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Symmetry
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Symmetry/Asymmetry in Design and Analysis of Electric Machines and Transformers
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Symmetry/Asymmetry in Design and Analysis of Electric Machines and Transformers

A special issue of Symmetry (ISSN 2073-8994). This special issue belongs to the section "Engineering and Materials".

Deadline for manuscript submissions: closed (10 August 2022) | Viewed by 14482

Special Issue Editors

Prof. Dr. Wenliang Zhao

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Guest Editor
School of Electrical Engineering, Shandong University, Jinan, China
Interests: design and analysis of electric machines and apparatus
Prof. Dr. Dezhi Chen

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Guest Editor
School of Electrical Engineering, Shenyang University of Technology, Shenyang, China
Interests: design and analysis of transformers; motor control
Prof. Dr. Jinhua Chen

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Guest Editor
Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, China
Interests: design and analysis of permanent magnet machines

Special Issue Information

Dear Colleagues,

Electric machines and transformers play important roles in the process of energy generation, transmission, and consumption, which are generally designed, analyzed, and operated in symmetric states. Asymmetric design and operation could result in problems such as overheating, faults, noise, and even operating failure. However, in recent years, with the development of design and analysis technologies, it has also been found that the specific asymmetric phenomenon existing in electric machines and transformers will also lead to positive effects on their performance. Therefore, it will be very interesting and important to comprehensively study the symmetric and asymmetric issues for electric machines and transformers for the purpose of improving their performance. On one hand, it is necessary to deal with the disadvantageous problems caused by asymmetric factors. On the other hand, it will be wise to rationally utilize the advantageous effects of asymmetric designs. This Special Issue of Symmetry will provide a timely opportunity for researchers and engineers from industry and academia to present the latest results and findings on the above points in the design and analysis of electric machines and transformers, including topologies, structures, analysis approaches, control strategies, applications, etc. Guest editors invite original manuscripts in those fields with innovative academic and engineering research results.

Prof. Dr. Wenliang Zhao
Prof. Dr. Dezhi Chen
Prof. Dr. Jinhua Chen
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. Symmetry is an international peer-reviewed open access monthly 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 2400 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

  • Symmetrically/asymmetrically advanced design technologies
  • Advanced analysis methods for symmetric/asymmetric phenomena
  • New topologies with the use of symmetric/asymmetric effects
  • Modeling and simulation considering symmetric/asymmetric factors
  • Advanced control strategies considering symmetric/asymmetric factors
  • Multiphysics coupling analysis under symmetric/asymmetric conditions
  • Multi-objective optimization techniques
  • Fault diagnosis and online operation status monitoring under asymmetric states

Published Papers (7 papers)

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Research

13 pages, 3533 KiB  
Article
Temperature Rise Calculation of Magnetic Core Considering the Temperature Effect of Magnetic Properties in an Electrical Steel Sheet
by Zhen Wang, Kai Xu and Yufeng Du
Symmetry 2022, 14(11), 2315; https://doi.org/10.3390/sym14112315 - 04 Nov 2022
Cited by 2 | Viewed by 1929
Abstract
The magnetic properties of electrical steel sheets are affected by magnetization patterns, working temperature, and external pressure. In order to study the temperature effect of electrical steel sheets on the temperature rise of a transformer core, in this paper, based on the magnetic [...] Read more.
The magnetic properties of electrical steel sheets are affected by magnetization patterns, working temperature, and external pressure. In order to study the temperature effect of electrical steel sheets on the temperature rise of a transformer core, in this paper, based on the magnetic property test system of an electrical steel sheet, the permeability and loss of a 50AW600 grain non-oriented electrical steel sheet and a 30ZH120 grain oriented electrical steel sheet under different temperatures and excited frequencies were measured, and the influence of temperature on the properties of the material was analyzed. A magneto-thermal iterative coupling method considering the temperature effects of magnetic properties in the electrical steel sheet was investigated. Based on the above measurement data and iterative coupling method, the temperature distribution of the core of a 500-kV power transformer was simulated and analyzed, and compared with the simulation results of the traditional coupling method without considering the temperature effect of the electrical steel sheet. Magneto-thermal coupling simulation under no-load operation is a symmetrical problem. It was found that the temperature of the hottest spot of the transformer core calculated by the magneto-thermal iteration method proposed in this paper was significantly reduced, the temperature of the hottest spot on the core column was about 45 °C, and the temperature of the hottest spot on the upper and lower yoke was about 39 °C, which provides an effective simulation method for accurately calculating the temperature rise distribution of electrical products such as transformers. Full article
(This article belongs to the Special Issue Symmetry/Asymmetry in Design and Analysis of Electric Machines and Transformers)
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13 pages, 6204 KiB  
Article
Accurate Analytical Models of Armature Reaction Field for Multi-Segment Primaries Ironless PMLSM Based on Subdomain Method
by Fugang Zhang, Haibin Yin and Yufeng Li
Symmetry 2022, 14(10), 2091; https://doi.org/10.3390/sym14102091 - 08 Oct 2022
Viewed by 956
Abstract
Multi-segment-primary (MSP) ironless Permanent Magnet Linear Synchronous Machine (PMLSM) can be widely applied in long primary, long stroke, and heavy load applications. Therefore, an accurate armature reaction field analysis is very important to control this novel topology motor. In order to simplify the [...] Read more.
Multi-segment-primary (MSP) ironless Permanent Magnet Linear Synchronous Machine (PMLSM) can be widely applied in long primary, long stroke, and heavy load applications. Therefore, an accurate armature reaction field analysis is very important to control this novel topology motor. In order to simplify the research process, a two-segment-primary (TSP) ironless PMLSM in this article was proposed as the smallest unit. The analytical models of the armature reaction field of the motor based on the subdomain method (SDM) were established considering the finite length of the segment-primary (SP) and the interval distance between the TSP. Then, the coupling effect between the TSP and the end effect of the TSP on the armature reaction field were quantitatively analyzed. Furthermore, the coupling inductance between the TSP can be analytically calculated, which is influenced by the coupling effect. To validate the effectiveness of the proposed models, a prototype of the 24s/28p TSP ironless PMLSM was manufactured and tested. It was shown that the proposed models match well with the simulated and experimental results. As well, the maximum variation rate of the end coupling inductance was about 50.13%. Full article
(This article belongs to the Special Issue Symmetry/Asymmetry in Design and Analysis of Electric Machines and Transformers)
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15 pages, 7836 KiB  
Article
Optimal Design and Control of a Spoke-Type IPM Motor with Asymmetric Flux Barriers to Improve Torque Density
by Hao Wu, Wenliang Zhao, Gefei Zhu and Min Li
Symmetry 2022, 14(9), 1788; https://doi.org/10.3390/sym14091788 - 28 Aug 2022
Cited by 4 | Viewed by 1960
Abstract
This paper studies the optimal design and control scheme of a spoke-type interior permanent magnet motor (SIPM). An asymmetric rotor structure with flux barriers is designed to improve the torque density of SIPM. The design method improves the torque density by approximating the [...] Read more.
This paper studies the optimal design and control scheme of a spoke-type interior permanent magnet motor (SIPM). An asymmetric rotor structure with flux barriers is designed to improve the torque density of SIPM. The design method improves the torque density by approximating the maximum value of the magnetic torque and the reluctance torque, wherein the torque components are separated by the frozen permeability method (FPM) to evaluate the contribution. This scheme does not increase the amount of permanent magnets or the motor size, and reduces motor weight while increasing motor torque output. Firstly, the asymmetric flux barriers are applied in a 27/4 SIPM to illustrate the design principle. Further, by optimizing the width of flux barriers, based on finite-element analyze (FEA), a higher torque density is obtained. Compared with the basic model, the output torque and the torque density of the optimal model are both increased. Based on the optimal model, an angle scanning method is proposed to orient the flux vector and dq-axis. Then, the mathematical model of the optimal model is established, and the maximum torque per ampere (MTPA) control system is designed. Compared with the conventional control system, the proposed control system has a higher torque per ampere (TPA), which shows that the designed control system can give full play to the advantages of the high torque density. Full article
(This article belongs to the Special Issue Symmetry/Asymmetry in Design and Analysis of Electric Machines and Transformers)
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17 pages, 7348 KiB  
Article
Research on Vibration and Noise of Induction Motor under Variable Frequency
by Zhonghuan Su, Longfu Luo, Jun Liu, Zhongxiang Li, Hu Luo and Haonan Bai
Symmetry 2022, 14(3), 569; https://doi.org/10.3390/sym14030569 - 14 Mar 2022
Cited by 1 | Viewed by 2058
Abstract
Studies have substantiated that the vibration and noise produced by the iron core of an electromagnetic device are closely related to the magnetostriction of the iron core silicon steel sheet. Moreover, when the induction motor works under the condition of frequency conversion, the [...] Read more.
Studies have substantiated that the vibration and noise produced by the iron core of an electromagnetic device are closely related to the magnetostriction of the iron core silicon steel sheet. Moreover, when the induction motor works under the condition of frequency conversion, the symmetry of the core silicon steel sheet will change, and the distribution of the vibration and noise field of the motor will be asymmetric, which will aggravate the vibration and noise. This paper completes the experimental measurement and analysis of the electromagnetic characteristics and magnetostrictive characteristics of silicon steel sheets. The magnetic field of a 1140 V/75 kW variable-frequency motor is calculated analytically based on the analytical method, and the stator/rotor magnetic induction intensity and permeance are calculated separately to obtain the air gap magnetic density and the radial electromagnetic force. The vibration and noise of the 1140 V/75 kW variable-frequency motor are analyzed by the finite element method, while the magnetization curve and magnetostrictive characteristic curve of a silicon steel sheet under different conditions are considered. An experimental platform is built to measure and analyze the vibration displacement and acceleration of the variable frequency motor, which verifies the correctness of the proposed scheme. Considering the influence of the magnetostrictive effect will make the result of calculating the vibration and noise of variable-frequency motors more accurate. Full article
(This article belongs to the Special Issue Symmetry/Asymmetry in Design and Analysis of Electric Machines and Transformers)
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13 pages, 4602 KiB  
Article
The Vibroacoustic Characteristics Analysis of Transformer Core Faults Based on Multi-Physical Field Coupling
by Degui Yao, Longfei Li, Songyang Zhang, Dianhai Zhang and Dezhi Chen
Symmetry 2022, 14(3), 544; https://doi.org/10.3390/sym14030544 - 07 Mar 2022
Cited by 4 | Viewed by 1980
Abstract
Power transformers play an important role in the safe and reliable operation of the whole power grid. Once a fault occurs, it will endanger the normal operation of the transformer, and even result in power grid accidents. Accurate and practical methods of transformer [...] Read more.
Power transformers play an important role in the safe and reliable operation of the whole power grid. Once a fault occurs, it will endanger the normal operation of the transformer, and even result in power grid accidents. Accurate and practical methods of transformer fault monitoring and type identification have attracted extensive attention in the field of electrical engineering. However, it is difficult to obtain a large number of measurement data for different fault types on a large power transformer. The vibroacoustic characteristics of transformer faults have significant asymmetry. For the power transformer in service, it is complex and uneconomic to obtain the vibroacoustic signals under different fault conditions. To handle this problem, this paper proposes simulation methods of several common transformer core faults, based on multi-physical field coupling, and then analyzes the vibroacoustic signals generated by the operating transformer. Finally, it verifies the results of acoustic and vibration signals under several faults, through physical experiments. The results show that the transformer fault simulation method is reasonable and accurate. Furthermore, a change in the transformer core state will cause a change in the transformer vibroacoustic characteristics, and different types of core faults can be distinguished by the analysis of vibroacoustic characteristics. Full article
(This article belongs to the Special Issue Symmetry/Asymmetry in Design and Analysis of Electric Machines and Transformers)
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16 pages, 16279 KiB  
Article
Harmonic and Vibration Analysis of Dual Three-Phase PMSM with One-Phase Open Circuit Fault
by Shihao Zhao, Jinhua Chen, Yunpeng Gao and Chi Zhang
Symmetry 2022, 14(2), 290; https://doi.org/10.3390/sym14020290 - 31 Jan 2022
Cited by 1 | Viewed by 2144
Abstract
This paper analyzes the harmonics and vibration under different fault-tolerant current control when one-phase winding of dual three-phase permanent magnet synchronous motor (PMSM) is an open circuit fault. Firstly, the dual three-phase load condition subdomain model of breadloaf surface-mounted permanent magnet (PM) PMSM [...] Read more.
This paper analyzes the harmonics and vibration under different fault-tolerant current control when one-phase winding of dual three-phase permanent magnet synchronous motor (PMSM) is an open circuit fault. Firstly, the dual three-phase load condition subdomain model of breadloaf surface-mounted permanent magnet (PM) PMSM is established. Secondly, the working conditions of an open circuit fault of one-phase winding are set from the perspectives of no fault-tolerant (NFT) control, maximum torque (MT) control, minimum copper loss (MCL) control and single three-phase mode (STPM) control. The torque harmonics and electromagnetic force harmonics of the four working conditions are analyzed. Then, considering the multi-physical field of electromagnetic and structural coupling, the electromagnetic force in the motor air gap acts on the stator core, and the vibration under four different working conditions is calculated and analyzed. Through the comparison between the analytical method and finite element method, the accuracy of the established model is verified. The calculation method is effective and accurate, it can quickly predict the motor performance in case of one-phase open circuit fault of dual three-phase PMSM. Full article
(This article belongs to the Special Issue Symmetry/Asymmetry in Design and Analysis of Electric Machines and Transformers)
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15 pages, 4712 KiB  
Article
A Full-Period Mathematical Model for a Hybrid-Rotor Bearingless Switched Reluctance Motor
by Zeyuan Liu, Mei Chen, Yan Yang, Chengzi Liu and Hui Gao
Symmetry 2021, 13(12), 2383; https://doi.org/10.3390/sym13122383 - 10 Dec 2021
Cited by 5 | Viewed by 1856
Abstract
A bearingless switched reluctance motor (BSRM) has the combined characteristics of a switched reluctance motor (SRM) and a magnetic bearing. The hybrid-rotor BSRM (HBSRM) discussed in the paper has a twelve-pole stator and an eight-pole hybrid rotor, which is composed of a cylindrical [...] Read more.
A bearingless switched reluctance motor (BSRM) has the combined characteristics of a switched reluctance motor (SRM) and a magnetic bearing. The hybrid-rotor BSRM (HBSRM) discussed in the paper has a twelve-pole stator and an eight-pole hybrid rotor, which is composed of a cylindrical rotor and a salient-pole rotor. Although the asymmetry of the hybrid rotor makes the structure and magnetic field of the HBSRM more complex, it can always produce a significant amount of magnetic pulling force to levitate a rotor shaft at all the rotor angular positions of each phase, which is not available in a traditional BSRM. The classical mathematical model for a conventional BSRM is valid only when its rotor rotates from the start of the overlap position to the aligned position, and the radial force and torque derived from this model are discontinuous at the aligned positon, which is harmful to the motor’s stable operation. In this paper, a full-period mathematical model on the assumption that the gap permeance is cut apart by straight lines or improved elliptical lines for a 12/8-pole HBSRM is provided. On the basis of this mathematical model, the continuity of the radial force and torque at all the rotor angular positions can be guaranteed, and the fine characteristics of this mathematical model have been verified by simulations. Full article
(This article belongs to the Special Issue Symmetry/Asymmetry in Design and Analysis of Electric Machines and Transformers)
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