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Attempting to apply rkfixed to a PMSM motor

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Getting huge phase currents. The equations on the right for tt and vv are from a worked out problem from the internet the results there look ok.

So I think I have the correct format for the motor currents.

Could someone check me out?

1_PMSM-currents-and-torques-vs-time-mcd.zip

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23-Emerald V

Could you provide a link to the internet problem, please?

Thanks,

Stuart

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1-Visitor

Stuart,

Thanks for looking at the problem! I can't find a hard copy or soft copy on my computer of the problem from the source. I just kept it in the PMSM currents and torques vs time.mcd file. My motor current problem is on the left and the example is on the right side.

Regards,

Chuck

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19-Tanzanite

Do you mean B(tt,y) is the example? It's a different equation, with different scaling factors, over a different time frame.

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23-Emerald I

If we put units to it, we get a significantly larger current.

Where are we solving for torque? Don't you change current if you load the motor?

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1_PMSM-currents-and-torques-vs-time-A-xmcd.zip

19-Tanzanite

van (or VAN) should be 260*0.3V. At least, I assume that is the correct number and it's not a typo.

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1-Visitor

oops

VAN = Vrms phase A to neutral = 460 VrmsLL/1.732 = 265.6

I meant to use 260 V

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23-Emerald I

Thank you--long day, bad eyes!

With that correction the solutions collapse.

But we still don't have torque and load weighing in.

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1-Visitor

Ke = 81.7 V/krpm measured

or

Ke = 81.7*60/(1000*2*pi) = 0.78 V/rad/sec

Kt = (3/2)^.5 * Ke = (3/2)^.5 *.78 = 0.955 Nm/Apk

or

Kt = (0.955 Nm/pk)*1.414 = 1.35 Nm/Arms

The the internal setting of our Voltech power analyzer measurements was incorrect. So now the voltage and current measurements are in question.

Plan to retest in a few weeks.

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