Smart Buck-Boost Converter Unit operations for aeronautical applications

In this paper, sliding mode control for DC/DC Buck/Boost bidirectional converters (BBCU, Buck-Boost Converter Unit) is considered. The approach stems from aeronautic applications, and aims to produce an intelligent device able to autonomously switch from buck mode, where the battery pack onboard is recharged, to boost mode, where some energy from the battery is required to supply critical loads.Two levels of control are detailed: low-level switching, based on the sliding mode mathematical theory, and supervisory control of the device, based on hybrid control. Proofs of stability are provided. A scenario with standard operating conditions, then an overload and finally a return to standard condition is presented, and numerical simulations show the effectiveness of the proposed novel control strategy in terms of stability and performance of the smart converter. Direct implementation with hysteretic controllers or PWM are possible, and also finite-time stability considerations are given.