A efficiency improvement methodology for active mode efficiency regulation

The impact on the environment, in regards to power supply energy efficiency, has attracted growing attention in the international community. This paper proposes a hybrid control method that combines the conventional hard-switched PWM operation and variable frequency quasi-resonant operation. The proposed approach reduces the switching loss at medium and light load effectively without increasing the conduction loss. The proposed scheme was implemented and tested with a 90~265Vac/5V, 30W off-line flyback converter.