Coexistence of fast-scale and slow-scale instability in CUK power factor correction AC-DC pre-regulators under non-linear current-mode control

Power factor correction (PFC) converters using conventional control strategies have been reported tremendously as exhibiting slow- and fast-scale bifurcations. This study investigates the fast-scale and slow-scale instabilities in a PFC ĆUK converter under non-linear carrier (NLC) control, which is proved advantageous compared with other conventional control strategies. It is found that the fundamental periodic orbit loses its stability via period-doubling bifurcation and later bifurcates to chaos. Bifurcation studies of NLC controlled higher-order converters have not been reported so far in literature. Computer simulations as well as experimental investigations are performed to study the qualitative behaviour of the system under variations of different parameters. It is found that both the fast- and slow-scale instabilities may cause distortion in the line current and degrade the supply power factor. The results offer useful information of parameter space for the design and operation of the converter in the desired fundamental stable regime.