I am trying to learn about the torque profile of two coupled machines. I believe that if a DC motor is driving a DC generator of identical ratings, the generator will exert rated torque on the motor if it is supplying rated load current. Moreover, the torque profile will be constant.
Suppose that the DC generator is replaced by a synchronous generator, and the generator drives a three phase resistive load (Y or delta).
(1) Will the generator exert sinusoidal torque on the DC motor's shaft?
(2) What will be the torque profile if the load is unbalanced?
(3) What will be the answer to (1) and (2) above, if the synchronous generator is replaced by a 3-phase BLDC machine?
Thank you very much for your helpful inputs!