Design consideration for power factor correction boost converter operating at the boundary of continuous conduction mode and discontinuous conduction mode

A boost power converter operating at the boundary of continuous conduction mode (CCM) and discontinuous conduction mode (DCM) for power factor correction is described. Theoretically, the operation at the boundary of CCM and DCM is considered constant on-time for the boost switch. Due to finite switching frequency and capacitor filter effect, the switch turn-on time varies throughout the entire cycle. This variation of the switch on-time affects the average switching frequency and the circuit component selection criterion. The relationship between the circuit components and the switch on-time based on the fundamental principle of the power circuit operation is derived. A 44 W boost converter is designed and constructed accordingly. Experimental results show that the theoretical analysis along with practical design consideration can accurately predict the switch on-time and switching frequency