Hi bhanu.kassel@gmail.com,
In general, the main difference between a Torque Control and the Speed Control is just the what is happening in the Slow Loop:
- In the Speed Control, the reference is the Speed Command that is compared with the Measured Speed and then the PI Speed Controller give a torque reference.
- In the Torque Control, there is no controller in the slow loop. Basically you impose the Torque Reference automatically since you (as a person) are the one that act as a controller
Now, a true Torque Control System, requires a position sensors like an encoder/resolver that can provides the rotor actual position even at low speed or stall. The Hall sensors which are equipped for this motor in the kit, do now actually allows you to control the torque at low speed. For such purpose you really need to have a proper motor+sensor setup.
In the M7 we tried to show, what it takes to build such a system, but if you analyse the model you will see that is just a incremental variation over the open loop V/f control method. Basically, the rotor position is imposed based on on a ramp while the torque is selected from a LUT (see figure 3 from the lecture)
Controlling the motor in Torque Mode - might be challenging without a proper load since the rotor might accelerate until the voltage is saturate.
Hence, my advice:
- try to evaluate the Speed Control first
- if possible, replace the Hall sensor as primary speed/position feedback with an encoder ( your motor + your sensor)
- update the model to make your the SW is still working
- then, remove the Speed Controller and impose the command as a Torque/Current Reference
Hope this helps!
Daniel
