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Sensor for DC motor

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Cyril  CRIER
Cyril CRIER on 26 Aug 2020
Commented: Cyril CRIER on 26 Aug 2020
Hello all,
I come here again for your help.
I try to simulate a DC motor functionning on the basis of the model "ssc_dcmotor" from Simscape (see picture):
The outcomes seem to be consisten regarding what I expect (value and profile of speed/current).
Then, I made some changes (actually I copy/paste this model in a bigger one to link with a gear box and a lead screw). The modifications are: adding a Torque sensor, as well as change the mask of the DC motor to display the name of my ports (which should not influence the functionning...).
Now comes the drama: my speed is 0 and my current comes to his max. and stay at the maximal value for the rest of simulation time (blocked rotor behavior).
Sensors subsystem:
I just don't understand what did I do wrong... Somebody know this issue?
Enclosed is the concerned model
Thanks in advance

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Answers (1)

Vasco Lenzi
Vasco Lenzi on 26 Aug 2020
Hi Cyril
you connected the Torque Sensor directly to ground . This will cause the entire system to be fixed to ground. Is actually consistent with how a torque sensor would work in the real world. You ahve these kind of sensor on a shaft, and if you block one of the two extremity you block the movement of the entire shaft.
Try againg but put the torque sensor on the shaft itself.
If you look at the top right subsystem "Load" in this example you can see how the torque sensor is not wired to ground:
Cheers
Vasco

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Cyril  CRIER
Cyril CRIER on 26 Aug 2020
Hello Vasco and thank you.
I modified my model according your explanation:
The C_T1 port now goes to the C prot of the DC Motor block (see following pictures)
The Speed is no longer equal to zero and take a ramp profile, with a value changing according the Stap value of the Torque source.
However, my Torque and current looks like before. Meaning that they look like I block my shaft :
As my Torque source get a step from 1 sec, I should get a no-load operating profile from 0 to 1 sec (with a peak showing the start current). Do you have any idea where that come from? Should I play with the friction block values?
Thanks in advance

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