Regarding motor speed PI control, there are tons of articles about it. However, I searched many and noticed that most of them just tell you how to tune Kp and Ki following different methods. But they seldom tell you how to get the very first Kp guess, i.e., for my motor, should it start with 0.1, 0.01, or 0.001?
Since we already have all the detailed parameters of the motor, back-emf constant, torque constant, inertia, rpm/v, speed range, PWM duty cycle range of the inverter, etc., and the controller spec such as sampling time, max acceleration, etc., what I want to understand is that, can we estimate at least Kp based on those parameters and give a good guess of it that could be close to the optimal value as the start point for tuning?
Edited To make it clearer, I added the picture of motor and its transfer function of voltage vs speed. (pictures from http://ctms.engin.umich.edu/CTMS/index.php?example=MotorPosition§ion=SystemModeling)