Fault-tolerant operation of a medium voltage drive based on the Cascaded H-bridge inverter

In this paper, a fault-tolerant strategy for operation of a cascaded H-bridge multilevel drive is presented. A faulty power cell in the Cascaded H-bridge (CHB) inverter may lead to expensive downtime and great losses in the motor side. With a fault-tolerant control strategy, the operation can continue and the system reliability increases in this way. Here, the operating principle and the space vector modulation strategy for the 3-phase CHB inverter are explained in detail. Using the proposed algorithm, the medium voltage induction machine will operate symmetrically even when a failure happens in a power cell or in a phase leg. A multi level fault-tolerant CHB inverter is designed for a 2.3 kV induction motor and its performance is verified by Matlab/Simulink program in different faulty situations. Simulation results confirm the effectiveness of the proposed strategy for MV machines.