THE DETERMINATION OF THE BOUNDARIES BETWEEN CONTINUOUS AND DISCONTINUOUS CONDUCTION MODES IN PWM DC-TO-DC CONVERTERS USED AS POWER-FACTOR PREREGULATORS

The determination of the boundaries between both modes of conduction ( continuous and discontinuous) in PWM de-to-de switching converters use d as power factor preregulators (PFP) is presented in this paper. When a de-to-de switching converter works as a power factor preregulator, its operating point is constantly changing due to the fact that both t he de voltage conversion ratio and the load ''seen'' by the converter are constantly changing in each half-sinusoid of the line voltage (inp ut voltage of the converter), In these conditions, the conduction mode cannot be directly determined, In this paper, the boundaries between both conduction modes in each angle of the half-sinusoidal input volta ge have been determined. The Conditions to always operate in continuou s or in discontinuous conduction modes have been determined as well, F inally, these results have been verified by simulations and experiment al results.