Experimental verification of Hopf bifurcation in pulse-width modulated inverter fed cage induction motor drive system

Abstract

Bifurcation theory deals with the change of qualitative behaviour in a parameter space of dynamical systems. This study investigates the bifurcation phenomenon of an industrial drive having typically constant speed requirement for which pulse-width modulated inverter fed cage induction motor (IM) is a good choice. The focus is on bifurcation analysis of the stator voltage controlled IM drive, with a particular emphasis on the dynamics and stability under variations of load torque and proportional integral controller gain. Extensive computer simulations are performed to capture the system's dynamic behaviour and demarcate the bifurcation boundaries. Trajectory and Poincaré section before and after the bifurcation are shown. The detailed mathematical model of the closed-loop system is derived and is used to analyse the observed bifurcation phenomena. The describing equations reveal that the system loses stability via supercritical Hopf bifurcation. Experimental results are also provided to confirm the theoretical analysis. ©The Institution of Engineering and Technology 2014.