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Maximum Duty Cycle

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josh
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Maximum Duty Cycle

Hello,

I was snooping through the settings once again and noticed that the maximum duty cycle was set to 95%. Is there a reason for this? Could it be bumped up to 99 or 100% for an esk8 board motor? 

Thanks!

Roger Wolff
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The problem with 100% is twofold. 

 

First there is the highside FET-driver: The FET needs to be driven with VMOT+12V on its gate. That voltage is generated from the 12V into a capacitor when the driven signal is low. If you drive the FET 100%, the signal is never low, so no time to charge the capacitor. 

 

Second and probably more important.... On the older VESC the measurement of the current was done while the signal was low. If you turn it "high" for 100% of the time, you can't measure the current anymore. With the newer phase-sensors it might be possible to go higher because this is now less of an issue. 

josh
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Thanks for the reply Roger. I did try running it at 99% and 100% and there were audible issues at 100%. Everything seems to work fine at 99% with a slight speed increase. Not sure if it is stable/safe to run it at 99  all the time and under load though. Hopefully Ben can give us one of his phenomenal explanations on the matter.