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acmotor
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Post by acmotor »

Johny wrote: Bottom one is Star/delta switching at 36 km/hr

Speed     10    20    30    40    50    60    70    80     90    100
415V       0.9   1.9   2.8   4.5   7.4   12.7 24    630     -    -
200V       1.3   2.6   3.9   5.3   6.6   8     9.7   11.7   14.5   19
346/200   0.9   1.8   2.8   3.9   5.3   6.7   8.3   10.3   13.1   17.6


Ok starting with some data....
346V star part...

Image

This was to ~42kmph then back off with brakes (well there was a corner you see).
Torque drops off after this speed anyway.

and...

Image

Torque remains much the same to ~70kmph. I'll get some more data.
Motor current sits flat at 97.xx Amps after ~10kmph.
I guess that is what we wanted to see ! Image
40% regen is on for both runs.

How are we looking on the predictions ?

Now I need to stitch the two together with star delta switching.
Not that I think I can win back the <1.5 seconds, just that star takeoff on some hills would be useful.    Image
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Post by Johny »

Pretty exciting. Did you see it woody - did ya?

acmotor, it looks like you are doing about 5-10% better than predictions which is GREAT! Spreadsheet doesn't take vector or torque boost into account so it's on the money as far as I am concerned.

Thanks a LOT for getting us some data acmotor. I feel inspired.

Congratulations woody - spreadsheet is a giant success.
This also means we can model vehicle behaviour with lighter batteries etc.
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Post by acmotor »

Image You mean I've spent years building this EV and you guys did it all on a spreadsheet and got the same numbers ? Man I'm going back to the BMS pcbs for the Rodeo ! Image

Seriously... well done. You must have a good handle on the numbers.

BTW, the emotor runs <20°C above ambient with just the computer fans after 10km of on/off driving. Even cooler than before. It probably prefers the v/f keeping up with the revs !
Image
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Post by acmotor »



This may be easier to visualise...
Image

Oh, and I checked, the start torque boost was on thus the 0.5 second launch at the start.
Last edited by acmotor on Tue, 01 Sep 2009, 20:54, edited 1 time in total.
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Post by vince »

Tuarn;How has the speed/range changed since the rewind?Maybe you haven't had a chance to check yet?
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Post by Richo »

How does that graph compare with the origianl base line of 400V Delta?
So the short answer is NO but the long answer is YES.
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Post by acmotor »

Vince, given the motor running cooler (probably due to the maintained v/f ?) I could only think positively about range. Speed ? I don't intend higher top speed, just getting there faster. Image


Just looking at the graphs again, it is worth remembering that the star delta difference only exists because of limited controller current capability. i.e. motor just does what it can with what is available from the controller and with a larger controller, the torque can be more like the boost section of the star mode all the way up to whatever RPM (6000 if you had the controller and battery).

Note the start torque boost is available in star but basically none in delta (controller already at current limit). Available start boost is a controller limit (although it may be entering saturation in the emotor)

Oh BTW, torque limit was set at 300% in star (367% available but can cause pullout as the revs climb) So this test was mildly conservative, but there is not much more.
In 200V delta the torque limit was set at the drive max of 232%(thereabouts) for the configuration so VFD was giving all ! (as the 97A showed in motor current) This could have been set to the same 300% as in star if the VFD was bigger !

So Richo, this probably answers your question ?
With the emotor configured for any higher voltage e.g. original 415V before rewind, there would be no more torque as the system would be emotor Tmax limited not controller limited.
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Post by vince »

Tuarn; it sounds like once a pleasing donor has been chosen the next purchase should be a controller with a large enough capacity to handle whatever you throw at it within reason (family/highway car)?
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Post by vince »

Is there a stock motor that would compare to your rewound motor or is it now considered unique?
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Post by acmotor »

Vince,

In ABB at least, 220V delta and 380V star seems to be the lowest off the shelf voltage rating for 3 phase motors on the world market (but not available in Oz over 3kW).
In reality, this would give similar performance to the 11kW I have had re-wound at the 200/346V configuration so nothing special there.

I would have bought a lower voltage motor if it was available (at less cost than a re-wind !)

It is only the 100/173V option that is perhaps more special in the industrial motor area at least. It will by no means be the first. People have rewound motors to lower voltages in the 1970s for EVs. Unfortunately they didn't have the IGBT VFDs to run them off back then.

I think also that some of these early re-winds were just to obtain lower operating voltages and not to run the motor at higher frequency while maintaining v/f ratio.

As I have noted before, solectra, siemens, ACpropulsions etc. have been into lower (nominal) voltage higher frequency motors for EVs for many years. I'm just playing around and finding that it doesn't have to be megga $ (although prices are getting better).

That's an overview and by no means covers all points !
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Post by vince »

Tuarn,
Oz gets the shaft in a lot of ways!!
Moving on.You have the brains there and i've got the glut here in Canada.My contact here,who has been rewinding motors for over 50 yrs is supposed to meet with me and show me his personal stock of motors that he has stored for e few years since he folded his business.I don't know what to tell him i'm looking for or what he has.Assuming I were to have a similar donor as yours what shold i shoot for?Appreciate any help you can offer,Thanks,vince
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Post by Richo »

I started a new thread for you HERE to work out what to look out for.

So the short answer is NO but the long answer is YES.
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Post by Johny »

You can tell when my mind is not on my work.
This won't be totally accurate but should help to see what to expect.
All with 97.6 Amp Danfoss except the last one when I give you a 180 Amp controller. The Star/Delta is 346/200 Volts.
Image

Edit: There is something a bit pessimistic going on that shows the 415V winding really taking a huge time to get to 80km/hr.
Last edited by Johny on Thu, 03 Sep 2009, 08:40, edited 1 time in total.
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Post by acmotor »

Given that the original ICE was 34kW 72Nm and gave a terminal speed of 104kmph in data sheets (BTW, far too fast in a 1982 sierra !) I am not targetting anything over 80kmph !

Yes, the star 346/delta 415 seem to fall short of actual performance. Maybe the higher voltage ~420VAC and the squaring up of the sine wave that the VFD does to get extra torque when voltage is limited, have more afffect ?

I'm going to the letter box right now. When does that 180A arrive ??? Image

Star/Delta seems a good compromise for now.

Looks like I need to run some tests to higher speeds.

Image
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Post by Johny »

acmotor wrote:I'm going to the letter box right now. When does that 180A arrive ??? Image
It should be there tomorrow - I managed to get the postage down to $1.10 by sending it as a letter. Image
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Post by acmotor »

Oh great !!! a hard copy ! Image

Hey Johny, make me smile, put a 100V delta enough amps controller for Tmax line on that graph ! Image
Have to show it to TJ !
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Post by Johny »

I didn't want to redo the graph so I dropped the 415V and included 100V 350Amps with 6.5:1 diff and replaced the 415 with 100V 350A 10.5:1 ratio.
8000 RPM at 100km/hr.
A 350 Amp controller gives it everything - more amps have no effect.
Image
Data (columns are speed, rows are seconds)
I didn't bother going over 110 km/hr but the 100V 6.5:1 diff was still going fairly strong at 140km/hr.
The 10.5 ratio hit 100km/hr in 6.545 seconds. (Graph data is rounded)
Image
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Post by acmotor »


Putting that data on one graph....

Image

The last two on the legend being the live data.

Nearly ready to test star delta. Make sure you've saved and have a torch ready ! Image
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Post by woody »

Yep, good idea to test it before the end of the Danfoss 5042 ebay listing...
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Post by Johny »

I have my thumbs crossed.
Edit: and my toes
Last edited by Johny on Mon, 07 Sep 2009, 11:18, edited 1 time in total.
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Post by Hemonster »

Excellent work ACMotor, an inspiration to all of us. How much was the rewind mind you? and can a rewind be done in the same way for a 2 pole original motor as for a 4 pole?
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Post by acmotor »

Rewind started off at $700, but climbed to $900 with the two sets of thermistors (130/150 deg) and the k-type thermocouple and 12 wire connection. This was all in the name of research and proof of pudding to the naysayers !

The motor should be wound ex factory for the desired voltage IMHO as some EVers are having done.

Why do a 2 pole ? the rev range will not suit direct drive and if you go to 1/4V then the 12,000RPM alone will be a challenge !
But yes, 2 pole can be done the same I'd guess.
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Post by Hemonster »

Why do a 2 pole ? the rev range will not suit direct drive and if you go to 1/4V then the 12,000RPM alone will be a challenge !
But yes, 2 pole can be done the same I'd guess.
Only because I've got one Image

I meant really was it possible to change a 2 pole into the same motor as you have done by just changing the windings? or is there more to it than that?
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Post by woody »

It may be possible to change a 2 pole into a "consequent pole" 4 pole depending on the winding pitch. This may put your efficiency in the toilet and/or it may be impossible is the connections are buried, or there may be something essential in the stator that a 4 pole has and a 2 pole doesn't. If you ask a few rewinders if it's possible, they may have a "you can't because of X, Y & Z" answer, or a "it depends" or a "Sure, any 2 pole".
From memory your motor was quite heavy - a second hand 100kg Aluminium 4 pole 160 frame 15kW may be < $500 from an industrial 2nd hand store.
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Post by Hemonster »

Quite right, I do need a lighter motor anyway. Sounds like it might not be that easy - ie. the flux path may be different??

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