Reconfigurable three-phase active filter into an auxiliary uninterruptible power supply

This paper presents an active power filter reconfigurable into an Auxiliary/Uninterruptible Power Supply (AUPS). This work consists in introducing a storage element of energy to mitigate the failures on the electrical system (sags, brief cut…). The purpose is to maintain the functioning of the load during the persistence of failures or, eventually, the necessary time for the starting up of another auxiliary source of electric energy. The storage element is a battery that is linked to active filter by means of a dc/dc bidirectional converter. This converter functions as a “buck” converter while the battery is recharged or as a “boost” converter when the battery supplies the load. The aim of this configuration is to reduce the bulky and heavy of the batteries banc. The new system (inverter, dc/dc converter and battery) has to work then in one of the following two modes according to the availability of the electric system: as an active filter and battery charger if the grid is available or as an AUPS.