AC Generation Systems Research Articles

Electrical Power Generation in Aircraft: Review, Challenges, and Opportunities

The constant growth of air traffic, the demand for performance optimization, and the need for decreasing both operating and maintenance costs have encouraged the aircraft industry to move toward more electric solutions. As a result of this trend, electric power required on-board of aircraft has significantly increased through the years, causing major changes in electric power system architectures. Considering this scenario, this paper gives a review about the evolution of electric power generation systems in aircraft. The major achievements are highlighted and the rationale behind some significant developments discussed. After a brief historical overview of the early dc generators (both wind- and engine-driven), the reasons which brought the definitive passage to the ac generation, for larger aircraft, are presented and explained. Several ac generation systems are investigated with particular attention being focused on the voltage levels and the generator technology. Furthermore, examples of commercial aircraft implementing ac generation systems are provided. Finally, the trends toward modern generation systems are also considered giving prominence to their challenges and feasibility.

Experimental Validation of a Space-Vector-Modulation Algorithm for Four-Leg Matrix Converters

Most variable-speed AC generation systems use back-to-back converters to supply electrical energy, with fixed electrical frequency and voltage, to a stand-alone load or grid. Matrix converters (MCs) are a good alternative to back-to-back converters because they have several advantages in terms of size and weight. Therefore, MCs can be advantageously used in any variable-speed generation system where high efficiency, reliability, small size, and low weight are considered important factors. Nevertheless, to interface an MC-based generation system to an unbalanced 3φ stand-alone load, a four-leg MC is required to provide a path for the zero-sequence load current. Space-vector-modulation (SVM) algorithms for the operation of four-leg MCs have been proposed in the literature. However, these modulation methods have high computational burdens, and they are difficult to implement, even in fast DSP-based control platforms. Therefore, only simulation results have been reported in these publications. In this paper, an SVM algorithm is optimized and experimentally tested. Moreover, the harmonics produced in the input current when a four-leg MC is feeding an unbalanced or nonlinear load are also mathematically analyzed in this paper, with experimental verification being provided.

Development of Superconducting AC Generator

The superconducting ac generator is expected to be the optimum choice among ac generation systems in the future because of its reduced size, weight, high efficiency, and its contribution to stability of power systems and higher generator terminal voltage. Conceptual design on a 2P-1000MVA class superconducting ac generator has been completed to clarify problems and to confirm advantages. Fundamental studies are performed on key technologies that have to be solved for realization of superconducting generators. As a summary of those fundamental studies, a scaled-down superconducting generator of 3000kVA capacity is constructed and tested. Also clarified are effects of major design parameters for commercial superconducting ac generators such as dimensions, reactances, and weight.