Supervised control of buck-boost converters for aeronautical applications

Recent MEA (More Electric Aircraft) concepts require new approaches to design and management of the electric system onboard. Bidirectional Buck-Boost Converter Units (BBCU's) used like bridges between power buses with different voltage require intelligent supervisory control for autonomous selection of operating modes. In this paper at low-level, sliding manifold-based strategies are employed to track desired current references, or to recover from overload within a prescribed time. At a higher level, three working modes are defined, (Buck-, Boost- and Intermediate-Mode), and scheduled by a high-level supervisory strategy. Stability proofs of the overall strategy require estimates of the Region of Attraction (ROA) for each controller, that are discussed in the paper. A typical aeronautic scenario is presented, with standard operating conditions followed by two types of overloads (the second more severe than the first) and finally a return to standard condition. Detailed numerical simulations show the effectiveness of the proposed novel control strategy in terms of stability and performance of the smart converter.