Improvement of power-conversion efficiency at light-load using a variable-duty burst mode

This paper proposes a new burst-mode driving method to increase the power-conversion efficiency (PCE) of a power supply at light load. The burst mode minimizes the power consumption by stopping the converter operation when load is light. The proposed method changes the off-period of the converter according to the load to achieve optimized efficiency across the entire load range. The PCE at 6% load was measured as 83.6% and 85.1% for 75-W flyback and LLC Half-bridge converters, repectively, when applying the proposed burst mode; these values were 8% and 16.5% higher respectively than those for the converters without it.