Permanent Magnet Synchronous Machine - meaning of Mechanical System parameters

Hi, What does it mean the parameters of mechanical equation for PMSM model? Is there any reference with explanations of parameters like 'Shaft static friction torque', 'Combined viscous friction of rotor and load' etc. I'm looking for any link/book/video which will explain and will help me to understand these terms. The link for the PMSM model is the following http://www.mathworks.com/help/physmod/sps/powersys/ref/permanentmagnetsynchronousmachine.html - section 'Mechanical System (for all models)'. Thank you.

Answer 1

[Sabin]

The combined viscous friction coefficient in a motor model is a parameter that describes the effect of friction on the motor's performance. This friction is primarily due to the viscous drag experienced by the moving parts of the motor. The combined viscous friction coefficient is the constant of proportionality that relates the motor's angular velocity to the frictional torque opposing the motor's motion.