Bifurcations and chaos in the tolerance band PWM technique

In this paper we study the dynamical behavior of the tolerance band PWM technique, which is used in controlling power electronic ac inverters and dc-dc converters. We demonstrate numerically as well as experimentally the existence of three basic modes: quasiperiodic, chaotic, and square wave mode. We also observe saddle node bifurcation as the cause of boundary crises with transient chaos, merging crisis following symmetry breaking bifurcations and interior crisis. The critical value of the amplitude of external reference for saddle node bifurcation is evaluated analytically by the Tsypkin method.