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Originally Posted by MPaulHolmes
I can just have the software scan through the rotor test results, and pick the best one, and then save it to EEProm. Also, I can have it automatically save the best PI values too. If we want to get really fancy, we could have the controller turn on, and if there's no valid EEProm data, it could automatically do the PI test and then rotor test, and then save it. That way you wouldn't need to communicate through the serial port. All a person would have to do is, connect the controller to the motor, go have a bowl of cereal, come back, and it's ready to go!
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Plug it in and go is good for 'eventually' but I'd like to make it work with the command line first
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There is a way to list preset settings. I think I had it commented out or something. I'll include that too. What word should it be? Fran had used "config" for the 144v 500amp DC controller. How about "settings"? Or we could allow both to do the same thing.
Also, I'm going to add a new "bad command or file name" (yay dos!) error message when a command doesn't exist.
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Good idea - bad command would have shown me that I made a typo!
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Well, I think a serial connection is necessary.
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Me too
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I"ve been reading up on sensorless FOC, and it doesn't look that bad. It requires knowledge of the line to line resistance and line to line inductance. Here's a way to compute that:
If you put 100% duty across phase 1 to phase 2 (phase 3 off), then, you can measure
I1 = Vb/R * (1 - e^(-t1*R/L))
I2 = Vb/R * (1 - e^(-t2*R/L))
Where
Vb = battery pack voltage
R = resistance of phase 1 (or 2 or 3)
e = 2.7182818
1 = 1
- = -
^ = exponent
L = inductance of phase1 (or 2 or 3) stator coil.
t1 = time #1 (first measurement time)
t2 = time #2 (2nd measurement time)
then you have 2 equations with 2 unknowns, and you can solve for R and L. But the stator coils aren't really isolated inductors, but primaries of transformers, with the rotor being the secondary. I bet that changes how that works. dang it.
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The primary versus secondary of the transformer problem seems like a pretty big deal. Industrial drives (all of the ones we deal with) do a small amount of rotation during the 'rotating tune'. Perhaps this helps with the coupling between primary and secondary? Take readings L1 to L2, L1 to L3, L2 to L3 ... rotate the rotor a little bit .. take the readings again .. rinse and repeat until you the rotor is back where it started (1/2 turn for 2 pole, 1/4 turn for 4 pole, 1/6 turn for 6 pole, whatever).
Maybe it would make sense to do the whole thing twice? How much room do you have for data in the controller?
The industrial controllers can also do a 'static tune', where they do not rotate the shaft. It is not as accurate, and your starting torque suffers (125% to 150% instead of 200%) but if you can't de-couple your motor from your load (like a compressor, for example) it gets you decent values for control.
BTW - none of these numbers is displayed anywhere.. for any of the vendors. If the tune works, the values are stored. If not, there is a 'fail' message and you try again or use Volts per Hz open loop control.