Decentralized Control of a Cascaded H-Bridge Multilevel Converter

Despite its inherently modular hardware structure, the control system of most cascaded H-bridge converters is usually highly centralized, and relies on a high bandwidth intra-converter communication system to transmit time critical control signals to the module controllers. In contrast, this paper presents a decentralized control strategy for a modular cascaded converter, where each module controller determines its own switching actions based on local sensors, a local current regulator and a local modulator. The system achieves the same performance as a centralized control system, with a low bandwidth requirement for the intra-converter communication system. Controller high voltage isolation requirements are also reduced because most of the system measurement sensors can be embedded within each converter module slave controller.