Seok-Min Kim, June-Seok Lee, and Kyo-Beum Lee, "A Modified Level-Shifted PWM Strategy for Fault Tolerant Cascaded Multilevel Inverters with Improved Power Distribution," IEEE Transactions on Industrial Electronics, vol. 63, no. 11, pp. 7264–7274, Nov. 201 > Paper

To increase the fault tolerance for cascaded H-bridge multilevel inverters (CHMIs) based on level-shifted pulse width modulation

(LS-PWM), a modified LS-PWM method is proposed for the inverters operating under faulty conditions. To cover both open- and

short-device fault cases, two types of switching scheme are included in this PWM method. With this PWM method, the neutral shift

can be applied as fault-tolerant control for CHMIs based on LS-PWM. Finally, three-phase-balanced line-to-line voltages and

currents with minimum harmonic distortion are produced for the inverter with disabled power cells. In addition, this LS-PWM

method has the capability to improve power distribution among the H-bridge power cells under the faulty conditions. Simulation

and experimental results show that the proposed PWM method performs satisfactorily to achieve fault tolerance.