hi!

i have to control a system in which i have a variable speed drive which control the speed of an induction motor. i want to know if i can take the gain placed in the variable speed drive as the transfer function of the variable speed drive, or i must model each part of the variable speed drive in order to obtain its transfer function. please help me.

 

As a first order approximation the variable speed can be described as a control block. The gain (if voltage controlled) is G=Volts/Radians/sec.

The bandwidth can be modeled as a single pole.