Dynamic bifurcation in DC drives

Dynamic bifurcation as well as chaotic behavior in a fixed-frequency current-mode controlled DC chopper-fed DC motor drive system is presented. The key is to derive an iterative map that describes the nonlinear dynamics of the system operating in the continuous conduction mode. It illustrates that different bifurcation diagrams can be obtained by varying different system parameters. Analytical modeling of period-1 and hence period-p orbits as well as their stability analysis using the characteristic multipliers are also presented. Hence, those stable ranges of various system parameters can be determined. Moreover, chaotic behavior is quantified by evaluating the Lyapunov exponents. The proposed approach is so general that it can readily be applied to other current-mode DC drives.