Paul and Sabrina's Cheap 3 Phase Inverter (AC Controller) with Field Oriented Control - Page 100 - Fuel Economy, Hypermiling, EcoModding News and Forum

MPaulHolmes · 08-23-2014, 08:42 PM

wait!!!

stop!!!!

They are only single IGBTs. That board you are getting assumes half bridge modules (2 igbts in a single package)

I'm sure you could get it to work, but the board is designed around a "dual" 600v 600amp or 1200v 600amp or 1200v 400amp or 600v 400amp IGBT.

For a 3 phase AC controller, you would need 6 of them, but it would be much cleaner and easier to do 3 half bridge modules. The board will plug right in, with no fuss.

4x4EV · 08-23-2014, 08:45 PM

Removed link .. stopped

MPaulHolmes · 08-23-2014, 08:48 PM

Lol phew!

4x4EV · 08-23-2014, 09:01 PM

2 Pcs Powerex IGBT CM400DU 12NFH 400A 600V Dual Transistors | eBay

So like this

MPaulHolmes · 08-23-2014, 09:02 PM

Exactly. You would need 3 of them.

MPaulHolmes · 08-23-2014, 09:04 PM

You know, I have 3 of those... I've done a little testing with them, but they are basically new. I got them from Adamj12b when he did a group buy. Do you want to buy them from me instead?! haha. No pressure. I'm trying to scrape together money for a motor so I can actually test this dang thing.

MPaulHolmes · 08-23-2014, 09:09 PM

I could sell you my 3 for $100 if you wanted to pay that much. Otherwise, I would sell them for $50 for 3. If you are impoverished and have no money, I'll just give them to you for free. haha. They are just going to waste at the moment. Sitting on my shelf, minding their own business.

Astro · 08-23-2014, 09:30 PM

Quote:

Originally Posted by MPaulHolmes

I could sell you my 3 for $100 if you wanted to pay that much. Otherwise, I would sell them for $50 for 3. If you are impoverished and have no money, I'll just give them to you for free. haha. They are just going to waste at the moment. Sitting on my shelf, minding their own business.

Wow Paul that's a generous offer. Hope you aren't losing too much money on us.

I was just about to let 4x4EV know that the eBay seller allpraisebob is selling lots of 6 NEW modules for $250 (so about $42 each) which is much cheaper than the link 4x4EV posted at $120 for two USED modules ($60 each).
When i purchased my modules and had them sent to Paul one of the other testers bought the excess 3 modules and that money went towards the cost of my controller.

But Paul, your offer makes that look expensive.

Just wondering what sort of motor you will get if you give the modules away for free?
How much is the motor?

e*clipse · 08-23-2014, 10:17 PM

Quote:

Originally Posted by MPaulHolmes

I could sell you my 3 for $100 if you wanted to pay that much. Otherwise, I would sell them for $50 for 3. If you are impoverished and have no money, I'll just give them to you for free. haha. They are just going to waste at the moment. Sitting on my shelf, minding their own business.

LOL! You sure are one hell of a salesman, in the Woodie Guthrie world!

Thank you very much for the 3-phase voltage explanation.

Is this right: the DC link capacitor (depending on the inductance it's subjected to) just has to deal with a reasonable amount over whatever the battery pack is:

Quote:

Originally Posted by Paul

If you have a battery pack of 293VDC, you get a phase to phase voltage peak of 293v, which makes for a RMS voltage from phase to phase of 208VAC.

It seems smart to give yourself some headroom - (due to the inductance of the motor and even controller causing the motor controller to act like a voltage booster) - on top of the phase to phase peak voltage. Also, for a 208VAC phase to phase voltage, we are looking at a 120V peak phase voltage, right?

I thought I had an reasonable understanding for 3 phase after working out the numbers for 3-phase power, but that didn't include rectification or creating 3 phase from a DC source...

MPaulHolmes · 08-23-2014, 10:47 PM

I have no official motor in mind. I'm just lying in wait, ready to pounce like a puma, once I save up enough money.

The beauty of those ring capacitors is, "occasional spikes over 600v are not a good reason to get a higher voltage ring cap." That's a quote from one of the SBE engineers. They were trying to push the 450v cap on me when I was going to run it at 300v. They don't need much derating at all.

The 3 phases to neutral are 120Vac. But I think that only makes sense when talking about filtered real life sine waves that are 120 degrees apart. Starting with DC, we are just getting pwm'ed square waves that instantaneously don't look like 120Vac from phase to neutral. They have to be filtered before looking like that.

EDIT: Or maybe it really is 120Vac sine waves, 120 degrees out of phase that are across each phase coil, but the phase coil voltage (to neutral) is not accessible to us. Sure, let's go with that! haha.