Switching power converters act as quasi-ideal power interfaces between a supply and a load and can provide tightly regulated DC and variable frequency AC power as needed. Power distribution systems consisting of extensively interconnected networks of power converters are becoming increasingly common. The problem of stability and performance of multi-converter systems is a nonlinear multi-loop control problem and it is relevant to many important emerging applications such as electric cars, electric ships, and alternative energy systems using fuel cells and supercapacitors. These systems present special challenges for design and reliable operation because they are prone to stability problems caused by interactions among converters. Existing control methods focus on control of a single converter. In contrast, an objective of this project is to explore coordinating control strategies taking a systemic point of view. Novel nonlinear control techniques such as synergetic control and dynamic phasors will be used. Another objective is to use active filters and adaptive techniques with online monitoring of system stability. A third objective is to develop design-oriented stability criteria for both DC and AC case starting from existing single-converter stability criteria. The methods to be employed include theoretical investigation of the nonlinear multi-loop control problem at hand, identification of relevant example systems, synthesis of appropriate coordinating controllers using synergetic control and other linear and nonlinear control approaches, and verification of performance through simulation and laboratory experimentation on small-scale systems. The project integrates research and education and includes curriculum development and participation of undergraduate and high school students.
