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Energy Recovery Rate from an Electric Air-cycle System under the Cruising Altitude and Speed.

Akita University-Takahiro Adachi, Mikio Muraoka
IHI Corporation-Naoki Seki, Hitoshi Oyori
  • Technical Paper
  • 2019-01-1905
To be published on 2019-09-16 by SAE International in United States
In this study, we focus on an electric air-cycle system in an electric aircraft, where the system has an electric compressor instead of a hydraulically-operated oil-based compressor. The electric compressor consumes the power to compress the rarefied air outside and take it in the system. The air goes through the air-cycle as a working fluid to exchange the heat and work. The main purpose of the air-cycle is to adjust the temperature and pressure in a cabin. Therefore, the working fluid of the air repeats compression and expansion. The working fluid passing through the cabin absorbs heat from the passengers and avionics. After that, the air is discharged outside with higher heat level and pressure levels. This means that the discharged air has a potential energy to recover the power consumption in the electric compressor. So, we have analytically estimated an energy recovery rate which is defined as a ratio of the potential energy of the discharged air to the energy consumption in the compressor, and shown the recovery rate under the condition of cruising…

Gradationally Controlled Voltage Inverter for More Electric Aircrafts

IHI Corporation-Hitoshi Oyori
Mitsubishi Electric Corp.-Tetsuya Kojima, Masahiro Sugahara, Yusuke Shirouchi, Hisatoshi Fukumoto, Akihiko Iwata
  • Technical Paper
  • 2019-01-1913
To be published on 2019-09-16 by SAE International in United States
Over recent decades, there has been a lot of progress toward a more electric aircraft (MEA) to reduce emissions and fuel consumption. In MEAs, many subsystems that previously used hydraulic or pneumatic power have been replaced by electrical systems with inverters and electrical machines. Therefore, MEAs reduce the weight, i.e. fuel consumption, and maintenance cost. To achieve advanced electrical systems, the weight of inverters has significant importance. In this work, a gradationally controlled voltage (GCV) inverter is proposed to reduce the weight and enhance reliability. A GCV inverter can supply gradational quasi-sinusoidal voltages combining two different voltages from a 3-phase 3-level (main) inverter and three single-phase H-bridge (sub) inverters. A dc power supply is required only for the main inverter. A main inverter with Si-IGBTs supplies the fundamental voltage by only one switching in the fundamental period. Consequently, the switching loss is minimized and hence the weight of cooling systems can be reduced. Sub inverters, which have the half of dc-link voltage of the main inverter, employ SiC-MOSFETs with higher switching frequency and compensate for…

Flight Optimization Model on Global and Interval Ranges for Conceptual Studies of MEA Systems

Akita University-Yotsugi Shibuya
IHI Corporation-Hitoshi Oyori, Hirotaka Sugawara, Naoki Seki
  • Technical Paper
  • 2019-01-1906
To be published on 2019-09-16 by SAE International in United States
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. Next, optimization for global range path involves whole flight path to find optimal operation condition in the flight. In aircraft energy management, fuel consumption converts into not only thrust power, but power of…

Electromagnetic Characteristic Comparison of Superconducting Synchronous Motors for Electric Aircraft Propulsion Systems

IHI Corporation-Hitoshi Oyori
The University of Tokyo-Yutaka Terao, Yusuke Ishida, Hiroyuki Ohsaki
  • Technical Paper
  • 2019-01-1912
To be published on 2019-09-16 by SAE International in United States
Aircraft service has been increasing today and it also results in the increase of the greenhouse gas emission. To solve this problem, the electric aircraft propulsion system is the key solutions to realize the clean and high efficiency aircraft, while demanding higher output density motors. So far, though 5 kW/kg is realized with permanent magnet type synchronous motors, the electric aircraft for over 100 passengers demands motors with 16 -20 kW/kg. Superconducting (S.C.) technology is one of the effective candidates for higher output density motors. In comparison with copper wires, the S.C. wires have higher current density at less than –200 ℃. And we can make a lighter weight coil with the S.C. wires. So far, many groups have been studying the S.C. motors over 16 kW/kg. Generally, there are two kinds of S.C motors. One is the S.C. motors made of the S.C. field coils and copper armature windings. The other is the fully S.C. motors using S.C. field and armature windings. We have been studying the fully S.C. motors with two kinds of…

Preventing Ice Buildup on Electric Aircraft

Aerospace & Defense Technology: August 2019

  • Magazine Article
  • 19AERP08_04
Published 2019-08-01 by SAE International in United States

Fuel economy is one of the biggest challenges facing the aviation industry. To overcome these challenges, researchers are working on next generation aviation systems. Next generation aircraft will be either hybrid power, or all-electric power, which would help with fuel consumption. But electric aircraft present challenges in other areas such as the prevention of ice formation. Ice formation on aircraft can degrade the aerodynamic performance significantly by reducing lift while increasing drag. Tech Briefs Media Group (TBMG) editor, Billy Hurley, interviewed researcher Afaq Ahmed Abbasi of Northwestern Polytechnical University's Department of Fluid Mechanics to learn more about these challenges.

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A Predictive Reference Governor for Synchronous Generator Regulation with a Pulsed Constant Power Load

US Air Force Research Laboratory-Jon Zumberge, Brandon Hencey
University of Dayton-Raul Ordonez
Published 2019-03-19 by SAE International in United States
In this paper, first an analytical model of a synchronous generator with a pulsed constant power load (CPL) is developed and numerically compared with a detailed simulation model. The analytical model is shown to possess good predictive abilities, thus enabling its use for control purposes. Second, the generator has a proportionalintegral (PI) control inner-loop, whose task is to regulate the generator’s output voltage to a desired reference. A novel outer-loop predictive reference governor (PRG) is designed and tested via simulation. The PRG uses the analytical model to predict the output behavior of the generator over a short time window, and continuously modifies the reference given to the inner-loop in order to maintain stringent steady-state requirements, in spite of demanding power requirements at the CPL. Simulation results illustrate the significant performance advantages of using the PRG versus using the inner-loop PI controller alone. The paper also discusses challenges of implementing standard model predictive control (MPC) on this problem, thus further strengthening the case for the potential usefulness of the PRG.
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Information on Electric Brakes

A-5A Wheels, Brakes and Skid Controls Committee
  • Aerospace Standard
  • AIR5937
  • Current
Published 2019-02-15 by SAE International in United States
This SAE Aerospace Information Report (AIR) describes the design, operation, and attributes of electrical braking systems for both military and commercial aircraft. At this time, the document focuses only on brakes utilizing electromechanical actuators (EMAs), as that is the present state of the art. As such, the discussions herein assume that EMAs can simply replace the hydraulic actuation portion of typical brake system leaving things such as the wheel and heat sink unchanged. Furthermore, the document provides detail information from the perspective of brake system design and operation. The document also addresses failure modes, certification issues, and past development efforts. Details on the design and control of electric motors, gear train design, ball or roller screw selection are available in the reference documents and elsewhere, but are outside the scope of this document. Other all-electric technologies such as piezoelectric actuation or more exotic methods of applying drag to a rotating wheel may be included at a later time. Important: Electric braking systems for aircraft are at the early stages of production implementation. There are also…
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Fundamentals of Electric Aircraft

Pascal Thalin
INSA-Jean-Charles Maré
  • Book
  • R-462
Published 2018-12-18 by SAE International in United States
Fundamentals of Electric Aircraft was developed to explain what the electric aircraft stands for by offering an objective view of what can be expected from the giant strides in innovative architectures and technologies enabling aircraft electrification. Through tangible case studies, a deep insight is provided into this paradigm shift cutting across various aircraft segments – from General Aviation to Large Aircraft. Addressing design constraints and timelines foreseen to reach acceptable performance and maturity levels, Fundamentals of Electric Aircraft puts forward a general view of the progress made to date and what to expect in the years to come. Drawing from the expertise of four industry veterans, Pascal Thalin (editor), Ravi Rajamani, Jean-Charles Mare and Sven Taubert (contributors), it addresses futuristic approaches but does not depart too far from the operational down-to-earth realities of everyday business. Fundamentals of Electric Aircraft also offers analyses on how performance enhancements and fuel burn savings may bring more value for money as long as new electric technologies deliver on their promises.
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The Use of Electric Batteries for Civil Aircraft Applications

Eagle Picher Technologies-Michael Waller
  • Progress In Technology (PT)
  • PT-192
Published 2018-12-10 by SAE International in United States

The Use of Electric Batteries for Civil Aircraft Applications is a comprehensive and focused collection of SAE International technical papers, covering both the past and the present of the efforts to develop batteries that can be specifically installed in commercial aircraft.

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Reliability Case Analysis of an Autonomous Air Cooling System (AACS) for Aerospace Applications

IHI Corporation-Naoki Seki
University of Strathclyde-Chung Man Fong, Patrick Norman
Published 2018-10-30 by SAE International in United States
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. One key advantage is the avoidance of liquid coolant leakage with the removal of liquid coolant from the MEA.It is necessary…
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