Control of Energy Storage Systems for Aeronautic Applications

Future aircraft will make more and more use of automated electric power system management onboard. Different solutions are currently being explored, and in particular the use of a supercapacitor as an intelligent energy storage device is addressed in this paper. The main task of the supercapacitor is to protect the electric generator from abrupt power changes resulting from sudden insertion or disconnection of loads or from loads with regenerative power capabilities, like electromagnetic actuators. A controller based on high-gain concepts is designed to drive a DC/DC converter connecting the supercapacitor to the main electric bus. Formal stability proofs are given for the resulting nonlinear system, and strong robustness results from the use of high-gain and variable structure control implementation. Moreover, detailed simulations including switching devices and electrical parasitic elements are provided for different working scenarios, showing the effectiveness of the proposed solution

Robust Control of Aeronautical Electrical Generators for Energy Management Applications

A new strategy for the control of aeronautical electrical generators via sliding manifold selection is proposed, with an associated innovative intelligent energy management strategy used for efficient power transfer between two sources providing energy to aeronautical loads, having different functionalities and priorities. Electric generators used for aeronautical application involve several machines, including a main generator and an exciter. Standard regulators (PI or PID-like) are normally used for the rectification of the generator voltage to be used to supply a high-voltage DC bus. The regulation is obtained by acting on a DC/DC converter that imposes the field voltage of the exciter. In this paper, the field voltage is fed to the generator windings by using a second-order sliding mode controller, resulting into a stable, robust (against disturbances) action and a fast convergence to the desired reference. By using this strategy, an energy management strategy is proposed that dynamically changes the voltage set point, in order to intelligently transfer power between two voltage busses. Detailed simulation results are provided in order to show the effectiveness of the proposed energy management strategy in different scenarios

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

Analytical approach to electrical distribution systems for aircraft

The More Electric Aircraft concept (MEA) is one of the most discussed topics of the recent decades inside the aircraft market. It aims to enable the migration towards more efficient aircraft while reducing the environmental impact by substituting the hydraulic, pneumatic and mechanical parts with their electrical counterparts. As the electrical systems became more complex, it is inevitable the need of a control unit that can manage the EPS under all the possible scenarios. For this reason, this thesis presents different study cases that a supervisor controller (SC) unit must address for guarantying the optimal EPS operations. In particular, the SC must be able to manage the network overloads, for preventing unwanted operations or oversized design of the on-board generators. Moreover, applying constant EPS monitoring, the SC must be able to solve critical scenarios by splitting the power flow on a different path. Apart from failure and critical tasks, the SC must be also employed in the EPS optimization using a mathematical algorithm that ensures the correct power spreading across each bus. After the introduction to the actual employed algorithms and used EPS, all the described cases are simulated inside Simulink® environment and a test bench is then configured to emulate a portion of a scaled EPS in the laboratory