question regarding DC link inductors for ZVS circuit
Ash Small, Thu Aug 16 2012, 08:13PMI picked these ferrites up at a hamfest at the weekend.
I've read (I think) that you want yellow/green ferrites for the current limiting inductor for the Mazilli ZVS circuit.
These measure 1 1/16" OD, 9/16" ID and 7/16" thick.
Are these suitable cores for the inductor for the ZVS circuit, and if so, how many turns of wire should I use?
EDIT: These are, fom what I can gather, T106-40, T106 being the dimension spec (26.9±0.5 mm OD, 14.5±0.5 mm ID, 11.1±0.64 mm Thick), 40 being the material, AL(nHï¼N²) 81, Permeability (ui) 60, .
Re: question regarding DC link inductors for ZVS circuit
Forty, Fri Aug 17 2012, 05:58PM
I thought powdered iron was the way to go because of its frequency range and higher saturation point
Forty, Fri Aug 17 2012, 05:58PM
I thought powdered iron was the way to go because of its frequency range and higher saturation point
Re: question regarding DC link inductors for ZVS circuit
Harry, Fri Aug 17 2012, 06:37PM
Pretty much all toroids work, the better ones just don't get so hot
As for the turns there is no specific number, just choose a wire size that can handle 12 - 15 amps and start winding
Harry, Fri Aug 17 2012, 06:37PM
Pretty much all toroids work, the better ones just don't get so hot
As for the turns there is no specific number, just choose a wire size that can handle 12 - 15 amps and start winding
Re: question regarding DC link inductors for ZVS circuit
Steve Conner, Fri Aug 17 2012, 07:06PM
The inductance in the ZVS isn't really critical, it just needs to be "big enough" to smooth out the current.
A reasonable design process would be to pick a wire gauge that can barely handle the current you intend to run, and cram on as many turns as will fit on your core. If the inductance is too small, try stacking a bunch of cores.
Iron powder is the right thing to use. Ferrite toroids are not recommended, they saturate too easily with DC current. However, what you have there is a low permeability RF grade of ferrite, not the usual power electronic stuff, which has a permeability of about 2000. At low frequencies it may behave more like iron powder than ferrite.
Steve Conner, Fri Aug 17 2012, 07:06PM
The inductance in the ZVS isn't really critical, it just needs to be "big enough" to smooth out the current.
A reasonable design process would be to pick a wire gauge that can barely handle the current you intend to run, and cram on as many turns as will fit on your core. If the inductance is too small, try stacking a bunch of cores.
Iron powder is the right thing to use. Ferrite toroids are not recommended, they saturate too easily with DC current. However, what you have there is a low permeability RF grade of ferrite, not the usual power electronic stuff, which has a permeability of about 2000. At low frequencies it may behave more like iron powder than ferrite.
Re: question regarding DC link inductors for ZVS circuit
Ash Small, Fri Aug 17 2012, 07:43PM
That's what I thought, but I'm sure a couple of people have posted on here that you should look for green/yellow toroids in ATX power supplies, so when I saw some at a hamfest I grabbed a handful.
I assume I don't want it to saturate, so should I double up or 'treble up' on the cores? (I have plenty of them, and I assume more 'ferrite' = less heating)
I've read I want between 47 and 200 ?Henries (I'll have to check the units (micro or milli)), but there does seem to be a lack of infomation on the 'net regarding exact specs for the inductor.
EDIT: Thanks for the input, Steve, I was composing my reply and missed your post.
Ash Small, Fri Aug 17 2012, 07:43PM
Forty wrote ...
I thought powdered iron was the way to go because of its frequency range and higher saturation point
I thought powdered iron was the way to go because of its frequency range and higher saturation point
That's what I thought, but I'm sure a couple of people have posted on here that you should look for green/yellow toroids in ATX power supplies, so when I saw some at a hamfest I grabbed a handful.
Harry wrote ...
Pretty much all toroids work, the better ones just don't get so hot
As for the turns there is no specific number, just choose a wire size that can handle 12 - 15 amps and start winding
Pretty much all toroids work, the better ones just don't get so hot
As for the turns there is no specific number, just choose a wire size that can handle 12 - 15 amps and start winding
I assume I don't want it to saturate, so should I double up or 'treble up' on the cores? (I have plenty of them, and I assume more 'ferrite' = less heating)
I've read I want between 47 and 200 ?Henries (I'll have to check the units (micro or milli)), but there does seem to be a lack of infomation on the 'net regarding exact specs for the inductor.
EDIT: Thanks for the input, Steve, I was composing my reply and missed your post.
Re: question regarding DC link inductors for ZVS circuit
Harry, Fri Aug 17 2012, 08:40PM
That's because pretty much every thing will work. I had a yellow toroid with only 6 turns on it and it still worked. I have also used a RFI suppression ring from a home cinema SMPS wound with 15 turns of standard 0.75mm wiring.
Here is a video which shows what I mean:
Apparently using a higher inductance means higher voltage, but I can't really see any difference.
I used my ZVS for induction heating once without an inductor, it drew more current but still survived.
Harry, Fri Aug 17 2012, 08:40PM
lack of infomation on the 'net regarding exact specs for the inductor
That's because pretty much every thing will work. I had a yellow toroid with only 6 turns on it and it still worked. I have also used a RFI suppression ring from a home cinema SMPS wound with 15 turns of standard 0.75mm wiring.
Here is a video which shows what I mean:
Apparently using a higher inductance means higher voltage, but I can't really see any difference.
I used my ZVS for induction heating once without an inductor, it drew more current but still survived.
Re: question regarding DC link inductors for ZVS circuit
Ash Small, Fri Aug 17 2012, 09:08PM
But people do say to avoid the usual ferrites that we use for HF power circuits. (as Forty and Steve have pointed out).
I picked these toroidal transformers up at the hamfest for a few quid each, which I assume have powdered iron cores, but they'd be a bit 'overkill' for this application. I'll probably use the cores for Hf chokes, though. I used a HUGE one (much bigger than these) as part of the choke curcuit in my HF TIG welder.
Ash Small, Fri Aug 17 2012, 09:08PM
Harry wrote ...
That's because pretty much every thing will work.
lack of infomation on the 'net regarding exact specs for the inductor
That's because pretty much every thing will work.
But people do say to avoid the usual ferrites that we use for HF power circuits. (as Forty and Steve have pointed out).
I picked these toroidal transformers up at the hamfest for a few quid each, which I assume have powdered iron cores, but they'd be a bit 'overkill' for this application. I'll probably use the cores for Hf chokes, though. I used a HUGE one (much bigger than these) as part of the choke curcuit in my HF TIG welder.
Re: question regarding DC link inductors for ZVS circuit
Harry, Fri Aug 17 2012, 09:31PM
Yes that would be just a tad overkill! What voltage do they kick out? They might be good for powering your ZVS.I use a 30V 600VA transformer, and control it with a dimmer switch, which works surprisingly well though it probably isn't too good for the dimmer, controlling a large inductive load and such.
So to sum up you can use most inductors for the ZVS, there are good inductors and bad inductors, which heat up.
As Steve said, just cram as many turns of adequately rated wire onto it and see what happens
Harry, Fri Aug 17 2012, 09:31PM
Yes that would be just a tad overkill! What voltage do they kick out? They might be good for powering your ZVS.I use a 30V 600VA transformer, and control it with a dimmer switch, which works surprisingly well though it probably isn't too good for the dimmer, controlling a large inductive load and such.
So to sum up you can use most inductors for the ZVS, there are good inductors and bad inductors, which heat up.
As Steve said, just cram as many turns of adequately rated wire onto it and see what happens
Re: question regarding DC link inductors for ZVS circuit
Ash Small, Fri Aug 17 2012, 09:53PM
They have two secondaries, each putting out 15 volts, which could be wired in series to give 30 volts.
Unfortunately, they only put out 3 amps (according to the vendor), so, even if I connected both secondaries in series, and both transformers in parallel, I'd only get 30V @ 6A, not really enough for a Mazilli ZVS. (Maybe I should have bought a few more
)
Ash Small, Fri Aug 17 2012, 09:53PM
Harry wrote ...
Yes that would be just a tad overkill! What voltage do they kick out? They might be good for powering your ZVS.
Yes that would be just a tad overkill! What voltage do they kick out? They might be good for powering your ZVS.
They have two secondaries, each putting out 15 volts, which could be wired in series to give 30 volts.
Unfortunately, they only put out 3 amps (according to the vendor), so, even if I connected both secondaries in series, and both transformers in parallel, I'd only get 30V @ 6A, not really enough for a Mazilli ZVS. (Maybe I should have bought a few more
)Re: question regarding DC link inductors for ZVS circuit
Harry, Fri Aug 17 2012, 10:30PM
It does demand a lot of power, I blew the thermal fuse on my transformer after 10 minutes of arcing. Thankfully the fuse was on the outside of the primary so I could bypass it; some transformers have one that is near impossible to get to without unwinding most of it.
But if you put the 15V secondaries in parallel for 12A, then rectify for 20V after diode drop and such, that is pretty good. you could then series in another power supply, like a computer PSU for 32V, or a drill battery for 40V when it's full charged.
Get on Freecycle and see if there are any audio amps or stereos, that's where I got my transformer, from a big ass subwoofer
Harry, Fri Aug 17 2012, 10:30PM
It does demand a lot of power, I blew the thermal fuse on my transformer after 10 minutes of arcing. Thankfully the fuse was on the outside of the primary so I could bypass it; some transformers have one that is near impossible to get to without unwinding most of it.
But if you put the 15V secondaries in parallel for 12A, then rectify for 20V after diode drop and such, that is pretty good. you could then series in another power supply, like a computer PSU for 32V, or a drill battery for 40V when it's full charged.
Get on Freecycle and see if there are any audio amps or stereos, that's where I got my transformer, from a big ass subwoofer
Re: question regarding DC link inductors for ZVS circuit
Ash Small, Fri Aug 17 2012, 10:43PM
I picked up a couple of audio amps on Freecycle yesterday
I'm planning on using car batteries for the ZVS.
If I wanted to use a xformer I'd probably try a welding buzz-box (I have a few lying around), look out for my 600A rectifier thread (coming soon)
Ash Small, Fri Aug 17 2012, 10:43PM
Harry wrote ...
Get on Freecycle and see if there are any audio amps or stereos, that's where I got my transformer, from a big ass subwoofer
Get on Freecycle and see if there are any audio amps or stereos, that's where I got my transformer, from a big ass subwoofer
I picked up a couple of audio amps on Freecycle yesterday
I'm planning on using car batteries for the ZVS.
If I wanted to use a xformer I'd probably try a welding buzz-box (I have a few lying around), look out for my 600A rectifier thread (coming soon)
Re: question regarding DC link inductors for ZVS circuit
Harry, Fri Aug 17 2012, 11:10PM
600 amps?!?! I'll keep an eye out for that!
Harry, Fri Aug 17 2012, 11:10PM
600 amps?!?! I'll keep an eye out for that!
Re: question regarding DC link inductors for ZVS circuit
Sulaiman, Sat Aug 18 2012, 12:15AM
I doubt that a 50/60 Hz inductor will work well at zvs frequencies
- but in unexpected ways it might.
and the matching primary capacitor ???
Sulaiman, Sat Aug 18 2012, 12:15AM
I doubt that a 50/60 Hz inductor will work well at zvs frequencies
- but in unexpected ways it might.
and the matching primary capacitor ???
Re: question regarding DC link inductors for ZVS circuit
Ash Small, Sat Aug 18 2012, 09:42AM
I assume there is a misunderstanding here.
This inductor isn't for the zvs driven transfomer, its for the current limiting inductor in the positive supply rail.
Ash Small, Sat Aug 18 2012, 09:42AM
Sulaiman wrote ...
I doubt that a 50/60 Hz inductor will work well at zvs frequencies
- but in unexpected ways it might.
and the matching primary capacitor ???
I doubt that a 50/60 Hz inductor will work well at zvs frequencies
- but in unexpected ways it might.
and the matching primary capacitor ???
I assume there is a misunderstanding here.
This inductor isn't for the zvs driven transfomer, its for the current limiting inductor in the positive supply rail.
Re: question regarding DC link inductors for ZVS circuit
Steve Conner, Sat Aug 18 2012, 09:59AM
Maybe refer to it as the DC link inductor to avoid confusion. Current limiting inductor is definitely the wrong name: inductors do nothing to limit DC current.
A 50/60Hz toroidal transformer is the worst DC link inductor you can imagine. It has lots of inductance, but it saturates very easily. However, due to the easy saturation, they work well driven by a Royer oscillator in ferroresonant mode. (that is to say, DC link inductor left out, frequency controlled by saturation.)
Steve Conner, Sat Aug 18 2012, 09:59AM
Maybe refer to it as the DC link inductor to avoid confusion. Current limiting inductor is definitely the wrong name: inductors do nothing to limit DC current.
A 50/60Hz toroidal transformer is the worst DC link inductor you can imagine. It has lots of inductance, but it saturates very easily. However, due to the easy saturation, they work well driven by a Royer oscillator in ferroresonant mode. (that is to say, DC link inductor left out, frequency controlled by saturation.)
Re: question regarding DC link inductors for ZVS circuit
m4ge123, Sat Aug 18 2012, 10:20AM
The inductor you're referring to isn't for current limiting; it's just to keep constant current flowing into the circuit. Basically, do what Steve said, but you should make sure the input inductor has at least 20x the inductance of the tank inductor (a bit more is better) and won't saturate too much. You can find a graph and formulae to calculate saturation here
m4ge123, Sat Aug 18 2012, 10:20AM
The inductor you're referring to isn't for current limiting; it's just to keep constant current flowing into the circuit. Basically, do what Steve said, but you should make sure the input inductor has at least 20x the inductance of the tank inductor (a bit more is better) and won't saturate too much. You can find a graph and formulae to calculate saturation here
Re: question regarding DC link inductors for ZVS circuit
Ash Small, Sat Aug 18 2012, 10:40AM
@ Steve and M4ge, thanks fr the input, I'll change the thread title to 'DC link inductor'.
(I suppose it's more of a 'current controlling inductor' than 'current limiting inductor' )
This thread is certainly answering most of my queries regarding these inductors.
Ash Small, Sat Aug 18 2012, 10:40AM
@ Steve and M4ge, thanks fr the input, I'll change the thread title to 'DC link inductor'.
(I suppose it's more of a 'current controlling inductor' than 'current limiting inductor'
)This thread is certainly answering most of my queries regarding these inductors.
Re: question regarding DC link inductors for ZVS circuit
Sulaiman, Sat Aug 18 2012, 09:40PM
I (briefly) posted this yesterday then when I saw mention of 600A changed it to my post above, it may add a little;
Ash Small,
a couple of thoughts;
1) The (Cotswold Electronics) transformer cores would not make good inductors for the dc link in a zvs because they are almost certainly strip=wound steel cores,
(a thin ribbon of steel tape wound up) and are the best choice for small ac power transformers im many ways.
2) the VA (power) rating is pretty much determined by the weight, so if you find a similar weight toroidal transformer your VA will be close enough to that.
e.g. 50VA/0.7kg, 100VA/1.2kg, 200VA/2.2kg for one (random) manufacturer.
3) the transformers are also inductors,
high inductance/low current primary
high current/low inductance secondary
BUT the core will saturate easily with dc
You can also just wind over the existing windings for your own value of inductance
(careful though as the original primary windings may produce very large voltages)
this way when you realise that they don't make good inductors you will still have two good transformers ;)
4) I don't think there CAN be a formula for calculating the dc inductor because each application will be different,
some will want high efficiency good sinewaves
(high inductance / low loss)
some will want as much power throughput as the core/wire will allow, running hot,
(thin wire/some small saturation allowed)
and it seems many get best power throughput when the "zvs' is not actually operating in zero-switching, so short-term overheating/core saturation can also work in this circuit.
5) I'm not sure what the other cores are, on my monitor they look Grey/Yellow,
(with a bit of research you can find different manufacturers color codes)
(being from a HAM fest they're probably some popular mix)
if you find a match you can look up the specifications,
if you can measure their Al (nH/turn2) you can measure the core and look for similar,
(amp.turns = (1 to 2) x Al/Ae) Ae=core cross-section in m2
or, as above, experiment ........
(I really must learn to be more concise ..still rambling ..sorry)
Sulaiman, Sat Aug 18 2012, 09:40PM
I (briefly) posted this yesterday then when I saw mention of 600A changed it to my post above, it may add a little;
Ash Small,
a couple of thoughts;
1) The (Cotswold Electronics) transformer cores would not make good inductors for the dc link in a zvs because they are almost certainly strip=wound steel cores,
(a thin ribbon of steel tape wound up) and are the best choice for small ac power transformers im many ways.
2) the VA (power) rating is pretty much determined by the weight, so if you find a similar weight toroidal transformer your VA will be close enough to that.
e.g. 50VA/0.7kg, 100VA/1.2kg, 200VA/2.2kg for one (random) manufacturer.
3) the transformers are also inductors,
high inductance/low current primary
high current/low inductance secondary
BUT the core will saturate easily with dc
You can also just wind over the existing windings for your own value of inductance
(careful though as the original primary windings may produce very large voltages)
this way when you realise that they don't make good inductors you will still have two good transformers ;)
4) I don't think there CAN be a formula for calculating the dc inductor because each application will be different,
some will want high efficiency good sinewaves
(high inductance / low loss)
some will want as much power throughput as the core/wire will allow, running hot,
(thin wire/some small saturation allowed)
and it seems many get best power throughput when the "zvs' is not actually operating in zero-switching, so short-term overheating/core saturation can also work in this circuit.
5) I'm not sure what the other cores are, on my monitor they look Grey/Yellow,
(with a bit of research you can find different manufacturers color codes)
(being from a HAM fest they're probably some popular mix)
if you find a match you can look up the specifications,
if you can measure their Al (nH/turn2) you can measure the core and look for similar,
(amp.turns = (1 to 2) x Al/Ae) Ae=core cross-section in m2
or, as above, experiment ........
(I really must learn to be more concise ..still rambling ..sorry)
Re: question regarding DC link inductors for ZVS circuit
Ash Small, Sat Aug 18 2012, 10:11PM
Thanks for the input, Sulaiman.
Apparently these are standard colour codes, green/yellow indicates type 40 ferrite (not actually ferrite at all, but as follows):
I'll try and find a link that gives all the standard colour codes for toroidal ferrite cores.
Ash Small, Sat Aug 18 2012, 10:11PM
Thanks for the input, Sulaiman.
Sulaiman wrote ...
5) I'm not sure what the other cores are, on my monitor they look Grey/Yellow,
(with a bit of research you can find different manufacturers color codes)
5) I'm not sure what the other cores are, on my monitor they look Grey/Yellow,
(with a bit of research you can find different manufacturers color codes)
Apparently these are standard colour codes, green/yellow indicates type 40 ferrite (not actually ferrite at all, but as follows):
Ash Small wrote ...
These are, fom what I can gather, T106-40, T106 being the dimension spec (26.9±0.5 mm OD, 14.5±0.5 mm ID, 11.1±0.64 mm Thick), 40 being the material (MnZn NiZn)), 81 AL(nHï¼N²), Permeability (ui) 60, .
These are, fom what I can gather, T106-40, T106 being the dimension spec (26.9±0.5 mm OD, 14.5±0.5 mm ID, 11.1±0.64 mm Thick), 40 being the material (MnZn NiZn)), 81 AL(nHï¼N²), Permeability (ui) 60, .
I'll try and find a link that gives all the standard colour codes for toroidal ferrite cores.
Re: question regarding DC link inductors for ZVS circuit
Steve Conner, Sun Aug 19 2012, 07:55AM
I believe the colour codes were invented by Micrometals. You can see a list of the codes on their website.
Yellow with a grey top is the cooking grade of iron powder for low-frequency applications: green with a blue top is a similar but improved grade that I've used in a few projects. Either makes a fine DC link inductor.
You seem to have grey with a yellow top which is something else entirely.
Steve Conner, Sun Aug 19 2012, 07:55AM
I believe the colour codes were invented by Micrometals. You can see a list of the codes on their website.
Yellow with a grey top is the cooking grade of iron powder for low-frequency applications: green with a blue top is a similar but improved grade that I've used in a few projects. Either makes a fine DC link inductor.
You seem to have grey with a yellow top which is something else entirely.
Re: question regarding DC link inductors for ZVS circuit
Ash Small, Sun Aug 19 2012, 09:33AM
These are definitaly green with yellow top, it also shows up as green on my (Compaq) screen.
Thanks for the input again Steve, they had yellow/grey and green/blue at the hamfest, I wish I'd known.
Micrometals has the T106-40 cores listed,Al 80.1. (40=green/yellow). Apparently it's the cheapest material they supply.
Material characteristics for -40 is here;
Unfortunately I don't know what properties to look for in an ideal DC link inductor. (Hence the purpose of this thread........)
Ash Small, Sun Aug 19 2012, 09:33AM
Steve Conner wrote ...
You seem to have grey with a yellow top which is something else entirely.
You seem to have grey with a yellow top which is something else entirely.
These are definitaly green with yellow top, it also shows up as green on my (Compaq) screen.
Thanks for the input again Steve, they had yellow/grey and green/blue at the hamfest, I wish I'd known.
Micrometals has the T106-40 cores listed,Al 80.1. (40=green/yellow). Apparently it's the cheapest material they supply.
Material characteristics for -40 is here;
Unfortunately I don't know what properties to look for in an ideal DC link inductor. (Hence the purpose of this thread........)
Re: question regarding DC link inductors for ZVS circuit
m4ge123, Sun Aug 19 2012, 10:14AM
As you can tell from the graphs, #40 is very similar to #26 and #52 (yellow/white and green/blue respectively). It should work fine.
m4ge123, Sun Aug 19 2012, 10:14AM
As you can tell from the graphs, #40 is very similar to #26 and #52 (yellow/white and green/blue respectively). It should work fine.
Re: question regarding DC link inductors for ZVS circuit
Ash Small, Sun Aug 19 2012, 11:13AM
Well, thanks to everyone who has contributed to this thread. I now know that the cores I have should work ok.
But, for the benefit of others in the future, what general properties are we looking for, and what factors should we consider when buying cores for this task?
I know most will work to some extent, but some get hot (wasting power), etc.
So many problems associated with this circuit have been attributed to people choosing the wrong core.
What are the ideal qualities that we should be looking for? (these cores cost next to nothing, blown mosfets,etc. cost consderably more, not to mention the frustration incurred when this circuit fails to work as expected.)
I'm trying to approach this scientifically, using a bit of maths, rather than just 'suck it and see'.
Ash Small, Sun Aug 19 2012, 11:13AM
Well, thanks to everyone who has contributed to this thread. I now know that the cores I have should work ok.
But, for the benefit of others in the future, what general properties are we looking for, and what factors should we consider when buying cores for this task?
I know most will work to some extent, but some get hot (wasting power), etc.
So many problems associated with this circuit have been attributed to people choosing the wrong core.
What are the ideal qualities that we should be looking for? (these cores cost next to nothing, blown mosfets,etc. cost consderably more, not to mention the frustration incurred when this circuit fails to work as expected.)
I'm trying to approach this scientifically, using a bit of maths, rather than just 'suck it and see'.
Re: question regarding DC link inductors for ZVS circuit
Steve Conner, Sun Aug 19 2012, 02:50PM
The qualities you should be looking for are yellow/whiteness or green-blueness. These materials are designed for DC filter inductors in switch mode power supplies.
Ferrite E-cores are also acceptable if you use an air gap.
Steve Conner, Sun Aug 19 2012, 02:50PM
The qualities you should be looking for are yellow/whiteness or green-blueness.
These materials are designed for DC filter inductors in switch mode power supplies.Ferrite E-cores are also acceptable if you use an air gap.
Re: question regarding DC link inductors for ZVS circuit
Ash Small, Wed Aug 22 2012, 08:44AM
I found this on Uzzor's site:
"Powdered iron cores are generally color coded, and most often with two different colors. Ferrites on the other hand tend to be a single color, or unpainted. "
It looks like, as a general rule, torroidal cores which are two colours are better suited to this application than single colour cores.
Ash Small, Wed Aug 22 2012, 08:44AM
Steve Conner wrote ...
The qualities you should be looking for are yellow/whiteness or green-blueness. These materials are designed for DC filter inductors in switch mode power supplies.
Ferrite E-cores are also acceptable if you use an air gap.
The qualities you should be looking for are yellow/whiteness or green-blueness.
These materials are designed for DC filter inductors in switch mode power supplies.Ferrite E-cores are also acceptable if you use an air gap.
I found this on Uzzor's site:
"Powdered iron cores are generally color coded, and most often with two different colors. Ferrites on the other hand tend to be a single color, or unpainted. "
It looks like, as a general rule, torroidal cores which are two colours are better suited to this application than single colour cores.
Re: question regarding DC link inductors for ZVS circuit
GeordieBoy, Tue Aug 28 2012, 11:06AM
Micrometals Type-40 is a Hydrogen reduced iron-powder much like the yellow/white (Type-26) and green/blue (Type-52) cores Steve Conner suggested.
Any of these material grades should work fine for your DC link choke up to 500kHz or so. Since your cores are small but you have more than one core available, you can always stack cores side-by-side and wind around the stack to get the combination of inductance and resilience to DC saturation that you require.
-Richie,
GeordieBoy, Tue Aug 28 2012, 11:06AM
Micrometals Type-40 is a Hydrogen reduced iron-powder much like the yellow/white (Type-26) and green/blue (Type-52) cores Steve Conner suggested.
Any of these material grades should work fine for your DC link choke up to 500kHz or so. Since your cores are small but you have more than one core available, you can always stack cores side-by-side and wind around the stack to get the combination of inductance and resilience to DC saturation that you require.
-Richie,
Re: question regarding DC link inductors for ZVS circuit
Daedronus, Tue Aug 28 2012, 12:31PM
A question that hunted me for some time regarding DC filter inductors...
Do you need to use litz wire with proper diameter for the sink depth at the ripple frequency? Or a single big fat wire is Ok considering the majority of the carried current is DC?
Daedronus, Tue Aug 28 2012, 12:31PM
A question that hunted me for some time regarding DC filter inductors...
Do you need to use litz wire with proper diameter for the sink depth at the ripple frequency? Or a single big fat wire is Ok considering the majority of the carried current is DC?
Re: question regarding DC link inductors for ZVS circuit
GeordieBoy, Tue Aug 28 2012, 02:46PM
I think you've answered your own question
Whether you really need to use Litz depends on what the ripple current is. The purpose of a choke is to allow the passage of considerable DC current whilst limiting AC ripple, so in general the DC current will be large and the AC current will be comparatively small. This makes the larger copper fill of a solid conductor more efficient than the individually insulated bundles of Litz with the same overall OD. It's also cheaper.
Iron-powder cores tend to be quite lossy for rapid large flux excursions, so I'd go as far as to say that you would want solid copper for iron-powder chokes that normally run in continuous-current mode with quite a small percentage of actual ripple current. If the ripple current got bigger you'ld likely notice the core overheating before skin losses in the copper.
If the desired ripple current is actually a large percentage of the DC current, (like when running a SMPS choke in discontinuous current mode,) a gapped ferrite core will be less lossy than iron-powder, and Litz wire may then be more efficient for carrying the combined AC+DC current.
In a recent active PFC front-end I designed I used "ripple-steering" where one winding on the PFC boost choke was done with single core copper wire to carry the line-frequency current, and the other ripple-steering winding was made with Litz wire to support the modest AC ripple current in this design.
You use the cheapest cores and winding regimes you can get away with for the job!
-Richie,
GeordieBoy, Tue Aug 28 2012, 02:46PM
Or a single big fat wire is Ok considering the majority of the carried current is DC?
I think you've answered your own question
Whether you really need to use Litz depends on what the ripple current is. The purpose of a choke is to allow the passage of considerable DC current whilst limiting AC ripple, so in general the DC current will be large and the AC current will be comparatively small. This makes the larger copper fill of a solid conductor more efficient than the individually insulated bundles of Litz with the same overall OD. It's also cheaper.
Iron-powder cores tend to be quite lossy for rapid large flux excursions, so I'd go as far as to say that you would want solid copper for iron-powder chokes that normally run in continuous-current mode with quite a small percentage of actual ripple current. If the ripple current got bigger you'ld likely notice the core overheating before skin losses in the copper.
If the desired ripple current is actually a large percentage of the DC current, (like when running a SMPS choke in discontinuous current mode,) a gapped ferrite core will be less lossy than iron-powder, and Litz wire may then be more efficient for carrying the combined AC+DC current.
In a recent active PFC front-end I designed I used "ripple-steering" where one winding on the PFC boost choke was done with single core copper wire to carry the line-frequency current, and the other ripple-steering winding was made with Litz wire to support the modest AC ripple current in this design.
You use the cheapest cores and winding regimes you can get away with for the job!
-Richie,
Re: question regarding DC link inductors for ZVS circuit
Patrick, Tue Aug 28 2012, 07:49PM
those mains freq toroidal transformers are nice, id hate to see them trashed for a simple device. youd be wiser (in my opinnion) to save them for one of your other greater projects. 30 volts at 3 amps could be used for many other apps that youd rather not series a bunch of batteries for.
Patrick, Tue Aug 28 2012, 07:49PM
those mains freq toroidal transformers are nice, id hate to see them trashed for a simple device. youd be wiser (in my opinnion) to save them for one of your other greater projects. 30 volts at 3 amps could be used for many other apps that youd rather not series a bunch of batteries for.
Re: question regarding DC link inductors for ZVS circuit
Ash Small, Tue Aug 28 2012, 08:22PM
Thanks for the input Richie.
A few webites, such as this one:
say the following, or similar:
"Iron powder core, MnZn NiZn core, Toroidal core, Ferrite core, Metal core, Ferrite magnet core, ceramic ferrite magnet,Iron powder,Iron Powder Core -40 Green/Yellow,Magnet"
I assume that by mixing MnZn and NiZn in the correct ratio, you get a core with similar properties to the iron powder core you mention.
as mine came from a stall at a hamfest I've no idea what make they are, just that they are type 40.
Ash Small, Tue Aug 28 2012, 08:22PM
GeordieBoy wrote ...
Micrometals Type-40 is a Hydrogen reduced iron-powder much like the yellow/white (Type-26) and green/blue (Type-52) cores
Micrometals Type-40 is a Hydrogen reduced iron-powder much like the yellow/white (Type-26) and green/blue (Type-52) cores
Thanks for the input Richie.
A few webites, such as this one:
say the following, or similar:
"Iron powder core, MnZn NiZn core, Toroidal core, Ferrite core, Metal core, Ferrite magnet core, ceramic ferrite magnet,Iron powder,Iron Powder Core -40 Green/Yellow,Magnet"
I assume that by mixing MnZn and NiZn in the correct ratio, you get a core with similar properties to the iron powder core you mention.
as mine came from a stall at a hamfest I've no idea what make they are, just that they are type 40.
Re: question regarding DC link inductors for ZVS circuit
Steve Conner, Tue Aug 28 2012, 08:29PM
MnZn and NiZn are types of ferrite, nothing to do with iron powder, which is made of... iron.
Steve Conner, Tue Aug 28 2012, 08:29PM
MnZn and NiZn are types of ferrite, nothing to do with iron powder, which is made of... iron.
Re: question regarding DC link inductors for ZVS circuit
Ash Small, Tue Aug 28 2012, 10:20PM
Yes, but why are they mentioned in descriptions of Chinese 40 grade toroids?
Ash Small, Tue Aug 28 2012, 10:20PM
Steve Conner wrote ...
MnZn and NiZn are types of ferrite, nothing to do with iron powder, which is made of... iron.
MnZn and NiZn are types of ferrite, nothing to do with iron powder, which is made of... iron.
Yes, but why are they mentioned in descriptions of Chinese 40 grade toroids?
Re: question regarding DC link inductors for ZVS circuit
Steve Conner, Wed Aug 29 2012, 08:55AM
Because the guy who maintains the website pastes every piece of technical crap he has on every page to get more search engine hits?
Steve Conner, Wed Aug 29 2012, 08:55AM
Because the guy who maintains the website pastes every piece of technical crap he has on every page to get more search engine hits?
Re: question regarding DC link inductors for ZVS circuit
Ash Small, Wed Aug 29 2012, 09:51AM
That makes sense. It did cause some confusion, though.
(EDIT: first post in thread now edited)
Ash Small, Wed Aug 29 2012, 09:51AM
Steve Conner wrote ...
Because the guy who maintains the website pastes every piece of technical crap he has on every page to get more search engine hits?
Because the guy who maintains the website pastes every piece of technical crap he has on every page to get more search engine hits?
That makes sense. It did cause some confusion, though.
(EDIT: first post in thread now edited)
Re: question regarding DC link inductors for ZVS circuit
Redstone, Sun Sept 09 2012, 01:22AM
So ferrites are for ??? and iron powder toroids are for flitering/inductor with DC.
Redstone, Sun Sept 09 2012, 01:22AM
So ferrites are for ??? and iron powder toroids are for flitering/inductor with DC.
Re: question regarding DC link inductors for ZVS circuit
Steve Conner, Sun Sept 09 2012, 07:44AM
Yes, ??? would be things like high frequency transformers and common-mode chokes for EMI suppression. Basically any application where the core isn't required to store magnetic energy.
Ferrite cores with air gaps can be used in energy storage applications. The energy is stored in the air gap. Some people prefer them to iron powder toroids. I've tried both and they seem to perform about the same.
Steve Conner, Sun Sept 09 2012, 07:44AM
Yes, ??? would be things like high frequency transformers and common-mode chokes for EMI suppression. Basically any application where the core isn't required to store magnetic energy.
Ferrite cores with air gaps can be used in energy storage applications. The energy is stored in the air gap. Some people prefer them to iron powder toroids. I've tried both and they seem to perform about the same.
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