Current Control with Mathematical Model


#1

Hello,

I want to use the ODrive for a model based control project with current mode. The relation from current to torque seems to be:
T = Back_emf_const*(f(phi)*i_a + f(phi-(2pi/3))*i_b + f(phi+(2pi/3))*i_c)
with f being the trapezoidal function, phi the current angle and i_x the current of each phase.
Using current mode I will be able to set one value for the current.

How can I model the output torque?

Thank you very much


#2

I don’t think that’s a good model, that assumes a BLDC motor with trapezoidal back-emf. Almost all brushless motors (including hobby outrunners) are not BLDC motors, but PMSM motors. You can read more about the difference here.

I would suggest equation 2.30 from this resource to model the torque.