Twin Motor 2-Speed Drive

[mainsource]

Has it been done here or elsewhere? Each motor is set up to drive through different gearing arrangements, and is automatically or manually switched into or out of service. Would be clutching arrangements be the biggest hurdle? I guess direct drive for each system would be a no no cuz 1 motor would try to overrun the other? What if only the final drive was coupled directly and kept powered in both high and low gear situations? Just thinking about stuff... or perhaps still groggy from sleep deprivation :?

Keith.

 

[E-racer]

If you have the power of two motors I would want the power of both of them through both gears.

 

[amberwolf]

It's kind of a waste to carry a motor around only to use with one speed/gearing, while carrying a second that's also only used for a different speed/gearing. You have the weight and cost and complexity of two motors and two controllers, as well as their mountings and whatnot.

Why not just use one motor with a selectable gear ratio, like Thud's two-speed dog-clutch shifter or similar if you need high power, or a simple bike gearshifter/derailer if you only use lower power?


If you are wanting two motors so that you have a backup system in case of one failure, like I want on my trike if I ever get it done, that's different.

 

[mainsource]

I find RC motors light-weight enough so as not to introduce a huge weight penalty. Also I was thinking about one controller with some kind of electrical/ electronic switching arrangement. I would go for the 2-speed gearbox as a first option but Thuds, nor anyone else's seems to be readily available. Regarding power, I was thinking about the Turnigy 80/ 100s.

Thanks.

 

[Kin]

It's not just about the weight...You'd have to have a freewheeling system with proper gearing ratio, an entirely new controller+input caps and a system for mounting all of that the bike....It's substantially more than just the 80-100 weight.

What use are you considering? I can think of few situations that an 80-100 wouldn't be enough, and in those, you may as well go with 2 80-100s both contributing always rather than just part time.

 

[sn0wchyld]

how about wantting something for both trail riding at <30km/h and something for higher speeds, say, 60+. wouldnt even a double 80100 bog down/not run happily on trails/up 20% grades if geared for like 75km/h? I know it'd have the power to go up those hills... im more thinking having something that'll go up a 20% grade at 20km'h, stop/start, etc etc.

and I think he's talking about switching the phase wires between the motors... not having 2 controllers. though that'd require some seriosly large relays or something similar to handle the amps.

 

[flathill]

The only way two motors makes sense if you do like the gm/BMW dual mode

One high speed wind motor and one low speed wind motor
Brain that controls two controllers and transitions depending on load for max efficiency

Both can be full on for max thrust

Still though usually you be better off in most situations with one big motor due to end turn losses...or two stators in one motor

 

[E-racer]

If you are considering using w/e insanely beefy relays or w/e just make a delta wye switch for one motor... Or wind the motor with two sets of winding per tooth and you can parallel or series them. Hell do both and have an electric 4 speed... There would be delta and wye on the leads in series and then delta and wye one the leads in parallel. Regardless, having two motors and only using one is just wasting the potential of having twice as much power.

 

[Kin]

The winding idea seems kinda bad- you'd have half the copper fill. Neat if someone did that for kicks, though.

However, the delta-wye switch option is pretty cool. You can basically have option 1 geared to, say, 50mph, and option two, geared to about 29mpg. That's not bad.

 

[E-racer]

The winding idea seems kinda bad- you'd have half the copper fill. Neat if someone did that for kicks, though.

It was a half baked idea. Seems to me the copper fill would be the same though. Say you wound two sets of 6 turn per tooth. In parallel you would have both sets of wires to make 6 turn. Then in series you would have both sets of wires to make 12 turn. The copper fill would be the same.

 

[Kin]

. hey now. Maybe I didn't think that full thoroughly. I'm still suspicious, but it's a shame I was a naysayer.

Ok, so one trick is that ...actually, that thought is not a problem.

Hey, maybe there's something to this idea. I'm surprised no one has trick it before.


Well, ok, one big problem- how are you going to switch from paralleled windings to series? These are high amp lines; a switch won't fit on the stator. The problem isn't on the parralel connection, but on the series connection with extra windings, part of those windings will involve traveling up the phase wire (until the switch) and then back into the motor. I don't know how much of a problem that would be.

 

[E-racer]

I'm just speaking theoretical. I wouldn't do any of it. I would run 1 80-100 through a NuVinci. Or I would run 2 80-100 motors through a pit bike transmission.

 

[flathill]

The winding idea seems kinda bad- you'd have half the copper fill. Neat if someone did that for kicks, though.

It was a half baked idea. Seems to me the copper fill would be the same though. Say you wound two sets of 6 turn per tooth. In parallel you would have both sets of wires to make 6 turn. Then in series you would have both sets of wires to make 12 turn. The copper fill would be the same.

Not half baked at all. Industrial drives use one method or the other but no reason you cant use both except cost/weight

4 speed ratios

1:1
1:sqrt(3)
1:2
1:2*sqrt(3)

 

[Kin]

I agree my initial judgement was off, but my second thought was trying to figure out how to make the series to paralleled switch. You'd have the very high amp relay (has to deal with the phase current) right at the point the phase wires enter the can, since the switch can't fit inside the can. Now, will having all the current enter the can, go through the first half of the series connection, exit the can a little, go through the switch, go back into the can, then exit again- will that be a problem with how the motor works?

Also, how will the controller react if you suddenly switch to the series connection or vice versa?


This is a pretty cool question, is it too much off topic to this thread, or does anyone know where this conversation has happened before on ES (as half of all conversations have).

 

[Miles]

This is a pretty cool question, is it too much off topic to this thread, or does anyone know where this conversation has happened before on ES (as half of all conversations have).

http://www.endless-sphere.com/forums/viewtopic.php?f=2&t=9215

 

[E-racer]

This is a pretty cool question, is it too much off topic to this thread, or does anyone know where this conversation has happened before on ES (as half of all conversations have).

http://www.endless-sphere.com/forums/viewtopic.php?f=2&t=9215

I am telling you this forum is full of gold... truley an amazing thing.

 

[wingtip]

This company has developed a 2 speed/2 motor system for a trike.

http://www.santamonicaev.com/page2/page2.html