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

[thingstodo]

Originally Posted by freebeard

Can you describe how CANbus deals with collisions by making messages dominant and recessive? I know EVTV did.

My info on CANbus came in large part from EVTV. If you want more details, it would make sense to go there directly. Wikipedia is good as well, but they get fairly technical early in the description. Here is a summary:

The CANbus message arbitration is handled in hardware, based on the address of the device. Lower is more important. The device transmitting monitors the bus and verifies that what they 'sent' is what is on the bus. Since the address is first, and active low is 0, 0 trumps 1. So the lowest address wins - ie 000 0000 0001, or decimal 1 as 11 bits of binary. If a device sends a 1 and reads back a 0, it stops sending and waits for the message to end before retrying.

Any device can transmit 'whenever it wants' if the bus is not busy. 'Not busy' is defined as no active bits (low or 0), plus wait until the end of a message in progress - End of Frame (7 high bits) followed by 3 more high bits (recessive). After that you can try to transmit as long as you monitor the bus and make sure someone with a lower address is not transmitting at the same time.

There are only 8 bytes of payload or data in CANbus, the simple version. So any one device does not have to wait for long to transmit.

This collision stuff is .. handled in hardware .. and as long as you are not looking at the data with a data scope ... it doesn't really affect your programming at all. The physical layer takes care of it.

[freebeard]

I know it's in there, I just despair at finding it.

I see MPaulHolmes appreciated it.

The physical layer takes care of it.

This is the point I though should be brought out. I think the way it's done is slick. It's also an example of why I think having the information tailored to export into the wiki, for future reference, would be good.

I was at the Toyota dealer talking about the rear axle in the current Highlander/RAV4. I think I'll stop by the Buick dealer and see if they can tell me the dimensions of the eAssist unit.

[thingstodo]

Originally Posted by MPaulHolmes

thingstodo, I never posted anything much about the BMS. A microcontroller powered by the 12v system supply monitoring 'n' battery voltages. It monitors the 'n' batteries by receiving the voltages from little attiny25 microcontrollers that are powered by each cell. They send the voltage by a sort of morse code across optocouplers. The attinys are only powered when their cell circuit is enabled, so if the 12v power is off, there's zero draw from the cells. One neat trick was, for each attiny25 to measure its cell's voltage, it would just measure a 1.25v reference on the A/D channel. Then, from that you can infer the cell's voltage. For example, if you read 1023, that would mean the cell's voltage was 1.25v. But if you read 512, that would mean the cell's voltage was 2.5v, etc...

Too bad you didn't post earlier on the BMS. I need something simple, no balancing ..

.. I like no power used when not enabled .. I like opto's so the differential voltage is not a big deal ... the cell voltage measurement sounds interesting. It would be interesting to see if the resolution could be boosted in the 2.75 - 3.00 V area without messing up any of your other advantages. mV resolution on the low end would help when I am bottom balancing batteries

.. having the 12V power the ATtiny's sounds like a hundreds of volts isolation isolated supply with a small current output ... another of your magic circuits?

An ATTiny that I can epoxy to the plastic case of .. whatever I use - NiCd, NiMH, LiPolymer. Flexibility, tied to a product that is easy to source. Not the latest battery management IC that is sampling .. sometime ... and I won't get unless I buy 1000's. Running code I just *MAY* understand. That's what Open Source is about!

Sorry about that .. sometimes I get carried away

[thingstodo]

Originally Posted by HaroldinCR

These have an encoder or resolver with 10 poles. The stator is 72 poles and the rotor is 56 poles.

I heard that in the video too. It confuses me a bit

The encoder should have at least 10 pulses per revolution. But the lobes on the shaft don't look like they are driving discrete signals. Maybe I need my eyes checked? It kinda looks more like lobes on a resolver?

freebeard, RPM's of the altermotor get to 30,000 when driven by the stinko engine. Altermotor has a 175A fuse and uses a 115V battery. Possibly 60 HP ??

I'm going to talk this through .. or maybe type this through?

3600 / (2 * poles) = rpm. 72 poles is kinda high. Like 25 rpm at 60 Hz.

Maybe 72 slots in the stator? That would make more sense.

The slots are overlapped, so the same slot seems to be used for 2 windings. They are stacked on top of each other.

The configuration is Y, so there is a center point that he shows at the back, and it looks to me like 3 pairs of windings are connected together to form the center point. But I don't see video of the other end, so there may be many coils in parallel for each phase or they could mostly be in series. It looks like the phase terminals have at least 2 coil connections on them.

I'm not a motor guy - I think the windings are put in series and parallel to balance out the phases for voltage and current. But we can't see the other side of the stator. 72 pairs of poles / 3 phases = 24 coils each. With no other information, and given the high rpm ... I'd say the coils are in series. 2 sets of coils each on the motor terminals means .. to me .. at least 2 coils per phase, meeting at the center point. So that would be 2 poles. But there could be hidden connections on the other end of the stator.

30,000 rpm is pretty high. If it's 2 pole, that generator would put out .. 500 Hz? With no slip? At 4 pole, the output would be 1000 Hz. 6 pole, 1500 Hz. That is quite high for a controller to put out. The carrier frequency is usually in the 4000 - 16000 Hz, 4 - 16 Khz range ... and it needs to make the pulses look like a sine wave to the motor. I must be missing something.

At 60 HP, 30,000 rpm gives not very much torque. 10 foot-lb or so.

So my guess would be a 2 pole generator, rated for 30K rpm, that will put out (or consume) 500 Hz at that speed, with about 10 foot-lb of torque. I know that the slots in the rotor are a factor in the output frequency, but I don't know how.

I'm sure that someone else will chime in!

[freebeard]

I looked at it the other way (I was going to let this go, but...)

A 30Krpm alternator on an engine good for maybe 6Krpm would be 5:1 ratio. If the alternator pulley were 3" the crank pulley would be 15". That's THIS BIG.

[HaroldinCR]

It's difficult to find technical info, at least for me. What info I posted so far comes from that video in this latest part of the thread, and, from another site online. I wondered about that RPM figure myself. Maybe I can find that article solely for a link here.

My contact in Spain has done tests with Curtis controllers. He feeds me info, and I try to help with what I find. I will ask him if I can put out the info online.

I shipped a Ford Cmax battery down here that has a controller/inverter in it, and, a Hyundai same deal. I will see if I can get them and open them up. My buddy has no use for them. Might be useful parts if nothing else.

[freebeard]

I wasn't too concerned about the RPMs, as that can be compensated with pulley sizes. And with ruggedized and cooled electrical circuits you can lug right down to 0rpm.

My intent is to visit the local Buick dealer. They won't know anything but maybe there will be an example on the lot.

[HaroldinCR]

I just found out that we have possibly 2 Ford C-max controllers that I thought had been discarded and was given the Hyundai controller my buddy has, besides the Honda controller I had recently bought.

Should have enough parts at least, to make 1 good controller, maybe more.

[freebeard]

Do you have an example of the motor/generator?

I just stopped by a Buick dealer and they let me look under the hood of a LaCrosse. The unit appears to be 8" in diameter and 8" overall. There was a lot of paraphernalia in the way, but it looks like the cooling and electrical connections are on the rear face; which means I couldn't just scab a stock VW cooling fan onto it.

[HaroldinCR]

freebeard
The encoder/resolver is on the back end of the altermotor. There is no room for a fan.

Rig up a belt drive fan off the front shaft/pulley. Might need a jackshaft to do it.

Oh. VW. Forgot how they work. Fan on generator. Let me check around how others do it.

edit--Ummm, why do you need air cooling if you change out the engine for an altermotor ?? Cabin heating, maybe ?