The synchronous buck converter (SBC) with traditional pulse-width modulation has several disadvantages, such as poor efficiency at light loads. Therefore, this study proposes a new control technique for the SBC that allows power switches to operate with quasi-resonant valley switching in light load conditions. The voltage ripple produced during the capacitor charging and discharging processes is utilised to simulate an inductor current ripple, and thus the zero position of the inductor current can be emulated without requiring a current sensor. The technique has several advantages, including easily built-in integrated circuits. A 5-V/25-W SBC laboratory prototype was implemented to verify the feasibility of the proposed technology and control scheme, and the experimental findings were satisfactory.
['Jian-Min Wang', 'Sen-Tung Wu']
Sensorless control scheme for synchronous buck converter