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Induction motors, particularly single‐phase induction motors (SPIMs), represent the major consumption of power in the household sector. SPIMs that fail during their life cycle represent the best opportunity to improve their efficiency by replacing or repairing them. Although replacing faulty motors with new and efficient ones results in significant energy savings, this replacement is uneconomical due to its high initial costs. Additionally, this option requires extensive energy and materials to manufacture, resulting in a considerable environmental impact. This article aims to introduce a three‐phase rewinding of a failed SPIM using a rewinding algorithm that significantly improves the machine's efficiency and performance in an economically viable way. The 0.75 HP single‐phase capacitor‐start induction motor has been rewound to convert it into a three‐phase motor with the required 110 V line voltage and 50 Hz frequency. The economic analysis implies that the rewound machine's life‐cycle cost is 6% and 18% lower than the purchased SPIM IE1 and existing SPIM by below efficiency class respectively. The rewound motor achieves a payback period of 1–1.6 years for different motor loading levels, based on the world average electricity price, indicating an economically viable solution. [ABSTRACT FROM AUTHOR]

Here, the authors present a new constrained multi‐objective optimization method for maximizing output power and efficiency of switched reluctance motor (SRM). The constraints play a significant role in this process. Artificial neural network‐based models are created to represent the SRM behaviour which is a difficult task. For this reason, a single neural network for each objective is built and the number of training data has been increased to reach a good accuracy. The authors propose a neural network‐based adjoint Lp metric technique to combine several objective functions and constraints with different weight factors to a single function which should be minimized. To apply the constraints, an adjoint term is added to the original Lp function including only objective functions. The flux densities of the magnetic materials are selected as the optimization constraints. When approaching as close as possible to the saturation level, the SRM has a better performance. Adding an adjoint term to the original Lp leads to better optimization results which were proved by comparing with a conventional optimization. Also, all obtained results were finally validated by the Ansoft Maxwell software. [ABSTRACT FROM AUTHOR]

The results of numerical and experimental analysis of passive magnetic bearings are presented. The proposed structure is composed of three radially stacked ring‐shaped permanent magnets. The improvements of stiffness and load capacity are proven in comparison to the classical passive magnetic bearing composed of two rings. A preliminary sensitivity analysis is carried out by means of the 2‐dimensional finite element method (FEM) modelling, which is used to provide the initial points for the stochastic optimisation and also to define the best fitness and penalty functions. Finally, the 2‐dimensional FEM is used to compare the force density and the cost of the proposed structure to those of the classical passive magnetic bearing composed of two rings. The optimised structure was manufactured and validated by experimental measurements. The proposed passive magnetic bearing exerts greater axial force and stiffness than similar structures. [ABSTRACT FROM AUTHOR]

The present study investigated the design, simulation, and manufacturing of a new coreless stator axial‐flux permanent‐magnet motor. In addition, to magnets with magnetisation along the motor axis, the new structure included magnets that were magnetised circumferentially and buried at the rotor surface. The electromagnetic design of the conventional axial‐flux motor and the new motor was evaluated according to nominal values and design equations. In this regard, the number of poles and coils, as well as the outer diameter of both motors were assumed to be identical. It was observed that the axial length of the new motor is shorter than the conventional axial‐flux motor. Simulations were continued through comparing the motors in terms of air‐gap flux density, torque, and back electromotive force using the transient finite element method. A comparison of the results showed that the new motor had a better performance than the conventional axial‐flux motor. Subsequently, the new motor was manufactured and tested; the experimental results proved to be close to those presented in the analytical section. [ABSTRACT FROM AUTHOR]

The current distribution, ampacity and magnetic field of parallel power cables are calculated. The calculations are performed in both sinusoidal and harmonic current profiles. The simulations are conducted on the underground medium voltage cables with metallic sheaths. The effects of single‐point bonding and solid bonding of sheaths grounding system are evaluated. In this study, cables are installed in flat formation with three cables in each phase and the effect of different distances between cables on the parallel cables parameters is studied. Computations are conducted for all possible arrangements of parallel cables and the worst and the best arrangements from the point of balancing current division, maximum ampacity and minimum magnetic field are presented. Furthermore, the effects of placing parallel cables in one row or two rows above each other are investigated. Calculations of current distribution and magnetic field are performed using the sub‐conductors method that considers the skin and proximity effects. Finite element method thermal simulations are excited to determine the power cable ampacity in different configurations. Experimental tests on parallel cables in both single‐point bonding and solid bonding systems are carried out and the results verify the accuracy of simulations. [ABSTRACT FROM AUTHOR]

ABSTRACT This paper presents losses distribution in power cables conductors and metallic sheaths. Losses are computed in sinusoidal and non-sinusoidal currents with considering all sequences harmonics. Two numerical methods as finite element and integral method are used to determine the distributions and also total harmonic losses. Thus skin and proximity effects of all metallic parts of cables are considered accurately. Integral method is utilized for losses calculation by considering of earth return path and eliminating it. Furthermore, IEC formulations are used for losses computations. Numerical results suggest inserting the earth return path effect on cable losses in some harmonic frequencies of currents. Power cables are assumed to be single core medium voltage type. Lead sheaths of cables are bonding together and grounded at both ends for calculation of circulating current losses. Also the effects of different distances between cables in losses calculations are assessed. For validation of integral method, finite element simulation, as proven method in accurate power cable losses computations is used. These methods are completely described in this paper. Accuracy of integral method for harmonic losses computations of conductor and sheaths is verified by finite element simulation results. Also it is shown that proximity and skin effects are considered very well by integral method even in metallic sheaths. © 2016 Wiley Periodicals, Inc. Comput Appl Eng Educ 24:692-705, 2016; View this article online at ; DOI [ABSTRACT FROM AUTHOR]