| Abstract |
PWM Regulated Boost and Buck-Boost converters can show hysteresis phenomena in their bifurcation paths. Conditions for parameters that imply multiple attractors, i.e., multistability, are evaluated in the context of the average model approximation. The averaged system, without taking into account its physical limits (named border collisions), contains some symmetry, showing either one, always antisaddle (node or focus) or three, one saddle and the other two antisaddles, equilibrium points. Frequently, the antisaddles are spiral (foci) and show Hopf bifurcation. The global behaviour varying some parameter shows a pattern with two ending saddle-node (most frequently repellor) bifurcations. Then, the system changes from three to one equilibrium point (or vice-verse). The inclusion of border collisions bifurcations breaks the symmetry and modifies the mentioned scheme. Finally, limit cycles associated with Hopf bifurcation (which is subcritical) play an important role near stability transitions. Partitions in 2D parameter space are used as a tool in order to help to understand these phenomena. |
