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Stepping down 200kv to 1kv

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Erlend^SE

Mon Aug 26 2013, 06:33PM

Registered Member #1565 Joined: Wed Jun 25 2008, 09:08PM
Location: Norway
Posts: 159

Andy: rectified mains? you are dealing with 300-400V if so, and a 500/600V FET/IGBT would fit nicely.

For the 555 timer, you should add a FET-driver. (why a 555 timer anyway? no SMPS controller?)

What are you actually trying to build? or is it a school project?

Andy

Mon Aug 26 2013, 07:11PM

Registered Member #4266 Joined: Fri Dec 16 2011, 03:15AM
Location:
Posts: 874

Hi Erlend^SE
I'm trying to design a diesel generator setup, using a capacitor type genny, the output will be dc, and I think more power will be made at high voltages with the ohms staying the same, but it needs to be stepped down to 400-700volt for the inverter.
The idea was to use rectified mains, below is a picture that might work, but the mosfet is rated at 100volt, what FET/IGBT would you use in place of the mosfet?

Thanks

The power FET has a square wave across it, but know the inductors aren't working....?

Antonio

Wed Aug 28 2013, 01:41AM

Registered Member #834 Joined: Tue Jun 12 2007, 10:57PM
Location: Brazil
Posts: 644

An easy to find transistor is the MJE13003. CFL ballasts almost always have two. NPN, 400 V, 1.5 A. PC power supplies also have good switching high-voltage NPN transistors with higher maximum current. PNP transistors are usually used to switch current from a positive supply to a grounded load. To use a 555 as driver, it's easier to use NPN transistors, switching the load between a positive supply and the transistor's collector, with the emitter grounded.

Andy

Wed Aug 28 2013, 03:20AM

Registered Member #4266 Joined: Fri Dec 16 2011, 03:15AM
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Thanks Antonio, so PNP is used with a load after the emitter?

Below is the final one I think, question the cap C4, would the inductor act as a switch allowing the cap to charge then discharge through the inductor. Measure the voltage it stays at battery voltage. The 100uf cap hopeful will have say 0.001<ohms positive to ground.

At 100khz would a 1:1000 transformer be doable, thinking of driving it at 2kv, more of a pulse transformer.

Andy

Thu Aug 29 2013, 08:07PM

Registered Member #4266 Joined: Fri Dec 16 2011, 03:15AM
Location:
Posts: 874

Hi
What would be the EMI from a 128679H coil, with current of 276kA, at 100khz, the wave form is sine. Its probable a crazy question but would neighbors 100meters loss TV reception.

Thanks

Proud Mary

Thu Aug 29 2013, 09:59PM

Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992

Andy wrote ...

What would be the EMI from a 128679H coil, with current of 276kA, at 100khz, the wave form is sine. Its probable a crazy question but would neighbors 100meters loss TV reception.

The whole installation and its overhead power cables and safety railings could mean having to bulldoze your neighbour's house to construct it. It sounds like the kind of installation that would require safety certificates and planning permission before you could even get in the concrete for the foundations, and the crane to lift your coil with

Andy

Thu Aug 29 2013, 11:40PM

Registered Member #4266 Joined: Fri Dec 16 2011, 03:15AM
Location:
Posts: 874

Hi Proud Mary
:)
The network operate wants a electrical consultant to design and spec the system from the inverter to the grid. I don't think they mind to much from the inverter inwards. I'm guessing the EMI will be bad so might have to move from the place I was planning to use.

I suppose what I'm ask is, If a pacemaker came within 1km would it be dangerous, what would it do to nearby power lines(voltage spikes maybe), what would the induction heating be like on parts, would it send metal parts flying around, would it EMP electronics at a certain range, would it effect other inductive electronics like a buck-boost circuit.
I'm guessing the formulas and maths would be hard to workout, but was hoping for ballpark figures on range from the transformer.

Thanks

Andy

Fri Aug 30 2013, 04:34AM

Registered Member #4266 Joined: Fri Dec 16 2011, 03:15AM
Location:
Posts: 874

Using the calculator from

it shows
1.10986e+7 Tesla over a 100m3 coil which is stupid. What would be the voltage spike from a coil like this . The below equations says its strength Would 500meters from the power lines increase/decrease 5volt max.
At 500meters its 0.2218Tesla

Proud Mary

Fri Aug 30 2013, 07:16AM

Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992

Andy, I guess I'm one of the few old dinosaurs that still use LF chokes to smooth HV supplies, and believe me, lifting even a 100H 1A choke can do your back in, or severely mangle your foot if you dropped it.

Why not divide everything by 1000 so we don't have to think in panorama mode to visualise your project i.e. build something you can put on a bench. :)

PS: I'm not clear how your monstrous inductance goes with 100 kHz. What is its reactance at that frequency?

Andy

Fri Aug 30 2013, 07:40AM

Registered Member #4266 Joined: Fri Dec 16 2011, 03:15AM
Location:
Posts: 874

Hi Proud Mary

I think its dc current, it sets up a field, then the 14awg wire off a 0.001H at 1amp 10 turns times 10 in parallel is switched at 100khz this fights the dc current field and removes it, making the large H coil have high resistance to dc current for the time of the resistance of the system.
The 0.001H coil has 80-120Mohm, the 1286H coil has 20-300Mohm across it, but it still allows the current thought like its dc, with a load the 1286H coil has inf ohms, but the driver coil still bounce around 20-80Mohm

To test it was going to build a coil of hookup wire maybe 2000turns to 10 with a MOT core and have a 0.1k, and the 555 setup, and see if a ferrite 1:1 transformer will pass the voltage through. I haven't got a scope, but if a 12volt source and 1 ohm resistor lets 72watts through the transformer, alls good.

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