A Novel Isolated LED Driver with Passive Power Factor Correction

In this paper, a novel LED driver based on a combination of a charge pump power factor correction (PFC) circuit and a single ended half-bridge (HB) resonant converter has been proposed. The proposed converter consists of two parts: the charge pump PFC circuit and the single ended half-bridge resonant converter. In the charge pump PFC is utilized to reduce the high total harmonic distortion (THD) and achieve high power factor (PF). In the single ended half-bridge (HB) resonant converter, a lossless resonant snubber is added in parallel with the output rectifier, which can suppress ringing across the rectifier so that Schottky diode can be applied. Thus, the efficiency of the converter has been improved. At the same time, the added lossless resonant snubber can also help to further reduce the THD. Detailed theoretical analysis along with design considerations and procedures has been presented. A $\mathbf{40}\mathbf{V}/\mathbf{1}\mathbf{A}$ prototype of the LED driver with 180~265Vac input has been built-up. Experimental results demonstrate that the PF of the prototype is greater than 0.97, THD is lower than 12% over the input voltages range and the full load efficiency is always higher than 91%.