Boost-Integrated Two-Switch Forward AC–DC LED Driver With High Power Factor and Ripple-Free Output Inductor Current

This paper proposes a boost-integrated two-switch forward ac-dc light-emitting diode (LED) driver with a high power factor and ripple-free output inductor current. In the proposed LED driver, the maximum switch voltages are clamped to the voltage level of the dc-link capacitor without an RCD snubber circuit by adopting a two-switch forward structure, and the magnetizing inductor energy is restored in the dc-link capacitor to prevent the magnetizing inductor from saturating without a tertiary winding. Moreover, the relatively small capacitance can be utilized by the output capacitor, as the output inductor current ripple is significantly reduced by the additional circuit, unlike in the conventional LED driver. Hence, the LC filter at the output stage is simplified. The proposed LED driver has a high power factor and the power efficiency is improved. The theoretical analysis results of the proposed LED driver are verified on an output 24 [V]-1.4 [A] prototype.