Line-started permanent magnet synchronous motors emerged in the market in response to strict efficiency goals. Despite being a synchronous motor, the rotor of a line-started permanent magnet synchronous motor contains a squirrel cage and, consequently, the behaviour under transient periods and/or faulty operation is not the same as for a conventional synchronous motor. In order to study this kind of electrical machine, it is proposed in this paper an equivalent circuit model and a set of experimental tests to extract the parameters of the equivalent circuit of a line-started permanent magnet synchronous motor. To validate the presented approach, a computer model of the machine, based on the obtained parameters, was developed, and the simulation results were compared with the experimental motor performance.

This paper presents a historical equivalent circuit of the three-phase induction machine, including the modern approach, the theory of the axes and the model in steady state. Also presented is an analysis that observes the consequent effects of the variation of the rotor resistance and the reactances of the stator and the rotor in several models of the equivalent circuit. A methodology is proposed for the determination of equivalent circuit parameters in order to represent the effect of harmonic components of the air gap magnetomotive force. The inclusion of the skin effect is discussed and it is proposed that inclusion of the equivalent circuit in which there is a representation of the harmonic effects. Is proposed equivalent circuits for solving the problem and computing the parameters and torque are illustrated. From this methodology a second analysis of the circuit is made by varying the same parameters of the first analysis. Two examples of engines are used to illustrate and validate the methodology and its analysis.

Abstract In this article, equivalent circuit modeling with study and analysis of band notch characteristics for a triple band notched UWB antenna has been discussed to develop a better understanding of the antenna functioning and its behavior. A small square ultra wideband antenna having overall size of 24 × 31 mm2 with tri- band rejections is designed and simulated using HFSS software. Very narrow band notching is accomplished by placing C slots and inverted C slot of different dimensions on the radiating patch which makes maximum space utilization without performance deterioration. The antenna operates from 3.1 to 14 GHz (VSWR < 2) with the presence of 3 narrow band notches (VSWR >2) of 3.3-3.7 GHz (WiMAX), 5.1 – 5.4 GHz (Lower WLAN and HIPERLAN/2) and 5.7 − 6 GHz (Upper WLAN) as shown by the simulated and measured results (VSWR<2) of the UWB antenna, with and without the presence of triple notches, thus utilizing the maximum UWB bandwidth. The radiation pattern plots for simulated and measured results are also presented to validate the working of the antenna. This antenna can be a respectable candidate for future European and USA high capacity UWB applications. The group delay and peak gain plots are also found to be stable in the range of operation of the antenna. The study and analysis of the band notching is discoursed in terms of current distribution and impedance plots to provide a greater and better perception into the working of the antenna and hence an equivalent circuit for the tri-band notched UWB antenna has been proposed.

Abstract The single phase equivalent circuit is largely used to model the three-phase induction motors in steady-state operation and under sinusoidal balanced voltages. Depending on the desired application, the circuit may or may not represent core losses, a double cage or even the variation of parameters due to skin effect and saturation. However, the determination of the circuit parameters through standard methods, such as those described in IEEE Standard 112, may not be possible in many situations given the lack of the necessary resources. This paper presents initially a survey on the determination of circuit parameters from alternative methods, i.e., non-standard tests. Special focus is given to methods which employ only data usually provided by manufacturers on catalogs and nameplates. Six analytical methodologies used in the context of efficiency estimation at steady-state operation are assessed, compared and then combined in order to improve results. The assessment is based on the closeness of the resulting parameter values to reference values and on the inexistence of absurd results, such as negative electrical resistances. The combination of methods has improved the accuracy of calculations for the studied motors.

Nowadays the economic analysis of electric motor’s life cycle is the most effective way to measure the economic viability of the energy efficiency actions to the end users, specially the industrial sector. The replacement of aged electric motors by new and energy-efficient ones is an well-known trade that leads to energy savings however the cost-effectiveness in motors’ repla- cement does not take into account the life cycle costs, how the efficiency value is measured or calculated, and economical features as the variation and growth of electricity tariff in a local sce- narium. Thus, this work presents the technical feasibility and cost-effectiveness of the low-power induction motors that have their efficiency improved after rewinding aiming better investment viability and presents the value of energy saved promoting energy efficiency. The induction motor’s analysis is performed before and after rewinding, in sequence the motors are simulated by a commercial software based on finite elements method (COMSOL Multiphysicsr). The motors are rewound using a rewinding strategy that use feasible windings at rewinding workshops, i.e., concentric and imbricated windings. The test workbench for efficiency measurement by A and B methods from IEEE 112/2017 makes possible locked-rotor current measurement and winding temperature measurement for each tested motor. Among rewound motors which were simulated and tested, they have the best cost-effectiveness after replacement instead IR3/IE3/Premium motors directly sold in the market and even a hypothetical IE4/Super-Premium motor where an IR4 minimum energy performance standard is proposed to make real this comparison. The rewound motors increase their efficiencies between 3 and 4 percentage points in relation to the former winding and the payback is less than 2 years regardless of the efficiency measurement method used. From the motor with concentric winding and efficiency level IE2/IR2 some rewound motors reach IR3/IE3 with differents imbricated windings and one motor reaches the borderline between IE4/Super-Premium and IR3/IE3 levels.

Nowadays the economic analysis of an induction motor’s life cycle is the clearest way to measure the viability of actions to promote energy-efficient technologies to the end user. The cost effectiveness in motors replacement by energy-efficient motors is a well-known practice that leads to energy savings, however this paper presents the cost-effectiveness of low-power induction motors which have their efficiency improved after rewinding. This process improves the investment viability and brings the greatest financial and energetic savings. In this paper, low-power induction motors are rewound and their efficiencies are measured by tests A and B from IEEE standard 112/2017. The rewound motors have better cost-effectiveness than replacement by IE3/Premium and even IE4/Super-Premium units. The rewound motors increase between 3 and 4 percentage points in relation to former efficiency and the payback is less than 2 years, regardless of the efficiency measurement method.

Researches conducted by energy distribution companies on several industry segments showed that about 30%of inductionmotors are operating undersized, i.e. with less than 70%of the rated load. Under these conditions induction motors have low efficiency. Due to the characteristics of industrial processes, traditional methods of efficiency and operation analysis can not be used. In order to meet the requirements of these applications, several methods have been proposed. Most of these methods require only the measurement of voltages, currents and in some cases rotor speed. Often these methods estimate, using different techniques, the shaft torque and calculate the output power and efficiency. The purpose of this study is to develop and implement a real-time method to monitor operating conditions and efficiency of induction motors operating at steady state. The proposed method, by means of measured three-phase voltages and currents and the equivalent circuit of the machine, estimates the shaft torque and speed. Then, based on these estimations, calculates the power output and efficiency. The machine equivalent circuit is estimated by an iterative algorithm that uses only the machine nameplate data and the stator resistance. According to present tendencies a wireless system was developed were a central computer can monitor in real time the efficiency and the operational conditions of one or more motors in a industrial plant. This document presents the theoretical development of the proposed method and the results of computer simulations under different situations. Finally it presents an experimental implementation of the method where its performance is evaluated for different motors.

This work presents a diagnosis faults system (rotor, stator, and contamination) of three-phase induction motor through equivalent circuit parameters and using techniques patterns recognition. The technology fault diagnostics in engines are evolving and becoming increasingly important in the field of electrical machinery. The neural networks have the ability to classify non-linear relationships between signals through the patterns identification of signals related. It is carried out induction motor´s simulations through the program Matlab R & Simulink R , and produced some faults from modifications in the equivalent circuit parameters. A system is implemented with multiples classifying neural network two neural networks to receive these results and, after well-trained, to accomplish the identification of fault´s pattern

Agradecimentos: The authors would like to thank Prof. Dr. Adriano L. Toazza, Dr. Napoleão S. Ribeiro, and Dr. Rafael C. Figueiredo for their contributions to previously stages of this work. This work was supported in part by the Brazilian agencies São Paulo Research Foundation (FAPESP - grants 2017/20121-8, 2015/50063-4, 2015/24517-8, and 2007/56024-4) and National Council for Scientific and Technological Development (CNPq - grants 301409/2017-0, 159388/2017-1, 400129/2017-5, 402923/2016-2, and 301420/2015-7