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This paper describes study for fuel pump system configuration which is suitable for the MEE (More Electric Engine) system. The MEE is a new engine system concept which intends engine efficiency improvement, which results in a reduction of engine fuel burn and CO₂ emissions from aircraft. Final configuration of the MEE will contain various engine systems, such as fuel system, oil system and electric generating system, but we focus on high efficiency fuel systems as a first step of the MEE development. The MEE is an advanced engine control technology utilizing recent innovations in electric motors and power electronics and replacing conventional engine accessories, such as AGB-driven pumps and hydraulic actuators with electric motor-driven pumps and EMAs (Electro-Mechanical Actuators), which are powered by generators. Because fuel pump system configuration is a key for the MEE fuel system, we conducted comparison of several pump systems and adopted a fixed displacement gear pump system.

This paper describes a concept related to fault-tolerant design for a redundant motor control system. The design comprises components driven by an electric motor, a motor controller, and a power source, referred to as the More Electric Aero Engine (or MEE). The MEE dramatically improves the engine efficiency and reduces fuel burn and CO2 emissions. However, the MEE system must demonstrate that it can ensure engine safety and reliability before it can take the place of conventional systems. The proposed unique redundant system presented in this paper incorporates Active-Active control and multi-winding motors. Engine fuel flow is controlled by the motor speed control of the MEE electric fuel pump, which uses this redundant system. This concept provides a solution for helping to ensure engine safety and reliability, since it enables a complete one-fail operational engine fuel system for the MEE. Another key technology for the MEE system involves a power generating solution.

With airlines increasingly directing their attention to operating costs and environmental initiatives, the More Electric Architecture for Aircraft and Propulsion (MEAAP) is emerging as a viable solution for improved performance and eco-friendly aircraft operations. This paper focuses on electric taxiing that does not require the use of jet engines or the auxiliary power unit (APU) during taxiing, either from the departure gate to take-off or from landing to the arrival gate. Many researchers and engineers are considering introducing electric taxiing systems as part of efforts to improve airport conditions. To help cut aircraft emissions at airports, MEAAP seeks to introduce an electric taxiing system that would reduce the duration for which engines and APUs operate while on the ground. Given this goal, the aircraft electrical system deployed for use at airports must rely on a power source other than the jet engines or APU.

The authors are currently developing the MEE (More Electric Engine) electric motor-driven fuel pump system for aircraft engines. The electric fuel system will contribute to the reduction of engine power extraction to drive the fuel pump; thus, an improvement in engine efficiency will be expected. In addition, the engine system reliability will be improved by introducing advanced electric architecture, and the reduction of hydraulic components, fuel tubes and fittings is effective to enhance the maintainability of the engine. Although it is considered that the MEE electric fuel system will realize several benefits, there are technical challenges to introduce such new electric system into aircraft. One of the key technical challenges is to construct a redundant and simplified electric fuel system, because continuous operation of the fuel pump system is crucial for aircraft safety.

This paper describes a study on electrical power management for the More Electric Aircraft (or MEA) and the More Electric Engine (or MEE). This study explored power management solutions based on an integrated engine/power control system and a permanent magnet motor. In recent years, electrical power management has emerged as a key aspect of aircraft system design. In cases in which the Electromechanical Actuator (or EMA) systems are used for flight control, the power bus systems must also be designed to dissipate the power regenerated from flight control systems. In their study, the authors focused on achieving an optimal balance between aircraft power management and operational requirements of the aero-engines. The study results suggest an effective and novel power control concept based on integrated engine control technologies that ensure stable power systems.

Electrical power management is a key technology in the AEA (All-Electric Aircraft) system, which manages the supply and demand of the electrical power in the entire aircraft system. However, the AEA system requires more than electrical power management alone. Adequate thermal management is also required, because the heat generated by aircraft systems and components increases with progressive system electrification, despite limited heat-sink capability in the aircraft. Since heat dissipation from power electronics such as electric motors, motor controllers and rectifiers, which are widely introduced into the AEA, becomes a key issue, an efficient cooling system architecture should be considered along with the AEA system concept. The more-electric architecture for the aircraft has been developed; mainly targeting reduced fuel burn and CO2 emissions from the aircraft, as well as leveraging ease of maintenance with electric/electronic components.

Aircraft designers determine the optimum aircraft configuration to meet performance requirements. Aircraft secondary power systems are very important for aircraft operation, however, traditionally these systems have not been considered in detail while the aircraft configuration and specifications are preliminary studied. Therefore, we constructed an aircraft conceptual design tool considering the many aircraft systems. Furthermore, we applied this design tool to a simple design problem taking into account two different kinds of secondary power system architectures (i.e. the conventional bleed air system and the more electric system), and discussed how the introduction of new aircraft systems affects results. Although the present method is theoretical and conceptual with limited applicability, the effect of the aircraft's secondary power system upon the concerning aircraft specifications was made clear both for the bleed air system and the more electric system.

With the growth in onboard electrification referred to the movement of the More Electric Aircraft, or MEA, and constant improvement in ECO standards, aircraft electricity load has continued to soar. The airline and authors have discussed the nature of future aircraft systems in the next two decades, which envisages the further More Electric Aircraft or the All-Electric Aircraft, or AEA, concept helping provide some effective aviation improvements. The operators, pilots and maintenance crews anticipate improved operability, ease of maintenance and fuel saving, while meetings depends for high reliability and safety by electrification. As part of initial progress, the authors approach the methodology of energy management for aircraft systems.

This paper describes the concept of an air/fuel integrated thermal management system, which employs the VCS (Vapor Cycle System) for the refrigeration unit of the ECS (Environment Control System), while exchanging the heat between the VCS refrigerant and the fuel into the engine, and presents a feasibility study to apply the concept to the future all electric aircraft systems. The heat generated in an aircraft is transferred to the ECS heat exchanger by the recirculation of air and exhausted into the ram air. While some aircraft employ the fluid heat transfer loop, the transferred heat is exhausted into the ram air. The usage of ram air for the cooling will increase the ram drag and the fuel consumption, thus, less usage of ram air is preferable. Another source for heat rejection is the fuel. The heat exchange with the fuel does not worsen the fuel consumption, thus, the fuel is a preferable source.

The more electric aircraft (MEA) concept has been attracting attention over recent decades to reduce emissions and fuel consumption. In MEAs, many subsystems that previously used hydraulic or pneumatic power have been replaced by electrical systems, and hence the weight of inverters has significant importance. The weight of inverters is largely attributed to passive filters that reduce the derivative of output voltages dv/dt and electromagnetic interference noises caused by common-mode voltages. To reduce the size of passive filters, multilevel inverters with 5 or more voltage steps are preferred. However, classic multilevel inverters have some challenges to achieve these step numbers without using plural dc power supplies that require massive transformers. In this work, a gradationally controlled voltage (GCV) inverter is proposed for MEAs.

In development of more electric aircraft applications, it is important to discuss aircraft energy management on various level of aircraft operation. This paper presents a computationally efficient optimization model for evaluating flight efficiency on global and interval flight ranges. The model is described as an optimal control problem with an objective functional subjected to state condition and control input constraints along a flight path range. A flight model consists of aircraft point-mass equations of motion including engine and aerodynamic models. The engine model generates the engine thrust and fuel consumption rate for operation condition and the aerodynamic model generates the drag force and lift force of an aircraft for flight conditions. These models is identified by data taken from a published literature as an example. First, approximate optimization process is performed for climb, cruise, decent and approach as each interval range path.

Aircraft electrification is one of technological innovations to achieve the goal of CO2 emission reduction in civil aviation. In present research, we focus ourselves on an Electric Fuel Metering System (EFMS). Aircraft systems are commonly expected to make not only simplified configuration and improvement of controllability, but also safety and reliability. The electrification of fuel system also requires the similar approach. Therefore, a simple and reliable redundancy concept is a crucial challenge. In addition, stable and responsive controllability that does not affect engine operation is required, especially in fuel system, it is desired to achieve both accurate metering and short settling time without overshoot or undershoot. However, in such a system, the response is nonlinear due to the fuel flow circuit and the motor drive during current limiting.