Design of a harmonic free three-phase UPS

In this paper a novel three phase, step-up, converter for industrial UPS applications is proposed. The system basically consists of three, star-connected, boost-type DC/DC converters working together like a three-phase voltage source inverter, but with intrinsic step-up capability. The main advantages of the system are the smaller dimensions of the passive components and the reduced number of switching devices that do not need reverse voltage blocking capability. Test results show the effectiveness of the proposed system both during steady state and dynamic operations as well.