The expert on this subject is Mark Nave ([email protected]). He has a book out (probably out-of-print now) on "Power-Line Filtering for Switched Mode Power Supplies." Also a paper in the 1991 IEEE EMC Symposium record, "On Modeling the CM Inductor." In that paper, he shows how to calculate the leakage inductance (dm component of cm inductance). It is this leakage inductance which causes saturation.
---------- >From: Derek Walton <[email protected]> >To: IEEE EMC Discussion Group <[email protected]> >Subject: Common Mode Choke >Date: Thu, Dec 2, 1999, 1:46 PM > > > Good day all, > > I'm refining the input filter of a 150 watt SMPS. Nothing flashy, just a > few caps and a common mode choke. > > The current is drawn by the supply in short bursts as the DC link cap is > charged. I've shown that peak current reaches 6 amps for up to 2 ms. > I've also demonstrated that the CM choke, while rated for the RMS > current ( a 2 amp device ), does saturate when the current exceeds about > 4 amps. > > I've been trying to find out from the vendors, what current it takes to > saturate the CM choke. I've had answers from CM chokes can't saturate to > "that's not an important parameter, use the rms figure".... > > My question is, with over 20 potential vendors of this type of > component, is there any way I can find out saturation performance > without buying one of each type and testing it. I've played with 3 so > far, the most expensive was NOT the best! I guess, I'm curious why more > folks don't know about this effect also..... > > Thanks, > > Derek Walton > Owner > L. F. Research EMC Design and Test Facility > 12790 Route 76, > Poplar Grove, > IL 61065. > www.lfresearch.com > > > --------- > This message is coming from the emc-pstc discussion list. > To cancel your subscription, send mail to [email protected] > with the single line: "unsubscribe emc-pstc" (without the > quotes). For help, send mail to [email protected], > [email protected], [email protected], or > [email protected] (the list administrators). > > --------- This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to [email protected] with the single line: "unsubscribe emc-pstc" (without the quotes). For help, send mail to [email protected], [email protected], [email protected], or [email protected] (the list administrators).
