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-   -   Motor Calcs with <100% PWM output (http://www.chiefdelphi.com/forums/showthread.php?t=108630)

Nemo 22-09-2012 18:11

Motor Calcs with <100% PWM output
 
How do I adjust a motor speed calculation if my DC motor controller is set at, say, 50% PWM output? Do the stall torque and free speed go down proportionally?

Ether 22-09-2012 18:23

Re: Motor Calcs with <100% PWM output
 
1 Attachment(s)
Quote:

Originally Posted by Nemo (Post 1186913)
How do I adjust a motor speed calculation if my DC motor controller is set at, say, 50% PWM output? Do the stall torque and free speed go down proportionally?

As a first approximation, yes.

http://www.chiefdelphi.com/media/papers/2432



Nemo 22-09-2012 20:33

Re: Motor Calcs with <100% PWM output
 
Thanks! You've posted all sorts of useful things here - that is much appreciated.

Joe Ross 22-09-2012 20:41

Re: Motor Calcs with <100% PWM output
 
One other thing to consider is that without additional compensation, 50% pwm on a jaguar will be close to 50% speed. On a victor, it will be significantly faster.

Nemo 22-09-2012 20:50

Re: Motor Calcs with <100% PWM output
 
Quote:

Originally Posted by Joe Ross (Post 1186935)
One other thing to consider is that without additional compensation, 50% pwm on a jaguar will be close to 50% speed. On a victor, it will be significantly faster.

This is a good point. I'm actually looking at this for FTC using Hitechnic DC motor controllers; getting more than 2:1 or 3:1 reduction using Tetrix parts gets bulky, so I am figuring out when it makes sense to do part of the speed reduction with lower PWM output. After your comment, it occurs to me that I don't know how linear those controllers are, so maybe we'll have to do a bit of rough testing.

Ether 22-09-2012 23:21

Re: Motor Calcs with <100% PWM output
 

FWIW, the Victors get a lot more linear once you put a load on them.



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