A Decentralized Fault-Tolerant Control Strategy for Multilevel CHB Inverters Based on a Multiband Hysteresis Modulation

In recent decades, multilevel inverters have become increasingly common in medium-voltage applications. Among the various topologies, the cascaded H-bridge (CHB) stands out as a particularly fault-tolerant configuration. Its modular structure, composed of multiple H-bridge inverters connected in series, allows for the implementation of a decentralized control strategy in which every H-bridge module is considered to act autonomously. In this paper, such decentralized control is described for the current control loop based on a multiband hysteresis controller, aiming at increasing the flexibility of the system and guaranteeing the fault-tolerant operation while inherently balancing the states of charge
$(\text{SoC})$
of the power sources without further communication. Simulations have been carried out to validate the proposed method and identify its limitations. A hardware implementation is used to demonstrate the load balancing between the modules under non-ideal conditions.