Light Emitting Diode(LED) has the advantages in high efficiency, long lifetime, energy saving and environmental protection. To achieve the high power factor fed by AC power supply, electrolytic capacitors are usually used to buffer the imbalance between input alternating AC power and output constant DC power in a power factor correction(PFC) circuit.
However, the electrolytic capacitor has shorter lifetime compared with LED light source. To solve this issue, this paper proposed a novel flyback PFC converter with two outputs, where one directly supplies the LED load, and the other cascades a DC-AC ripple cancellation circuit(RCC). Based on series compensation structure, RCC generates an opposite ripple waveform to cancel the total ripple current, such that the electrolytic capacitor can be saved. The flyback PFC converter in discontinuous current mode(DCM) can realize PFC automatically. RCC uses a full-bridge inverter topology, which has no DC bias and the input power near the zero-crossing point can still support the required voltage to generate the opposite ripple waveform for ripple cancellation. A 17W LED driver prototype has been built in the laboratory. Experimental results are consistent with the theoretical analysis and verify that the proposed LED driver has good performances of electrolytic capacitor-less, wide AC input voltage range, high power factor and high efficiency.