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Old 07-23-2009, 11:53 PM   #2082 (permalink)
squiggles
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Quote:
Originally Posted by MPaulHolmes View Post
Hey squiggles! That's a good question! I should try that.

Also, on the EVTech list, they suggested the following. I'm trying to understand it right now:

What if you lower the motor current limit as the PWM duty cycle
raises, but not in such an extreme fashion?

currentCommand = throttle*(constant - pwmDuty)

or

currentCommand = throttle / (pwmDuty + constant)

The second method is basically what you're currently doing, except
with a constant added to pwmDuty to make the low-rpm behavior act
reasonable.
So, let me see, pwmDuty + constant = throttle / currentCommand
therefore pwmDuty = (throttle / currentCommand ) - constant.

Hmm, I think that is the opposite to what I was suggesting.
In my mind the constant would effectively be the minimum limiting factor for PWM. But it would not need to be applied through the whole process.

I would add to whatever your code is...
If PWM <= 5%
PWM = 5%

or whatever % seems appropriate. Worth a try at least.

Last edited by squiggles; 07-23-2009 at 11:54 PM.. Reason: spellunk
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