Design of single stage single switch switch mode rectifier based on equal area criterion

The family of power factor corrected (PFC) switching power supplies normally consists of two stages in the power circuit, viz. the input PFC stage and the output dc-dc converter stage. By integrating the PFC stage and dcdc converter stage using a single switch, the new class of power supplies known as single stage single switch switch mode rectifier (S4SMR) has been emerged. A major problem associated with the S4SMR is strong dependency of DC bus voltage stress with the output load. A design solution to avoid this problem is presented by suitable selection of boost inductor using equal area criterion (EAC) and by implementing closed loop control. Converter topology is selected in such a way that the input PFC stage is discontinuous current mode (DCM) boost converter and the output stage is continuous mode converter providing wide band width response. Analytical expressions are derived for boost inductance, critical inductance of output flyback converter, and voltage transfer function. Based on this a 100 W, 230 V, 50 Hz A.C / 50 V D.C S4 SMR was designed, fabricated and tested. Simulation results using SABER software package and actual test results are compared and analyzed. The problem of voltage stress was found almost eliminated.