An Improved Control Scheme for Single-Phase Buck-Type Differential Rectifier with Low DC Voltage Ripple and AC Current Distortion

Single-phase Buck-type differential rectifier can realize low DC voltage output with only one stage power conversion. However, like other single-phase rectifiers, it suffers from the inherent double-line frequency ripple power and corresponding DC side ripple voltage. Due to the electrolytic capacitor has a relatively short lifetime, active power decoupling is much more preferred to filter the ripple power. In this paper, the active power decoupling is realized by utilizing the filter capacitors of the differential Buck-type rectifier without using additional power devices. The DC ripple voltage is employed as the control variable, then a power decoupling controller will force the DC ripple power to zero while generating the required reference for tracking. An additional AC current compensator is adopted to ensure the unity power factor operation and low AC current distortion. Experimental results verify the effectiveness of the proposed scheme.