Design of modular, CFRP-encased electrical power systems for more-electric aircraft applications

Decarbonisation of aviation is directly supported by the twin trends of electrification of aircraft, and use of light-weight, carbon fibre reinforced polymer (CFRP) aircraft structures. The concept of creating a modularised electrical power system (EPS), with EPS equipment encased in CFRP opens up new design opportunities for electrification of aircraft systems; reduced weight and volume, reduced time out-of-service due to maintenance. Such systems necessitate an understanding of how electrical and structural systems interact, and the design boundary between the CFRP providing combined electrical and structural functionality, versus CFRP with a purely structural functionality, with a separate electrical system encased in CFRP. A power electronic converter (PEC) is an enabling technology for the more-electric aircraft EPS. The paper identifies the key design interdependencies, trades and integrated systems design levers for design of a CFRP casing for a PEC module through a conceptual case study. This includes the capture of high and low frequency electrical functionality, thermal management requirements, and their interdependencies with the topology and functional role of the PEC and the wider EPS architecture. This knowledge is combined to present a design methodology for the design of composite casings for PEC in modularised, on-board electrical power systems

Electrical and Thermal Effects of Fault Currents in Aircraft Electrical Power Systems with Composite Aerostructures

The upwards trend for the use of electrical power on state of the art aircraft is resulting in significant change to the design of power system architectures and protection systems for these platforms. There is a pull from the aerospace industry to integrate the electrical power system with the aircraft’s structural materials to form an embedded system, reducing the need for bulky cable harnesses. This directly impacts the fault response for ground faults and ultimately the development of appropriate protection systems. Such structural materials include composites such as carbon fibre reinforced polymer (CFRP). This paper presents the experimental capture and analysis of the response of CFRP to electrical fault current, which indicates the need for two distinct sets of electrical ground fault detection criteria for low and high resistance faults and identifies the threshold resistance for this distinction. By extrapolating these results to develop models of CFRP for use in transient simulation studies, the key electrical fault detection thresholds for speed, selectivity and sensitivity for a DC system rail to ground fault through CFRP are identified. This provides the first set of key factors for electrical fault detection through CFRP, providing a platform for the design of fully integrated structural and electrical power systems, with appropriate electrical protection systems

Nurses' perceptions of aids and obstacles to the provision of optimal end of life care in ICU

Contains fulltext : 172380.pdf (publisher's version ) (Open Access

Adaptive V/f-Based Control for Induction Machines in Distributed Electric Propulsion Systems

A novel adaptive control function is presented as an improvement to the classic volts per hertz (V/f) technique where high torque oscillations occur during rapid changes of the rotating speed. The proposed adaptive feature of an improved controller limits torque oscillations by injecting a pulse and imposing the pre- determined bands on a voltage reference waveform whenever the scheduled change in speed occurs. This adaptive function has been integrated with the closed-loop V/f control scheme, subsequently modelled and evaluated numerically using transient simulation studies, as well as experimentally using an induction machine drive test rig. The results have shown that the proposed adaptive element provides an improved dynamic performance for using the V/f method, which is required in compact distributed drive systems with single voltage source inverter (VSI) controlling multiple interconnected motors