains: “An equally important benefit of applying 3D FEA will be the engineer’s development of intuition based on viewing many real-life 3D electromagnetic field configurations and their impact on the circuit. After a while, FEA will be needed for only the truly tough cases.”

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Author & Publication:

Peter Markowski, Envelope Power, Ansonia, Conn., How2Power Today, Oct 15 2014

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