The fundamental issues faced in the aircraft electrical power systems are addressed. A brief description of the conventional and advanced aircraft power system architectures, their disadvantages, opportunities for improvement, future electric loads, role of power electronics, and present trends in aircraft power system research is given, followed by a brief outline of projected future advancements.

Aircraft power systems: technology, state of the art, and future trends

The purpose of this paper is to present an assessment of the negative impedance instability concept of the constant power loads in the More Electric Aircraft (MEA) power systems. We address the fundamental problems faced in the stability studies of these multi-converter power electronic systems. An approach to the design of sliding-mode controllers for PWM DC/DC converters with constant power loads is presented. Because of the negative impedance destabilizing characteristics of constant power loads, conventional linear control methods have stability limitations around the operating points. However, the proposed controllers improve large-signal stability and dynamic responses. The proposed controllers are simulated and their responses under different operations are discussed. Finally, we verify the stability of the controllers using the second theorem of Lyapunov.

On the Concept of Negative Impedance Instability in the More Electric Aircraft Power Systems with Constant Power Loads

The More-Electric Aircraft (MEA) underlines the utilization of the electrical power to power the non-propulsive aircraft systems. Adopting the MEA achieves numerous advantages such as optimizing the aircraft performance and decreasing operating and maintenance costs. Moreover, the MEA reduces the emission of the air pollutant gases from the aircraft, which can contribute in solving the problem of climate change. However, the MEA put some challenge on the aircraft electrical system either in the amount of the required power or the processing and management of this power. This paper introduces a review for the MEA. The review includes the different options of generation and power system architectures.

https://asat.journals.ekb.eg/article_23726_d651e3d27a968a3f2f5dbc6112c742c2.pdf

A Review of More-Electric Aircraft

In multi-converter power electronic systems, different converters such as DC/DC choppers, DC/AC inverters, and AC/DC rectifiers are used in source, load, and distribution subsystems to provide power at different voltage levels and forms. Most of the loads are also in the form of power electronic converters and motor drives. The most popular examples of these systems are automotive systems and more electric/hybrid electric vehicles. These systems have unique characteristics, dynamics, and stability problems that are just beginning to be appreciated. In this paper, we take a closer look at multiconverter power electronic systems and address the fundamental problems faced in these systems.

Multi-converter power electronic systems: definition and applications

Conventional aircraft power system is a constant-frequency (CF) supply based on mechanical-regulated constant-speed mechanism that has relatively low efficiency. Replacing the CF system with variable-frequency (VF) power improves overall efficiency, and reduce the system's weight and volume. However, this creates a new tier of requirements and design challenges. Novel VF-power architecture is developed with minimization of the power losses throughout the stages of power conversions. Optimal partitioning and grouping of onboard AC loads has been discussed with specific system data. New VF-input multi-functional power converters are also briefly discussed.

New VF-power system architecture and evaluation for future aircraft

This paper describes the secondary power sources available on a large transport aircraft and discusses expectation that power electronics will enable the transforming of present aircraft systems into new highly integrated systems. The benefits expected from integrating all of the engine-based hydraulic and pneumatic power sources into a single electrical system are identified in qualitative terms. The estimated capacity of an all-electric secondary power system for a tri-jet and a new large transport are compared. A power system architecture that eliminates the need for a pneumatic and hydraulic power distribution system is illustrated. Particular emphasis is given to the flight control system and the electrical power system needs to ensure integrity of power and data for critical flight control functions. The data bus and power source redundancy for flight control actuation is discussed using an integrated power and cable concept in conjunction with an intelligent power controller. >

L.J. Feiner

Papers

Power electronics transforms aircraft systems