New H-bridge multilevel current-source PWM inverter with reduced switching device count

Abstract

This paper introduces a novel circuit configuration of multilevel current-source inverter (CSI) that has many steps with fewer power switches. In this new topology, an H-bridge CSI is connected with current-cell circuits working to generate the intermediate level currents of multilevel current waveform. Using the proposed topology, the switching power device count, isolated gate drive circuits and inductor conduction losses can be reduced. Moreover, in order to reduce the inductor size of the multilevel CSI, chopper based DC current sources are presented. Five-level and seven-level PWM inverter configurations are examined through computer simulations. Furthermore, an experimental prototype of a five-level CSI is setup and is tested. The results show that the circuit works properly to generate the multilevel output current waveform with low harmonic currents and small inductors which proves feasibility of the proposed multilevel CSI.