Stability Approach for Vehicles DC Power Network: Application to Aircraft On-board System

Abstract

Vehicles of the future will store, transport and use large amounts of electrical energy. The main components of DC networks are power electronic converters. Combinations of such converters are known to be unstable in certain situations. By investigating the causes of instability and comparing current methods, a state space representation is chosen for converter modelling. The concepts of sensitivity and participation factors applied to network models are proposed to address the requirement for algorithms aimed at optimisation. Conclusions are drawn for converters under development for aircraft systems. It is possible to identify parameters responsible for instability, sensitivity to network parameters at different operating points and the safety margins available. Thanks to this method, passive elements are optimised by reducing their global weight and volume.

Energetic impedances: Application to large signal stability analysis of DC power systems

“…In fact, for an electric device, the characteristic impedances are efficient around a given operating point and for a given set of system parameters. To investigate stability properties of the system in case of parameters variations, some authors have introduced first order methods based on µ analysis or modal approach to ensure the stability for bounded variations of parameters [6], [7]. Nevertheless with these approaches, the behavior of the system for large magnitude perturbations is yet unknown.…”

A new methodology for aircraft HVDC power systems design

“…On-board aircraft electrical power system is then set to evolve, with the "All Electrical" concept, to a High Voltage DC structure, mainly for weight gain, efficiency, reliability and reduced maintenance cost reasons [1]. This evolution was initiated by the European aircraft manufacturers in the "Power Optimized Aircraft" EU project and is now followed by the "More Open Electrical Technologies" project [2,3,4]. To achieve efficient operation conditions, several standards are imposed by the aircraft manufacturer to the individual devices suppliers.…”

Stability studies of critical DC power system component for More Electric Aircraft using μ sensitivity

“…It is already recognized that the regulated DC/DC converter, e.g. the buck converter, is one of the most critical components in on-board electric networks [3]. Switching-mode regulators have a negative input resistance at low frequencies and may become unstable by the addition of an input filter [15].…”

“…Only the input impedance of the load subsystem and the output impedance of the source subsystem and their Bode diagrams are needed [15]. But the Middlebrook criterion is restrictive and not appropriate for design and optimization goals [3]. The analytic calculation of the input/output impedances may be extensive while there is no information on the sensitivity of the impedances to parameter variations available for an hardware measurement approach [5] or automated calculation with a simulation tool.…”