Quote:
Originally Posted by ale0502
Hi everyone.
I made some progress on my controller, will soon begin testing !
But now I 'm with my silly questions.
If I use a 120V battery pack means that the three-phase voltage will generate is 60 + 60V is true?
So, for calculating power of my motor, I must use 60 or 120v?
P = sqrt(3) * V * I * cos (fi)
thanks!
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Sometimes it's easier, for me, to think about DC out of the battery pack. P = 120V * I. If you use the voltage and current going into your controller and subtract a bit for losses (mostly from the voltage drop across the IGBTs) it's a good estimate.
I have problems with the cos (fi) part where where cos(fi) gives you the portion of the current that is doing work. The angles are the challenge to calculate so that's where Paul gets into the complex math.
At work my instruments give me RMS current and RMS voltage. I use a graph to estimate the power factor based on motor size, and that's how I come up with the power the motor is putting out. It's a bit .. isolated .. from the raw signals that Paul gets from the hall effect sensors and voltage sensors ...