Five-Level Switching-Cell Current Source Inverter Immune to Open-Circuit Fault Issue

Open-circuit fault (OCF) is the most common and destructive failure among traditional current source converters (CSCs). To address this issue, a topology called immune five-level switching-cell current source inverter (CSI) (I5L-(SCSI)-S-2) is proposed in this article. Furthermore, the proposed circuit avoids the parallel connection of input smoothing inductors (chokes) compared with the different 5L-CSI (D5L-CSI). This modification brings several key advantages: 1) the size/value of one inductor can be dramatically reduced, as its current does not experience low-frequency ripple; 2) tolerance or mismatch in inductor values is no longer a concern, eliminating the need for an additional closed-loop controller; 3) the proposed structure enjoys lower footprint/size in comparison with existing ML-CSIs. Moreover, the proposed inverter features a reduced number of power devices compared to the conventional ML-CSIs, similar to D5L-CSI. The phase-shifted pulse width modulation (PS-PWM) scheme is employed to control the proposed I5L-(SCSI)-S-2, as other modulation methods such as level-shifted, and low/fundamental frequency, or half-cycle PWMs struggle with frequent OCF occurrences. Simulation and experimental results justify the feasibility of the suggested configuration.