In this paper, we have attempted to give a general framework (from bifurcation theory point of view) for understanding the structural stability and bifurcation behavior in following phase synchronized systems: (a) coupled Poincare systems; (b) controlled linear oscillator and (c) ‘predator-prey’ system, on the base of a specifíc version of bifurcational theory (based on the computing first Lyapunov value (not exponent)). Our results suggest that for these three systems soft stability loss take place. and Obsahuje seznam literatury