the best way to stack flyback transformers secondaries?
father dest, Tue Sept 10 2019, 06:34PMhi errbody.
can you help me a little bit with flyback transformers? in this video
there is 4 of them - two in parallel, another two in parallel too and those 2 groups in series, with primaries out of phase (like center tapped nst). so maximum voltage between secondary output of each transformer in each group and the core is no more than rated secondary voltage, about 8 kv. thats great, but total output is 16 kv only - i need 32. so i want to connect all secondaries in series, or two in series and and two groups in series too, as i did before while paralleling them, or some other variants. but this time some secondaries can see 2 or 3 their rated voltage, depending on the variant of their connection, which is bad.
so maybe you know the best way to stack transformers? which will result in minimum overvoltage on the secondary? or the minimum number of overvolted secondaries in total.
and there is one more problem here - flybacks work on something like 60 khz, so capacitive currents build up like crazy - i think primaries are acting like directly connected to the ground through transistors of the half bridge and mains, so probably i need not only configuration of secondaries connection that results in minimum overvoltage, but configuration that results in minimum secondary to core/primaries capacitance too? or both at the same time?
and maybe that capacitive high frequency stress on the dielectric of the secondary is even worse than just overvoltage, coz it heats dielectric up?
so there is 4 variants of interconnection as i see it in the pic below, with one wire of secondary connected to the core (inner wire - beginning of the winding) - core is that vertical line:
the variant on the right is the easiest one which is the worst one at the same time. so what variant is the best?
plz give your own vars & thougts.
Re: the best way to stack flyback transformers secondaries?
Patrick, Sun Sept 22 2019, 06:19PM
Putting flybacks in series isnt generally done. After 2 (or including 2) you get secondary to core arcing, which theres now way to insulate against. Even if you improved that, you tend to get secondary to primary/source/transistor arcing, which you cant improve.
Best is to move up to a better transformer, i have a flyback that puts out 52 kV using in native primary. new flybacks are better then scavenged ones. check ebay.
Patrick, Sun Sept 22 2019, 06:19PM
Putting flybacks in series isnt generally done. After 2 (or including 2) you get secondary to core arcing, which theres now way to insulate against. Even if you improved that, you tend to get secondary to primary/source/transistor arcing, which you cant improve.
Best is to move up to a better transformer, i have a flyback that puts out 52 kV using in native primary. new flybacks are better then scavenged ones. check ebay.
Re: the best way to stack flyback transformers secondaries?
father dest, Mon Sept 23 2019, 03:43PM
with no current i guess, so no power also. while each of my four flybacks give about 200ma shorted on the secondary side, so around 600W from each, 2400W in total.
that's the difference.
father dest, Mon Sept 23 2019, 03:43PM
Patrick wrote ...
i have a flyback that puts out 52 kV
i have a flyback that puts out 52 kV
with no current i guess, so no power also. while each of my four flybacks give about 200ma shorted on the secondary side, so around 600W from each, 2400W in total.
that's the difference.
Re: the best way to stack flyback transformers secondaries?
Sulaiman, Mon Sept 23 2019, 04:18PM
What is the intended purpose of the high voltage ?
This will usually determine the design.
Sulaiman, Mon Sept 23 2019, 04:18PM
What is the intended purpose of the high voltage ?
This will usually determine the design.
Re: the best way to stack flyback transformers secondaries?
father dest, Mon Sept 23 2019, 04:35PM
power source for some home x-rays, 100-300kv, 1-3kw.
father dest, Mon Sept 23 2019, 04:35PM
Sulaiman wrote ...
What is the intended purpose of the high voltage ?
What is the intended purpose of the high voltage ?
power source for some home x-rays, 100-300kv, 1-3kw.
Re: the best way to stack flyback transformers secondaries?
Sulaiman, Tue Sept 24 2019, 02:16AM
300 keV is in the gamma ray range, 10 mA beam current is a lot of radiation,
sorry, I do not want to help with this project as I feel it is too hazardous.
Sulaiman, Tue Sept 24 2019, 02:16AM
300 keV is in the gamma ray range, 10 mA beam current is a lot of radiation,
sorry, I do not want to help with this project as I feel it is too hazardous.
Re: the best way to stack flyback transformers secondaries?
jpsmith123, Tue Sept 24 2019, 03:01PM
So you've got four HV transformers that can produce 8 kv and you're looking to get a reliable +/- 16 KV to drive a full wave CW voltage multiplier, or something like that?
Can you just wind some ferrite core isolation transformers with secondaries insulated for high voltage? IOW each HV transformer will be driven by, say, a 1:1 ferrite transformer whose secondary is insulated?
jpsmith123, Tue Sept 24 2019, 03:01PM
So you've got four HV transformers that can produce 8 kv and you're looking to get a reliable +/- 16 KV to drive a full wave CW voltage multiplier, or something like that?
Can you just wind some ferrite core isolation transformers with secondaries insulated for high voltage? IOW each HV transformer will be driven by, say, a 1:1 ferrite transformer whose secondary is insulated?
Re: the best way to stack flyback transformers secondaries?
father dest, Tue Sept 24 2019, 06:42PM
who said you can help? you just lacking info for that.
"gamma ray" - LOL.
for your information - i already have 110kv 25ma working unit, it's just too weak for me.
and you can't help with that eather : )
"beam current" - LOL.
exactly - it's just the easiest way. my 110kv head does just that, it's simply not designed for continuous operation - not thermally, nor electrically.
so am doing other (much more beefier) one from scratch.
i have enough leakage inductance in those 4 flybacks already - my concern is that any additional one can cap my power below 3-4kw, which i don't like.
and i am too lazy to wind another 8 windings - there must be easier way : D
i'll save this variant for backup plan tho.
father dest, Tue Sept 24 2019, 06:42PM
Sulaiman wrote ...
I do not want to help with this project as I feel it is too hazardous.
I do not want to help with this project as I feel it is too hazardous.
who said you can help? you just lacking info for that.
"gamma ray" - LOL.
for your information - i already have 110kv 25ma working unit, it's just too weak for me.
and you can't help with that eather : )
"beam current" - LOL.
jpsmith123 wrote ...
So you've got four HV transformers that can produce 8 kv and you're looking to get a reliable +/- 16 KV to drive a full wave CW voltage multiplier, or something like that?
So you've got four HV transformers that can produce 8 kv and you're looking to get a reliable +/- 16 KV to drive a full wave CW voltage multiplier, or something like that?
exactly - it's just the easiest way. my 110kv head does just that, it's simply not designed for continuous operation - not thermally, nor electrically.
so am doing other (much more beefier) one from scratch.
wrote ...
Can you just wind some ferrite core isolation transformers with secondaries insulated for high voltage? IOW each HV transformer will be driven by, say, a 1:1 ferrite transformer whose secondary is insulated?
Can you just wind some ferrite core isolation transformers with secondaries insulated for high voltage? IOW each HV transformer will be driven by, say, a 1:1 ferrite transformer whose secondary is insulated?
i have enough leakage inductance in those 4 flybacks already - my concern is that any additional one can cap my power below 3-4kw, which i don't like.
and i am too lazy to wind another 8 windings - there must be easier way : D
i'll save this variant for backup plan tho.
Re: the best way to stack flyback transformers secondaries?
jpsmith123, Tue Sept 24 2019, 07:48PM
If you use a big ferrite core maybe you could put the primary and four secondary windings on it? With a big core you wouldn't need many turns so I think leakage inductance would not be excessive.
BTW check out this power supply:
jpsmith123, Tue Sept 24 2019, 07:48PM
If you use a big ferrite core maybe you could put the primary and four secondary windings on it? With a big core you wouldn't need many turns so I think leakage inductance would not be excessive.
BTW check out this power supply:
Re: the best way to stack flyback transformers secondaries?
father dest, Wed Sept 25 2019, 03:34PM
that's all great and such, but, the question of this topic was "can you help me a little bit with flyback transformers? / maybe you know the best way to stack transformers?"
it wasn't about how to build high voltage supply per se, or how to build it in a proper way, etc.
it's just about those 4 flybacks, and nothing more, like "gamma rays" for example, LMAO.
so i guess the answer is number 2 from the left, coz all secondaries to core voltages would be no more than their rated voltage, the maximum would be 32kv between two primaries, but since primaries are wound by myself, i can isolate those as much as i want. which is not the case for the secondaries.
father dest, Wed Sept 25 2019, 03:34PM
jpsmith123 wrote ...
If you use a big ferrite core
BTW check out this power supply:
If you use a big ferrite core
BTW check out this power supply:
that's all great and such, but, the question of this topic was "can you help me a little bit with flyback transformers? / maybe you know the best way to stack transformers?"
it wasn't about how to build high voltage supply per se, or how to build it in a proper way, etc.
it's just about those 4 flybacks, and nothing more, like "gamma rays" for example, LMAO.
so i guess the answer is number 2 from the left, coz all secondaries to core voltages would be no more than their rated voltage, the maximum would be 32kv between two primaries, but since primaries are wound by myself, i can isolate those as much as i want. which is not the case for the secondaries.
Re: the best way to stack flyback transformers secondaries?
jpsmith123, Thu Sept 26 2019, 12:41AM
I'm sorry; I took the liberty to offer unsolicited advice based on what I might do in that situation.
Because you said: "i think primaries are acting like directly connected to the ground through transistors of the half bridge and mains..."; and because I cannot see the subject transformers and therefore do not know any details of their design and construction, I suggested an isolation transformer as a "holistic" approach to solving the problem. For a person with your knowledge and resources, I thought it was a reasonable suggestion.
jpsmith123, Thu Sept 26 2019, 12:41AM
father dest wrote ...
that's all great and such, but, the question of this topic was "can you help me a little bit with flyback transformers? / maybe you know the best way to stack transformers?"
it wasn't about how to build high voltage supply per se, or how to build it in a proper way, etc.
it's just about those 4 flybacks, and nothing more, like "gamma rays" for example, LMAO.
jpsmith123 wrote ...
If you use a big ferrite core
BTW check out this power supply:
If you use a big ferrite core
BTW check out this power supply:
that's all great and such, but, the question of this topic was "can you help me a little bit with flyback transformers? / maybe you know the best way to stack transformers?"
it wasn't about how to build high voltage supply per se, or how to build it in a proper way, etc.
it's just about those 4 flybacks, and nothing more, like "gamma rays" for example, LMAO.
I'm sorry; I took the liberty to offer unsolicited advice based on what I might do in that situation.
Because you said: "i think primaries are acting like directly connected to the ground through transistors of the half bridge and mains..."; and because I cannot see the subject transformers and therefore do not know any details of their design and construction, I suggested an isolation transformer as a "holistic" approach to solving the problem. For a person with your knowledge and resources, I thought it was a reasonable suggestion.
Re: the best way to stack flyback transformers secondaries?
Patrick, Fri Sept 27 2019, 12:15AM
Im bowing out, No need to take part in Gamma rays.
Patrick, Fri Sept 27 2019, 12:15AM
Im bowing out, No need to take part in Gamma rays.
Re: the best way to stack flyback transformers secondaries?
Plasma, Fri Sept 27 2019, 06:59AM
Supposable that can go through 2meters of concrete, and portable too, heck 5MV is easy but if what you ask and plan to do...
Plasma, Fri Sept 27 2019, 06:59AM
Supposable that can go through 2meters of concrete, and portable too, heck 5MV is easy but if what you ask and plan to do...
Re: the best way to stack flyback transformers secondaries?
Plasma, Sun Oct 13 2019, 04:32AM
Its with NST just replace that with flyback, that picture should get 120kV at 20mA output
With two 15kV 60mA nst, if you don't mind lower current, add a stage to the multiple for more volts.
Plasma, Sun Oct 13 2019, 04:32AM
Its with NST just replace that with flyback, that picture should get 120kV at 20mA output
With two 15kV 60mA nst, if you don't mind lower current, add a stage to the multiple for more volts.
Re: the best way to stack flyback transformers secondaries?
father dest, Sun Oct 13 2019, 06:24PM
so now i need 4 invertors instead of 1? i mean - anybody can stack up battery powered anything, coz such things are isolated from each other per se.
so this answer has nothing to do with my question, again : )
father dest, Sun Oct 13 2019, 06:24PM
so now i need 4 invertors instead of 1? i mean - anybody can stack up battery powered anything, coz such things are isolated from each other per se.
so this answer has nothing to do with my question, again : )
Re: the best way to stack flyback transformers secondaries?
Plasma, Sun Oct 13 2019, 06:49PM
What about inverter to 4 1:1 ferrites then partellel them to the primary of the flyback.
Just have 150kV cable for the 1:1
If you only want 1 ferrite just have 4:1*(4)
Plasma, Sun Oct 13 2019, 06:49PM
What about inverter to 4 1:1 ferrites then partellel them to the primary of the flyback.
Just have 150kV cable for the 1:1
If you only want 1 ferrite just have 4:1*(4)
Re: the best way to stack flyback transformers secondaries?
father dest, Mon Oct 14 2019, 06:31PM
this suggestion is on previous page - written by "jpsmith123 Tue Sep 24 2019, 03:01PM".
and my answer to it is on the same page too : )
father dest, Mon Oct 14 2019, 06:31PM
this suggestion is on previous page - written by "jpsmith123 Tue Sep 24 2019, 03:01PM".
and my answer to it is on the same page too : )
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