A series compensator based on AC-AC power converters with virtual quadrature modulation

This paper presents a new topology of a three-phase dynamic voltage restorer (DVR) that is based on an ac-ac power converter. Two different operations of realizing of the ac-ac converter are proposed in accordance to the application requirement whether phase shift is involved in the output voltage with respect to the input voltage. For inphase compensation, the ac-ac power converter can be realized with four active power switches. Alternatively, if phase-shift is needed for the injection voltage, a new modulation scheme is proposed for the six-switch realization. The modulation and control schemes for both types of realization have been verified via detailed numerical simulation. The contributions of this paper will enable the realization of the DVR topology with reduced switch count. Furthermore, the novel modulation scheme will significantly expand the operating regime of ac-ac converters and potentially apply the ac-ac converter in the other applications beyond the example of DVR presented in this paper.