A Single-Switch AC-DC LED Driver Based on a Boost-Flyback PFC Converter With Lossless Snubber

A single-switch ac-dc light-emitting-diode (LED) driver based on boost-flyback power factor correction (PFC) converter with a lossless snubber is proposed. In the proposed LED driver, the boost PFC module is designed to be operated in the discontinuous-conduction mode to achieve a high power factor. The dc-dc flyback module is designed to provide input-output electrical isolation to improve safety. The lossless snubber circuit clamps the peak voltage spike of switch to a low voltage and the leakage inductor energy is recycled via the dc-dc flyback module. Additionally, a low-voltage-rating capacitor can be used as the dc-bus capacitor because some of the input power is directly conducted to the output; the remaining power is stored in the dc-bus capacitor. Therefore, the proposed LED driver can provide a high power factor and a high power conversion efficiency. These results are verified for an output of 48 V and 2 A for the experimental prototype.