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Originally Posted by gshosford
I'm sorry that I was not more specific. Does anyone have the stall-torque data over the full range of PWM outputs through the Victor, comparable to the free-speed data in the graph to which Mike Betts' response (#18) is linked?
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There is a lot of debate as to why the freespeed vs PWM value does not follow a linear relationship as one would expect by the simplication of saying
(Voltage to Motor) = K * (PWM Duty Cycle)
I have seen this in my former day job with Delphi. I will put in my two cents as to how to understand this nonlinear response on the tail end of that message at some later date.
BUT... ...everything I have seen in my outside FIRST experience is that this non-linearity pretty much disappears at when the motor is stalled.
(Stall Torque of Motor) = K * (PWM Duty Cycle)
There is some loss due to frequency effects especially at low duty cycles but for the most part, my experience has found this to be a minor effect.
Getting data on this is more bother than free speed because the motors get hot which causes its own problems. If I had time, I would run this case in a Matlab simulation... ...too much to do... ...too little time...
Joe J.