Comparing motors

[DaveAK]

I got such a good deal on them though, and the controllers too. They might not be the absolute best for my application, but the price is hard to beat. Plus I know the Sevcon controllers reasonably well and I can use some of my (as yet undeveloped) bike tech on them. The nature of this project is very much experimental, and if I decide I need a better drive system I'll be able to make a much more informed decision. If I do switch them out I'll probably be abloe to recover most of the money I'll have invested.

And I hate cancelling orders or sending things back, especially in this economy.

So, are series wound motors that much better for torque than shunt wound?

[larryrose11]

Series vs shunt? All depends on speed. With series wound, it will generate monster tq, but it falls off pretty quick with speed. If you keep the armature current a constant, and decrease the field current, the motor has less torque, butr will also generate less back EMF, allowing it to spin faster. The idea setup is to have the field current some multiple between 0-1 of the armature current. This 0-1 multiplier needs only to be a function of speed. The details of this function depend on the motor.
As an example, I worked it out for something like the ADC9 a bit back. The ratio should be 1 (armature and field are the same) up to about 900RPM, then decreasing to about 10% by 5000 RPM. I programmed it all a bit back into Simulink as part of grad school. I can make it available to anyone who is comfortable in the Matlab / Simulink environment.

[Remotecontact]

Thanks for the link Larry, I'll check it out. I'm not a very patient man though, so yes I have already pulled the trigger on the motors. I should have thought of you crazy battle-bot guys!

Now that you mention it. Battlebots Pro 2011 competition is in Miami this year and I'm entering with my robot Witch Doctor. Here's a fight from last year and a video of this year's testing, launching a 45lb aluminum frame into the air.

http://www.youtube.com/watch?v=8XElkUqzMz4

http://www.youtube.com/watch?v=QxVz3EryThc


I'm going to try to have some live streaming video of the event incase anybody is curious about how a battlebots event rolls.

/end shameless rant on my robot

[DaveAK]

Yeah, like I said, crazy!