Multiple motor & controller approach?

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MalcolmB
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Postby MalcolmB » Sun Sep 07, 2008 1:23 pm

I just came across these the other day Jeremy. Not sure if they have what you want, but the prices look pretty good: http://www.bearingboys.co.uk/Transmissions-1001-c

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Jeremy
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Postby Jeremy » Sun Sep 07, 2008 2:21 pm

Thanks for that, Malcolm.

I'd looked at that site a day or two ago, but couldn't really confirm what the pulleys were. They purport to be 5M series, which implies that they are HTD section, but they don't look like HTD pulleys in the pictures, they look more like H section. This may be just because they use the same photo for each pulley though!

Ideally I want GT2/HTD section pulleys to be able to get them to handle the power and rpm that this little unit needs to work at. I'd also prefer alloy pulleys if at all possible, although if those cheap Bearing Boys ones are steel then I think I could live with it.

I may give them a call tomorrow to see if they can answer these questions.

I've revised the layout, increased the reduction ratio to 3.333:1 and managed to lose 20mm off the length. The module overall dimensions (excluding the output shaft) are now 103mm high, 112mm wide and 270mm long.

Here's a revised sketch:

Image

Regards,

Jeremy

Delinquent
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Postby Delinquent » Tue Sep 23, 2008 10:24 pm

Any update on this Jeremy?

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Jeremy
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Postby Jeremy » Wed Sep 24, 2008 8:02 pm

I'm in Poland at the moment, so no news, I'm afraid. I get back to the UK in a couple of days time and should have some news on progress in a week or two.

Jeremy

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Postby Delinquent » Fri Sep 26, 2008 12:45 pm

tsk, you can't go taking trips abroad at important times like this! :wink:

Look forward to hearing more soon.

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Jeremy
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Postby Jeremy » Fri Oct 24, 2008 7:50 pm

I'm back on this project now and have ordered some more parts. For the test rig I've opted to simplify things by fitting both motors on a common shaft. The shafts are just lengths of ground 8mm steel, with machined flats where grub screw fit. The rotors are identically aligned, as are the stators, so it looks as if it might be possible to run them on a single controller.

For the time being I'm going to use two controllers, so I've ordered some that are capable of handling 110A continuous at 28V. With two motors and two controllers this set up will give around 3.8kW (the motors are rated at 2.8kW each when run at 36V, but these cheap controllers won't take more than 28V) . I intend to mount the motors either side of a bit of alloy box section, with the drive pulley inside the box. The driven pulley will drive a 12mm output shaft.

The controller price was as reasonable as that for the motors, £31 each including delivery.

I've found a source for suitable alloy pulleys, belts etc and have purchased a couple of lengths of silver steel to make the new shafts. A quad motor set up, a little like the layout above, but with double motors on each end, looks feasible. This would give over 7.6kW for a total price (four motors, four controllers, hardware, pulleys etc) of about £300.

The pound/dollar exchange rate has pushed the price up a fair bit recently, but this still seems like reasonably cheap power.

I now need to go and find a couple of hefty batteries to power the test rig, as I need around 160A at 24V. It still seems a bit surreal to think of putting 80A through a motor that comfortably fits in the palm of your hand.

I'll let everyone know if any smoke escapes.........

Jeremy

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qdos
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Postby qdos » Fri Oct 24, 2008 9:20 pm

Good to hear you're back on it Was just thinking about this earlier. Must see if we can get together for a chat sometime

MalcolmB
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Postby MalcolmB » Tue Nov 04, 2008 9:25 am

Saw these and thought of you Jeremy:

http://www.youtube.com/watch?v=5cnNkPdMfZY
http://www.youtube.com/watch?v=2E32KLzAoDs
http://www.youtube.com/watch?v=vwODx028_Jw

Hard to believe the power these little RC brushless motors generate :D

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qdos
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Postby qdos » Tue Nov 04, 2008 12:26 pm

Definately looks like this sort of set up can work :D

I love the battery connection set up in the 3rd video :lol:

I'm doing some trikes I'd like to try this in, if you guys want to work on the motor set up. My aim is to get them to schools I've already got one school looking for 4 as projects. It would be great if we could put together some sort of inter school project perhaps with or along the lines of Greenpower

bobc
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Postby bobc » Tue Nov 04, 2008 1:30 pm

Problem with these things from a greenpower perspective is that they're too good; anything over 400W output will end up at lethal speeds with the little darlings in.....
Present greenpower motor is 240W but gets run up to twice that, & we hit max speed of 42mph at the final. You really don't want kids goin any faster than that. (note, winning car max speed was 34mph - it's an efficiency contest, not a speed contest!)


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