High Voltage SMPS

[JackStraw]

It is for an RF amplifier for 2 meter band. It will have two 4KW water cooled Russian tubes. I have 300 amp 220v service here at the house, when I built it I asked for it specifically. I just want to build a PS that I can actually move. I built a conventional PS for a 10KW amp I did once and it weighted over 300 lbs, we had to move it with a fork lift... I was just trying to get it smaller and lighter if possible... Most SMPS designs are lighter and smaller then their counter part would be in a standard design....

 

[ke5frf]

For 2 meters? As in 144 MHz/2 meters? Do you plan on keeping your license? Do you have a license?

 

[rikilshah]

I think Switching would be much Complex.You need a very high rating Switching Devices which in turn are costlier than Transformer but not as Heavy as later one.

 

[tcmtech]

If portability is a concern break it down into several smaller modules that plug into each other.

Just pricing out the switching devices (IGBT's) required for a welder or plasma cutter switching power supply of that capacity and the HV capacitors, control circuits and the misc pieces I came up with a realistic price tag that is still around $2500 not including labor or screw ups.

four 240:480 3 KVA transformers are around $500 or less if you know where to look. and the large capacitors are about another $300 or less. The HV diodes are around $15 and a good 120:24/48 500 VA transformer to act as an output filter choke is around $35.

For about $800 in materials is what I could build a 2700 VDC 5 amp power supply with basic filtering for. Add a simple phase angle voltage regulation circuit on the primary side for another $150 and it can have built in output voltage regulation as well!

 

[smanches]

What is the voltage rating of "conventional" transformers? Will they be able to handle 2700v?

 

[Nigel Goodwin]

What is the voltage rating of "conventional" transformers? Will they be able to handle 2700v?

The voltage rating of a transformer is suitable for it's designed voltage - so it's obviously perfectly fine.

 

[tcmtech]

If you where referring to their isolation voltage rating between primary and secondary or windings to core most commercial types have around a 5 KV safe rating for the lower most common line voltages. Typical lower quality ones are still around 2500 - 3500 volts or more.

The application specific designs intended for HV use on one winding are much higher.

 

[Rey]

Jesus, 5 amps? Don't quote me on this, but that could very well take a 3 phase input. And your primary current draw is going to be 62.5 amps, assuming 100% efficiency on an iron core.

Also, I doubt you would want to do this with an SMPS. It would be much more expensive, complicated, and possibly even less reliable than an iron core transformer (At this level of power). But that's just me.

I won't say it can't be done, but..it won't be easy.

 

[tcmtech]

I think the available power capacity varies greatly from one location to another. Some of the old home UK guys dont have 10 KW to play with but many of us American farmers have 48 Kw or more available as standard issue service capacity.
My big plasma cutter knocks on the 35+ Kw input levels (105 amps @ 300+ arc volts) and thats a full single phase input to a true SMPS system!
For me personally I dont consider the need for three phase power until at least 100 KW!

 

[smanches]

I live in town and still have a 200A service. Some idiot in the 70's thought putting electric radiant heat in ceilings was the way of the future. Obviously didn't have much practical physics knowledge.

 

[Sceadwian]

@smanches Subfloor radiant heating, mmm toasty toes! Mix with good insulation shake vigorusly enjoy nearly uniform room temperature all winter long.

@jack 2 meter band? Isn't that just a pinch above the commercial FM broadcasting spectrum? That's some serious power, what're you doing EME transmission?

 

[smanches]

I actually put in hydronic baseboards. Still has that amazing radiant heat that just feels so much warmer than hot air. Plus it's easy to heat with wood.