How to buy Kool mu torroids? - Page 1
Forum section: electronics / general

author: Faringdon
author_rank: Super Contributor
timestamp: March 27, 2022, 02:02:29 pm
content: Hi,Ive emailed Mag-inc on how to buy their kool mu torroids in qtys of 1.......they havent yet replied from yesterdays qu from me, but do you think its impossible?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: March 27, 2022, 02:56:27 pm
content: It's the weekend..?I guess you can ask for samples. I doubt they do direct sales.Their EU distributor doesn't look like they'd be much more receptive, hmph... website is a big wanky runaround, no catalog, no cart. Basically nothing doing without a phone call. Eh, magnetics suppliers are still very old-fashioned.Tim

author: dmills
author_rank: Super Contributor
timestamp: March 27, 2022, 04:51:38 pm
content: Have you tried Power Magnetics?I have a feeling they do or used to do Kool Mu, and are usually good about small quantities.

author: Cerebus
author_rank: Super Contributor
timestamp: March 27, 2022, 05:22:16 pm
content: "kool mu torroids" (sic) sounds like some sort of cough sweet, or throat lozenge."Take kool mu torroids for instant relief from the misery of the common cold.Soothes your throat, loosens mucus, and clears that 'stuffed up' feeling.Buy some at your pharmacy today.May cause voltage spikes, loss of high frequencies, and magnetic disturbances. Not to be taken orally."

author: jonpaul
author_rank: Super Contributor
timestamp: March 27, 2022, 11:47:54 pm
content: Kool Mu is a trademark for Magnetics Inc ferrites, but nothing special about it.Competitors like Siemens, EPCOS, TDK and others make similar materials.We use TDK.JonYou can easily find an equivalent.

author: Faringdon
author_rank: Super Contributor
timestamp: April 07, 2022, 09:21:11 am
content: Hi,I must admit ive tried the above but still no luck.The only place that shows what they've got in stock is power magnetics...but their stock at the bigger torroid level , as in for a 4kW boost PFC, is very limited....in fact, they dont have anything i can use.I am not getting emails back from the listed distributors, or the vendors, which seems concerning.Ive tried Fair-Rite, Mag-inc and Micrometals.Wurth, TDK , Ferroxcube dont have any of the large kool mu type torroids....or anything similar.Do you know where i can source big torroids for 4kW PFC inductors?

author: jonpaul
author_rank: Super Contributor
timestamp: April 07, 2022, 10:37:13 am
content: Farrington, once again hard for me to comprehend the problem.....Cool mu is not the only type, just an old trademarkIt seems like your design requirements needs review.1/ A 4 KVA PFC can use several shapes and materials of core2/ Toroids have no gappiin, poor core loss dissipating, difficult to wind, or insulate so, we avoid themmodern PFC designs use EE,EI, EER, PQ and other easy to wind ferrite shapes with bobbins and optimization of core losses at operating Tcore.3/ Can you please explain why your application requires a toroid of cool mu for your design ?With Kind RegardsJon

author: Faringdon
author_rank: Super Contributor
timestamp: April 07, 2022, 11:58:16 am
content: QuoteHi, the PFC is 4kW, and we cant use any offtheshelf ferrite core. AN53 from power integrations tells why.We can only use "powdered iron" type torroids for our high power...so its Kool mu, sendust or mollypermalloy....mollypermalloy is expensive so probably not that.....but if its available i will buy it.AN53https://www.powerint.cn/downloads/product-docs/an53.pdfAt the moment, i cant source these torroids anywhere on the planet...please advise on where to buy?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: April 07, 2022, 12:34:36 pm
content: You could be more specific...On page 15 I see ferrite rated as "best" for boost PFC, while Sendust is merely "fair".Also, I'm not sure what they mean by ferrite being "worst" for line filtering; I guess they mean L_DM1 (Fig.21) because they list High-Flux as "best", but L_CM is part of that too and the latter is terrible for that. I don't see any explanation for Table 7, nor Table 5.These seem like things Power Integrations should know well, so I wonder if it's just appnote-itis, or poorly phrased, or something.Anyway, cores for a multi-phase interleaved system are readily available, and strongly recommended at this power level. Hell, it's recommended even at just a few hundred watts. Shit's good. (Yet another thing inexplicable about the above document, the apparent lukewarm reception, to outright dismissal, of multiphase.)Tim

author: jonpaul
author_rank: Super Contributor
timestamp: April 07, 2022, 01:51:05 pm
content: I would never take an IC manufacturer EVB or application note as gospels especially for magnetics.Those are merely starting points.Powdered iron magnetic cores were developed decades ago at Micrometals in California, by Jim Cox.Cool mu,was after. Micrometals has many shapes and sizes, as well as application notes and calculators.https://micrometals.com/Huge stock of parts and samples at least in the USA.Bon courageJon

author: Faringdon
author_rank: Super Contributor
timestamp: April 07, 2022, 01:58:25 pm
content: QuoteThanks, though the ferrite cores for 4kW PFC, as you know, are very big, and need gapping, we cant afford to get them gapped.Yes i agree ferrite is best...but just too big and needing the custom gapping when power levels are high.So yes, i did bottle it away from the ferrite....specially since i also feared near gap heating of the PFC wire, which wont be Litz.So sorry to bottle it away from ferrite guys.....but in some ways, all i want is to shovel a 400vdc rail out there so that the 4kw LLC can be tested up.......so yes youve guessed it.....i may be shovelling three COT non-PFC boost converters in parallel using UC3842 hacked to COT..(easy to make them share...just have one vout error amp feeding back to all three)....Any old 400vdc 4kw rail will do for this prototype......then i can work on PFC Later.As you know, Kool mu not as good as Mollypermalloy....but cheaper.QuoteMultiphase interleaved PFC is good, but theres only two chips in the world that can do it, and i think the infineon one is now obselete.....ti.com used to do one...but i dont know if they still do.......as you know, multiphase interleaved can be done with micro but we dont have time to program one up for that.Theres a way of paralleling normal ccm pfc chips by using two CST's in each Booster, then using them to reconstruct the sense res signal.