Study of a new technique to reduce the dc-link capacitor in a power electronic system by using a series voltage compensator

A novel concept for reduction of dc-link capacitors is proposed in this paper. It is based on introducing a voltage compensator connected in series with the dc bus line. The compensator processes the ripple voltage and reactive power only and thus can be implemented with switches and capacitors of low voltage ratings. The overall required energy storage is reduced, allowing the replacement of electrolytic capacitors by alternatives with longer lifetime and comparable or reduced volume and cost. A general theory that illustrates the proposed concept is presented. The theoretical predictions are favorably verified by simulations and experiments.