Ripple Compensation for a Single-Phase Rectifier by 2-Quadrant Chopper and Auxiliary Capacitor

Abstract

The single-phase converter or rectifier always has a voltage ripple in the output DC voltage, because the instantaneous power of the single-phase AC line varies on the double frequency of the line. In order to obtain a smooth DC voltage, an energy storing element is necessary. The smoothing capacitor is used to reduce the ripple voltage in the DC output. Usually, it has much larger capacitance than that needed to absorb the ripple energy.
This paper discusses the required capacitance to absorb the ripple energy, and represents a ripple compensation circuit with a small auxiliary capacitor controlled by a 2-quadrant chopper connected in parallel to the smoothing capacitor. The appended capacitor works under large ripple voltage and efficiently absorbs the ripple energy. The ripple compensation curcuit works as an equivalent capacitor which has a large capacitance.