Field Of Electrical Machines Research Articles

Investigation of Key Parameters on Cogging Torque in Permanent Magnet Machines Based on Dominant Harmonic Contents

The investigation of design parameters on the cogging torque has been a classical and common research subject over the last few decades. Nevertheless, an accurate analysis of major contributors to the cogging component is still difficult to find in past published works. This paper aims to address this knowledge gap by identifying the dominant harmonic contents responsible for the amplitude of cogging torque. As a result, a new factor is introduced to denote the level of cogging torque, rectifying the defect of the well-known existing factor called the goodness factor. The correlations between the key parameters (i.e., pole and slot numbers, pole arc to pole pitch ratio, and slot opening to slot pitch ratio) and the cogging torque are clarified by the proposed methodology. Finally, finite element (FE) and statistical results demonstrate the validity of the proposed results. It is expected that the key findings reported in this paper will serve as a valuable reference in the field of electric machines.

MODELING OF THE EXTERNAL MAGNETIC FIELD OF ELECTRIC MACHINES

Powerful electric machines – such as electric generators, electric motors generate a magnetic field of great tension. These fields negatively effect on personnel and can to violate the stability of electronic equipment. To determine safe areas for workers, laying communication cables and placing sensitive electronic equipment, it is advisable to model the propagation of magnetic fields of electrical machines. This will make it possible to rationalize the placing of electrical equipment at design stages. The most common high-power electrical machines are four-pole electrical machines with a dipole-quadrupole structure of the external magnetic field. The purpose of the research is a development of models of the propagation of the external magnetic field generated by alternating current electric machines. Results of the research: it is substantiated that to simulate the propagation of the magnetic field of electric machines, it is advisable to use the Gauss equation for the magnetic scalar potential. This will make it possible to take into account the required number of spatial harmonics of the magnetic field to ensure an acceptable calculation error. An electric machine is considered in a spherical approximation. Calculations were carried out in spherical coordinates. The distances were determined in relative radii of the electric machine - the ratio of the radius of the machine to the definition of field strength. The calculations were made for two planes of spherical coordinates and a three-dimensional image was obtained. As a result of the simulation, it is possible to determine the magnetic field strength of a four-pole electric machine at selected distances and directions around the electric machine with the required accuracy. It has been established that there are points of zero external magnetic field strength around electrical machines. Verification of the simulation results was carried out using the method of full-scale measurements of the magnetic field strength around a real four-pole machine. The measurement results showed acceptable agreement with the calculated data. Conclusions: the chosen approach and the results of modeling the propagation of the external magnetic field of electrical machines can be used to design the placement of electrical equipment, taking into account the requirements for electromagnetic safety and electromagnetic compatibility of technical equipment.

Comparison of Aluminum and Copper Winding Materials for Switched Reluctance Machines with Finite Element Analysis

Today, with the decrease in fossil fuel reserves, interest in electric vehicles has grown. Undoubtedly, electric machines are one of the most important parts of electric vehicles. Studies on electrical machines directly affect vehicle performance. Since the electrical machine used is mounted on the vehicle, reducing the total weight without changing the output power will positively affect the overall performance of the vehicle. The windings used to create the magnetic field in electrical machines are made of copper. Electrical machinery manufacturers try to use completely different materials instead of copper or partially reduce its use. At this point, aluminum emerges as an attractive material for various manufacturers. This study analyzed the winding structure of a switched reluctance machine (SRM) proposed for an electric vehicle by using copper and aluminum at an equivalent resistance value, the results of which were compared. As a result of a 2D finite element analysis, it was observed that the machine’s output performance is largely kept when aluminum is used instead of copper for the winding. It was also observed that the aluminum total winding weight decreased by 43,40% compared to that of copper.

Recent Trends in Additive Manufacturing and Topology Optimization of Reluctance Machines

Additive manufacturing (AM) or 3D printing has opened up new opportunities for researchers in the field of electrical machines, as it allows for more flexibility in design and faster prototyping, which can lead to more efficient and cost-effective production. An overview of the primary AM techniques utilized for designing electrical machines is presented in this paper. AM enables the creation of complex and intricate designs that are difficult or impossible to achieve using traditional methods. Topology Optimization (TO) can be used to optimize the design of parts for various purposes such as weight, thermal, material usage and structural performance. This paper primarily concentrates on the most recent studies of the AM and TO of the reluctance machines. The integration of AM with TO can enhance the design and fabrication process of magnetic components in electrical machines by overcoming current manufacturing limitations and enabling the exploration of new design possibilities. The technology of AM and TO both have limitations and challenges which are discussed in this paper. Overall, the paper offers a valuable resource for researchers and practitioners working in the field of AM and TO of electrical machines.

Design of Multivariate PID Controller for Power Networks Using GEA and PSO

The issue of proper modeling and control for industrial systems is one of the challenging issues in the industry. In addition, in recent years, PID controller design for linear systems has been widely considered. The topic discussed in some of the articles is mostly speed control in the field of electric machines, where various algorithms have been used to optimize the considered controller, and always one of the most important challenges in this field is designing a controller with a high degree of freedom. In these researches, the focus is more on searching for an algorithm with more optimal results than others in order to estimate the parameters in a more appropriate way. There are many techniques for designing a PID controller. Among these methods, meta-innovative methods have been widely studied. In addition, the effectiveness of these methods in controlling systems has been proven. In this paper, a new method for grid control is discussed. In this method, the PID controller is used to control the power systems, which can be controlled more effectively, so that this controller has four parameters, and to determine these parameters, the optimization method and evolutionary algorithms of genetics (EGA) and PSO are used. One of the most important advantages of these algorithms is their high speed and accuracy. In this article, these algorithms have been tested on a single-machine system, so that the single-machine system model is presented first, then the PID controller components will be examined. In the following, according to the transformation function matrix and the relative gain matrix, suitable inputs for each of the outputs are determined. At the end, an algorithm for designing PID controller for multivariable MIMO systems is presented. To show the effectiveness of the proposed controller, a simulation was performed in the MATLAB environment and the results of the simulations show the effectiveness of the proposed controller.

Perspectives on Electric Machines with Cryogenic Cooling

Cryogenic cooling is a well-established and expanding technology. In the field of electric machines, it allows the construction of more efficient machines with a high power density. This paper addresses the main cooling technologies and their impact on cryogenic machine construction, providing perspective for their use in future electrical machines. Although cost and safety issues of cryogenic systems are still holding back the uptake of cryogenic electric motors and generators, research in this field should provide significant improvements and promote their use at different levels.

Accurate sub-domain model for magnetic field computation in electrical machines with HTS materials

The primary aim of this study was to develop and validate an accurate sub-domain analytical model to estimate the magnetic field of electric machines with high-temperature superconducting (HTS) excitation and armature windings. The model was developed by utilizing the separation variable and harmonic analysis methods to solve Laplace’s or Poisson’s equations of the vector magnetic potential in two-dimensional polar coordinates. The theoretical derivations of the final analytical equations for the magnetic flux density distribution in the air-gap and in permanent magnets, electromagnetic torque, and no-load back-electromotive force (back-EMF) are explained in detail. Finally, the magnetic vector potential, flux density distribution of each sub-domain, no-load back-EMF, and inductive reactance of the armature winding were solved by considering the critical parameters of the superconducting materials, and the influence of higher harmonics. The finite-element method (FEM) was used to validate the accuracy of the developed analytical method for the investigated HTS generator. The results show the developed analytical method is accurate and time-saving.

Research on Slot-pole Combination in High-power Direct-drive PM Vernier Generator for Fractional Frequency Transmission System

Offshore wind energy is an important part of clean energy, and the adoption of wind energy to generate electricity will contribute to the implementation of the carbon peaking and carbon neutrality goals. The combination of the fractional frequency transmission system (FFTS) and the direct-drive wind turbine generator will be beneficial to the development of the offshore wind power industry. The use of fractional frequency in FFTS is beneficial to the transmission of electrical energy, but it will also lead to an increase in the volume and weight of the generator, which is unfavorable for wind power generation. Improving the torque density of the generator can effectively reduce the volume of the generators. The vernier permanent magnet machine (VPM) operates on the magnetic flux modulation principle and has the merits of high torque density. In the field of electric machines, the vernier machine based on the principle of magnetic flux modulation has been proved its feasibility to reduce the volume and weight. However, in the field of low-speed direct-drive machines for high-power fractional frequency power generation, there are still few related researches. Therefore, this paper studies the application of magnetic flux modulation in fractional frequency and high-power direct-drive wind turbine generators, mainly analyzes the influence of different pole ratios and different pole pairs on the generator, and draws some conclusions to provide reference for the design of wind turbine generators.

Two-dimensional Harmonic Modelling for Electro-magnetic Solution in Cartesian Coordinates

This paper first presents a general two-dimension (2D) harmonic analytical solution for the magnetic field of electric machines in the Cartesian coordinates. In this solution, the relative permeance is directly considered in Laplace and Poisson’s equations, and the particular solutions in Cartesian coordinates are solved. By applying the complex Fourier separation method, with the boundary and interface conditions, the magnetic field in the inhomogeneous region is solved from system equations. Numerical examples validate the presented method and the obtained results have a satisfactory agreement with the finite element analysis. The proposed model in this paper has a significant value for modelling electric machines, such as linear permanent magnet (PM) machines and axial flux PM machines.

Classification of Electrical Machines for Inventors and Artificial Intelligence Systems

The paper provides an overview of the existing classifications of electric machines and their criticism from the standpoint of logic and utilitarianism in the modern context. A modified approach to classification based on a set of features other than the generally accepted one is proposed. In particular, it is proposed not to use as the main ones such familiar features as the type of current in the network from which the machine is powered, the field and rotor rotation synchronism, and energy conversion direction. At the same time, such features as field sources and configurators, interaction force mechanisms, magnetic flux principal loop location relative to the gap plane and active parts motion direction are introduced. Pictograms are used as the main basic element of visualization and logical building block. The new approach seems to be more useful for inventors working in the field of electric machines and for application of artificial intelligence to develop new electric machine types and configurations. The classification for each of the selected features is illustrated by examples. A symbolic writing system is proposed for the new classification. Pictograms and code descriptions can be new means of the human-machine interface language.

The Key Role of 3D Printing Technologies in the Further Development of Electrical Machines

There is a strong general demand for the permanent improvement of electrical machines. Nowadays, these are at their near maximum potential, and even small further improvements can only be achieved with great effort and high cost. The single solution should be a paradigm shift in their development, by using radically new approaches to topology, materials, and fabrication. Therefore, the application of diverse 3D printing techniques for advanced fabrication in this field is inevitable. Therefore, these new approaches are receiving a great deal of attention among electrical machines designers. In the paper, the possible applications of these new fabrication technologies in the field of electrical machines are surveyed. The focus is set on emphasizing the advancement over the traditional manufacturing approaches.

Approach for the Model and Parameter Selection for the Calculation of Induction Machines

The solution of multiphysical problems in the field of electrical machines is a complex task that involves the modeling of a wide variety of coupled physical domains. Different types of models and solution methods can be used to model and solve the individual domains. In this paper a procedure for the methodical selection of the most suitable model for a given multiphysics task is presented. Furthermore, an approach for the selection of the most suitable variable machine parameters for a design optimization is presented. The model selection is presented on the basis of the electromagnetic calculation of an induction machine. For this purpose, models of different value ranges and levels of detail, such as analytical and numerical ones, are considered. The approach of the model selection is explained and applied on the basis of a coupled electromagnetic-thermal simulation of an exemplary induction machine. The results show that the model selection presented here can be used to methodically determine the most suitable model in terms of its value range, level of detail and computational effort for a given multiphysical problem.

Effect of the Temperature on the Magnetic and Energetic Properties of Soft Magnetic Composite Materials

In recent years, innovative magnetic materials have been introduced in the field of electrical machines. In the ambit of soft magnetic materials, laminated steels guarantee good robustness and high magnetic performance but, in some high-frequency applications, can be replaced by Soft Magnetic Composite (SMC) materials. SMC materials allow us to reduce the eddy currents and to design innovative 3D magnetic circuits. In general, SMCs are characterized at room temperature, but as electrical machines operate at high temperature (around 100 °C), an investigation analysis of the temperature effect has been carried out on these materials; in particular, three SMC samples with different binder percentages and process parameters have been considered for magnetic and energetic characterization.

Применение метода композиционных противоречий ТРИЗ для поиска новых решений в области электрических машин

The aim of this work is to increase the quantity and quality of innovations in the field of electrical machines by increasing the quantity and quality of ideas in this field. The application of the theory of inventive problem solving (TRIZ) in electromechanics is demonstrated as one of the ways to achieve the goal. The TRIZ is an empirical, constructive, qualitative, and universal methodology for generating effective ideas and solving problems based on models of contradictions and methods for resolving them, which are extracted from known examples of effective solutions. The application of one of the TRIZ algorithms is demonstrated on examples of solving three complex engineering problems: improving the reliability of electrical machine insulation, extending the operational ranges of electric drive torques and rotation frequencies, and achieving better cooling of an electric vehicle rotor. The accompanying complexities and the ways to overcome them are shown. The minimum necessary tools for conducting independent work in this area are given. The principle of drawing up the new professional vocabulary “TRIZ-Electromechanics” is shown. A brief overview of the skills of inventors and methods of their work is given.

Performance Analysis of Axial-Flux Induction Motor with Skewed Rotor

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.

Remembering Prof. Thomas A. Lipo: A Giant in the Field of Electrical Machines, Power Electronics, and Drives [In Memoriam

Remembering Prof. Thomas A. Lipo: A Giant in the Field of Electrical Machines, Power Electronics, and Drives [In Memoriam

Modeling of Dispersion Magnetic Fields Developed by the Main Electromagnetic Systems Used on Military Ships

Abstract In this paper, the authors present the modelling methods and numerical calculation of the dispersion magnetic field of electrical machines, as well as the results of their validation through practical measurements. An adequate analytic formula for magnetic induction calculation is proposed by the authors. The experimental results validate the proposed analytic model. Moreover, the proposed model is valid for both near and far field regions.

Multi-Objective Optimal Design of Permanent Magnet Synchronous Motor for Electric Vehicle Based on Deep Learning

Recently, a large amount of research on deep learning has been conducted. Related studies have also begun to apply deep learning techniques to the field of electric machines, but such studies have been limited to the field of fault diagnosis. In this study, the shape optimization of a permanent magnet synchronous motor (PMSM) for electric vehicles (EVs) was conducted using a multi-layer perceptron (MLP), which is a type of deep learning model. The target specifications were determined by referring to Renault’s Twizy, which is a small EV. The average torque and total harmonic distortion of the back electromotive force were used for the multi-objective functions, and the efficiency and torque ripple were chosen as constraints. To satisfy the multi-objective functions and constraints, the angle between the V-shaped permanent magnets and the rib thickness of the rotor were selected as design variables. To improve the accuracy of the design, the design of experiments was conducted using finite element analysis, and a parametric study was conducted through analysis of means. To verify the effectiveness of the MLP, metamodels was generated using both the MLP and a conventional Kriging model, and the optimal design was determined using the hybrid metaheuristic algorithm. To verify the structural stability of the optimized model, mechanical stress analysis was conducted. Moreover, because this is an optimal design problem with multi-objective functions, the changes in the optimal design results were examined as a function of the changes in the weighting. The optimal design results showed that the MLP technique achieved better predictive performance than the conventional Kriging model and is useful for the shape optimization of PMSMs.

SUB-DOMAIN ANALYSIS OF ASYMMETRICAL MAGNETIC FIELD IN ELECTRICAL MACHINES

SUB-DOMAIN ANALYSIS OF ASYMMETRICAL MAGNETIC FIELD IN ELECTRICAL MACHINES

Additive Manufacturing and Testing of a Soft Magnetic Rotor for a Switched Reluctance Motor

Additive manufacturing is acknowledged as a key enabling technology, although its adoption is still constrained to niche applications. A promising area for this technology is the production of electrical machines (EMs) and/or their main components (e.g. magnetic cores, windings, heat exchangers, etc.) due to the potential of creating lightweight, highly efficient rotating motors, suitable for applications requiring a low moment of inertia. This work investigates the readiness of metal additive manufacturing, specifically Laser Powder Bed Fusion (LPBF), applied to the field of EMs to bridge the gaps of how to use this technological approach in this field. A soft magnetic material featuring high silicon content (Fe-5.0%w.t.Si) has been developed for LPBF and a rotor has been 3D-printed for a switched reluctance machine. The printed rotor was assembled into a conventionally laminated stator and the performance of the whole machine was evaluated. Its performance was compared against an identical machine equipped with a laminated rotor of the same dimensions made of conventional non-oriented silicon steel. A comparative study was carried out through both finite element simulations and experimental tests. The efficiency of the two machines was assessed together with the principal electrical and mechanical quantities under several operating conditions.