Single-Loop Current Sensorless Control for Half-Bridge Based AC/DC Converter

Instantaneous current measurement increases the cost and size of the control system in switched-mode power supplies. This paper presents the first attempt to apply current sensorless control in conjunction with a half-bridge converter. The proposed single-loop current sensorless control algorithm allows shaping sine-form current in the rectifier mode by using only one voltage control loop (no current loop is needed) to stabilize the DC bus voltage. Mathematical equations were defined for capacitor voltages, inductor current peaks, and transistor conduction time during discontinuous conduction mode and continuous conduction mode. The verification of our theoretical assumptions and analytical equations were confirmed by the simulation and experimental analysis. Applications of the proposed control approach are described in the conclusions.