Fault Detection and Management of the Three-Phase 4-Leg Voltage Source Inverter

A novel fault detection and ride-through method for the three-phase 4-Leg Inverter (3$\Phi$4L Inverter) used in off-grid applications is addressed in this paper. Open circuit and short circuit faults of the power devices located in the $3 \Phi 4 \mathrm{~L}$ Inverter have been theoretically analyzed. Hence, the fault detection and converter protection strategy has been implemented using a combination of a resonant controller in the $\alpha \beta$ frame and a repetitive observer. The proposed strategy has been at first validated by means of simulation results performed in MATLAB/Simulink environment. The fault detection and ride-through algorithm has been then implemented in FPGA using LabVIEW environment and full experimental verification are performed on the prototype of the three-phase 4-leg inverter.