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# How to make a lightweight 10kv 500 watt power supply? Answered

I need to convert up to 500 watts of 12 volt to at least 10 kv. It's important that it has both +10kv and -10kv. Right now I'm thinking flyback converter driven by a 555 to 1000 volts then voltage multiplier to 16kv. It's important that it's light so I don't want a regular flyback transformer. I'm wondering how duty cycle effects a transformer. Does it effect it like it would with an inductor-based boost converter? If so, then according to this calculator http://www.ladyada.net/library/diyboostcalc.html I would need an 88% (88% high?) duty cycle to get 12 volts up to 100 volts with a boost converter. Does this mean with a 1-10 transformer I could get 1000 volts from 12 volts with an 88% duty cycle?

If so, then I need a light weight 1-10 transformer. I'm thinking winding a toroidal transformer will be best? So I could get a ferrite toroid (I'm thinking material 61, size 114) and wind a 1-10 transformer, but I need to make sure it doesn't saturate. Do I find out the saturation just like I would an inductor in a boost converter? If so, then according to the same calculator, the higher the output current, the less henries I need. So that means if I don't draw enough power it will saturate? I'm probably going to use 25 khz, so according the the calculator, if it's 100 watts then I need a little over a 25 henry primary. But if I use 500 watts, then I only need a little over 5 henries? This doesn't seem right. Soooo according to this toroid winding calculator http://www.66pacific.com/calculators/toroid_calc.aspx with a material 61, size 114 toroid, I would need 2 primary turns if it was drawing a minimum of 100 watts (the lower inductance/higher current can't be right can it?) and then I would need 200 turns.

Sooo my question are (haha) is this a good idea for a light weight high power hv power supply, if so are the similarities I'm assuming between boost and flyback converter correct, and if so, how many/how do I figure out how many windings I would need on each side of a toroidal transformer/ how do I figure out what inductance I need for the primary. I have pretty good experience making boost converters but I've never made anything hv. Very long question thank you this is for an ion thruster.

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## 14 Replies

IceMetal (author)2012-09-26

LOL, all this negative nancy make me laugh :)
you can use a old automotive ignition, they convert 12V to 10KV to ignite the spark plugs, they are alot of you tube videos about that.

iceng (author)2012-09-26

Hey my wife's name is Nancy.....

Now, a spark coil is at most only a couple of watts

Leaving 498 watts to come out of the zero point aether... :)

A

iceng (author)2012-02-21

Power is proportional to weight
weight is inversely proportional to frequency
Saturation is inversely proportional to frequency
( lower frequency saturates sooner )
12V to 10,000V is a turns ratio of 1:833 twice for +- 10kv
500watts at 10kv is 50ma reflected back to 12v is 42 Amps
at a 100% efficiency .  A 12V 50 Amp battery is heavy !
To support the energy transfer your core material BH curve
must be known, how many watt seconds it can support
I don't think you can get away with 2 primary turns more like 30
and you will not be able to fit the secondary winding even on a
split core toroid .

A

sk8aseth (author)2012-02-21

Okay so it is probably better to use a microcontroller, maybe 20mhz. How does saturation relate to current?

steveastrouk (author)2012-02-21

A's running through the outlines of the power transformer design you need to follow to make a 10kV 500W, high frequency transformer. It's a difficult thing to do even when you're a professional designers, like A. and me. In fact, unless our palms were crossed with enormous amounts of money AND there was an overwhelming need to make a special supply, we'd probably buy a suitable design in from a specialist.

Switchers at this kind of power/voltage are HIGHLY specialist designs.

sk8aseth (author)2012-02-21

Okay but couldn't I use a flyback transformer to generate 1kv then voltage multiplier to get it up to 16kv? And I'm not sure about this but can't I get 1000 volts from a 1-10 transformer with the correct duty cycle?

iceng (author)2012-02-22
You are under a mistaken concept,
• Duty cycle control can only reduce a transformer's output voltage at the secondary.
• A flyback is never going to deliver 500W at 10KV.
• A Multiplier also cannot deliver 500 Watts.
• A 1:10 transformer can only multiply the primary voltage by ten at the secondary.  It also divides the available current by ten at the secondary.

steveastrouk (author)2012-02-23

+10 (kV ?)

This isn't a project for a beginner.

steveastrouk (author)2012-02-22

Not really. Like I said, you've chosen a very hard problem.

iceng (author)2012-02-21

+2

iceng (author)2012-02-21

One way to look at it is,

The 12V supply must be capable of 550 Watts
When running depending on efficiency of design, the transformer
will take 15 Watts  85% eff.

If the core Saturates fore some reason ( power transistor shorted )
the windings will begin to absorb all of the 550 Watts and get very hot ! ! !

A

iceng (author)2012-02-21

Saturation of a magnetic core occurs when the amps × winding_turns
generates more flux then the core can contain forcing additional flux to
permeate the surrounding space which does not require energy to align magnetic core domains ( inductive reluctance )..
Now as long as there is voltage the current will raise up to the limit of
the DC copper wire winding resistance turning the coils into a toaster !

A

lemonie (author)2012-02-21

You wouldn't lie to us would you; it's not for a suicide-machine?

L

rickharris (author)2012-02-21

500 watts at 12 volts means the power supply will be supplying 41 amps!

I think this may be your first problem.

10Kv isn't something you should be playing with unless your fully experienced - Your talking about the sort of voltages that you get on the electricity transmission pylons - Would you mess with them?

Sorry to be negative but
a) I don't think your going to get this to work.
b) it is going to be costly
c) It would be VERY dangerous.