On the Decentralized Energy Management Strategy for the All-Electric APU of Future More Electric Aircraft Composed of Multiple Fuel Cells and Supercapacitors

In this article, a decentralized energy management strategy (EMS), which is derived from the conventional droop control, is proposed for the auxiliary power unit composed of multiple fuel cells (FCs) and supercapacitors (SCs) of a more electric aircraft. By utilizing a virtual inductor droop scheme to the FC converter and a virtual resistor droop scheme to the SC converter, the proposed EMS is able to split the load power automatically into low and high frequency components and allocate them to the FC and SC units, respectively. In addition, by optimally designing the droop parameters, accurate power sharing among different source units is achieved. The proposed strategy is not only suitable for extending the service life of the system by adding State of Charge (SoC) protection mechanism in the energy management, but also can improve the system reliability as it is compatible for the disconnection of some source units when fault occurs. The operational principle of the proposed EMS and the detailed system design methodology are elaborated, followed by which hardware-in-the-loop simulation study based on Typhoon HIL 602 is done to verify its validity.