An Energy-feedback Method for Single-Stage LED Drivers to Eliminate Low-Frequency Current Ripple

AC-DC single-stage LED driver with ripple cancellation circuit cannot only achieve low cost and high efficiency, but also suffers from seriously twice-line-frequency output current ripple. However, the input energy is insufficient to maintain the ripple cancellation voltage during the zero-crossing zone of input voltage. An energy-feedback method is proposed to maintain flicker free operation. An auxiliary ripple cancellation circuit is used to generate a compensation voltage to offset the output voltage ripple. The auxiliary circuit transfers part of the energy back to the transformer core to guarantee the energy can be extracted from the input side during the zero-crossing zone of input voltage. Therefore, High Power Factor (PF) performance can be achieved without the input platform voltage generating circuit. A 100W (50V/2A) simulation topology base on flyback is designed on PSIM to verify the capability and excellent performance of the proposed method.