Twin Impulse 9 motors

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Sparky Brother
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Post by Sparky Brother »

Hi all

While I just bought the car I believe fulfills my notions I started "hallucinating" on what would I do and what I would not.

Eventually it is a Daihatsu Feroza 4WD which for now I intend to re-register as a rear wheel drive getting rid of as much weight as I can. I also plan to make it as direct drive and here is where my wacky ideas come in place.

Due to the limits of the budget I set to my self I will be opting for an Impulse9 Motor with ZEVA (if everything goes right and Ian manage to release them on time) controller. Now realising that the GVM of the car will most likely end up to around 1600kg. I am wandering what if I hook up a second in-line Impulse9 pre-set to engage when rapid acceleration is needed at say three speed ranges 0-40, 40-60 and 60-80km. This will be governed by a separate PLS and relevant contactors capable of handling the current.

I admit I am not a specialist but I`m keen to learn and experiment. I`ll be probably shot down in flames by the experts in the forum. Nevertheless I can handle it as long as I lern something usefull.smileys/smiley18.gif

Bottom line everyone invited to the party!


Last edited by Sparky Brother on Tue, 09 Sep 2008, 18:03, edited 1 time in total.

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Post by zeva »

Dual motors work great (I hope to do such a thing with my next conversion), but there really is nothing to be gained by only using the second one sometimes - you might as well drive both at all times, as the efficiency will be better (with each motor seeing a lower load).

That said, parallel-series switching (electrically) is one of the biggest advantages to dual motors so you should definitely consider implementing this. It sort of gives you two "gears", where in series you'll get twice the torque but in parallel you get twice the top end speed.
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Post by Sparky Brother »

Hi Ian I am glad to have you answering the thread first as I was about to contact you for at least one Impulse9. I certainly see the advantages of using dual motors. However I plan to go for one direct to drive shaft one installed where the gear box currently is living adequate space for the second one in front of the first one than if the performance of one motor only in such a conversion is too sluggish (which I pretty much anticipate) than I will surely be going for that second one.

Just two questions though;
Do you think your Controller will be able of handling those two motors. And most important one which probably most of the other AEVA entousiasts are waiting the answer for -WHEN approximately I will be able to get one of them? Having in mind your reputation I volunteer to test one on my conversion

Cheers!

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Post by zeva »

Firstly, direct drive is very hard on motors so to avoid overworking them, I usually recommend total motor(s) weight being about 8-10% of the total vehicle weight. (For series DC motors, anyway. Other motor flavours have different power densities.) So one ImPulse 9 would not be happy trying to drive a 1.6 tonne vehicle, but two should be fine, especially if you take off with them electrically in series.

Any good controller should be able to drive dual motors, though I usually recommend 1000A+ controllers such as the CafeElectric Zillas for any direct drive application - otherwise the controller will quickly hit its current limit and stay there under acceleration, which is hard work for them. (As you may have heard, I recently blew up a Curtis 1231C in my MX5 because it couldn't handle the DD setup!)
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Post by Lowndsy »

out of interest Ian, what made you choose the single 11" over twin 9s or even 8s?

it interests me as white zombie improved itsd ET swapping from an 11 to twin 8s, admittedly the 11 was an old industrial russian unit.

I have pondered a similar conversion to this and was wondering whether twin impulses or a single 11 like your mx5 would be a better option.

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Post by zeva »

For the MX5, choosing the single 11" was mostly due to space restrictions. Two 8-9" motors takes up quite a lot more space (length particularly), and there's not much room to start with in an MX5.

In future I'd probably rather go with dual 9s, but would have to do it with a more spacious donor vehicle..
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Post by Richo »

Here's a car with two motors!
http://www.evalbum.com/152
So the short answer is NO but the long answer is YES.
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Post by EV2Go »

Just playing with some numbers... As some of you may be aware I am getting closer and closer to jumping both feet first into building a mini.

I want insane performance (well at least what I would call acceptable) this thread got me to thinking...

I have so far been thinking that a single Warp 11 or TransWarp 11 is the only way I could get sufficient jollies.

Several times I have come across threads outlining the benefits of running two motors, but figured two Warp 9’s might be a little over the top (only just).

But if I used something like the TransWarp 7 and an inpulse 8 and joined them together like this http://www.evalbum.com/152 I could get better torque, higher revs, and higher efficiency with comparable weight. Also using two motors the weight could be kept even lower and spread out.

Cost wouldn’t be hugely different going off the NetGain pricelist.

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Post by Richo »

If it fits great, if it doesn't bend something 'til it does. Image

Would you be using one controller or two?
Don't forget that there is extra cost involved joining them together.
So the short answer is NO but the long answer is YES.
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Post by EV2Go »

Dollars are a secondary concern once a project starts Image

Good to know what it will roughly cost... but I never expect it to come in under budget.

The whole project hinges on me being able to get my hands on either a 1k or 2k Zilla.

I know they are currently out of production but without the right control I may as well pick up my bat and ball and go home.

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Post by fuzzy-hair-man »

EV2Go wrote: Several times I have come across threads outlining the benefits of running two motors, but figured two Warp 9’s might be a little over the top (only just).

But if I used something like the TransWarp 7 and an inpulse 8 and joined them together like this http://www.evalbum.com/152 I could get better torque, higher revs, and higher efficiency with comparable weight. Also using two motors the weight could be kept even lower and spread out.
I wonder if it would easily be possible to do like the Dual motor but have drive come off from a point in between the two motors so you could have the rear diff centred and the motors laying down almost inside the rectangle that is the rear mini subframe, once space is used up for the diff it might also mean you chew up less of the space in the back of the mini...

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Post by EV2Go »

Hmmm you could be onto something there FHM... I was thinking last night maybe put them end to end with a sprocket in the middle driving down to a bigger sprocket (diff gearing) but couldn’t work out how to get some form of planetary system for corners.

But I could put an IRS diff in its normal RWD location with small Warp or Impulse motors side by side direct above the diff, bolt a cog on diff output flange, and just do a big triangle with a chain... Hmmm worth giving further thought for refinement.

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Post by Johny »

Have you seen the drive arrangement in the Tango?
I think that's the one. It uses 2 motors east-west but one behind the other.
How about that setup. Run 2 chains - one to each wheel. Yours might fit side by side but still east-west. Readjust the brush timing on the one that runs backwards. You can still series them for low speed, high torque - no diff.

Edit: One day I'll post something without tiipose Image
Last edited by Johny on Thu, 19 Feb 2009, 11:46, edited 1 time in total.

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Post by fuzzy-hair-man »

Hey that's even better than the image I had in my mind, cool!!

How do the Warps etc deal with sideways loads on the bearings? Do I remember something about it not being great for them? Or does the plate you use to mount them together along with some big bearings deal with that issue?

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Post by Johny »

Add some reasonably primitive voltage comparison monitoring across each motor and wind back throttle voltage when a preset difference is exceeded - traction control. Doesn't work when the motors gets paralleled but that would be at higher speeds so not a big deal.

Yes I believe you would need a bearing setup to take the sideways thrust. If the shafts holding the gears was long enough and the gears mounted as far from the motor bearing as possible) close to the 'other' bearing) then it might be OK. If using Warps then I seem to remember that they can be ordered with higher load bearings.

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Post by EV2Go »

The TransWarp have beefier bearing but probably not necessary...

Motor end bearing – cog – bearing set in alloy plate (provides motor end bearing support, chain guard, chassis structure support). Since the cog would be supported with a bearing either side over the space of a couple of inches it would take big side load.

Not sure I trust running two motors that are not connected. One drops voltage and you spear off left or right... not nice Image
Last edited by EV2Go on Thu, 19 Feb 2009, 13:00, edited 1 time in total.

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Post by fuzzy-hair-man »

EV2Go wrote:But I could put an IRS diff in its normal RWD location with small Warp or Impulse motors side by side direct above the diff, bolt a cog on diff output flange, and just do a big triangle with a chain... Hmmm worth giving further thought for refinement.


I was thinking about this again and I figure you might be able to do something like this:

Image

Red circles being the motors, blue being the pulleys (middle pulley goes to the diff) and black being the belt. It hopefully will allow you to put the motors low in the subframe and give you some space on top for controllers chargers etc.

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Post by Johny »

I don't believe a motor/control failure would result in massive out-of-control. It would be fairly easy to monitor that instance and back off power if it happened. Avoiding the shaft-joined assembly like Jim Husted put together for White Zombie and Kilocycle is preferable - it's expensive to do and doesn't save the diff.
Image

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Post by fuzzy-hair-man »

I was then thinking a bit that there's no reason the pulleys have to go directly to the diff and as the mini is kind of small space was going to be at a premium especially in the front to back (from memory there's probably a bit of width to spare) if you wanted to get away without chopping up the rear seat.

What if you mounted the motors something like this:

Image

Does joining the motors like that reduce their ability to get rid of heat? (reduced air flow into the joined ends) I know these were for drag cars/bikes so they don't have much time to build up heat but for a road car...Image

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Post by woody »

fuzzy-hair-man wrote: Image

Red circles being the motors, blue being the pulleys (middle pulley goes to the diff) and black being the belt. It hopefully will allow you to put the motors low in the subframe and give you some space on top for controllers chargers etc.
Or join each motor independantly to its own pulley for redundancy.

Chain drive gives you good control over the final drive ratio too.

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Post by fuzzy-hair-man »

woody wrote: Or join each motor independantly to its own pulley for redundancy.

Chain drive gives you good control over the final drive ratio too.
Of course! that's simpler and it would give you more freedom on where you wanted to put the diff and it's pulley. Snap a belt/chain and you can still get home Image

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Post by EV2Go »

or maybe even...(cheated reused yours Image)

Image

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Post by zeva »

How about:

Image

More engineering work but would avoid differential losses and allow for better traction control.
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Post by EV2Go »

Thought about that but what if one motor fails it would spear you off in one direction extremely quickly. Even if it was designed to shut down that fraction of a sec would be the difference between safe and a wall somewhere.

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Post by Electrocycle »

the likelihood of a motor failing is probably similar to a diff or axle failing.
Also, loss of traction on one wheel (pretty common) would have a similar effect.
Usually loss of drive to one wheel will start the other one spinning rather than spearing the car off the road. If you have intelligent traction control it would be monitoring the motors anyway and could detect fail conditions.

If I was going to use twin motors there's no way I'd be using a diff.
With series wound motors you could even just wire them in series / parallel and you'll get enough diff effect.
Twin controllers give you the traction control capabilities though.
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