Paul and Sabrina's Cheap 3 Phase Inverter (AC Controller) with Field Oriented Control

[P-hack]

It looks like it is starting to saturate at 260A (130%), which is pretty much the bias current (510v*70a/144v), and beyond rated current, but otherwise it is a nice inductor. Interesting how they specify things.

The datasheet shows it is dual coil, does it have an air gap (not needed if it is meant as common mode choke AFAIK, definately needed as a single ended choke)? Do you know if it is 300uh/200A per coil?

[cts_casemod]

Originally Posted by MPaulHolmes

I just talked to Signal Transformer, and they sent me a graph of the CH-200 inductance vs. current graph.



I have used it 24/7 at 10KHz (even at night it's trying to track max power. talk about lazy programming on my part!) over the last couple years in a maximum power point tracker, running at about 90 amps during the peak sun hours of the day, in a shop that gets over 120degF. Not a dent in the fender! haha.

Notice the graph shows that the inductance is still 120uH at 300amp input.

Thats looks good. Is this something a common mortal can get his hands on?

What's the max frequency this can work at? Looks like a mains choque

[P-hack]

Originally Posted by cts_casemod

For 100Khz it would be AWG26 or 0.40mm, 41 strands. At this point makes sense to get the litz wire, doing it manually would yield a very large diameter conductor.

Recalculating it is more like 168 strands of 26awg magnet wire for ~70A, 4awg equivilant, litz or twisted. Twisting copper wire is actually how you straighten it, so without the braiding it should actually be a bit narrower. unless you use a untwisted braid. Just hoping to avoid more sourcing headaches than necessary.

[cts_casemod]

Originally Posted by P-hack

Recalculating it is more like 168 strands of 26awg magnet wire for ~70A, 4awg equivilant, litz or twisted. Twisting copper wire is actually how you straighten it, so without the braiding it should actually be a bit narrower. unless you use a untwisted braid. Just hoping to avoid more sourcing headaches than necessary.

Thats possible. I did the calculations for AWG10 equivalent, which is the maximun diameter litz wire I've found so far. For larger diameters one has to use several paralleled turns.

The polish guys have a good price and they also sell cores, altough the product documentation for the cores is very basic. Just some pearmibility indications.

Now all this inductor stuff I was wondering if one could do boost with a passive PFC choque. I have this one rated for 15Amps RMS (25Amps peak)

[P-hack]

same question I have about the ch200, does it have an air gap?

[cts_casemod]

Originally Posted by P-hack

same question I have about the ch200, does it have an air gap?

Is that for me? If so, yes, it does have an air gap of about 2-3mm.

[MPaulHolmes]

It's signal transformer. Yes, you can order the inductors straight from them. In quantity 1, they are $334 I believe (almost $400 from Digikey). In quantity 10 they are like $297. I asked about the gap in the core, and other stuff, but haven't heard back. I do know it works at 10KHz though, and doesn't get that hot at almost 100 amps.

[P-hack]

if it happens to have a gap, and is 300uh @ 200A X2 then possibly just one would work for 510v@70a (or even if they are 150uh @200a X2), the coils could use separate switches and diodes to help keep their relative inductance values (need to confirm that theory), but probably have to be switched at the same time because of mutual inductance. I get the feeling that they weren't designed for this though. What are you running it in?

I wonder if somehow the mutual inductance could be useful in interleaved, somehow, or if it would just be simulating 20khz.

[MPaulHolmes]

Oh ya, I forgot, it's not in series. I called and asked. There are other versions (lower current) that are configurable as series or parallel though.

[Astro]

Most of this inductor discussion is going way over my head but i am curious. Isn't an inductor at it's simplest just a coil of wire? Couldn't we make our own? I know there is probably a lot of sophisticated and precision manufacturing involved to get every last percent of performance from an inductor but couldn't we devise a way to DIY something that gets us close?