I am working on a project in which I want to use State Feedback Control to position control a BLDC motor in combination with a motor controller. I want to do this since translating time domain specifications into controller gain using this method is way more exact than the heuristic method of PID tuning. I would run the current control PD on the microcontroller and the state feedback on a microcontroller. For this to work, a state space representation needs to be made of the whole BLDC system. Using the control scheme shown below, I wanted to determine the state space representation of the green box, where the current command is the input, as shown by the red arrow, and the motor position is the output. I have done much research and have found complicated versions which will require also modeling the inverter, or simple 2nd/3rd order systems.
My questions are:
What is the correct state space model to use?
Would you advise to take the other approach of applying system identification methods to determine the state space?