Bi-directional power electronic transformer based compact dynamic voltage restorer

In this paper a dynamic voltage restorer (DVR) circuit with a bi-directional power electronic transformer (PET) structure is proposed to correct input utility voltage distortions on a sensitive load. This DVR-PET contains full-bridge DC-link inverter (FBDCI), high frequency isolating transformer (HFIT), cyclo-converter and output filter. A phase shift modulation (PSM) control scheme is used to regulate compensation voltage. The proper reference voltage is estimated to adjust the amount of battery (or capacitor) charged energy as well as minimizing energy transfer between utility power and DVR circuit. A circuit model has been simulated with PSCAD/EMTDC software and the results are presented which verify the analysis.