Abstract:
The increasing adoption of renewable and clean energy technologies within the electric
power grid has spurred a keen interest in reliable and efficient multilevel inverter
configurations. Among these, the cascaded H-bridge (CHB) inverter has received
attention due to its simplicity and scalability. However, concerns regarding the reliability
of semiconductor switches have prompted the exploration of fault-tolerant solutions. This
research work introduces a novel fault-tolerant CHB topology, which incorporates a
modified H-Bridge (MHB) requiring just two additional switches, a capacitor, and a diode.
During a fault event, the MHB produces a five-level output and doubles the voltage,
effectively compensating for the missing voltage level in the bypassed faulty H-Bridge.
By maintaining consistent output voltage levels, this approach ensures continuous system
functionality, even in the presence of switch failures. Consequently, it reduces complexity
and costs while enhancing power density. Importantly, the proposed MHB can be
seamlessly integrated into any multilevel inverter topology, making it a versatile fault tolerant solution. This work provides a comprehensive description of the operational
analysis and functioning of the MHB. Simulation and Hardware-in-the-loop (HIL)
verification are conducted, alongside the hardware experimental prototype
implementation of the seven-level CHB. The results validate the fault-tolerant operation
of the proposed topology during switch faults, thereby demonstrating its effectiveness in
enhancing the reliability of multilevel inverter systems.
