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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 In MEAs, many subsystems that previously used hydraulic or pneumatic power have been replaced by electrical systems, and hence the weight of inverters has significant importance.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.

This paper describes the comparison of electromagnetic characteristics of two different superconducting-motor structures for electrified aircraft propulsion systems. Future electrified aircraft demand higher output (over 16 kW/kg) and higher efficiency (> 98%) for their motors in comparison with current ones. To satisfy the demands, two kinds of superconducting motors are dealt in this study: one is partially superconducting motors (PSCMs), made of superconducting field coils and copper armature windings; the other is the fully superconducting motors (FSCMs) made of superconducting field/armature windings. They are cooled at 20 K with liquid hydrogen. We designed these two motors with finite element method to obtain the output density of 16-20 kW/kg for future electrified propulsion systems. We selected 3.0- and 5.0 MW superconducting motors, considering the application to aircraft for almost 180 passengers and 44 MW rated power for take-off.

Current More Electric Aircraft (MEA) utilize Liquid Cooling Systems (LCS) for cooling on-board power electronics. In such LCS, coolant pipes around the structure of the aircraft are used to supply water glycol based coolant to sink heat from power electronics and other heat loads in the electronic bay. The extracted heat is then transferred to ram air through downstream heat exchangers. This paper presents a reliability examination of a proposed alternative Autonomous Air Cooling System (AACS) for a twin engine civil MEA case study. The proposed AACS utilizes cabin air as the coolant which is in turn supplied using the electric Environmental Control System (ECS) within the MEA. The AACS consists of electrical blowers allocated to each heat load which subsequently drive the outflow cabin air through the heat sinks of the power electronics for heat extraction. No additional heat exchanger is required after this stage in which the heated air is directly expelled overboard.

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.

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.