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Old 11-09-2015, 12:24 PM   #2314 (permalink)
thingstodo
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Quote:
Originally Posted by MPaulHolmes View Post
It was accurate when I used a 100mV = 100amp shunt connected to the DC bus, so I wouldn't bother with doing that.
Excellent - Pack amps measurement not required!

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Ya, I get used to using the terms, and I forget what the heck they are. haaha. My understanding is, Vd is the voltage responsible for the stator field generation, so I think Vd*Id would be the instantaneous reactive power, and Vq*Iq + Vd*Id would be the true (or apparent) power being used by the system, so I guess the power factor would be Vq*Iq/(Vq*Iq + Vd*Id). Hey, I bet power factor would be a nice variable to see too.
I don't believe I have a method to measure reactive power. Vq and Iq would be great to log. Vd and Id are optional for me as is the power factor. I don't think you can really do anything to change power factor unless you want to add some weight and put an LRC filter in parallel with the motor. It would be more efficient ... at moving the heavier vehicle ...

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Unfortunately I don't have DC voltage as a possible measurement We can look at the 3 phases of V and the 3 phases of I on the output side. We could then do an instantaneous Vphase1*Iphase1 + Vphase2*Iphase2 + Vphase3*Iphase3 to get the instantaneous power out?
I can put a meter on it for now. If you want to calculate it and log it we can compare and see how accurate the calculation is (likely more accurate than my measurement!) But it would be good to prove it one way or the other.

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That is awesome. I would very much like to know how to do it too when you figure it out.
I will post a link to the tutorial .. perhaps maybe 2 .. that were the most help if it works as described. Multiple video sources mixed to one video is kinda exciting for me!

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First I think it would be good to see that Id really is following IdReference, and Iq is following IqReference on your motor.
Hmm.. As long as those are logged, that should be pretty easy. No specific test is required for this, right?

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Then, because we used the "autotune" PI feature, I would feel good about it. I'm not sure of what the new RTD format is, but this data can be streamed right to a text file, and then pasted into Excel. That would allow updates at maybe 1KHz rather than just 10Hz, not that 1KHz would be required. You wouldn't see it live as it happens, but could go back and see what the last minute looked like on a graph.
I have no source code. I will power up the Cougar and see what it streams, then paste that into a message here. I am pretty confident that Adam's code will deal with the information in a different order .. maybe I should test that!

At 115,200 baud (I think) .. 10 bits per byte with start bit and stop bit = 11,520 characters per second. At 1 Khz or 1000 samples per second, there is only 11 characters, including CR and LF, per sample. Since we are talking about maybe 80 characters, plus a bit of headroom .. how about 100 Hz sampling instead?

If you are going ahead with a 16 bit word of flags for which data to log, can you add a logging rate as well? That way we can log only one or two values at super-high rate, or log everything at a slower rate ...

Last edited by thingstodo; 11-09-2015 at 12:54 PM.. Reason: corrected bit numbers
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MPaulHolmes (11-09-2015)