Digital Predictive Peak Current-Mode Control for Three-Level Buck Converters

This paper addresses the application of digital predictive current-mode control (DPCMC) to three-level flying-capacitor Buck converters (3LFC). While DPCMC has been extensively studied for basic dc-dc topologies, its reliable application to multilevel converters is subject to the constraint that the flying capacitor voltage(s) remains stable. This work clarifies the stability properties of predictive peak current-mode control for three-level converters when operated in single-sampling and multisampling mode. A specific implementation of the multisampled DPCMC through a fast-update of the duty cycle command is also disclosed and analyzed which guarantees system stability and FC voltage balancing while significantly extending the dynamic capabilities of the converter. Results are validated in simulation and experimentally on a low-voltage 3LFC prototype.