Effect of intermediate capacitance on slow‐scale instability of Cuk power factor correction converter operating in discontinuous capacitor voltage mode

Due to features of near‐unity power factor, soft turn‐off switching and low switch current stress, Cuk power factor correction (PFC) converter operating in discontinuous capacitor voltage mode (DCVM) has attracted much attention. However, it is found that with the increase of intermediate capacitance, slow‐scale instability occurs in voltage mode control (VMC) DCVM Cuk PFC converter. In this study, a simplified model for VMC DCVM Cuk PFC converter is established, upon which the effect of intermediate capacitance on the slow‐scale instability and the corresponding bifurcation behaviours are studied by using harmonic balance method and Floquet theory. Furthermore, the stability boundaries in terms of the intermediate capacitance under different load resistance and input voltage are given, which is helpful for parameter design of VMC DCVM Cuk PFC converter. Finally, numerical simulations and experimental results are provided to verify the analysis results.