Optimised reference wave generation method for cell-fault treatment of cascaded inverter

To increase the fault tolerance for cascaded H-bridge inverter, an optimised reference waveforms generation method is proposed for cell-fault treatment of cascaded H-bridge inverter. The optimised reference waveforms were obtained by normalization of the unbalanced phase voltage fundamental, and which were used to replace the sine wave reference signals in pulse width modulation process to improve the voltage utilization. Compared with conventional control methods, this method generates balanced line to line voltage with a higher magnitude in most fault modes; the reliability of the system is then enhanced. The simulation results agree with the theoretical analysis.