Author Topic: Incorrect current measusrement of BLDC motor using ADC  (Read 2 times)

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Online jeet55Topic starter

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I am controlling a BLDC motor using drv8301 and stm32, using trapezoidal control,
and taking position feedback using backemf using 3 opamps and current feedback using the drv's built in opamp.

Currently I am not measuring current by cycle by cycle basis of pwm but taking the average of the rectangle of pwm's as a whole.

I have configured adc sampling rate high enough to take multiple sample per cycle of pwm so we don't have to worry about that.

what problem I am facing is I assumed the current average to give me the phase current but the reading is off by a lot, when duty cycle is close to 100% the current reading is close to the actual but its incorrect and larger than actual current when duty cycle is low.

so I have to multiply the current average to the duty cycle to get a correct value. this doesn't make sense to me.
What I am missing here? maybe its obvious help me out here!



 


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