Hitoshi Oyori

Fault-tolerant control for the More Electric Engine

This paper describes a unique fault-tolerant control design concept for More Electric aero-Engine (MEE). The MEE is based on a new control system architecture for aircraft engines, introducing electrical motor-driven accessories in place of conventional accessory gearbox driven pumps or hydraulic actuators. The MEE reflects a highly advantageous approach that improves engine efficiency and reduces fuel burn and CO2 emissions. However, it raises several issues with respect to engine safety and reliability. Using a redundant motor control system for the MEE based on a unique fault-tolerant design concept, the authors sought to resolve these issues. Studies of this system and the results of tests and experiments indicate that the proposed MEE fault-tolerant design should result in a safe, highly reliable engine control system.

All Electric System Architecture for Aircraft and Propulsion

This paper describes a system architecture for future All Electric Aircraft (AEA). The proposed AEA system integrates electrical power management, which uses an HVDC grid system to control supply and demand of electrical power, and thermal management, which provides adjustable cooling of power electronics with an autonomous air-cooling system. The proposed system concept will achieve efficient and adequate energy and power management of the aircraft system, helping to reduce overall energy consumption and consequently reducing fuel burn of the aircraft.

Fuel System Design for the More Electric Engine

This paper describes the system design of an electric motor-driven fuel pump system for the MEE (More Electric Engine). The MEE is a new aircraft engine system concept which will reduce fuel burn and CO2 emissions, and improve engine safety, reliability and maintainability. At the initial concept design stage of the MEE, a feasibility study indicated that the electric fuel pump system helped improve engine efficiency. The selected fuel pump system configuration for the MEE was a fixed displacement gear pump system, the speed of which is controlled by an electric motor. Simplification of the fuel system will be expected because the electric gear pump itself is used as a metering device, but there are several technical challenges which should be overcome to realize the system.One of the technical challenges involves ensuring fuel metering accuracy via motor speed control. To address the issue, studies of the fuel flow rate feedback system were performed. A novel flow feedback system was investigated and the potential to ensure metering accuracy was confirmed.The other technical challenge is the wide speed range operation of the gear pump system. If only a single electric gear pump is used in the MEE system, the pump should accommodate a speed range of 5 to 100% because the ground starting flow rate is about 5% of the maximum flow. Operation at such low speeds is significantly harsh for the LP pump pressurizing capability and bearing film lubrication. However, optimized pump performance and operational condition were established, and it is expected that a single pump system, in which both LP and HP pumps are directly motor-driven via a single shaft, can be constructed. In addition, there is a technical challenge involved in supplying electrical power to the pump motor during the windmill engine start-up.The system design focused on the above technical challenges, and the consequent feasibility of the simplified MEE fuel pump system construction was confirmed.© 2012 ASME

Development of Fuel Control System for More Electric Engine

This paper describes the experimental rig test result and an investigation into issues of system stability and pressure oscillation transmission in the MEE (More Electric Engine) fuel system. This system employs an electric motor-driven pump and directly meters the fuel flow based on the motor rotating speed. The MEE is a system architecture concept for the aircraft turbine engine that reduces fuel consumption and environmental load while improving safety, reliability and maintainability. The improvements were demonstrated by conducting a feasibility study of MEE system for small sized turbofan engine [5, 6]. The authors also conducted an experimental rig test showing capabilities in terms of fuel-metering range, accuracy and response [7]. The capability of the feedback loop control under the engine start condition was shown by the result, but meanwhile, pressure oscillation under the higher fuel flow condition was also observed. The authors repeated the rig test to investigate its root cause. This paper describes the study, which investigates the characteristics of the MEE fuel system and seeks stable control methods under conditions of higher pressure fluctuation, higher instrumentation noise or applying worn gear pump. The paper also describes the study of the pressure oscillation transmission from pump to engine combustor, which may damage the engine combustor and structures. As a result of these studies, a novel control method for the MEE fuel system is proposed, with improved oscillation stability.Copyright

Development of the Electric Fuel System for the More Electric Engine

This paper describes the experimental rig test result of the electric motor-driven fuel pump system for the MEE (More Electric Engine). The MEE is an aircraft engine system concept, which replaces conventional mechanical/hydraulic driven components with electric motor-driven components. Various MEE approaches have been studied since the early 2000s and one of its key concepts is an electric motor-driven fuel pump [1–4]. The authors commenced a feasibility study of the electric motor-driven gear pump system for what was assumed to be a small-sized turbofan engine. The concept study and system design were conducted, whereupon technical issues for the electric fuel pump system, which both supplies and meters fuel via the motor speed control, were clarified [5, 6]. Since one of the key issues is fuel-metering accuracy, the electric fuel system, including a flow feedback closed-loop control, was designed to ensure accurate fuel-flow metering for aircraft engine applications.To verify the rig system, an experimental model of the electric fuel pump system is assumed for a small-sized turbofan engine. The hardware of the motor-driven fuel pump and flow measurement mechanism, including an FPV (Fuel-Pressurizing Valve) and orifice, were designed, manufactured and fabricated and a differential pressure sensor for flow feedback was selected. Other equipment was also prepared, including a motor controller, power source and measurement devices, and the entire rig set-up was constructed.A bench test using the rig test set-up was conducted to verify the fuel-metering accuracy, response and system stability. Data, including the static performance and frequency response, were obtained for the electric motor, motor-driven fuel pump and entire fuel system respectively. The rig test results indicate the feasibility of the system, which will provide an accurate engine fuel flow (Wf) measurement and frequency response required for actual engine operation, via an electric motor speed control and fuel-flow feedback system, as proposed in the MEE electric fuel system.Copyright

High-voltage DC power grid system for the More Electric Architecture

This paper proposed a new concept of more electric architecture for aircraft and propulsion. The High-Voltage Direct Current system is anticipated as one of the optimized systems for future aircraft power system and offers numerous advantages associated with increasing electric power consumption and changing the power supply of mission-critical systems, such as flight control actuators and/or engine accessories, from conventional hydraulic and pneumatic to electric. This study introduces solutions to resolve the problem of setting up the HVDC power grid and related equipment.

Fault-tolerant and resilient electrification for the More Electric Engine

This paper describes a safe, high-reliability engine control system configured for the More Electric Aero engine, in particular for the electrical motor-driven fuel pump and the EMA for engine variable geometry. By applying the unique active/active control system for electrical motors and the summing method, we devised a high-reliability, fault-tolerant redundant system whose key focus is jamming prevention/protection and immediate failover. MEE is a new engine concept that should lead to more efficient engines and aircraft, lower environmental impact, and lower life cycle costs. The simple, highly reliable fault-tolerant power control system proposed here is essential to MEE, since engine safety and reliability are the first priority when applying a new system concept to an engine. Only the system proposed here meets all these requirements.

Integrated power management system for the More Electric Aircraft

The More Electric Engine (or MEE) is a next-generation turbofan engine expected to lead the way for engine control research and development for the More Electric Aircraft (or MEA). We recently began investigations to tackle the challenge of creating “an eco-friendly engine for the future.” This paper gives an overview of our studies of electrical power management solutions based on an integrated engine/power control system for MEE and MEA. Electrical power management in recent years has emerged as a key aspect of aircraft systems design. In cases in which Electromechanical Actuator (or EMA) systems are used for flight control, the power bus systems must also be designed to absorb the power regenerated from flight control actuations. Our study focused on achieving an optimal balance between aircraft power management and the operational requirements of aeroengines. The results point to a novel effective power control concept based on integrated engine control technologies that ensure stable power systems.

Improved Engine Efficiency via the More Electric Engine

A MEE system targeting reduced fuel burn and CO2 emissions from an aircraft engine is being developed. It is apparent that although the MEE will achieve improved efficiency for small, medium and large turbofan engines, the weight and volume impact of the electric motor-driven components cannot be ignored for medium/large engines. This paper describes the evaluation result of the engine efficiency improvement and the weight impact on medium/large MEE.