Author Topic: Non-constant Torque issue in FOC algorithm (Simulink)  (Read 733 times)

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Offline cadenaTopic starter

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Non-constant Torque issue in FOC algorithm (Simulink)
« on: April 16, 2020, 11:04:35 pm »
Hi everyone,

I am trying to develop an FOC algorithm in Simulink (see image attached) but I am having extrange results in my simulation. My torque is not constant, when it should, but varying periodically (see image attached), when it should be constant at 2 Nm. Also the scope for my q-axis current my probe is giving me a strange graph (see image attached) I can't even make sense of. Please if anyone could help me I would really appreciate it since I have no clue what is going on. I don't know if it could be the values of my PI regulator but I have already tried all sorts of values and have no idea what else I can do. Please could someone help me out ?

P.S. Simulink file can be downloaded from my OneDrive: https://1drv.ms/u/s!AokIrMv_d8kz3BMaImhVY_guP_N-?e=3H9HRJ
 

Offline cadenaTopic starter

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Re: Non-constant Torque issue in FOC algorithm (Simulink)
« Reply #1 on: April 20, 2020, 10:25:58 am »
Does anyone know why my model isn't working ?
 

Offline cadenaTopic starter

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Re: Non-constant Torque issue in FOC algorithm (Simulink)
« Reply #2 on: April 21, 2020, 06:50:36 pm »
Hi does anyone know what is wrong ? Is there something I need to further clarify ? I have beent trying to tune PI values but nothing has improved. I have tried playing around with the motor and nothing either. I thought it would simple to implement since it's basically linking blocks together. I hope you are just not answering because they genuily don't know the answer but if there is another reason nobody is replying please let me know because I really need to do what I am doing wrong. Thanks.
 

Offline max_torque

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Re: Non-constant Torque issue in FOC algorithm (Simulink)
« Reply #3 on: April 21, 2020, 07:25:47 pm »
I would suggest that you run "open loop" and disable the PI controllers, just run with a fixed output to the SVM. Then scope the motor's back emf, and the average output voltage of the SVM blockset. You will only get a "constant" phase current (which leads to a constant torque) if the forward voltage (produced by the SVM) accurately tracks the motor's actual backemf.
 


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