How to measure power consumption of a brushless DC motor

Question

Hi,
    I need to measure the power consumption of a moog 23-23 motor using a PXI platform because I need to save the instant power consumption data. I have a Dqmx 6259 and a FPGA module. The problem is that I don't know if I should measure the current and voltaje of all three coils of the motors or if it is enuogh measuring just one, plus is it better to measure in differential mode all the signals directly with the DAQmx or shoul I use a differential amplifier first?

Answer 1

I don't see anything wrong with your approach; however, I'll throw out a few thoughts:
If you could tie the sending of the change-voltage command (in your DLL) to the START TASK command for DAQ, you could reduce the variability in the time between the two events. Maybe that's important, maybe not.
Can you set the voltage via some LabVIEW code, rather than a DLL?
You might or might not want a variable sampling rate - if you expect 10 mSec, you might want to sample at 10 kHz to catch the 1% difference between 10.2 and 10.3 mSec. But if you're expecting 500 mSec, you could sample at 200 Hz to catch the 1% difference between 500 mSec and 505 mSec, thereby saving data space and processing time. Maybe that's important, maybe not.
Steve Bird
Culverson Software - Elegant software that is a pleasure to use.
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