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Energy Efficiency Improvement of Electric Machines without Rare-Earth Magnets
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Energy Efficiency Improvement of Electric Machines without Rare-Earth Magnets

A special issue of Energies (ISSN 1996-1073). This special issue belongs to the section "F: Electrical Engineering".

Deadline for manuscript submissions: closed (31 December 2022) | Viewed by 29685

Printed Edition Available!
A printed edition of this Special Issue is available here.

Special Issue Editors

Dr. Vladimir Prakht

E-Mail Website
Guest Editor
Department of Electrical Engineering, Ural Federal University, 620002 Yekaterinburg, Russia
Interests: energy efficiency; electric machines; electric motors; electric generators; electric drives; gearless generators; gearless motors; high-speed electric machines
Special Issues, Collections and Topics in MDPI journals
Dr. Mohamed N. Ibrahim

E-Mail Website
Guest Editor
Department of Electromechanical, Systems and Metal Engineering, Ghent University, 9052 Ghent, Belgium
Interests: synchronous reluctance machine; permanent magnet assisted synchronous reluctance motors; field-oriented control; winding function; harmonic analysis; star-delta; magnetic steel grade and optimization techniques
Special Issues, Collections and Topics in MDPI journals
Dr. Vadim Kazakbaev

E-Mail Website
Guest Editor
Department of Electrical Engineering, Ural Federal University, 620002 Yekaterinburg, Russia
Interests: electric drives; electrical machines; energy efficiency; energy saving; modeling; optimization

Special Issue Information

Dear Colleagues,

Electric motors consume about 70% of industrial electricity and about 40%–45% of produced electricity in the world. This reveals that using high-efficiency electric motors will reduce energy consumption and the environmental impact, resulting in saving a lot of money and reducing the emissions of CO2. In addition, it will significantly reduce the need for new power plants, thus reducing the invested resources to do so. Electric machines with rare-earth magnets have the highest efficiency and power density.

However, rare-earth magnets are expensive, and their manufacturing process, as well as mining rare-earth raw materials, is harmful for the environment. Therefore, developing energy-efficient electric machines without rare-earth magnets is of great interest. Topics of interest for this Special Issue include but are not limited to:

- Modeling and design of energy-efficient electric machines without rare-earth magnets;

- Synchronous reluctance machines;

- Permanent magnet assisted synchronous reluctance machines;

- Switched reluctance machines;

- Hybrid switched reluctance machines;

- DC excited flux-switching machines;

- PM excited flux-switching machines;

- DC excited synchronous machines;

- Direct-on-line and line start motors;

- Induction machines;

- Electric generators without rare-earth magnets for wind turbines;

- Other electric machines without rare-earth magnets;

- Control techniques for electric machines without rare-earth magnets.

Dr. Vladimir Prakht
Dr. Mohamed N. Ibrahim
Dr. Vadim Kazakbaev
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Energies is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • electric machines
  • electric motors
  • electric generators
  • control techniques for electric machines
  • electric drives

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Published Papers (11 papers)

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Editorial

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3 pages, 162 KiB  
Editorial
Energy Efficiency Improvement of Electric Machines without Rare-Earth Magnets
by Vladimir Prakht, Mohamed N. Ibrahim and Vadim Kazakbaev
Energies 2023, 16(8), 3573; https://doi.org/10.3390/en16083573 - 20 Apr 2023
Cited by 1 | Viewed by 1049
Abstract
Electric motors are one of the largest consumers of electricity and are responsible for 40–45% of the world’s energy consumption [...] Full article
(This article belongs to the Special Issue Energy Efficiency Improvement of Electric Machines without Rare-Earth Magnets)

Research

Jump to: Editorial

16 pages, 56118 KiB  
Article
Hybrid Switched Reluctance Motors for Electric Vehicle Applications with High Torque Capability without Permanent Magnet
by Vijina Abhijith, M. J. Hossain, Gang Lei, Premlal Ajikumar Sreelekha, Tibinmon Pulimoottil Monichan and Sree Venkateswara Rao
Energies 2022, 15(21), 7931; https://doi.org/10.3390/en15217931 - 26 Oct 2022
Cited by 7 | Viewed by 2551
Abstract
In electric vehicle (EV) applications, hybrid excitation of switched reluctance motors (HESRMs) are gaining popularity due to their advantages over other EV motors. The benefits include control flexibility, simple construction, high torque/power density, and the ability to operate over a broad speed range. [...] Read more.
In electric vehicle (EV) applications, hybrid excitation of switched reluctance motors (HESRMs) are gaining popularity due to their advantages over other EV motors. The benefits include control flexibility, simple construction, high torque/power density, and the ability to operate over a broad speed range. However, modern HESRMs are constructed by increasing the air gap flux density with permanent magnets (PMs) in the excitation system in order to generate more electromagnetic torque. This study aims to investigate a new topology for increasing the torque capabilities of HESRM without the use of permanent magnets (PMs) or other rare-earth components. This paper provides a comprehensive evaluation of the static and dynamic characteristics, software analysis using the Ansys 2D finite element method (FEM), and an experimental demonstration of the real-time motor with an advanced control strategy in MATLAB/Simulink. Our simulation and experimental results for a machine with 12/8 poles and a machine rating of 1.2 kW indicate that the HESRM designed without PMs has greater torque capability and efficiency than the conventional SRM. The proposed HESRM without PMs has a high torque/power density and a higher torque per ampere across the entire speed range, making it suitable for EV applications. Full article
(This article belongs to the Special Issue Energy Efficiency Improvement of Electric Machines without Rare-Earth Magnets)
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17 pages, 5221 KiB  
Article
Performance Analysis and Optimization of a Novel Outer Rotor Field-Excited Flux-Switching Machine with Combined Semi-Closed and Open Slots Stator
by Siddique Akbar, Faisal Khan, Wasiq Ullah, Basharat Ullah, Ahmad H. Milyani and Abdullah Ahmed Azhari
Energies 2022, 15(20), 7531; https://doi.org/10.3390/en15207531 - 12 Oct 2022
Cited by 2 | Viewed by 1636
Abstract
Slotting effect in electric machines reduces flux per pole that effect magnetic flux density distribution in the air gap which induces harmonics in magnetic flux density causing flux pulsation, that in turn generates dominant torque pulsation in the form of cogging torque and [...] Read more.
Slotting effect in electric machines reduces flux per pole that effect magnetic flux density distribution in the air gap which induces harmonics in magnetic flux density causing flux pulsation, that in turn generates dominant torque pulsation in the form of cogging torque and torque ripples. To overcome the abovesaid demerits, a novel outer rotor field-excited flux-switching machine (OR-FSFSM) with a combined semi-closed and open slots stator is proposed in this study. The developed OR-FEFSM offers a high-power factor, due to the utilization of the semi-closed slot for armature coils. The open slot stator structure was chosen for the field excitation coil, which effectively suppresses leakage reluctance that causes flux pulsation. Thus, the influence of torque ripples is reduced, and the average torque is improved. In order to investigate the effectiveness of the proposed OR-FEFSM, a detailed study of stator slot and rotor pole combinations are performed. Based on simplified mathematical formulation, 12S/7P (stator slot/rotor poles), 12S/11P, 12S/13P, and 12S/17P are the most feasible combinations. Finite Element Analysis (FEA) based on comprehensive electromagnetic performance is performed on each combination, and found that 12S/13P offers the highest average torque of 4.62 Nm, whereas 3.72 Nm, 2.72Nm, and 1.68 Nm average torque is offered by 12S/17P, 12S/7P, and 12S/11P, respectively. Based on the initial analysis, 12S/13P was considered for further analysis and optimized using JMAG built-in Genetic Algorithm (GA). Moreover, thermal analysis was performed, and the proposed design was compared with the conventional design. Full article
(This article belongs to the Special Issue Energy Efficiency Improvement of Electric Machines without Rare-Earth Magnets)
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18 pages, 4238 KiB  
Article
Design and Thermal Analysis of Linear Hybrid Excited Flux Switching Machine Using Ferrite Magnets
by Himayat Ullah Jan, Faisal Khan, Basharat Ullah, Muhammad Qasim, Ahmad H. Milyani and Abdullah Ahmed Azhari
Energies 2022, 15(14), 5275; https://doi.org/10.3390/en15145275 - 21 Jul 2022
Cited by 2 | Viewed by 1109
Abstract
This paper presents a novel linear hybrid excited flux switching permanent magnet machine (LHEFSPMM) with a crooked tooth modular stator. Conventional stators are made up of a pure iron core, which results in high manufacturing costs and increased iron core losses. Using a [...] Read more.
This paper presents a novel linear hybrid excited flux switching permanent magnet machine (LHEFSPMM) with a crooked tooth modular stator. Conventional stators are made up of a pure iron core, which results in high manufacturing costs and increased iron core losses. Using a modular stator lowers the iron volume by up to 18% compared to a conventional stator, which minimizes the core losses and reduces the machine’s overall cost. A crooked angle is introduced to improve the flux linkage between the stator pole and the mover slot. Ferrite magnets are used with parallel magnetization to reduce the cost of the machine. Two-dimensional FEA is performed to analyze and evaluate various performance parameters of the proposed machine. Geometric optimization is used to optimize the split ratio (S.R) and winding slot area (Slotarea). Genetic algorithm (GA) is applied and is used to optimize stator tooth width (STW), space between the modules (SS), crooked angle (α), and starting angle (θ). The proposed model has a high thrust density (306.61 kN/m3), lower detent force (8.4 N), and a simpler design with higher efficiency (86%). The linear modular structure makes it a good candidate for railway transportation and electric trains. Thermal analysis of the machine is performed by FEA and then the results are validated by an LPMEC model. Overall, a very good agreement is observed between both the analyses, and relative percentage error of less than 3% is achieved, which is considerable since the FEA is in 3D while 2D temperature flow is considered in the LPMEC model. Full article
(This article belongs to the Special Issue Energy Efficiency Improvement of Electric Machines without Rare-Earth Magnets)
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17 pages, 6782 KiB  
Article
Performance Improvement of a Switched Reluctance Motor and Drive System Designed for an Electric Motorcycle
by Seubsuang Kachapornkul, Ruchao Pupadubsin, Pakasit Somsiri, Prapon Jitkreeyarn and Kanokvate Tungpimolrut
Energies 2022, 15(3), 694; https://doi.org/10.3390/en15030694 - 18 Jan 2022
Cited by 4 | Viewed by 2163
Abstract
In this paper, the implementation of a switched reluctance motor (SRM) and drive system for the propulsion system of a two-seat electric motorcycle is described. The overall design focuses on the required vehicle speed, acceleration, driving distance, and overall system cost, as well [...] Read more.
In this paper, the implementation of a switched reluctance motor (SRM) and drive system for the propulsion system of a two-seat electric motorcycle is described. The overall design focuses on the required vehicle speed, acceleration, driving distance, and overall system cost, as well as reliability. The performance of the three-phase 6/4 pole (six-stator pole and four-rotor pole) and four-phase 8/6 pole (eight-stator pole and six-rotor pole) are investigated and compared by static performance analysis and dynamic performance analysis. Their performance is further investigated by finite element analysis. The indirect torque controller in a drive system for optimal torque and efficiency operation is also mentioned. A methodology for rotor position detection and its hardware implementation are also proposed. The designed 3.5 kW three-phase 6/4 pole SRM and its drive system were constructed and tested on the test bench. A maximum efficiency of about 82% could be achieved for the SRM and drive system. It was also installed on a 120-cc electric motorcycle, and the vehicle’s performance was also validated by on-road and dynamometer testing. The maximum vehicle speed reached was 82 km/h, and a cruising distance of about 98 km at a constant speed of 40 km/h was measured. Full article
(This article belongs to the Special Issue Energy Efficiency Improvement of Electric Machines without Rare-Earth Magnets)
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17 pages, 2113 KiB  
Article
Investigation of Torque Performance and Flux Reversal Reduction of a Three-Phase 12/8 Switched Reluctance Motor Based on Winding Arrangement
by Ruchao Pupadubsin, Seubsuang Kachapornkul, Prapon Jitkreeyarn, Pakasit Somsiri and Kanokvate Tungpimolrut
Energies 2022, 15(1), 284; https://doi.org/10.3390/en15010284 - 01 Jan 2022
Cited by 5 | Viewed by 1537
Abstract
The goal of this paper is to present a comparative analysis of two types of winding arrangements for a three-phase 12/8 switched reluctance motor (SRM), where short- and fully-pitched winding arrangements under unipolar operation are considered. From the analytical results, the short-pitched winding [...] Read more.
The goal of this paper is to present a comparative analysis of two types of winding arrangements for a three-phase 12/8 switched reluctance motor (SRM), where short- and fully-pitched winding arrangements under unipolar operation are considered. From the analytical results, the short-pitched winding has the best torque per copper weight ratio. The core loss based on counting the number of flux reversals in the stator yoke for each winding arrangement is also proposed and mentioned. To reduce the magnetic flux reversals in the stator core, changing the direction of the magnetic flux path by modifying the winding polarities of the short-pitched winding could reduce 10–13% of core loss compared to the conventional winding. A 1 kW, 12/8 SRM prototype for the ventilation fan application is constructed and tested in order to verify the design consideration of winding configuration. At the rated condition, a maximum efficiency around 82.5% could be achieved. Full article
(This article belongs to the Special Issue Energy Efficiency Improvement of Electric Machines without Rare-Earth Magnets)
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15 pages, 6848 KiB  
Article
A Study on the Rotor Design of Line Start Synchronous Reluctance Motor for IE4 Efficiency and Improving Power Factor
by Hyunwoo Kim, Yeji Park, Seung-Taek Oh, Hyungkwan Jang, Sung-Hong Won, Yon-Do Chun and Ju Lee
Energies 2020, 13(21), 5774; https://doi.org/10.3390/en13215774 - 04 Nov 2020
Cited by 21 | Viewed by 3654
Abstract
As international regulations of motor efficiency are strengthened, the line-start synchronous reluctance motor (LS-SynRM) is being studied to improve the efficiency of the electrical motor in industrial applications. However, in industrial applications, the power factor is also an important performance index, but the [...] Read more.
As international regulations of motor efficiency are strengthened, the line-start synchronous reluctance motor (LS-SynRM) is being studied to improve the efficiency of the electrical motor in industrial applications. However, in industrial applications, the power factor is also an important performance index, but the LS-SynRM has poor power factor due to the saliency characteristic. In this paper, the rotor design of LS-SynRM is performed to improve the efficiency and power factor. First, the barrier design is performed to improve the efficiency and power factor using the response surface method (RSM). Second, the rotor slot design is performed according to the length of bar for synchronization. Lastly, the rib design is performed to satisfy the power factor and the mechanical reliability. The final model through the design process is analyzed using finite element analysis (FEA), and the objective performance is satisfied. To verify the FEA result, the final model is manufactured, and experiment is performed. Full article
(This article belongs to the Special Issue Energy Efficiency Improvement of Electric Machines without Rare-Earth Magnets)
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26 pages, 9915 KiB  
Article
Design and Performance Assessment of a Small-Scale Ferrite-PM Flux Reversal Wind Generator
by Bharathi Manne, Malligunta Kiran Kumar and Udochukwu B. Akuru
Energies 2020, 13(21), 5565; https://doi.org/10.3390/en13215565 - 23 Oct 2020
Cited by 6 | Viewed by 2104
Abstract
Currently, there is increasing research interest in harnessing wind energy for power generation by means of non-conventional electrical machines e.g., flux-reversal machines. The flux reversal machine is usually designed using scarce rare–earth permanent magnet material which may be unattractive in terms of machine [...] Read more.
Currently, there is increasing research interest in harnessing wind energy for power generation by means of non-conventional electrical machines e.g., flux-reversal machines. The flux reversal machine is usually designed using scarce rare–earth permanent magnet material which may be unattractive in terms of machine cost. In this study, an attempt is made to re-design the flux reversal machine with non-rare-earth ferrite permanent magnet for wind energy applications. Because these machines possess high cogging torque, which results in vibration and noise, that are detrimental to the machine performance, especially at low speeds, a novel combined skewed and circumferential rotor pole pairing method is developed. The proposed cogging torque reduction method is implemented in 2-dimensional finite element analysis modeling and comparatively analyzed with other existing stand-alone methods viz., skewing, and rotor pole pairing. The results show that the proposed method led to 94.8% and 71% reduction in the cogging torque and torque ripple compared to the reference generator, respectively. However, the calculated torque density is reduced by 13%. Overall, the electromagnetic performance of the proposed ferrite PM machine exhibits desirable qualities as an alternative design for the direct drive wind generator. Full article
(This article belongs to the Special Issue Energy Efficiency Improvement of Electric Machines without Rare-Earth Magnets)
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15 pages, 4858 KiB  
Article
Performance Analysis of Axial-Flux Induction Motor with Skewed Rotor
by Fatma Keskin Arabul, Ibrahim Senol and Yasemin Oner
Energies 2020, 13(19), 4991; https://doi.org/10.3390/en13194991 - 23 Sep 2020
Cited by 16 | Viewed by 6762
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 [...] Read more.
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. Full article
(This article belongs to the Special Issue Energy Efficiency Improvement of Electric Machines without Rare-Earth Magnets)
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17 pages, 3035 KiB  
Article
Simulation-Based Coyote Optimization Algorithm to Determine Gains of PI Controller for Enhancing the Performance of Solar PV Water-Pumping System
by Jouda Arfaoui, Hegazy Rezk, Mujahed Al-Dhaifallah, Mohamed N. Ibrahim and Mami Abdelkader
Energies 2020, 13(17), 4473; https://doi.org/10.3390/en13174473 - 31 Aug 2020
Cited by 11 | Viewed by 2102
Abstract
In this study, a simulation-based coyote optimization algorithm (COA) to identify the gains of PI to ameliorate the water-pumping system performance fed from the photovoltaic system is presented. The aim is to develop a stand-alone water-pumping system powered by solar energy, i.e., without [...] Read more.
In this study, a simulation-based coyote optimization algorithm (COA) to identify the gains of PI to ameliorate the water-pumping system performance fed from the photovoltaic system is presented. The aim is to develop a stand-alone water-pumping system powered by solar energy, i.e., without the need of electric power from the utility grid. The voltage of the DC bus was adopted as a good candidate to guarantee the extraction of the maximum power under partial shading conditions. In such a system, two proportional-integral (PI) controllers, at least, are necessary. The adjustment of (Proportional-Integral) controllers are always carried out by classical and tiresome trials and errors techniques which becomes a hard task and time-consuming. In order to overcome this problem, an optimization problem was reformulated and modeled under functional time-domain constraints, aiming at tuning these decision variables. For achieving the desired operational characteristics of the PV water-pumping system for both rotor speed and DC-link voltage, simultaneously, the proposed COA algorithm is adopted. It is carried out through resolving a multiobjective optimization problem employing the weighted-sum technique. Inspired on the Canis latrans species, the COA algorithm is successfully investigated to resolve such a problem by taking into account some constraints in terms of time-domain performance as well as producing the maximum power from the photovoltaic generation system. To assess the efficiency of the suggested COA method, the classical Ziegler–Nichols and trial–error tuning methods for the DC-link voltage and rotor speed dynamics, were compared. The main outcomes ensured the effectiveness and superiority of the COA algorithm. Compared to the other reported techniques, it is superior in terms of convergence rapidity and solution qualities. Full article
(This article belongs to the Special Issue Energy Efficiency Improvement of Electric Machines without Rare-Earth Magnets)
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15 pages, 2456 KiB  
Article
Life Cycle Energy Cost Assessment for Pump Units with Various Types of Line-Start Operating Motors Including Cable Losses
by Vadim Kazakbaev, Vladimir Prakht, Vladimir Dmitrievskii, Safarbek Oshurbekov and Dmitry Golovanov
Energies 2020, 13(14), 3546; https://doi.org/10.3390/en13143546 - 09 Jul 2020
Cited by 7 | Viewed by 2745
Abstract
The paper presents a comparative analysis of life-cycle energy consumption for three different types of 4 kW line-start motors used in a pump unit with throttling: the most widely used induction motor with IE3 efficiency class, line start permanent magnet synchronous motor with [...] Read more.
The paper presents a comparative analysis of life-cycle energy consumption for three different types of 4 kW line-start motors used in a pump unit with throttling: the most widely used induction motor with IE3 efficiency class, line start permanent magnet synchronous motor with IE4 efficiency class and line start synchronous reluctance motor with IE4 efficiency class. The operating cycle for pump units with constant flow is considered for the above-mentioned types of motors taking into account not only the losses in the pump and motor, but also in the power supply cable. It is shown that the line start synchronous reluctance motor without magnets has the highest efficiency over the entire considered loading range. However, its power factor is lower than that of the synchronous motor with magnets and therefore it has more significant losses in power supply cable. Despite this disadvantage, the line-start reluctance motor is a good alternative to widespread induction motor since it allows saving of approximately 4000 euro more than the latter during the 20 years life cycle. It also provides similar savings in comparison to the permanent magnet synchronous motor, but unlike it, it does not have costly rare-earth materials in the rotor. Full article
(This article belongs to the Special Issue Energy Efficiency Improvement of Electric Machines without Rare-Earth Magnets)
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