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

[MPaulHolmes]

Ya, done got me a brand spanking new 3 phase AC induction motor on Ebay for $20. hehe.
Yahoo!!!

I'm also going to order a few digikey parts pretty quick too. Then I need to learn to program the stupid pic, and then I'm going to do a V/f = constant approach to control the motor. Then we'll take the rather large leap to space vector control! ya!

OK, I just ordered the stuff from digikey too. That was really financially unwise. hahahaha.

[NiHaoMike]

That motor looks a little big for running a power steering pump, but hey, it's only $20...

Maybe it can be used with an open drive HVAC compressor if you can find one. (For the most part, HVAC went direct drive a long time ago.) Small 3 phase HVAC compressors are very hard to find.

[MPaulHolmes]

I would just like to say that 3 phase AC induction motors are friggen cheap on Ebay! I saw some that would probably be really really good for an EV. I don't know about mounting though. Most seem to not be designed to be face mounted, like they are supposed to use belts. Oh well. hehe.

[MPaulHolmes]

I didn't actually get it for any reason other than for practicing controlling it with the software. I hadn't thought of the load I would hook up to it. hmm.... Maybe .... no, I've got nothin. haha.

I ordered the digikey stuff just before shipping! And it's now shipped! hahahaha perfect timing.

[NiHaoMike]

Maybe the motor can be modified to attach to a reduction gearbox? Some disassembly pictures of a large industrial motor can help determine where to drill and tap holes for bolts.

Also note that the HP rating of an industrial motor is a continuous rating with a very large margin. Which means that the HP rating only needs to meet or exceed the cruising HP usage. It will be overloaded during acceleration, but it should not be a problem for a short time. Temperature sensors can be installed if you're worried about overheating from heavy acceleration. Increasing the frequency (and voltage) beyond its design frequency will also increase the speed and effective HP, but I'm not sure how much higher than design it is possible to go. Industrial motors are definitely overbuilt for the HP rating.

[Janis]

To Paul, what parts did you order, I would like also to go on with research.

About motors, Australians have very good discussions on their site:
The Australian Electric Vehicle Asn: Electric motors and controllers

Preferable would be resolver instead of encoder, because resolver is more robust designed, there is just three windings, which is equvalent to encoder 1024 pulses per rev.

[Janis]

Look what russians have done to their army jeep, Hybrid drive:
?????????? ?? ???? ??? 3153 ? ????????? ??????? ??????????

There are also some usefull links, only they have built their system on freescale chip.
I have the same car and that is what I am going to do.

[Daox]

I just got a PM back from Bennelson. He says the link to donate to Paul is still up to date and can be used. I'd highly encourage anyone with an interest in seeing this project go forward just toss Paul a few bucks. You get a bunch of people to donate even a little bit and it adds up quick!

Click the link and then click the donate button in the upper right.

Donate to the open source AC controller project!

Amazing stuff Paul, thanks for the hard work!

[MPaulHolmes]

Hi Janis! Here's what I ordered so far:

IRAM136-1060B-ND

dsPIC30F2010

7815 voltage regulator (to power the igbt module)

1uF, 0.1uF, (and possibly others, I forgot) MLCC capacitors.

1/3 HP 3 phase AC induction motor. 3450 RPM, 208v/440v.

two 270uF 400v caps for making the DC supply from the house outlet.


Sawickm got me this bugger: PICKIT3. ya!

Here's what I still need:
120v to 120v AC-AC isolation transformer (for testing, so I don't need a bunch of optocouplers)

full bridge rectifier (Ebay has a nice cheap 30amp full bridge rectifier for like $2.50 I think. I'll order that soon)

Encoder ($85... ouch. That's why I want to get the sensorless version to work in the long run). Janis, you are absolutely correct. It would be better to get a resolver for real world driving, but this is just a small test circuit, and the encoder will keep the electronics to a minimum when I'm just trying to get it to work.

2 current sensors. I already have 1 LEM Hass 50-s, but I need one more. That will be another $26. Yuck... The nice thing is, these will be the same current sensors (with a higher amp rating though) for the full sized car version.

I'll add more later if I think of anything.

[Weisheimer]

Paul,

etischer's AC controller MOD thread on DIYElectriCar is a great read
though he has taken an existing VFD and modified it. He covers a lot
of important issues and you will find it interesting.

I have a DC servo driver that might help with your experimenting
that I can send to you. PM your address and I'll send you
a device that includes a Eupec 50a 1200v IGBT module
and some other parts.

IGBT's are good if you are going to run high voltage
but you will want to be sure to saturate the gate
when you drive it, and be sure it is shut off (negative voltage is best)
when the drive pulse is done. They are power monsters
when saturated but they are quite weak in the linear region.
For example, this device will easily handle 25amps
when fully driven into saturation, but will not handle
.5 amp if it is in the half on-half off linear region for very long,
and we're talking ms here.

here is a link to the device and there is a datasheet at this site too.

BSM50GD120DN2-E3226 Eupec/Infineon IGBT Modules

If this link doesn't work, look at Mouser.com and search for

BSM50GD120DN2-E3226

There is a current sensor in it and a pair of current transformers
if you ever want measure the current in a switched section.

Good Luck with your new controller!

Mark