Novel H-bridge multilevel current-source PWM inverter with inductor-cells

The paper proposes a new circuit configuration of multilevel current-source inverter (CSI). In this new topology, a basic H-Bridge CSI working as a main inverter is connected in parallel with inductor-cells operated as auxiliary circuits. The inductor cell is composed by four unidirectional power switches with an inductor across the cell circuit. The inductor-cells work generating the intermediate level currents to obtain a multilevel current waveform without additional external DC power sources. A simple PI controller is applied to control the intermediate level currents of multilevel output waveform. Five-level and nine-level PWM inverter configurations, with chopper based DC current source, are verified through computer simulations. Furthermore, an experimental prototype of a five-level CSI is setup and is tested. The results show that the proposed circuit works properly to generate the multilevel output current waveform with low harmonics distortion by using small inductors.