Large Ferrite Core with IGBT-Brick Driver

[davekni]

Wow, a very impressive project!  I do have two questions:

1) Is 3-phase power normal for residences in Austria (I that's where you are)?  It's certainly not here in USA - only available in commercial buildings.

2) How are you measuring power - by current and voltage or directly with a power meter?  With direct feeding of 3400uF (pair of 6800uF in series) from a rectifier off the power line, the power factor is likely fairly low, on the order of 60%.

Thank you for sharing your project!

[Mads Barnkob]

Wow, a very impressive project!  I do have two questions:

1) Is 3-phase power normal for residences in Austria (I that's where you are)?  It's certainly not here in USA - only available in commercial buildings.
Thank you for sharing your project!

3-phase 400VAC is normal in almost all of Europe, in households, we use it for oven, stove, washer, dryer etc. and can also install 3-phased industrial loads, it is nice!

In Denmark a normal house hold is 3x 400VAC @ 25A from the fuse box at the road.

[Phoenix]

Hello

Thank you for your replies 

@rikkitikkitavi

Yes you are right, a larger wheel would make it easier to adjust it faster. But it is not too hard to turn even with the smaller knob.

@LongLiveRocknRoll

I did not draw a schematic, the layout of the driver is the same as before. I just added a three phase full bridge rectifier and electrolytic capacitors with a higher voltage rating.

@davekni

Yes, I am from Austria. As Mads already said, 3 phase power is very common here in Austria. You can also get main fuses with higher current rating if you pay more. I believe you can get 25A, 35A, 50A and 63A. We have 50A fuses at our house input.

I measured the power with a normal analog panel meter. Yes, the power factor is horrible because of the large capacitive load, but i believe that the inductance of the variac improves it a bit. Of course the variac will never correct it to a 1, but maybe from 0.6 to 0.8.

Greetings
Phoenix

[ElectroXa]

Hello

in order to have a good power factor, I would suggest using an active PFC like the ones in  computer PSU's
Active PFC will also increase bus voltage from 325 V DC  to 400V DC

[rikkitikkitavi]

Hello

in order to have a good power factor, I would suggest using an active PFC like the ones in  computer PSU's
Active PFC will also increase bus voltage from 325 V DC  to 400V DC

Active PFC will give what bus voltage you want,within certain limits as it is a AC line syncronized step up converter, basically.

However with 3 ph input you need to end up well above 600V which will stress the semiconductors. 1200V rating would be minimum, higher rated semis are if not unobtanium atleast made out of expensium.

Designing this for a multi-kW solution is not done lightly. They are typically modular design with several in parallell.

It is not so peculiar that large welding inverters for 3ph connection demands 16A fuse rating despite the effective power drawn is in the range of 3-5kW at 100% welding at around 100-150 amps.

[davekni]

One more question - for this and any similar high-power arc experiments:  Any idea how much UV is generated, so what level of eye protection is appropriate for viewing?  I expect it's somewhere between Tesla coil sparks (low average current distributed over a long distance) and arc-welding (very high current from a tiny source size).

This inspired me to build a smaller version powered from a single 120V 15A circuit (USA standard wall outlet).  Hopefully I'll get some sort of crude UV measurement eventually.  (UV LED used as a photodiode is sensitive to UV only - shorter wavelengths than it's emission peak.  I'll compare to sky and other UV sources, but have no good information about it's spectral sensitivity.)

[Mads Barnkob]

It is not as bright as arc-welding, I did some experiments with different grade welding glass inserts in front of my camera to better record arcs and arc explosions.

My conclusion was that the lowest grade, least shading glass, gave the best result. After all this is not our day job and we do not stare into a arc 8 hours a day.

Tesla coil sparks are even weaker and moving up into high speed filming the glass made it impossible to get enough light in.

[Patrick]

Did you do any calculations on that massive ferrite ?