Analytical Approach to Design of Slip-Controller for Constant Volts/Hz Scheme Induction Motor Drive Using Motor Name-plate Details

A new method to design proportional integral (PI) type controller for speed control of a constant Volts/Hz (V/F) 3-phase induction motor drive using an analytical approach has been presented. The design procedure uses only the motor name-plate data. An approximate linear model of induction motor operating in constant Volts/Hz scheme is derived and a design example of slip-controller for a 3 hp motor is presented. Performance of the designed controller is verified with results from simulation using Matlab and experiments done in lab using digital signal processor (DSP)-controlled voltage source inverter (VSI). The results show satisfactory performance of the drive from rated speed to 10 % of rated speed at varying load conditions and during transients.