An Improved Symmetrical Three-Phase Multilevel Inverter

Authors

Faculty of Electrical and Computer Engineering, University of Tabriz, Tabriz, Iran

Abstract

In this paper the new structure of a symmetrical three-phase multilevel inverter is proposed. In the Proposed inverter six power switches are unidirectional and rest of the power switches that are used in the structure are bidirectional. In this inverter there isn’t a diode. A Single DC link feeds all the three phases. Also, due to the fact that there aren’t electrolytes capacitors, the control strategy for generating desirable voltage is simple. Both the sinusoidal pulse width modulation (SPWM) and the staircases modulation are effectively executed for generating voltage by proposed inverter. In this paper proposed inverter is compared from the viewpoints of the number of power switches, the number of gate drivers, the number of DC sources and the blocking voltage with the common inverters. Also, the calculation of losses for proposed inverter is done and it is compared from the viewpoint of loss with other three-phase inverters. Finally, the results of simulation that is done in PSCAD/EMTDC software package and experimental results are presented to validate the performance of the inverter.

Keywords