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-   -   Motors: Past and Future (http://www.chiefdelphi.com/forums/showthread.php?t=129835)

Richard Wallace 23-11-2014 21:36
Re: Motors: Past and Future
 
Quote:
Originally Posted by Ether (Post 1409708)
...
the RS-775-18 is designed to operate at 18 volts, and the speeds associated with that higher voltage.

can the same be said for the 12V FRC motors? who knows.
I don't.

But I strongly suspect that CIM motors, which are designed for 1000 hours mininum life when run at ~17% duty (3 minutes on CW 2 sec off 3 minutes on CCW 30 minutes off, repeating) with 64 oz-in load torque and 12V supply, would not survive that long if tested the same way at 18V supply. Maybe the reduced life would be sufficient for FRC application.

I wonder if CCL can be induced to provide life test data for the CIM at 18V?

Al Skierkiewicz 24-11-2014 08:23
Re: Motors: Past and Future
 
Quote:
Originally Posted by Ragingmain (Post 1409562)
Ether
Thank you for that document. That is exactly why I was thinking about this. V=IxR. So if the voltage increases the amps go down. Less heat, more efficient and as shown more power. But from reading the rules a bit closer it appears it is a no no. Thanks for all of your help:)
Not exactly, the motor series resistance doesn't change. Solving the above equation for increased V increases the current. You are thinking of transformer action where as the voltage is stepped up the current is decreased for a given power.

Ether 24-11-2014 10:40
Re: Motors: Past and Future
 
Quote:
Originally Posted by Al Skierkiewicz (Post 1409758)
You are thinking of transformer action where as the voltage is stepped up the current is decreased for a given power.
Or perhaps he was thinking of the electrical power supplied to the motor input: Pin=V*I. For a given input power Pin, the motor current is inversely proportional to the applied voltage.

Daniel_LaFleur 24-11-2014 14:31
Re: Motors: Past and Future
 
Quote:
Originally Posted by cgmv123 (Post 1409698)
With 30 motors available*, I think they need a step up in electrical storage (and current capacity of the main breaker).
I disagree.
Power management is a good exercise in proper engineering. Just because we have 30 motors available to us doesn't mean we should use 30 motors.

A limited supply of electrical energy forces teams to budget their available energy. Just another challenge.

DL

AllenGregoryIV 24-11-2014 14:45
Re: Motors: Past and Future
 
Quote:
Originally Posted by Daniel_LaFleur (Post 1409819)
I disagree.
Power management is a good exercise in proper engineering. Just because we have 30 motors available to us doesn't mean we should use 30 motors.

A limited supply of electrical energy forces teams to budget their available energy. Just another challenge.

DL
I agree, the current battery is fine. We ran an 8 motor drive (6 CIM, 2 MiniCIM) and didn't have problems last year. Matches are less than 3 minutes, a single battery is more than enough to work with. You have to make good decisions about wiring and things but that's part of the competition. Also the 775-18 at 12V is a great motor (now that it doesn't case short as often) and we don't need to run it at 18V for it to be very useful. With the last two years allowing 6 CIMs, 4 MiniCIMs, and 4 BB775-18s I think teams have plenty of power to build just about any mechanism they need/want.

Oblarg 24-11-2014 14:48
Re: Motors: Past and Future
 
Quote:
Originally Posted by Daniel_LaFleur (Post 1409819)
I disagree.
Power management is a good exercise in proper engineering. Just because we have 30 motors available to us doesn't mean we should use 30 motors.

A limited supply of electrical energy forces teams to budget their available energy. Just another challenge.

DL
Agreed. 6-CIM drives and the like are pushing the limits of what the current battery can do, and this adds depth to the engineering decisions that need to be made to field an effective robot. I think this is a good thing.

Whippet 24-11-2014 16:00
Re: Motors: Past and Future
 
Quote:
Originally Posted by Oblarg (Post 1409824)
Agreed. 6-CIM drives and the like are pushing the limits of what the current battery can do, and this adds depth to the engineering decisions that need to be made to field an effective robot. I think this is a good thing.
But without a more capable battery, how can drives like this become possible? :D

Daniel_LaFleur 24-11-2014 16:14
Re: Motors: Past and Future
 
Quote:
Originally Posted by Whippet (Post 1409846)
But without a more capable battery, how can drives like this become possible? :D
I'll still be able to out-push you with just 4 Cims :D


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