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current control mode with duty cycle limit based on throttle

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devin
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Last seen: 10 months 4 days ago
Joined: 2018-09-28 22:14
Posts: 21
current control mode with duty cycle limit based on throttle

i think someone over on the skateboard forum is requesting some mods to the current control mode and i think it does make a bit of sense but requires some tweaks.

basically they still want current control, but when they apply 50% of throttle they don't want the motor to turn more than 50% of no load speed, but they also want the motor to coast as they release the throttle.

i think it can be done in current control if the % throttle not only sets the motor current command, but also sets a limit to the duty cycle at the same % as the throttle.

in order for the motor to coast when the throttle is released though i think the duty limit will need an OR statement of some kind, because it will either need to equal to the throttle position OR the bemf voltage / the battery voltage - whichever is GREATER so that when the throttle is released, the max allowed duty cycle is still sufficient to avoid reverse current.

the idea came after i just a few moments ago tested my boosted board, and to my surprise, with the board turned upside down (no load)... when I do 50% throttle the motor doesn't turn more than 50% of the no load speed that it turns at full throttle, for example.

cheers.