Evolution and Modern Approaches for Thermal Analysis of Electrical Machines

In this paper, the authors present an extended survey on the evolution and the modern approaches in the thermal analysis of electrical machines. The improvements and the new techniques proposed in the last decade are analyzed in depth and compared in order to highlight the qualities and defects of each. In particular, thermal analysis based on lumped-parameter thermal network, finite-element analysis, and computational fluid dynamics are considered in this paper. In addition, an overview of the problems linked to the thermal parameter determination and computation is proposed and discussed. Taking into account the aims of this paper, a detailed list of books and papers is reported in the references to help researchers interested in these topics

Delving in the loss landscape to embed robust watermarks into neural networks

International audienc

Alpha Channel Fragile Watermarking for Color Image Integrity Protection

This paper presents a fragile watermarking algorithm`m for the protection of the integrity of color images with alpha channel. The system is able to identify modified areas with very high probability, even with small color or transparency changes. The main characteristic of the algorithm is the embedding of the watermark by modifying the alpha channel, leaving the color channels untouched and introducing a very small error with respect to the host image. As a consequence, the resulting watermarked images have a very high peak signal-to-noise ratio. The security of the algorithm is based on a secret key defining the embedding space in which the watermark is inserted by means of the Karhunen–Loève transform (KLT) and a genetic algorithm (GA). Its high sensitivity to modifications is shown, proving the security of the whole system

Erratum: Noninvasive Measurements and FEM Analyses for Estimating the Rotor Bar-Lamination Contact Resistance (IEEE Trans. Ind. Appl. (2021) 57: 1 (208-217) DOI: 10.1109/tia.2020.3028347)

In [1], the correct author affiliations should read: Z. Gmyrek is with the Institute of Mechatronics and Information Systems, Lodz University of Technology, Lodz 90-924, Poland (e-mail: [email protected]). S. Vaschetto, M. Ahmadi Darmani, and A. Cavagnino are with the Politecnico di Torino, Dipartimento Energia, Turin 10129, Italy (e-mail: [email protected]; [email protected]; andrea. [email protected])

Superconductivity and its Application in the Field of Electrical Machines

This paper provides a review on the most recent applications of superconductors in rotating electrical machines. The main types of superconductors for the present-day electrical applications are shown to highlight their main features. The main characteristics of superconducting synchronous machines, DC machines and induction machines for marine and vehicle propulsion, future electric aircraft, wind energy and industrial applications are discussed by presenting data of prototypes and demonstrators. The paper aims to raise awareness among researchers and engineers on the importance of superconductivity to enhance the performance of conventional electrical machines

Iron Losses and Parameters Investigation of Multi-Three-Phase Induction Motors in Normal and Open-Phase Fault Conditions

Among multi-phase solutions, multi-three-phase induction machines (IMs) are gaining an increasing interest in the industry due to their advantages to be configured as multiple three-phase units simultaneously on the same magnetic circuit. According to this scenario, the identification of the equivalent circuit parameters and conventional iron losses covers a key role in evaluating performance and efficiency, especially when the machine is operated in a wide torque-speed range. Therefore, the goal of this paper is to investigate the core losses and the saturation phenomena of multi-three-phase IMs operated in normal and open-three-phase fault conditions under different harmonic contents of the air-gap magnetomotive force. A procedure to identify the parameters of the equivalent circuit of the machine in faulty conditions is reported. Experimental results are presented on a 12-phase asymmetrical IM featuring a quadruple three-phase stator winding. Finally, a comparison between normal and faulty conditions in terms of efficiency and losses for several machine working points is reported

Experimental Assessment of Cryogenic Cooling Impact on Induction Motors

In this work, an experimental assessment of the influence of cryogenic cooling in a conventional induction motor is presented. The performance of a fractional kilowatt induction motor is evaluated when submerged in liquid nitrogen. Using the single-phase equivalent electric circuit, the influence of the temperature and skin-effect is analyzed in the variation of the machine's parameters, under ambient and cryogenic conditions. Also, the variation of the iron core and mechanical losses are evaluated. An analytical methodology is proposed to estimate the change of motor performance under cryogenic conditions. For the analyzed induction motor, measurements are performed to verify the predicted machine performance. The experimental tests in cryogenic conditions show the possibility of achieving higher efficiency levels with more than double the nominal torque. Also, due to the cryogenic environment, there was no thermal constraint in the operation of the induction motor