available toroids

[Piotr Wyderski]

Sergey Kubushyn wrote:

Wow, that's a lot for flyback... Did you already make its clamping network
and decided how are you going to deal with heat? What frequency is it
supposed to run at?

175V at 20A is just mere 3.5kW, child's play for a flyback, right?

Man, for such power you need a full bridge...

OTOH, the charger should be phase factor corrected, which implies a
similarly sized inductor for a boost converter. If the output current
doesn't need to be constant, but abs(sin(t)) is sufficient, the PFC
could be integrated with the flyback stage.

Bumping up the switching frequency from 100kHz to 1MHz, replacing the
switch with a SiC device and selecting a multiphase flyback topology
might in fact work with a low-loss ferrite "transformer" on, say, 3C95.

Best regards, Piotr

 

[Bill Sloman]

On Sunday, January 19, 2020 at 7:37:43 AM UTC+11, Hul Tytus wrote:

Thanks Piotr - generally ferroxcube appeared to be a supplier to check.
Having a specific target on their web site (or Newark's) is convenient.

TDK took over the Siemens EPCOS ferrite range, which always struck me as offering better value the Mullard/Philips/Ferrocube range. Siemens certainly had better application notes - Miullard's E.C.Snelling might have known a lot but he wans't good at making his knowledge accessible.

Piotr Wyderski <peter.pan@neverland.mil> wrote:
amdx wrote:

??You might need to stack them. Or use a potcore.

If you consider ferrites at all, SFDT says that to handle 80A at 14uH
you would need U100/57:

https://www.newark.com/ferroxcube/u100-57-25-3c90/transformer-cores-u100-3c90-308/dp/24W7833?ost=u100%2F57&ddkey=https%3Aen-US%2FElement14_US%2Fsearch

There are no pot cores that big.

Mouser does a 50x25mm half core

https://au.mouser.com/datasheet/2/400/pq_50_50-1527907.pdf

You might have to dig harder and find a specialist ferrite supplier to get something bigger.

https://ferrite.de/de/produkte/ferritkerne-und-zubehoer/

is a supplier I've used for prototype quantities, but they do seem to be a Ferrocube shop.

--
Bill Sloman, Sydney

 

[Piotr Wyderski]

Bill Sloman wrote:

> lists a bunch of higher frequency ferrites. 3C95 is listed as good to about 0.5MHz. 3F4 gets up to about 2MHz.

3C95/N95 is a super low loss ferrite, which is good for a wide B swing
topology like the flyback. I would design this power stage around the
FoM of the ferrite, whatever the switching frequency might turn out to be.

Best regards, Piotr

 

[Bill Sloman]

On Sunday, January 19, 2020 at 6:12:07 PM UTC+11, Piotr Wyderski wrote:

Sergey Kubushyn wrote:

Wow, that's a lot for flyback... Did you already make its clamping network
and decided how are you going to deal with heat? What frequency is it
supposed to run at?

175V at 20A is just mere 3.5kW, child's play for a flyback, right?

Man, for such power you need a full bridge...

OTOH, the charger should be phase factor corrected, which implies a
similarly sized inductor for a boost converter. If the output current
doesn't need to be constant, but abs(sin(t)) is sufficient, the PFC
could be integrated with the flyback stage.

Bumping up the switching frequency from 100kHz to 1MHz, replacing the
switch with a SiC device and selecting a multiphase flyback topology
might in fact work with a low-loss ferrite "transformer" on, say, 3C95.

https://www.ferroxcube.com/en-global/ak_material/index/power_conversion#6

lists a bunch of higher frequency ferrites. 3C95 is listed as good to about 0.5MHz. 3F4 gets up to about 2MHz.

--
Bill Sloman, Suydney

 

[Hul Tytus]

Thanks for the links, Bill. Mouser would be a handy avenue of supply.

Hul

Bill Sloman <bill.sloman@ieee.org> wrote:

On Sunday, January 19, 2020 at 7:37:43 AM UTC+11, Hul Tytus wrote:
Thanks Piotr - generally ferroxcube appeared to be a supplier to check.
Having a specific target on their web site (or Newark's) is convenient.

TDK took over the Siemens EPCOS ferrite range, which always struck me as offering better value the Mullard/Philips/Ferrocube range. Siemens certainly had better application notes - Miullard's E.C.Snelling might have known a lot but he wans't good at making his knowledge accessible.


Piotr Wyderski <peter.pan@neverland.mil> wrote:
amdx wrote:

??You might need to stack them. Or use a potcore.

If you consider ferrites at all, SFDT says that to handle 80A at 14uH
you would need U100/57:

https://www.newark.com/ferroxcube/u100-57-25-3c90/transformer-cores-u100-3c90-308/dp/24W7833?ost=u100%2F57&ddkey=https%3Aen-US%2FElement14_US%2Fsearch

There are no pot cores that big.

Mouser does a 50x25mm half core

https://au.mouser.com/datasheet/2/400/pq_50_50-1527907.pdf

You might have to dig harder and find a specialist ferrite supplier to get something bigger.

https://ferrite.de/de/produkte/ferritkerne-und-zubehoer/

is a supplier I've used for prototype quantities, but they do seem to be a Ferrocube shop.

--
Bill Sloman, Sydney

 

[Hul Tytus]

Piotr - "super low loss" does catch the eye at present. I'll take a look
in hopes a toroid of that mix would fit, numbers wise.

Hul

Piotr Wyderski <peter.pan@neverland.mil> wrote:

Bill Sloman wrote:

lists a bunch of higher frequency ferrites. 3C95 is listed as good to about 0.5MHz. 3F4 gets up to about 2MHz.

3C95/N95 is a super low loss ferrite, which is good for a wide B swing
topology like the flyback. I would design this power stage around the
FoM of the ferrite, whatever the switching frequency might turn out to be.

Best regards, Piotr

 

[Hul Tytus]

You may be right. I'll keep you informed.

Hul

Sergey Kubushyn <ksi@koi8.net> wrote:

Hul Tytus <ht@panix.com> wrote:

Wow, that's a lot for flyback... Did you already make its clamping network
and decided how are you going to deal with heat? What frequency is it
supposed to run at?

175V at 20A is just mere 3.5kW, child's play for a flyback, right?

Man, for such power you need a full bridge...

Thanks again Piotr. I'll take a look. As to the use of the flyback,
it is simple. The objective is charging a lead acid batter of 175
volts from a 120v ac line with a nearly continuous 20 amps without
a large cap on the the rectified line.

Hul

Piotr Wyderski <peter.pan@neverland.mil> wrote:
Hul Tytus wrote:

Stacking might work.

7x HF-106125-2. Not exactly compact.

Why a flyback in the first place? A half/full/push-pull bridge with a
current doubler looks more realistic. Or a planar core, say E43, with
the secondary made of copper a plate.

Best regards, Piotr

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