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Old 11-02-2009, 05:34 PM   #1 (permalink)
MPaulHolmes
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Location: Maricopa, AZ (sort of. Actually outside of town)
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Paul and Sabrina's Cheap 3 Phase Inverter (AC Controller) with Field Oriented Control

Let's face it, AC is better than DC! An AC motor will last forever, since there are no brushes to wear out. You get regenerative braking for free, which both recharges the batteries, and saves the brake pads! And the new lithium batteries can absorb huge currents. The main problem is cost. What a shocker!

With Field Oriented Control, you get to control the torque of an AC motor with a PI loop, like with a DC controller. This makes it very well suited to EVs. It's sort of confusing, but I've been reading about and I'm learning.

A high powered 3 phase AC inverter with field oriented control can cost $8000-$10,000. There already exists an open source inverter that has a parts cost of $2500. I would like to drive the price down further, and also it just sounds fun! hahaha. I've got very good help too. It will happen.

One thing I hope to do is take advantage of the surplus IGBT market once a process comes together, so people can make their own very cheaply. I would like to see the parts cost be under $500 for an inverter that will get a car on the freeway. Also it will have regen.

Also, the parts count isn't THAT much higher. There are no free-wheel diodes like in a series wound DC controller, but you need a 3 phase bridge, which is 6 IGBTs (or 6 banks of mosfets or whatever).

I'll first do a small one, that can drive a 1/2 HP 3 phase AC motor rated for maybe 220v/440v. Then I'll scale it up. I will probably do a more expensive scaled up version, then try to make it cheaper. My electronics background is not good, so I have to keep it simple.

Here's what I need:
Most of it is from Digikey/Mouser I think.

1) PICKIT 2
2) IRAM136-1060B-ND
3) dsPIC30F2010 microcontroller
4) U.S. Digital encoder, model E3-500-500-IHT. I don't know where to get this. Maybe I'll get a different one.

I should come up with a parts list of what I need to get moving! If anyone wants to donate to get those parts, I won't stop them. As usual, I get payed on the 10th, and am broke on the 11th. hahaha.

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Last edited by MPaulHolmes; 11-03-2009 at 11:19 AM..
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