A Multiphase Fault-Tolerant MLI With Preserved Rated Output for Emergency Load Applications

In multilevel inverters (MLIs), the increased number of switches directly impacts the system's reliability due to the lack of fault-tolerant capability. Thus, this work proposes a new T-type fault-tolerant MLI (TFTMLI) to enhance the system's reliability. The proposed converter is derived by adding a redundant unit and a resistor-switch circuit to the basic T-type MLI. The addition of these components improves redundant switching paths and resolves the capacitor voltage balancing issue during the postfault operation without any additional voltage sensory circuit. The operation of the proposed TFTMLI under healthy and different single-phase and multiphase faulty cases using level-shifted pulsewidth modulation is presented in detail. To validate the performance of the proposed TFTMLI, a 500-W experimental prototype is fabricated, and corresponding results are presented for healthy and different fault case studies. Furthermore, the reliability analysis is conducted with the help of Markov chain model, and an efficiency analysis is performed using PLECS software. In addition, the proposed TFTMLI is compared with the recent literature in terms of fault-tolerant capability and reliability. The higher reliability of the proposed TFTMLI integrating simple capacitor voltage balance technique is shown to be promising in remote and emergency applications.