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FOC control Speed and D-axis current oscillations

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sxv9616
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FOC control Speed and D-axis current oscillations

Hello all,

I am running a motor using sensorless FOC in PID speed control mode. 

The problem i have is: after certain load point motor oscillates and motor current sharply raises and falls for few seconds, during this time d axis currents is fluctuating. once the d axis current stabilizes, motor maintains speed and motor current, d axis current increases with load.  

what should i try to remove speed and d axis current oscillations.

I was able to reduce the oscillations by changing speed PID values in PID controllers settings, but motor overall efficiency significantly dropped and small oscillations still preset, though the peak current is reduced from 125A to 80A, as seen in attached image. 

thanks for any Hints!

 

 

 

frank
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Which HW version do you use? The issue could be related to HW 4.10 which uses only two shunts and suffers from noisy current readings.

sxv9616
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Last seen: 9 months 3 weeks ago
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Frank,

we have HW:75_300 with three shunts and SW:3.62.

Motor was unable to startup with the detected FOC parameters, we had to reduce FOC current Kp,Ki and observer gains to make it to spin. any hints on why this is happening? 

Also, real time data showing much less current input compared to actual current. any suggestion to fix this?

Thank you

 

sxv