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Special Issue "Permanent Magnet Synchronous Machines"

A special issue of Energies (ISSN 1996-1073). This special issue belongs to the section "Energy Fundamentals and Conversion".

Deadline for manuscript submissions: 28 February 2019

Special Issue Editor

Guest Editor
Assoc. Prof. Sandra Eriksson

Department of Engineering Sciences, Uppsala University, Box 534, 751 21 Uppsala, Sweden
Website | E-Mail
Interests: permanent magnet synchronous machines, generator design, FEM simulations, alternative permanent magnet materials, electrical systems, control strategies, wind turbines, wave power, electric propulsion systems

Special Issue Information

Dear Colleagues,

The interest in permanent magnet synchronous machines (PMSMs) is continuously increasing in the world. With the growing global energy demand and awareness of climate aspects, electrification is increasing in several areas. Permanent magnet synchronous generators are in demand for wind power, as well as for novel renewable energy technologies such as wave power and tidal power. Another emerging market for permanent magnet machines is as electric motors, mainly for cars but also for heavier road transport, as well as electrification of ships and aircraft.

This Special Issue will focus on PMSMs and the electrical systems they are connected to. Papers are invited in all different areas of PMSMs, as machines are a multidisciplinary topic involving research areas such as electromagnetism, mechanical design, thermal management, and material issues, as well as economical and environmental aspects. Both theoretical and experimental work, and, especially, the combination of these, are welcomed. Recently, an interest in reducing the use of rare earth metals has been raised, and therefore papers exploring substitution and reduction of rare earth metals in PM machines are encouraged.

Topics of interest for publication include, but are not limited to, the following:

  • Permanent magnet synchronous machine design
  • Modelling of PM machines
  • Innovative designs of PM machines
  • Drive systems for PM motors
  • Electrical systems and control strategies for PM generators
  • Substitution or reduction of rare earth metals in PM machines
  • Demagnetization risk for PMs in synchronous machines
  • Thermal design and losses
  • Mechanical design
  • PM pilot exciters
  • PM assisted synchronous reluctance machines

Assoc. Prof. Sandra Eriksson
Guest Editor

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 papers will be 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 1800 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

  • permanent magnet synchronous generator
  • permanent magnet synchronous motor
  • electric propulsion systems
  • renewable energy
  • energy conversion

Published Papers (10 papers)

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Research

Open AccessArticle Robust Nonlinear Predictive Current Control Techniques for PMSM
Energies 2019, 12(3), 443; https://doi.org/10.3390/en12030443
Received: 30 November 2018 / Revised: 29 December 2018 / Accepted: 16 January 2019 / Published: 30 January 2019
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Abstract
This paper proposes a robust nonlinear predictive current control (RNPCC) method for permanent magnet synchronous motor (PMSM) drives, which can optimize the current control loop performance of the PMSM system with model parameter perturbation. First, the disturbance caused by parameter perturbation was considered [...] Read more.
This paper proposes a robust nonlinear predictive current control (RNPCC) method for permanent magnet synchronous motor (PMSM) drives, which can optimize the current control loop performance of the PMSM system with model parameter perturbation. First, the disturbance caused by parameter perturbation was considered in the modeling of PMSM. Based on this model, the influence of parameter perturbation on the conventional predictive current control (PCC) was analyzed. The composite integral terminal sliding mode observer (SMO) was then designed to estimate the disturbance caused by the parameter perturbation in real time. Finally, a RNPCC method is developed without relying on the mathematical model of PMSM, which can effectively eliminate the influence of parameter perturbation by injecting the estimated disturbance value. Simulations and experiments verified that the proposed RNPCC method was able to remove the current error caused by the parameter perturbation during steady state operation. Full article
(This article belongs to the Special Issue Permanent Magnet Synchronous Machines)
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Open AccessArticle Commutation Error Compensation Strategy for Sensorless Brushless DC Motors
Energies 2019, 12(2), 203; https://doi.org/10.3390/en12020203
Received: 27 November 2018 / Revised: 4 January 2019 / Accepted: 4 January 2019 / Published: 9 January 2019
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Abstract
Sensorless brushless DC (BLDC) motor drive systems often suffer from inaccurate commutation signals, which result in current fluctuation and high conduction loss. To improve precision of commutation signals, this paper presents a novel commutation error compensation strategy for BLDC motors. First, the relationship [...] Read more.
Sensorless brushless DC (BLDC) motor drive systems often suffer from inaccurate commutation signals, which result in current fluctuation and high conduction loss. To improve precision of commutation signals, this paper presents a novel commutation error compensation strategy for BLDC motors. First, the relationship between the line voltage difference integral in 60 electrical degree conduction interval and the commutation error is analyzed. Then, in terms of the relationship derived, a feedback compensation strategy based on the line voltage difference integral is proposed to regulate commutation signals by making three-phase back electromotive force (EMF) integral to zero, and the effect of the freewheeling process on the line voltage difference integral is considered. Moreover, an incremental PI controller is designed to achieve closed-loop compensation for the commutation error automatically. Finally, experiment results verify feasibility and effectiveness of the proposed strategy. Full article
(This article belongs to the Special Issue Permanent Magnet Synchronous Machines)
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Open AccessArticle On Speed Control of a Permanent Magnet Synchronous Motor with Current Predictive Compensation
Energies 2019, 12(1), 65; https://doi.org/10.3390/en12010065
Received: 4 November 2018 / Revised: 25 November 2018 / Accepted: 10 December 2018 / Published: 26 December 2018
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Abstract
In this study, a current model predictive controller (MPC) is designed for a permanent magnet synchronous motor (PMSM) where the speed of the motor can be regulated precisely. First, the mathematical model, the specifications, and the drive topology of the PMSM are introduced, [...] Read more.
In this study, a current model predictive controller (MPC) is designed for a permanent magnet synchronous motor (PMSM) where the speed of the motor can be regulated precisely. First, the mathematical model, the specifications, and the drive topology of the PMSM are introduced, followed by an elaboration of the design of the MPC. The MPC is then used to predict the current in a discrete-time calculation. The phase current at the next sampling step can be estimated to compensate the current errors, thereby modifying the three-phase currents of the motor. Next, Simulink modeling of the MPC algorithm is given, with three-phase current waveforms compared when the motor is operated under the designed MPC and a traditional vector control for PMSM. Finally, the speed responses are measured when the motor is controlled by traditional control methods and the MPC approach under varied speed references and loads. In comparison with traditional controllers, both the simulation and the experimental results suggest that the MPC for the PMSM can improve the speed-tracking performance of the motor and that this motor has a fast speed response and small steady-state errors under the rated load. Full article
(This article belongs to the Special Issue Permanent Magnet Synchronous Machines)
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Open AccessArticle Finite Element Method Investigation and Loss Estimation of a Permanent Magnet Synchronous Generator Feeding a Non-Linear Load
Energies 2018, 11(12), 3404; https://doi.org/10.3390/en11123404
Received: 24 October 2018 / Revised: 28 November 2018 / Accepted: 2 December 2018 / Published: 4 December 2018
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Abstract
The purpose of this paper is the performance investigation of a Permanent Magnet Synchronous Generator (PMSG) system, suitable for wind power applications and the comparison of the machine electromagnetic characteristics under open and closed control loop implementations. The copper and iron losses are [...] Read more.
The purpose of this paper is the performance investigation of a Permanent Magnet Synchronous Generator (PMSG) system, suitable for wind power applications and the comparison of the machine electromagnetic characteristics under open and closed control loop implementations. The copper and iron losses are estimated and compared for the above control systems with the use of the Steinmetz-Bertotti loss separation equation. In addition, the effect of the rotating magnetic field on the total losses is studied. The generator is simulated using Finite Element Analysis (FEA), while the rest of the components are connected to the machine model using a drawing window of the FEA software and suitable command files. The close loop control used in the present study results to less losses and greater machine efficiency. The main novelty of the paper is the simulation of the PMSG coupled with a converter and control schemes using FEA, which ensures more accurate results of the whole system and allows the detailed machine electromagnetic study, while the majority of existing papers on this topic uses simulation tools that usually simulate in detail the electric circuits but not the machine. The FEM model is validated by experimental results. Full article
(This article belongs to the Special Issue Permanent Magnet Synchronous Machines)
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Open AccessArticle Cogging Torque Reduction Based on a New Pre-Slot Technique for a Small Wind Generator
Energies 2018, 11(11), 3219; https://doi.org/10.3390/en11113219
Received: 18 October 2018 / Revised: 7 November 2018 / Accepted: 15 November 2018 / Published: 20 November 2018
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Abstract
Cogging torque is a pulsating, parasitic, and undesired torque ripple intrinsic of the design of a permanent magnet synchronous generator (PMSG), which should be minimized due to its adverse effects: vibration and noise. In addition, as aerodynamic power is low during start-up at [...] Read more.
Cogging torque is a pulsating, parasitic, and undesired torque ripple intrinsic of the design of a permanent magnet synchronous generator (PMSG), which should be minimized due to its adverse effects: vibration and noise. In addition, as aerodynamic power is low during start-up at low wind speeds in small wind energy systems, the cogging torque must be as low as possible to achieve a low cut-in speed. A novel mitigation technique using compound pre-slotting, based on a combination of magnetic and non-magnetic materials, is investigated. The finite element technique is used to calculate the cogging torque of a real PMSG design for a small wind turbine, with and without using compound pre-slotting. The results show that cogging torque can be reduced by a factor of 48% with this technique, while avoiding the main drawback of the conventional closed slot technique: the reduction of induced voltage due to leakage flux between stator teeth. Furthermore, through a combination of pre-slotting and other cogging torque optimization techniques, cogging torque can be reduced by 84% for a given design. Full article
(This article belongs to the Special Issue Permanent Magnet Synchronous Machines)
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Open AccessFeature PaperArticle Current Spikes Minimization Method for Three-Phase Permanent Magnet Brushless DC Motor with Real-Time Implementation
Energies 2018, 11(11), 3206; https://doi.org/10.3390/en11113206
Received: 10 October 2018 / Revised: 9 November 2018 / Accepted: 14 November 2018 / Published: 19 November 2018
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Abstract
Due to their high efficiency and low cost of maintenance, brushless DC motors (BLDCMs) with trapezoidal electromotive forces (back-EMFs), have become widely used in various applications such as aerospace, electric vehicles, industrial uses, and robotics. However, they suffer from large current ripples and [...] Read more.
Due to their high efficiency and low cost of maintenance, brushless DC motors (BLDCMs) with trapezoidal electromotive forces (back-EMFs), have become widely used in various applications such as aerospace, electric vehicles, industrial uses, and robotics. However, they suffer from large current ripples and current spikes. In this paper, a new method for minimizing current spikes appearing during BLDCM start-up or sudden set point changes is proposed. The method is based on controlling the MOSFET gates of the motor driver using R-C filters. These filters are placed between the PWM control signal generator and the MOSFET gates to smooth these control signals. The analysis of the proposed method showed that the R-C filter usage affects the BLDCM steady-state performances. To overcome this limitation, the R-C filter circuit was activated only during current spikes detection. The effectiveness of the proposed method was analytically analyzed and then validated through simulation and experimental tests. The obtained results allowed a reduction of 13% in current spikes amplitude. Full article
(This article belongs to the Special Issue Permanent Magnet Synchronous Machines)
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Open AccessArticle On Field Weakening Performance of a Brushless Direct Current Motor with Higher Winding Inductance: Why Does Design Matter?
Energies 2018, 11(11), 3119; https://doi.org/10.3390/en11113119
Received: 14 October 2018 / Revised: 4 November 2018 / Accepted: 8 November 2018 / Published: 12 November 2018
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Abstract
This paper comprises the design, analysis, experimental verification and field weakening performance study of a brushless direct current (BLDC) motor for a light electric vehicle. The main objective is to design a BLDC motor having a higher value d-axis inductance, which implies [...] Read more.
This paper comprises the design, analysis, experimental verification and field weakening performance study of a brushless direct current (BLDC) motor for a light electric vehicle. The main objective is to design a BLDC motor having a higher value d-axis inductance, which implies an improved performance of field weakening and a higher constant power speed ratio (CPSR) operation. Field weakening operation of surface-mounted permanent magnet (SMPM) BLDC motors requires a large d-axis inductance, which is characteristically low for those motors due to large air gap and PM features. The design phases of the sub-fractional slot-concentrated winding structure with unequal tooth widths include the motivation and the computer aided study which is based on Finite Element Analysis using ANSYS Maxwell. A 24/20 slot–pole SMPM BLDC motor is chosen for prototyping. The designed motor is manufactured and performed at different phase-advanced currents in the field weakening region controlled by a TMS320F28335 digital signal processor. As a result of the experimental work, the feasibility and effectiveness of field weakening for BLDC motors are discussed thoroughly and the contribution of higher winding inductance is verified. Full article
(This article belongs to the Special Issue Permanent Magnet Synchronous Machines)
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Open AccessFeature PaperArticle Node Mapping Criterion for Highly Saturated Interior PMSMs Using Magnetic Reluctance Network
Energies 2018, 11(9), 2294; https://doi.org/10.3390/en11092294
Received: 19 July 2018 / Revised: 24 August 2018 / Accepted: 27 August 2018 / Published: 31 August 2018
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Abstract
Interior Permanent Magnet Synchronous Machine (IPMSM) are high torque density machines that usually work under heavy load conditions, becoming magnetically saturated. To obtain properly their performance, this paper presents a node mapping criterion that ensure accurate results when calculating the performance of a [...] Read more.
Interior Permanent Magnet Synchronous Machine (IPMSM) are high torque density machines that usually work under heavy load conditions, becoming magnetically saturated. To obtain properly their performance, this paper presents a node mapping criterion that ensure accurate results when calculating the performance of a highly saturated IPMSM via a novel magnetic reluctance network approach. For this purpose, a Magnetic Circuit Model (MCM) with variable discretization levels for the different geometrical domains is developed. The proposed MCM caters to V-shaped IPMSMs with variable magnet depth and angle between magnets. Its structure allows static and dynamic time stepping simulations to be performed by taking into account complex phenomena such as magnetic saturation, cross-coupling saturation effect and stator slotting effect. The results of the proposed model are compared to those obtained by Finite Element Method (FEM) for a number of IPMSMs obtaining excellent results. Finally, its accuracy is validated comparing the calculated performance with experimental results on a real prototype. Full article
(This article belongs to the Special Issue Permanent Magnet Synchronous Machines)
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Open AccessFeature PaperArticle Quantitative Comparisons of Six-Phase Outer-Rotor Permanent-Magnet Brushless Machines for Electric Vehicles
Energies 2018, 11(8), 2141; https://doi.org/10.3390/en11082141
Received: 20 July 2018 / Revised: 10 August 2018 / Accepted: 11 August 2018 / Published: 16 August 2018
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Abstract
Multiphase machines have some distinct merits, including the high power density, high torque density, high efficiency and low torque ripple, etc. which can be beneficial for many industrial applications. This paper presents four different types of six-phase outer-rotor permanent-magnet (PM) brushless machines for [...] Read more.
Multiphase machines have some distinct merits, including the high power density, high torque density, high efficiency and low torque ripple, etc. which can be beneficial for many industrial applications. This paper presents four different types of six-phase outer-rotor permanent-magnet (PM) brushless machines for electric vehicles (EVs), which include the inserted PM (IPM) type, surface PM (SPM) type, PM flux-switching (PMFS) type, and PM vernier (PMV) type. First, the design criteria and operation principle are compared and discussed. Then, their key characteristics are addressed and analyzed by using the finite element method (FEM). The results show that the PMV type is quite suitable for the direct-drive application for EVs with its high torque density and efficiency. Also, the IPM type is suitable for the indirect-drive application for EVs with its high power density and efficiency. Full article
(This article belongs to the Special Issue Permanent Magnet Synchronous Machines)
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Open AccessArticle Stability Analysis of Deadbeat-Direct Torque and Flux Control for Permanent Magnet Synchronous Motor Drives with Respect to Parameter Variations
Energies 2018, 11(8), 2027; https://doi.org/10.3390/en11082027
Received: 11 July 2018 / Revised: 30 July 2018 / Accepted: 30 July 2018 / Published: 4 August 2018
Cited by 1 | PDF Full-text (5494 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents a stability analysis and dynamic characteristics investigation of deadbeat-direct torque and flux control (DB-DTFC) of interior permanent magnet synchronous motor (IPMSM) drives with respect to machine parameter variations. Since a DB-DTFC algorithm is developed based on a machine model and [...] Read more.
This paper presents a stability analysis and dynamic characteristics investigation of deadbeat-direct torque and flux control (DB-DTFC) of interior permanent magnet synchronous motor (IPMSM) drives with respect to machine parameter variations. Since a DB-DTFC algorithm is developed based on a machine model and parameters, stability with respect to machine parameter variations should be evaluated. Among stability evaluation methods, an eigenvalue (EV) migration is used in this paper because both the stability and dynamic characteristics of a system can be investigated through EV migration. Since an IPMSM drive system is nonlinear, EV migration cannot be directly applied. Therefore, operating point models of DB-DTFC and CVC (current vector control) IPMSM drives are derived to obtain linearized models and to implement EV migration in this paper. Along with DB-DTFC, current vector control (CVC), one of the widely used control algorithms for motor drives, is applied and evaluated at the same operating conditions for performance comparison. For practical analysis, the US06 supplemental federal test procedure (SFTP), one of the dynamic automotive driving cycles, is transformed into torque and speed trajectories and the trajectories are used to investigate the EV migration of DB-DTFC and CVC IPMSM drives. In this paper, the stability and dynamic characteristics of DB-DTFC and CVC IPMSM drives are compared and evaluated through EV migrations with respect to machine parameter variations in simulation and experiment. Full article
(This article belongs to the Special Issue Permanent Magnet Synchronous Machines)
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Planned Papers

The below list represents only planned manuscripts. Some of these manuscripts have not been received by the Editorial Office yet. Papers submitted to MDPI journals are subject to peer-review.

Title: HRE-free Hot-deformed Magnets with High Magnetic Properties and Their Application for Traction Motor Mounted on Hybrid Vehicles
Author: Shingo Soma and Atushi Hattori
Abstract: The traction motors of hybrid and electric vehicles generally use Nd-Fe-B sintered magnets with heavy rare-earth (HRE) elements which are added to increase heat resistance. However heavy rare earth elements are scarce resources and produced from limited areas of the world. In order to decrease the heavy rare earth content in these Nd-Fe-B magnets, it is necessary to improve the coercivity in some other ways and it is well known that decreasing the grain size is an effective one. Therefore, our research was focused on the rapidly-quenched and hot-deformed magnets which have finer grains than the sintered magnets. The magnetic properties of the developed magnets were boosted by the reduction of the hot-deformation temperature, the optimized deformation speed and the proper design of chemical compositions. These approaches made it possible to develop an HRE-free magnet applicable to mass-production vehicles. In addition to the improvements in the magnets, by modifying the motor designs, Honda and Daido Steel have succeeded in making the traction motors completely free from using any heavy rare-earth elements.

Title: MULTIPHYSICS DESIGN, MANUFACTURE, AND PERFORMANCE VALIDATION OF AN INTERIOR PM SYNCHRONOUS TRACTION MOTOR FOR A FORMULA-ELECTRIC-STUDENT RACING CAR
Author: João Sarrico, João Fernandes and Paulo Branco
Abstract: The Formula Electric Student is a different and vigorously competition for engineering students with a common goal: design, manufacture, and racing with a single-seat electric car. The need for a specifically designed traction motor to consider the main characteristics of the racing circuits of the Formula Electric Student competitions also to the extremely demanding dynamic characteristics of a race car is an obligation. In this context, it is presented the design, construction, and experimental tests of a new PM synchronous motor with a flux concentration configuration, which is optimized to those competitions using genetic algorithms as: 1) Traction motor must be fixed in the wheels suspension system, thus restricting its volume and weight; 2) Regulation of the competitions limits the maximum traction power of the car to 80kW; 3) Cooling fluid must be water; and 4) Taking into account a racing track steady-state simulation carried out by our team, with the ideal car and driver, the motor must have a nominal power of 20kW, a maximum torque of 20 Nm, a maximum speed of 12.000 rpm, maximum voltage of 400V AC, a nominal current of 20A and peak current of 100A.

In the design phase and after taking into account the material and manufacturing methods selected, a multiobjective optimization based on genetic algorithm coupled to an electromechanical-thermal finite element model (Comsol Multiphysics) is developed. The objective is to identify the best parameters and design of the magnetic circuit regarding the torque generation while complying with the relevant constraints. Also, mechanical and thermal analyses were conducted in order to increase motor robustness and manufacturability. The main manufacturing methods used for the traction motor and test bench manufacturing included laser cutting, water-jet, CNC milling and lathe turning methods. Preliminary coil tests were done to validate the winding layout producing a Back-Electromotive Force capable of reaching 12 000 RPM and a maximum torque of 20 Nm without reaching the thermal limits. Subsequently, the final winding layout, performance and efficiency tests were performed. The design requirements values were reached, although a few limitations and issues have compromised some of the results as it will be discussed.

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