Low-Power Multi-Level Flying Capacitor Converters - Modeling and Control

The work presented in this thesis focuses on overall volume reduction of the dc-dc power supplies used in low-power applications, processing from fraction of watt up to tens of watts. In particular, applicability of multi-level flying capacitor topologies widely used in high-power kilowatt and megawatt ac-dc, ac-dc, ac-ac and dc-dc applications is investigated. It is shown that flying capacitor multi-level topologies can be attractive alternative to the conventional 2-level buck converter predominantly used in low-power applications through a quantitative analysis of passive volume and losses. Also, the dynamic behaviour of these converters is analyzed and related control challenges are presented. A novel dynamic model and additional insight into the physical behaviour of these converters are shown. A set of different control methods, grouped in different chapters, applicable in low, as well as in high power, applications are introduced. The control methods are developed using synthesizable Verilog code suitable for IC implementation. Their effectiveness, has been experimentally verified with several low-power multi-level dc-dc converters processing up to 50 W of output power.Ph.D.2020-03-26 00:00:0