An active-clamp resonant power factor correction converter with output ripple suppression is proposed and analyzed. It combines a buck power factor correction (PFC) unit and a resonant dc-dc unit by sharing one active switch. With another active-clamp switch, a recycling path is built to recover the leakage inductance energy of transformer, which improves the efficiency and the voltage stress of active switch. The effect of voltage ripple of dc link on output can be suppressed by fast voltage mode control loop. Therefore, low output current or voltage ripple can be achieved. With small voltage ripple across output of buck unit, the turn on time of active switch is almost constant in a half line cycle. Therefore, power factor correction can be achieved with inductor current of buck unit operating in discontinuous conduction mode (DCM). Finally, a 65W high power factor (PF) converter prototype for LED driver application with 91.08% peak efficiency and low output current ripple is built to verify the analytical results.

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.

No abstract