No abstract

No abstract

In recent years, with developing technology in the field of electrical machines, more efficient and high power density electric motors have been produced. The use of high energy efficiency motors gains importance due to the increase in global energy demand. The main purpose of this study was to design an Axial Flux Induction Motor (AFIM) with the same efficiency class as the Radial Flux Induction Motor (RFIM) in premium efficiency (IE3) class which is used commonly in industrial applications. Various AFIMs are designed with different rotor slot numbers and performance analyses as efficiency and torque ripple changes are investigated. It is known that torque ripple is one of the key parameters in electrical machine design which should be kept as low as possible without decreasing efficiency and torque. Accordingly, AFIMs’ rotor slots are skewed considering the stator and rotor slot numbers. The use of a Soft Magnetic Composites (SMC) material in design is also investigated. As a result of the analyses, many premium efficiency classes for AFIMs are obtained. In addition, using SMC material and skewing the rotor slots provides that torque ripples be reduced.

On-board electrical systems are the key components of each modern aircraft. They enable its safer, more comfortable, and environmentally friendlier operation. The strict regulations to reduce pollution and noise are produced by aircraft eventuated in projects like Clean Sky or ICAO Global Coalition for Sustainable Aviation. One solution to environmentally friendlier operation is the full electric propulsion of the aircraft, which enables the reduction of both noise and pollution. Such a concept requires a total change of all on-board power systems and enables the profound change in aircraft design. This paper presents the evolution of aircraft power systems into the so-called more electric aircraft (MEA) and discusses the state-of-the-art electrical systems. Furthermore, the concept of all-electric aircraft (AEA) is presented here.

The lifetime of insulation in a power transformer deteriorate in time by reason of high electrical/thermal stresses and contaminations from environmental factors. In particular, faults in oil type power transformers due to thermal stress ruin energy continuity and cause serious economic losses. Most of the faults due to thermal stress generally occur at the hot-spot location of transformer windings. Particularly, creeping of the spacer between windings and the resulting thermal stress constitutes a significant part of the transformer failures. Therefore, the determination of creep characteristics under different conditions is important in terms of fault estimation, aging calculations and product development. In this study, it is aimed to acquire creep characteristics and failure time of spacer for different test temperatures. For this reason, a test system is designed to determine the creep characteristics of the spacer between the windings. In order to specify temperature ranges of the tests to be done, thermal analysis is performed for different creep rates of the spacer. The test setup is designed according to the results of thermal analysis, and creep test results are presented. The results indicate that creep characteristics of spacers will provide to make the aging calculations and failure prediction algorithms more accurate.