Parallel Inductors in PSU

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monarodan

monarodan

Member
Joined 2005
Hi all,

I'm trying to source inductors to implement a PI Filter in my Aleph 2 amps. Suppliers in Australia are as rare as hen's teeth and international shipping is prohibitively expensive. I happened to find a local supplier carrying Solen inductors. They only stock 16AWG versions, which may get a little hot and steamy. I was looking for 14AWG or larger guage.

Now the good news – this local supplier is having a sale on 4.8mH inductors (about 1/3 retail price, and cheaper than buying direct from Solen). Would anyone advise against putting two of these inductors in parallel in place of a single 14AWG inductor? The resulting inductance and DCR would be fine – are there any other issues to take into account?

Hope that's not too silly a question...

Cheers,

Dan
 
monarodan

monarodan

Member
Joined 2005
They're not *that* affordable :)

PSU Designer is showing a ripple voltage under 8mV at full load, which I'm pretty comfortable with.

Given your suggestion, I assume that there is no reason not to put inductors in parallel in the PSU. I was kinda hoping that someone would suggest that it's advantageous to use a number of inductors in parallel (as many would suggest for filter caps).


Thanks,

Dan
 
S

sawreyrw

Member
Joined 2006
Putting 2 equal inductors in parallel is fine. The resistance and inductance of the pair will be 1/2 that of a single inductor. The total power loss will be 1/2 of the original loss, so each inductor has a loss of 1/4 of the original.

Note that the parallel inductors should be the same type. If they are not, then they won't share the current as well.
 
Babowana

Babowana

Formerly "jh6you". R.I.P.
Joined 2006
aheadamp.com
flg said:
I do not believe the inductance is /2 :whazzat: You have the same number of turns in paralell. The DCR will be /2 but I think the L will stay the same :confused:
Click to expand...


I believe you are confused

emf = - L x di/dt
Actually each L remains the same
But, di reduces half
so emf (voltage drop) reduces half, too

It's the same as the parallel-resistors

Happy New Year! :)
 
carpenter

carpenter

Member
Joined 2002
inlowsound.com
clarify question,please
Click to expand...

Well, your answer pretty well answers the second question. My 1000 v/a tranny is now 500v/a.

Or: 250 v/a per output tap because there's two pairs of taps...

For the standard ZV7-T, I should probably have more than 250v/a, so the two outputs should be rectified and then paralleled?

Rectified, then CLCLC, then loaded down, I'd probably have 30 volts. From each output pair there's 250 v/a divided by 30, which would give me 8.3 amps. The ZV7-T draws 6amps. So, it will take both taps (16.6 amps) for satisfactory operation?

Did I do this correctly?
 
Zen Mod

Zen Mod

Official Court Jester
Joined 2003
zenmod.in.rs/
Paid Member
carpenter said:


Well, your answer pretty well answers the second question. My 1000 v/a tranny is now 500v/a.

Or: 250 v/a per output tap because there's two pairs of taps...

For the standard ZV7-T, I should probably have more than 250v/a, so the two outputs should be rectified and then paralleled?

Rectified, then CLCLC, then loaded down, I'd probably have 30 volts. From each output pair there's 250 v/a divided by 30, which would give me 8.3 amps. The ZV7-T draws 6amps. So, it will take both taps (16.6 amps) for satisfactory operation?

Did I do this correctly?
Click to expand...


in calcs you must start from Vac ratings..........
where Iac=Pac/Uac

so ........mebbe Iac is smthng more than 8.3 calculated :cannotbe: :cannotbe:
 
monarodan

monarodan

Member
Joined 2005
macka said:
Hi Dan,

Call up Voller transformers in Melbourne.

He can wind hi current chokes to your specifications.

Macka
Click to expand...

Hi Macka,

Any idea what his rates are like? I can get Solen 4.7mH 16GA coils for AU$23 at the moment from Speakerbits (www.speakerbits.com). Their checkout quoted about AU$13 shipping to Perth. That's getting pretty hard to compete with.

I know I can rely on Solen quality. Can anyone vouch for Vollers quality? I should check him out for toroidals also...


Cheers,

Dan
 
Zen Mod

Zen Mod

Official Court Jester
Joined 2003
zenmod.in.rs/
Paid Member
carpenter said:


That would make me very happy.:D How does that formula work?
Click to expand...


lets say that one winding have 250VA
then,say, one winding is 25Vac
in that case -you'll have I = 250VA / 25Vac

I = 10A


play little games with PSUd..........starting with CC load in range of expected..........and then just increase load current in steps,and look what you get

PSUd is in every case smarter than I am.......
 
flg

flg

Member
Joined 2005
John, Actually that surpised me... But when series'ed and coupled, they are 4X right???
Sorry, I'm a little behind, Let's go back and catch up to my brothers phone connection...
It's not just the phone connection, I'm confused...
trying to catch up from last night I guess...
With the 2 windings coupled but paralelled You basically only have bigger wire and the same turns! Assentialy "BiFilar wound" and equivalent to a heaver guage wire! IMHO!
With the the 2 windings coupled and series'ed you should have 4X the L not 2X :D
With the 2 series'ed but not coupled you would have 2 X the L :D
When you have 2 115Volt windings on a 250VA xfmr, why do you think that is??? When you connect the 2 in series, you feed it with 230Volts RMS and get the same VA (more RMS volts but less current) still 250VA :D :D :D You also get 4X the Pri L that way Though :D
Just my 2Cents...
 
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