Boost-Flyback Single-Stage PFC Converter with Large DC Bus Voltage Ripple

The life time of lighting emitting diode (LED) can reach 100,000 hours. Compared to other power supplies, the power supply for LED requires long life time in addition to high efficiency and high power factor. Electrolytic capacitor has the shortest life in switching power supplies. In order to prolong the life time of power supply, it is necessary to reduce the storage capacitance and use other kind of capacitor instead of electrolytic capacitor. In this paper the relationship between storage capacitor voltage ripple and capacitance is analyzed. The PF and DC bus voltage of the boost-flyback single-stage PFC converter is analyzed. When flyback works in DCM, the DC bus voltage is independent of the load. Then the capacitance is reduced and the voltage ripple is increased, in this way, the high voltage ceramic capacitor can be used instead of electrolytic capacitor. The analysis is verified by the experiment.