A Single-Stage Step-Down Rectifier (S³R) for AC-DC Power Conversion

The actively controlled AC/DC power conversion has a limitation in certain moments that the output voltage could be higher than twice the peak value of the supply voltage. A SingleStage Step-Down Rectifier ($S^{3} R$) is proposed to overcome this limitation by having a half-bridge rectifier and a buck (stepdown) converter in single-stage. Both the half-bridge rectifier and the DC/DC step-down converter require two switches each, resulting in a total of four switches in the system. However, the proposed rectifier reduces the number of switches to three by connecting them in series within a single-leg configuration. The output inductor (step-down inductor) operates in continuous conduction mode (CCM) with a designed pulse width modulation (PWM) strategy. The proposed rectifier has a computed 2.83% total harmonic distortion (THD) and achieves almost unity power factor (PF) for 9.9 kW output power at $240 V_{\text {rms }}$ line voltage, in the simulation. Simulation results performed in MATLAB SIMULINK confirmed the feasibility and functionality of the proposed single-stage topology.