Permanent Magnet Synchronous Reluctance Machines Research Articles

Design and finite element analysis of a high‐performance surface‐permanent magnet synchronous reluctance machine with optimised robustness towards demagnetisation

AbstractThe aim of this paper is to design and Finite Element Analysis (FEA) of a novel rotor topology for a permanent magnet synchronous reluctance machine. According to the advantages and drawbacks of the PMSyncRM and the SPMSM, a conventional PMSyncRM rotor design combined with sur‐face‐mounted magnets is introduced as the SPMSyncRM. The surface‐PM arc size is investigated, so that it is considered as multiplication of an integer coefficient and the angle between two adjacent slots of the stator. The analysis involves simulation of the electromagnetic characteristics and the numerical model of each structure using finite element method. Each E‐Magnetic character is calculated for a better understanding of the benefits of the SPMSyncRM. Applying 2D FEA, the optimised surface‐PM arc size is calculated and the static and dynamic operational behaviour of the SPMSyncRM is simulated. Moreover, short circuit analysis is performed to study the demagnetisation of magnets. All results are reported comparatively considering a conventional PMSyncRM, so that the proposed SPM‐SyncRM topology presents high torque‐power density, lower values of cogging torque, higher values of power factor and efficiency, better static and dynamic performance, and robustness towards demagnetisation.

Circular Economy Aspects of Permanent Magnet Synchronous Reluctance Machine Design for Electric Vehicle Applications: A Review

Innovative technological solutions have become increasingly critical in addressing the transportation sector’s environmental impact. Passenger vehicles present an opportunity to introduce novel drivetrain solutions that can quickly penetrate the electric vehicle market due to their shorter development time and lifetime compared to commercial vehicles. As environmental policy pressure increases and customers demand more sustainable products, shifting from a linear business approach to a circular economy model is in prospect. The new generation of economically competitive machines must be designed with a restorative intention, considering future reuse, refurbishment, remanufacture, and recycling possibilities. This review investigates the market penetration possibilities of permanent magnet-assisted synchronous reluctance machines for mini and small-segment electric vehicles, considering the urban environment and sustainability aspects of the circular economy model. When making changes to the materials used in an electric machine, it is crucial to evaluate their potential impact on efficiency while keeping the environmental impact of those materials in mind. The indirect ecological effect of the vehicle’s use phase may outweigh the reduction in manufacturing and recycling at its end-of-life. Therefore, thoroughly analysing the materials used in the design process is necessary to ensure maximum efficiency while minimising the environmental impact.

Comparative study on torque characteristics of permanent magnet synchronous reluctance motors with different axial hybrid rotors

An axial hybrid permanent magnet synchronous reluctance machine (AHPM-SynRM) is proposed in this paper. The structure is a combination of synchronous reluctance rotor and two permanent magnet rotors. The proposed design includes three axially parallel rotors, the reluctance axis coincides in phase with the permanent magnet axis by rotating the synchronous reluctance machine (SynRM) rotor, which could increase the average torque. In the condition of the volume of permanent magnets stays unchanged, the relationship between the axial length ratio of different rotor parts and the maximum torque is also analyzed. Moreover, air gap magnetic isolation is designed between each rotor part, so there is no serious magnetic field coupling between different rotors and each rotor part could be separately designed. The analysis results prove the proposed machine has significantly higher torque performance than the permanent magnet assisted machine. (PM-SynRM).

Permanent Magnet Synchronous Reluctance Machines With Axially Combined Rotor Structure

A permanent magnet synchronous reluctance machine (PMSynRM) is studied in this article. It has a stack of surface-mounted permanent magnet (SPM) rotor and a stack of synchronous reluctance (SynR) rotor, which are axially combined on the shaft. Unlike the traditional PM-assisted SynR machine (PMASynRM), the magnets are not located in the flux barriers of the SynR rotor, and therefore, the magnets and flux barriers have no more geometric confliction between them. The two rotor stacks can be circumferentially shifted to any relative angle. Clearly, the shifting angle and the axial length ratio between the two rotor stacks, together with the phase angle of the armature current vector, influence the motor performance, and their optimal design is detailed in this article. Analysis of the prototypes shows that the studied PMSynRM evidently exhibits higher torque density than the conventional PMASynRM.

A Novel Method to Optimize Permanent Magnet Assisted Synchronous Reluctance Machines

This paper presents the characteristics of permanent magnets in a synchronous reluctance machine by employing analytical and finite element methods. Four possible designs are studied and their characteristics are compared against a base synchronous reluctance machine with linear barriers to reveal machine characteristics. Then, the paper proposes a novel optimization topology to optimize permanent magnet synchronous reluctance machine as a single object for better machine performance. An explicit investigation is conducted to reveal the operational behavior of the machine such as torque, power factor and torque ripples with various machine parameters and compares them with the base design. The study reveals that permanent magnet synchronous reluctance machine can be optimized to have significantly high-power factor and torque with acceptable torque ripples.

A Turn Fault Mitigation Strategy Based on Current Injection Technique for a Triple Three-Phase PMA SynRM

A turn-to-turn short-circuit fault usually causes excessive fault current because of very low impedance associated with a few fault turns. It should be dealt with promptly to avoid further damages to the machine, especially for a permanent magnet (PM) machine. In order to limit the turn fault current, a novel turn fault mitigation strategy based on current injection technique for a triple redundant 3 × 3-phase PM synchronous reluctance machine (PMA SynRM) is investigated in this paper. First, the flux linkage of the fault phase where the fault turns are located is estimated considering the influence of PM and currents in the healthy and fault three-phase sets. This flux linkage, including that of the fault turns, is subsequently reduced by injecting specific currents to the fault three-phase set, leading to much smaller fault current. The proposed current injection method does not affect the operation of the healthy three-phase sets that continue to produce torque. The effectiveness of the proposed method is validated by extensive finite-element (FE) simulation and experimental tests on a prototype 3 × 3-phase fault-tolerant PMA SynRM drive.

Design and analysis of a high-performance dual-rotor PM synchronous reluctance machine with toroidal windings

This paper presents a dual-rotor permanent magnet synchronous reluctance machine (PM-SynRM) with toroidal windings to improve the magnetic torque and the utilization of two torque components, thus to obtain high electromagnetic performance, such as torque, efficiency, and power factor. To highlight the advantages of the proposed dual-rotor PM-SynRM, all of its machine characteristics, including airgap flux density, back electromotive force (EMF), torque, power, efficiency, and flux weakening capability are compared to those of a conventional PM assisted SynRM (PMA-SynRM) with the same machine size and operating conditions, with the aid of a finite element method (FEM) using the JMAG-Designer. Furthermore, the proposed dual-rotor PM-SynRM is verified to have superior endurance against the magnet irreversible demagnetization within five times of the rated current excitation.

A New Hybrid Permanent Magnet Synchronous Reluctance Machine With Axially Sandwiched Magnets for Performance Improvement

This paper proposes a new hybrid permanent magnet synchronous reluctance machine (HPM-SynRM) with axially sandwiched magnets for improving machine performance including airgap flux density, back electromotive force, torque, torque ripple, efficiency, and power factor. The significant feature of the proposed machine is the configuration of axially integrating two kinds of independent and symmetrical rotors with a specific assembling angle, such that it can make full use of the magnetic torque and the reluctance torque for efficient production of the total torque. Meanwhile, the proposed machine greatly improves the PM utilization for high magnetic torque, and releases the stress condition of SynRM rotors for more proper design of ribs, thus to further improve the torque, efficiency, and power factor, especially when compared to the conventional PM-SynRM with the same machine specifications and operating conditions. The design of the proposed machine, including the PM optimization using the Kriging method and genetic algorithm, rib width and assembling angle design using the finite element method (FEM), has been first discussed in detail. Then, the advantages of the proposed machine are highlighted by quantitatively comparing to a conventional PM-SynRM by the FEM. Finally, the proposed machine is manufactured to validate its high performance by experiments.

Guest Editorial

Guest editorial - Special issue on permanent-magnet synchronous reluctance machines and their applications

Design of synchronous reluctance and permanent magnet synchronous reluctance machines for electric vehicle application

Purpose – The purpose of this paper is to minimize the optimization parameter number of synchronous reluctance machine (SynRM) and permanent magnet (PM) assisted SynRM, and compare their relative merits with interior permanent magnet (IPM) machine for electric vehicle applications, in terms of electromagnetic performance and material cost. Design/methodology/approach – The analysis of electromagnetic performance is based on finite element analysis, by using software MAXWELL. The genetic algorithm is utilized for optimization. Findings – The rotor design of SynRM can be significantly simplified by imposing some reasonable conditions. The number of rotor design parameters can be reduced to three. The electromagnetic performance of SynRM is much poorer than that of IPM, although the material cost is much cheaper, approximately one-third of IPM. The ferrite-SynRM is competitive and even better than IPM especially for high electric loading, in terms of torque capability, torque-speed characteristic, power factor, threshold speed and efficiency. In addition, ferrite-assisted SynRM has great advantage over IPM in material cost, 55 percent cheaper. The performance of NdFeB-assisted SynRM is close to IPM in terms of torque capability, torque-speed characteristic, power factor, torque ripple and efficiency. The material cost of NdFeB-assisted SynRM is ∼25 percent lower than IPM. Originality/value – Some conditions, which can simplify the optimization of SynRM rotor, are discussed. The electromagnetic performances and material costs of SynRM, ferrite-assisted, NdFeB-assisted SynRMs and IPM are quantitatively compared and discussed.