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

Deadline for manuscript submissions: 10 September 2024 | Viewed by 10671

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Special Issue Editors

Dr. Dan-Cristian Popa

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Guest Editor

Department of Electrical Machines and Drives, Technical University of Cluj-Napoca, 28 Memorandumului Street, 400114 Cluj-Napoca, Romania
Interests: design of electric machines; numerical and analytical analysis; transverse flux machines; induction machines; transformers
Special Issues, Collections and Topics in MDPI journals

Prof. Dr. Emil Cazacu

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Guest Editor

Department of Electrotechnics, Faculty of Electrical Engineering, University “POLITEHNICA” of Bucharest, Splaiul Independentei 313, Sector 6, 060042 Bucharest, Romania
Interests: electromagnetic field computation; magnetic levitation; nonlinear circuits; measurement and interpretation of power quality parameters for low-voltage consumers that operates in distorted and/or unbalanced states
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear colleagues,

The need for the efficient and high density power electric machines has led to study of various new topologies and optimization of the classic ones. The use of numerical analysis has become a regular used tool for the evaluation of the performances of the electrical machines. Also, the employment of various analytical models represents an important tool for the above mentioned purpose. In this context, the studies on these topics are always of interest for the researchers in this domain.

This Special Issue aims to publish researches on different topologies of electrical machines, based mainly on, but not limited to Magnetic Field Computations and Energy Efficiency Studies. These analyses are challenging for the researchers as efficiency increases cannot be achieved without finding innovative solutions. Also, analytical and numerical analyses are always subject to approaches leading to remarkable progresses in the study of the electrical machines. Given the above considerations, topics of interest are:

Innovative design of rotary and linear machines, with or without permanent magnets
Techniques for optimization
Analytical and numerical electromagnetic analysis
Application of new magnetic materials
Thermal and mechanical simulations
Control strategies
Noise, vibration and heat analysis
Energy Efficiency Studies
Energetical Optimisation Analysis

Assoc. Prof. Dr. Dan-Cristian Popa
Prof. Dr. Emil Cazacu
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

Transverse flux machines
Magnetic field
Numerical analysis
Novel topology
Optimized design
New magnetic materials
Losses calculations
Control algorithm
NVH (noise, vibration, and harshness)
Thermal field analysis
Energy efficiency
Otimisation study

Published Papers (6 papers)

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Research

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24 pages, 11017 KiB

Open AccessArticle

Accelerated 3D FEA of an Axial Flux Machine by Exclusively Using the Magnetic Scalar Potential

by Adrian Schäfer, Urs Pecha, Benedikt Kaiser, Martin Schmid and Nejila Parspour

Energies 2023, 16(18), 6596; https://doi.org/10.3390/en16186596 - 13 Sep 2023

Viewed by 979

Abstract

This article focuses on increasing the computational efficiency of 3D multi-static magnetic finite element analysis (FEA) for electrical machines (EMs), which have a magnetic field evolving in 3D space. Although 3D FEA is crucial for analyzing these machines and their operational behavior, it is computationally expensive. A novel approach is proposed in order to solve the magnetic field equations by exclusively using the magnetic scalar potential. For this purpose, virtual variable permanent magnets (vPMs) are introduced to model the impact of the machine’s coils. The effect on which this approach is based is derived from and explained by Maxwell’s equations. To validate the new approach, an axial flux machine (AFM) is simulated using both 2D and 3D FEA with the magnetic vector potential and current-carrying coils as a reference. The results demonstrate a high level of agreement between the new approach and the reference simulations as well as an acceleration of the computation by a factor of 15 or even more. Additionally, the research provides valuable insights into meshing techniques and torque calculation for EMs in FEA. Full article

(This article belongs to the Special Issue Magnetic Field Computations and Energy Efficiency Studies in Electrical Machines)

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12 pages, 2322 KiB

Open AccessArticle

Digital Twin as a Virtual Sensor for Wind Turbine Applications

by Mahmoud Ibrahim, Anton Rassõlkin, Toomas Vaimann, Ants Kallaste, Janis Zakis, Van Khang Hyunh and Raimondas Pomarnacki

Energies 2023, 16(17), 6246; https://doi.org/10.3390/en16176246 - 28 Aug 2023

Cited by 1 | Viewed by 1090

Abstract

Digital twins (DTs) have been implemented in various applications, including wind turbine generators (WTGs). They are used to create virtual replicas of physical turbines, which can be used to monitor and optimize their performance. By simulating the behavior of physical turbines in real time, DTs enable operators to predict potential failures and optimize maintenance schedules, resulting in increased reliability, safety, and efficiency. WTGs rely on accurate wind speed measurements for safe and efficient operation. However, physical wind speed sensors are prone to inaccuracies and failures due to environmental factors or inherent issues, resulting in partial or missing measurements that can affect the turbine’s performance. This paper proposes a DT-based sensing methodology to overcome these limitations by augmenting the physical sensor platform with virtual sensor arrays. A test bench of a direct drive WTG based on a permanent magnet synchronous generator (PMSG) was prepared, and its mathematical model was derived. MATLAB/Simulink was used to develop the WTG virtual model based on its mathematical model. A data acquisition system (DAS) equipped with an ActiveX server was used to facilitate real-time data exchange between the virtual and physical models. The virtual sensor was then validated and tuned using real sensory data from the physical turbine model. The results from the developed DT model showed the power of the DT as a virtual sensor in estimating wind speed according to the generated power. Full article

(This article belongs to the Special Issue Magnetic Field Computations and Energy Efficiency Studies in Electrical Machines)

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20 pages, 7435 KiB

Open AccessArticle

Numerical Aspects of a Two-Way Coupling for Electro-Mechanical Interactions—A Wind Energy Perspective

by Fiona Dominique Lüdecke, Martin Schmid, Eva Rehe, Sangamithra Panneer Selvam, Nejila Parspour and Po Wen Cheng

Energies 2022, 15(3), 1178; https://doi.org/10.3390/en15031178 - 05 Feb 2022

Viewed by 1862

Abstract

Generators in wind turbines are the key components to convert mechanical into electrical power. They are subject to electrical and mechanical excitation at the same time, which can cause electro-mechanical interactions. To avoid unwanted interactions, standard design approaches use conservative, stiff designs that lead to heavy generators of several hundred tons. New wind turbine designs, beyond 10 MW, need to revisit the conservative design approach as the tower top mass needs to be limited. To reduce the generator’s mass without large deformation that can damage the wind turbine, a better understanding of electro-mechanical interactions is key. This requires a detailed model including both the mechanical and the magnetic forces. This work presents a numerical setup of a coupled electromagnetic-structural multi-body model. While existing couplings are application-specific; the presented coupling is independent of the actual use case and allows for transient dynamic two-way coupled analyses. For validation, an experimental setup with basic components is introduced. The results show the applicability of the developed coupling for detailed analysis of general electro-mechanical interactions. Full article

(This article belongs to the Special Issue Magnetic Field Computations and Energy Efficiency Studies in Electrical Machines)

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17 pages, 7631 KiB

Open AccessArticle

High-Efficient Brushless Wound Rotor Synchronous Machine Topology Based on Sub-Harmonic Field-Excitation Technique

by Syed Sabir Hussain Bukhari, Qasim Ali, Jesús Doval-Gandoy and Jong-Suk Ro

Energies 2021, 14(15), 4427; https://doi.org/10.3390/en14154427 - 22 Jul 2021

Cited by 12 | Viewed by 2218

Abstract

This paper presents a new high-efficient three-phase brushless wound rotor synchronous machine (BL-WRSM) based on a sub-harmonic field excitation technique. In the proposed machine topology, the stator is equipped with two different three-phase windings: (1) main armature winding, and (2) additional armature winding. The main armature winding is based on a 4-pole winding configuration, whereas the additional armature winding is based on a 2-pole winding configuration. Both windings are supplied current from two different inverters, i.e., inverter-1, inverter-2, and simultaneously. Inverter-1 provides the regular input current to the main armature winding, whereas inverter-2 provides a three-phase current of low magnitude to the 2-pole additional armature winding. This generates an additional sub-harmonic component of MMF in the airgap beside the fundamental MMF. On the other side, the rotor is equipped with (1) harmonic, and (2) field windings. These windings are electrically coupled via a rectifier. The fundamental component of MMF produces the main rotating magnetic field, whereas the sub-harmonic MMF gets induced in the harmonic winding to produce harmonic current. This current is rectified to give DC to the rotor field winding to attain brushless operation. To authenticate the operation and analyze its performance, the proposed BL-WRSM topology is supported using 2-D finite element analysis (FEA) in JMAG-Designer. Later on, the performance of the proposed brushless topology is compared with the customary BL-WRSM topology to verify its high efficiency, high output torque, low torque ripple, and low unbalanced radial force on the rotor. Full article

(This article belongs to the Special Issue Magnetic Field Computations and Energy Efficiency Studies in Electrical Machines)

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Review

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27 pages, 6618 KiB

Open AccessReview

Iron Loss Calculation Methods for Numerical Analysis of 3D-Printed Rotating Machines: A Review

by Tamás Orosz, Tamás Horváth, Balázs Tóth, Miklós Kuczmann and Bence Kocsis

Energies 2023, 16(18), 6547; https://doi.org/10.3390/en16186547 - 12 Sep 2023

Viewed by 1301

Abstract

Three-dimensional printing is a promising technology that offers increased freedom to create topologically optimised electrical machine designs with a much smaller layer thickness achievable with the current, laminated steel-sheet-based technology. These composite materials have promising magnetic behaviour, which can be competitive with the current magnetic materials. Accurately calculating the iron losses is challenging due to magnetic steels’ highly nonlinear hysteretic behaviour. Many numerical methodologies have been developed and applied in FEM-based simulations from the first introduced Steinmetz formulae. However, these old curve-fitting-based iron loss models are still actively used in modern finite-element solvers due to their simplicity and high computational demand for more-accurate mathematical methods, such as Preisach- or Jiles–Atherton-model-based calculations. In the case of 3D-printed electrical machines, where the printed material can have a strongly anisotropic behaviour and it is hard to define a standardised measurement, the applicability of the curve-fitting-based iron loss methodologies is limited. The following paper proposes an overview of the current problems and solutions for iron loss calculation and measurement methodologies and discusses their applicability in designing and optimising 3D-printed electrical machines. Full article

(This article belongs to the Special Issue Magnetic Field Computations and Energy Efficiency Studies in Electrical Machines)

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41 pages, 5818 KiB

Open AccessReview

Inverter-Fed Motor Drive System: A Systematic Analysis of Condition Monitoring and Practical Diagnostic Techniques

by Muhammad Usman Sardar, Toomas Vaimann, Lauri Kütt, Ants Kallaste, Bilal Asad, Siddique Akbar and Karolina Kudelina

Energies 2023, 16(15), 5628; https://doi.org/10.3390/en16155628 - 26 Jul 2023

Cited by 5 | Viewed by 2110

Abstract

Due to their efficiency and control capabilities, induction motors fed with inverters have become prevalent in various industrial applications. However, ensuring the reliable operation of the motor and diagnosing faults on time are crucial for preventing unexpected failures and minimizing downtime. This paper systematically analyzes condition monitoring and practical diagnostic techniques for inverter-fed motor drive systems. This study encompasses a thorough evaluation of different methods used for condition monitoring and diagnostics of induction motors, with the most crucial faults in their stator, rotor, bearings, eccentricity, shaft currents, and partial discharges. It also includes an assessment of their applicability. The presented analysis includes a focus on the challenges associated with inverter-fed systems, such as high-frequency harmonics, common-mode voltages causing the bearing currents, and high voltage gradients (dv/dt) due to fast switching frequency, which can impact the motor operation, as well as its faults analysis. Furthermore, this research explores the usefulness and efficiency of various available diagnostic methods, such as motor current signature analysis and other useful analyses using advanced signal processing techniques. This study aims to present findings that provide valuable insights for developing comprehensive condition monitoring strategies, and practical diagnostic techniques that enable proactive maintenance, enhanced system performance, and improved operational reliability of inverter-fed motor drive systems. Full article

(This article belongs to the Special Issue Magnetic Field Computations and Energy Efficiency Studies in Electrical Machines)

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