1-Visitor

Question

Attempting to apply rkfixed to a PMSM motor

Forum|Forum|11 years ago
January 5, 2015
11 replies
3618 views

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

Other

23-Emerald V

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

Thanks,

Stuart

Author

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

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.

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?

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.

Author

1-Visitor

oops

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

I meant to use 260 V

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.

Author

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.