A fractal method of dynamics forecasting is investigated from. the viewpoint of practical application regarding pulsewidth modulation (PWM) energy converters (PECs). The method realizes the idea of PEC state estimation relative to the preliminary formed domains of periodic processes. With this purpose, a special space "is designed" into which the periodic process domains are mapped from the parametrical space and transient phase trajectories-from the phase space. Mapping is provided with use of geometrical interpretation of fractal regularities that exist in the structures of both periodic process and transient phase trajectories. Computational and experimental investigations of the fractal method efficiency are carried out within the bounds of the scenario of dynamics evolution toward chaos through period doubling.