Optimization of neutral shift in cell-fault treatment for cascaded H-bridge inverter

To improve the output performance of cascaded H-bridge multilevel inverter under faulty conditions, this paper presents an optimized method suitable for harmonic cancellation while the faulty inverter are operated with neutral shift. With some parameters adjusted according to the fault type, the line to line voltages of the cell-fault inverter are increased than traditional control method, while keeping balanced and less distorted; the reliability of the system is then enhanced. The experimental results verify the validity of the proposed method.