A multi-port power conversion system for the more electric aircraft

In more electric aircraft (MEA) weight reduction and energy efficiency constitute the key figures. Additionally, the safety and continuity of operation of its electrical power distribution system (EPDS) is of critical importance. These sets of desired features are in disagreement with each other, because higher redundancy, needed to guarantee the safety of operation, implies additional weight. In fact, EPDS is usually divided into isolated sections, which need to be sized for the worst-case scenario. Several concepts of EPDS have been investigated, aiming at enabling the power exchange among separate sections, which allows better optimization for power and weight of the whole system. In this paper, an approach based on the widespread use of multi-port power converters for both DC/DC and DC/AC stages is proposed. System integration of these two is proposed as a multiport power conversion system (MPCS), which allows a ring power distribution while galvanic isolation is still maintained, even in fault conditions. Thus, redundancy of MEA is established by no significant weight increase. A machine design analysis shows how the segmented machine could offer superior performance to the traditional one with same weight. Simulation and experimental verifications show the system feasibility in both normal and fault operations

Electrical power generation in aircraft: review, challenges and opportunities

The constant growth of air traffic, the demand for performance optimization and the need for decreasing both operating and maintenance costs have encouraged the aircraft industry to move towards more electric solutions. As a result of this trend, electric power required on board of aircraft has significantly increased through the years, causing major changes in electric power system architectures. Considering this scenario, the paper gives a review about the evolution of electric power generation systems in aircraft. The major achievements are highlighted and the rationale behind some significant developments discussed. After a brief historical overview of the early DC generators (both wind- and engine-driven), the reasons which brought the definitive passage to the AC generation, for larger aircraft, are presented and explained. Several AC generation systems are investigated with particular attention being focused on the voltage levels and the generator technology. Further, examples of commercial aircraft implementing AC generation systems are provided. Finally, the trends towards modern generation systems are also considered giving prominence to their challenges and feasibility

Advanced Electrical Machines and Machine-Based Systems for Electric and Hybrid Vehicles

The paper presents a number of advanced solutions on electric machines and machine-based systems for the powertrain of electric vehicles (EVs). Two types of systems are considered, namely the drive systems designated to the EV propulsion and the power split devices utilized in the popular series-parallel hybrid electric vehicle architecture. After reviewing the main requirements for the electric drive systems, the paper illustrates advanced electric machine topologies, including a stator permanent magnet (stator-PM) motor, a hybrid-excitation motor, a flux memory motor and a redundant motor structure. Then, it illustrates advanced electric drive systems, such as the magnetic-geared in-wheel drive and the integrated starter generator (ISG). Finally, three machine-based implementations of the power split devices are expounded, built up around the dual-rotor PM machine, the dual-stator PM brushless machine and the magnetic-geared dual-rotor machine. As a conclusion, the development trends in the field of electric machines and machine-based systems for EVs are summarized

Fly-By-Light/Power-By-Wire Requirements and Technology Workshop

The results of the Fly-By-Light/Power-By-Wire (FBL/PBW) Workshop held on March 17-19, 1992, at the NASA Langley Research Center are presented. The FBL/PBW program is a joint NASA LeRC/LaRC effort to develop the technology base for confident application of integrated FBL/PBW systems to transport aircraft. The objectives of the workshop were to ascertain the FBL/PBW program technical requirements and satisfy the requirements and needs from the industry viewpoint, provide a forum for presenting and documenting alternative technical approaches which satisfy the requirements, and assess the plan adequacy in accomplishing plan objectives, aims, and technology transfer. Areas addressed were: optical sensor systems, power-by-wire systems, FBL/PBW fault-tolerant architectures, electromagnetic environment assessment, and system integration and demonstration. The workshop consisted of an introductory meeting, a 'keynote' presentation, a series of individual panel sessions covering the above areas, with midway presentations by the panel chairpersons, followed by a final summarizing/integrating session by the individual panels, and a closing plenary session summarizing the results of the workshop

Electronic/electric technology benefits study

The benefits and payoffs of advanced electronic/electric technologies were investigated for three types of aircraft. The technologies, evaluated in each of the three airplanes, included advanced flight controls, advanced secondary power, advanced avionic complements, new cockpit displays, and advanced air traffic control techniques. For the advanced flight controls, the near term considered relaxed static stability (RSS) with mechanical backup. The far term considered an advanced fly by wire system for a longitudinally unstable airplane. In the case of the secondary power systems, trades were made in two steps: in the near term, engine bleed was eliminated; in the far term bleed air, air plus hydraulics were eliminated. Using three commercial aircraft, in the 150, 350, and 700 passenger range, the technology value and pay-offs were quantified, with emphasis on the fiscal benefits. Weight reductions deriving from fuel saving and other system improvements were identified and the weight savings were cycled for their impact on TOGW (takeoff gross weight) and upon the performance of the airframes/engines. Maintenance, reliability, and logistic support were the other criteria

Integration of magnetic bearings in the design of advanced gas turbine engines

Active magnetic bearings provide revolutionary advantages for gas turbine engine rotor support. These advantages include tremendously improved vibration and stability characteristics, reduced power loss, improved reliability, fault-tolerance, and greatly extended bearing service life. The marriage of these advantages with innovative structural network design and advanced materials utilization will permit major increases in thrust to weight performance and structural efficiency for future gas turbine engines. However, obtaining the maximum payoff requires two key ingredients. The first key ingredient is the use of modern magnetic bearing technologies such as innovative digital control techniques, high-density power electronics, high-density magnetic actuators, fault-tolerant system architecture, and electronic (sensorless) position estimation. This paper describes these technologies. The second key ingredient is to go beyond the simple replacement of rolling element bearings with magnetic bearings by incorporating magnetic bearings as an integral part of the overall engine design. This is analogous to the proper approach to designing with composites, whereby the designer tailors the geometry and load carrying function of the structural system or component for the composite instead of simply substituting composites in a design originally intended for metal material. This paper describes methodologies for the design integration of magnetic bearings in gas turbine engines

Structure development and simulation of plug-in hybrid electric vehicle

Electric-drive vehicles (EDVs) have gained attention, especially in the context of growing concerns about global warming and energy security aspects associated with road transport. The main characteristic of EDVs is that the torque is supplied to the wheels by an electric motor that is powered either solely by a battery or in combination with an internal combustion engine (ICE). This covers hybrid electric vehicles (HEVs), battery electric vehicles (BEVs), and plug-in hybrid electric vehicles (PHEVs), but also photovoltaic electric vehicles (PVEVs) and fuelcell vehicles (FCVs). [1] So we initiated research work with a view to assess the economic impacts,engineering constraints and user needs of a future market penetration of those car technologies, with a focus on PHEVs. As a starting step, we reviewed the literature and prepared this paper which provides a summary description of the technology aspects, the current state of the research and development in the field. It also elaborates consistent sets of data about the vehicle technologies in view of the subsequent modeling work to undertake the assessment. The paper also identifies a series of areas where more data and assessment are needed

Design rules to establish a credible More-Electric Engine baseline power architecture concept

The More-Electric Engine (MEE), with its electrified engine auxiliary systems and increased multi-shaft power offtake, is likely to become an increasingly central aspect of future More-Electric Aircraft. Consequently, lightweight but resilient electrical power architectures are needed for these future MEE applications. However, whilst a range of MEE architectures exist in the research literature, no effective baseline architecture or standardised feature identification has been proposed to specifically address their unique design requirements. Accordingly, any underpinning technology-focused research for critical MEE subsystems may ultimately have a reduced effectiveness without this credible baseline. Based on comprehensive design analyses, preliminary design requirements and anticipated operational modes, this article proposes key design rules for the formation of the first generic baseline MEE electrical power system architecture concept. Guidance is provided on features such as the number of power generation systems, the number and topologies of distribution channels, type of power conversion, essential load redundancy, and the location of emergency power supply. This article also provides full transparency of the design process so that key decision points can be revisited to capture application-specific requirements and updates to certification requirements

A Fault-Tolerant Control Architecture for Induction Motor Drives in Automotive Applications

International audienceThis paper describes a fault-tolerant control system for a high-performance induction motor drive that propels an electrical vehicle (EV) or hybrid electric vehicle (HEV). In the proposed control scheme, the developed system takes into account the controller transition smoothness in the event of sensor failure. Moreover, due to the EV or HEV requirements for sensorless operations, a practical sensorless control scheme is developed and used within the proposed fault-tolerant control system. This requires the presence of an adaptive flux observer. The speed estimator is based on the approximation of the magnetic characteristic slope of the induction motor to the mutual inductance value. Simulation results, in terms of speed and torque responses, show the effectiveness of the proposed approach