Energy Storage System Control for Energy Management in Advanced Aeronautic Applications

In this paper an issue related to electric energy management on board an aircraft is considered. A battery pack is connected to a high-voltage bus through a controlled Battery Charge/Discharge Unit (BCDU) that makes the overall behaviour of the battery “intelligent.” Specifically, when the aeronautic generator feeding the high-voltage bus has enough energy the battery is kept under charge, while if more loads are connected to the bus, so that the overload capacity of the generator is exceeded, the battery “helps” the generator by releasing its stored energy. The core of the application is a robust, supervised control strategy for the BCDU that automatically reverts the flow of power in the battery, when needed. Robustness is guaranteed by a low-level high gain control strategy. Switching from full-charge mode (i.e., when the battery absorbs power from the generator) to generator mode (i.e., when the battery pumps energy on the high-voltage bus) is imposed by a high-level supervisor. Different from previous approaches, mathematical proofs of stability are given for the controlled system. A switching implementation using a finite-time convergent controller is also proposed. The effectiveness of the proposed strategy is shown by detailed simulations in Matlab/Stateflow/SimPowerSystem

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

Nanotechnology-Assisted Cell Tracking

The usefulness of nanoparticles (NPs) in the diagnostic and/or therapeutic sector is derived from their aptitude for navigating intra-and extracellular barriers successfully and to be spatiotemporally targeted. In this context, the optimization of NP delivery platforms is technologically related to the exploitation of the mechanisms involved in the NP–cell interaction. This review provides a detailed overview of the available technologies focusing on cell–NP interaction/detection by describing their applications in the fields of cancer and regenerative medicine. Specifically, a literature survey has been performed to analyze the key nanocarrier-impacting elements, such as NP typology and functionalization, the ability to tune cell interaction mechanisms under in vitro and in vivo conditions by framing, and at the same time, the imaging devices supporting NP delivery assessment, and consideration of their specificity and sensitivity. Although the large amount of literature information on the designs and applications of cell membrane-coated NPs has reached the extent at which it could be considered a mature branch of nanomedicine ready to be translated to the clinic, the technology applied to the biomimetic functionalization strategy of the design of NPs for directing cell labelling and intracellular retention appears less advanced. These approaches, if properly scaled up, will present diverse biomedical applications and make a positive impact on human health

Selective modal control for vibration reduction in flexible structures

The design of a controller for selective reduction of vibrations in flexible low-damped structures is presented. The objective of the active feedback control law is to increase damping of selected modes only, in frequency regions where a disturbance is likely to produce largest effect. Moreover, the stabilizing controller is required to be band-pass, in order to filter out high-frequency sensor noise and low-frequency accelerometer drift, and stable to increase robustness to uncertain parameters. The control design is based on the Inverse Optimal Design approach, through the solution of a matrix Stein equation, resulting in the solution of an optimal H∞ control problem. A grey-box identification approach of the authors is employed for obtaining the model from experimental data or from detailed Finite Element Model (FEM) simulators. The problem of optimal actuator/sensor location is also addressed. Detailed simulation results are provided to show the effectiveness of the strategy

H-infinity Strongly Stabilizing Bandpass Controllers for Selective Natural Modes Damping in Flexible Structures

In this paper by extending previous work of one of the authors the design of a MIMO H∞ feedback controller for flexible systems is proposed. The controller has some very desirable properties for applications related to noise and vibration reduction, since it has limited bandwidth, zero dc-gain and can selectively increase the damping of only some selected natural modes of the flexible structure. This characteristic turns out to be very useful when dealing with lightly damped structures forced by broadband disturbances. Since however the controller is not necessarily stable, by solving an LMI problem, a stable version of the controller is also obtained. The effectiveness of the proposed control strategies is shown on a detailed COMSOL FEM model

Hierarchical control for generator and battery in the more electric aircraft

This paper addresses the problem of intelligent power management for the more electric aircraft framework. The main objective is to regulate the power flow between a low voltage and a high voltage busses through control of a Buck-Boost converter unit. This approach allows the battery to help the generator when an overload scenario occurs, keeping at the same time the battery state of charge above a prescribed threshold. Moreover, in case a continued severe overload causes the battery state of charge to drop below a prescribed threshold, partial shedding of (noncritical) loads occurs. The control objectives are achieved through the design of a hierarchical control strategy based on high gain control for the low level and a finite state automaton for the high level control. Rigorous mathematical proofs of stability are provided for both low level and high level control and a detailed simulator with accurate model of the battery is presented in order to demonstrate the correctness and effectiveness of the proposed approach

Integrated supervised adaptive control for the more Electric Aircraft

The innovative concept of Electric Aircraft is a challenging topic involving different control objectives. For instance, it becomes possible to reduce the size and the weight of the generator by using the battery as an auxiliary generator in some operation phases. However, control strategies with different objectives can be conflicting and they can produce undesirable effects, even instability. For this reason an integrated control design approach is needed, such that stability can be guaranteed in any configuration. In other words, the design of the supervisory controller must be interlaced with that of low-level controllers. Moreover, uncertainties and noisy signals require robust control techniques and the use of adaptiveness in the control algorithm. In this paper, the use of a new adaptive sliding manifold design is proposed for increase robustness against uncertainties and noisy signals, together with a new supervisor exploiting the estimate of the region of attraction of the control laws. A bidirectional voltage converter aiming at recharging batteries and to use the battery to withstand generator overloads is addressed. Detailed and rigorous stability proofs are given for any control configuration, including the switching phases among different control objectives. Effectiveness of the proposed strategies is shown by using a detailed simulator including switching electronic components

Buck-Boost Converter Control for Constant Power Loads in Aeronautical Applications

The design of control strategies for bidirectional DC/DC converters is proposed. The motivation for this paper is the increased request from aeronautic applications of innovative and 'smart' controllers able to manage automatically electrical energy distribution onboard. Two different control strategies are proposed, and also a higher level, supervisory control law is presented, to switch between the two low-level strategies in a safe way, i.e., ensuring the stability of the overall control law. The first low-level controller is based on the definition of a sliding manifold on which the system state evolution is confined by means of High-Gain or Variable Structure Control, while the second low-level controller exploits an adaptive approach to define a suitable reference current. The high-level switching strategy enables the commutation from one low-level controller to the other only if the Region of Attraction of the second controller has been reached, thus ensuring stability of the commutation. The strategies are designed for the case of Constant Power Loads (CPL), that are well known causes of instability. Detailed simulation results in MATLAB/Simulink are provided, in different scenarios, showing the effectiveness of the proposed controllers

MIL-Standards Verification of Battery Control for More Electric Aircraft Application

As a consequence of the increase of air traffic, the innovative topic of the More Electric Aircraft (MEA) has received increasing attention. In this paper, the control of a bidirectional DC/DC converter for battery management in the MEA framework is described. A detailed simulator and simulation campaign have been designed in order to verify the satisfaction of the MIL-STD-704F standard which regulates the behaviour of electric devices on-board the aircraft