Set desired torque in Nm

well, Torque is calculated by

_iq USER_computeTorque_Nm(CTRL_Handle handle, const _iq torque_Flux_sf, const _iq torque_Ls_sf)
{
CTRL_Obj *obj = (CTRL_Obj *)handle;

_iq Flux_pu = EST_getFlux_pu(obj->estHandle);
_iq Id_pu = PID_getFbackValue(obj->pidHandle_Id);
_iq Iq_pu = PID_getFbackValue(obj->pidHandle_Iq);
_iq Ld_minus_Lq_pu = _IQ30toIQ(EST_getLs_d_pu(obj->estHandle)-EST_getLs_q_pu(obj->estHandle));
_iq Torque_Flux_Iq_Nm = _IQmpy(_IQmpy(Flux_pu,Iq_pu),torque_Flux_sf);
_iq Torque_Ls_Id_Iq_Nm = _IQmpy(_IQmpy(_IQmpy(Ld_minus_Lq_pu,Id_pu),Iq_pu),torque_Ls_sf);
_iq Torque_Nm = Torque_Flux_Iq_Nm + Torque_Ls_Id_Iq_Nm;

return(Torque_Nm);
} // end of USER_computeTorque_Nm() function

so, if you assume the Flux from USER_MOTOR_RATED_FLUX, and you assume Id = 0 (or some other constant value if you are commanding it so), you could calculate an Iq value that you could command.

but the torque also depends on the load....you are only going to generate the torque requested if there is the appropriate load for that torque.

and I don't think it helps with your desire to "compare the desired torque with the measured torque". To do this you would need to actually measure the actual torque by some means, and then account for the differences in the torque measured to the estimate of the torque produced in the airgap (which is what we can calculate in InstaSPIN).