The paper reports on the peculiarities of the bifurcation approach to analysing emergencies in the dynamics of the pulse energy conversion systems (PECS). The approach to structural simplifications when making a bifurcation analysis of such systems is described. The bifurcation analysis results of mathematical and physical models of one of the PECS kinds, namely, D.C. electric drive with pulse modulation of energy are described. The experimental estimations of the adequacy of the bifurcation analysis of the dynamics of the PECS are discussed.