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Article

K. Wang, Z.Q. Zhu, G. Ombach, M. Koch, S. Zhang and J. Xu

The purpose of this paper is to reduce the torque ripple but not to decrease the average torque of synchronous reluctance machines by using one step or more than two…

Abstract

Purpose

The purpose of this paper is to reduce the torque ripple but not to decrease the average torque of synchronous reluctance machines by using one step or more than two axially laminated rotors with asymmetric flux-barrier.

Design/methodology/approach

A 24-slot four-pole synchronous reluctance machine with overlapping windings and asymmetric flux-barrier in the rotor is, first, described and designed by finite element (FE) method for maximizing average torque. The dimensions of asymmetric flux-barrier including the pole span angle and flux-barrier angle will be optimized to minimize the torque ripple and its influence on the average torque is also investigated by FE analysis. The impact of current angle on the average torque and torque ripple are also analysed. The step laminations together with the asymmetric flux-barrier are employed for further torque ripple reduction which can consider the both rotation directions.

Findings

The torque ripple of synchronous reluctance machine can be significantly reduced by employing asymmetric flux-barrier but the average torque is not reduced.

Research limitations/implications

The purely sinusoidal currents are applied in this analysis and the effects of harmonics in the current on torque ripple are not considered in this application. The 24-slot/four-pole synchronous reluctance machine with single-layer flux-barrier has been employed in this analysis, but this work can be continued to investigate the synchronous reluctance machine with multilayer flux-barrier. This asymmetric flux-barrier can be easily applied to permanent magnet (PM)-assisted synchronous reluctance machine and the interior PM machine with flux-barrier in the rotor, since the space which is used for PM insertion is the same as the SynRM machines.

Originality/value

This paper has analysed the torque ripple and average torque of synchronous reluctance machines with asymmetric flux-barrier and step laminations with asymmetric flux-barrier. The torque ripple can be reduced by this flux-barrier arrangement. The difference of this technique with the other techniques such as stator/rotor skew is that the average torque can be improved.

Details

COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering, vol. 34 no. 1
Type: Research Article
ISSN: 0332-1649

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Article

Mohammad Hossain Mohammadi, Tanvir Rahman and David Lowther

This paper aims to propose a numerical methodology to reduce the number of computations required to optimally design the rotors of synchronous reluctance machines (SynRMs…

Abstract

Purpose

This paper aims to propose a numerical methodology to reduce the number of computations required to optimally design the rotors of synchronous reluctance machines (SynRMs) with multiple barriers.

Design/methodology/approach

Two objectives, average torque and torque ripple, have been simulated for thousands of SynRM models using 2D finite element analysis. Different rotor topologies (i.e. number of flux barriers) were statistically analyzed to find their respective design correlation for high average torque solutions. From this information, optimal geometrical constraints were then found to restrict the design space of multiple-barrier rotors.

Findings

Statistical analysis of two considered SynRM case studies demonstrated a design similarity between the different number of flux barriers. Upon setting the optimal geometrical constraints, it was observed that the design space of multiple-barrier rotors reduced by more than 56 per cent for both models.

Originality/value

Using the proposed methodology, optimal geometrical constraints of a multiple-barrier SynRM rotor can be found to restrict its corresponding design space. This approach can handle the curse of dimensionality when the number of geometric parameters increases. Also, it can potentially reduce the number of initial samples required prior to a multi-objective optimization.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 36 no. 5
Type: Research Article
ISSN: 0332-1649

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Article

Xiping Liu, Ya Li, Zhangqi Liu, Tao Ling and Zhenhua Luo

The purpose of this paper is to propose a permanent magnet-assisted synchronous reluctance machine (PMASynRM) using ferrite magnets with the same power density as…

Abstract

Purpose

The purpose of this paper is to propose a permanent magnet-assisted synchronous reluctance machine (PMASynRM) using ferrite magnets with the same power density as rare-earth PM synchronous motors used in Toyota Prius 2010.

Design/methodology/approach

A novel rotor structure with rectangular PMs is discussed with respect to the demagnetization of ferrite magnets and mechanical strength. Some electromagnetic characteristics including torque, output power, loss and efficiency are calculated by 2D finite element analysis.

Findings

The results of the analysis show that a high power density and high efficiency for PMASynRM can be achieved using ferrite magnets.

Originality/value

This paper proposes a novel rotor structure of PMASynRM with low-cost ferrite magnets that achieves high power density as permanent machines with rare-earth PMs.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 35 no. 6
Type: Research Article
ISSN: 0332-1649

Keywords

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Article

Javier Martinez, Klaus Krischan and Annette Muetze

Synchronous Reluctance (SynRel) motors are known to suffer from excessive torque ripples. The classical way to avoid this drawback of the motor is skewing the slots. This…

Abstract

Purpose

Synchronous Reluctance (SynRel) motors are known to suffer from excessive torque ripples. The classical way to avoid this drawback of the motor is skewing the slots. This paper aims to provide an analytic estimation of the best skew angle to minimize the ripples in such SynRel motors with tooth windings. The approach used in this paper consists of the minimization of the spectral components of the magnetic energy that cause these oscillation torques. The method was validated by means of a multi-slice finite element model (FEM).

Design/methodology/approach

An analytic model, based on permeance theory, is derived to analyse the electromagnetic phenomena taking place inside of the motor. This model allows the identification of the causes underlying the torque ripple production. Based on this understanding, the most suitable skew angle can be determined. The analytic method, together with the best skew angle, is validated by means of an FEM of a SynRel machine.

Findings

A method to determine the optimum skew angle for a SynRel machine is presented. It depends on the wave-number of the magnetic waves producing the torque ripple. It is twice the one typically chosen for induction machines.

Practical/implications

The proposed approach allows improving on the design methodology for the production of smoothly running SynRel machines.

Originality/value

The methodology utilized in this paper is based on the relationship between the mechanical torque and the magnetic energy stored in the motor (virtual work law). From this, the best skew angle to eliminate the magnetic energy causing torque ripple can be determined. It, therefore, proposes an effective alternative to the common use of inductance models to determine such angles.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 36 no. 3
Type: Research Article
ISSN: 0332-1649

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Article

Nagarajan V.S., Balaji Mahadevan, Kamaraj V., Arumugam R., Ganesh Nagarajan, Srivignesh S. and Suudharshana M.

The purpose of this paper is performance enhancement of ferrite-assisted synchronous reluctance (FASR) motor using multi-objective differential evolution (MODE) algorithm…

Abstract

Purpose

The purpose of this paper is performance enhancement of ferrite-assisted synchronous reluctance (FASR) motor using multi-objective differential evolution (MODE) algorithm, considering the significant geometric design parameters.

Design/methodology/approach

This work illustrates the optimization of FASR motor using MODE algorithm to enhance the performance of the motor considering barrier angular positions, magnet height, magnet axial length, flux barrier angles of the rotor and air gap length. In the optimization routine to determine the performance parameters, generalized regression neural network-based interpolation is used. The results of MODE are validated with multi-objective particle swarm optimization algorithm and multi-objective genetic algorithm.

Findings

The design optimization procedure developed in this work for FASR motor aims at achieving multiple objectives, namely, average torque, torque ripple and efficiency. With multiple objectives, it is essential to give the designer the tradeoff between different objectives so as to arrive at the best design suitable for the application. The results obtained in this work justify the application of the MODE approach for FASR motor to determine the various feasible solutions within the bounds of the design.

Research limitations/implications

Analysis, design and optimization of synchronous reluctance motor has been explored in detail to establish its potential for variable speed applications. In recent years, the focus is toward the electromagnetic design of hybrid configurations such as FASR motor. It is in this preview this work aims to achieve optimal design of FASR motor using multi-objective optimization approach.

Practical/implications

The results of this work will supplement and encourage the application of FASR motor as a viable alternate for variable speed drive applications. In addition, the application of MODE to arrive at better design solutions is demonstrated.

Originality/value

The approach presented in this work focuses on obtaining enhanced design of FASR motor considering average torque, torque ripple and efficiency as performance measures. The posteriori analysis of optimization provides an insight into the choice of parameters involved and their effects on the design of FASR motor. The efficacy of the optimization routine is justified in comparison with other multi-objective algorithms.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 36 no. 1
Type: Research Article
ISSN: 0332-1649

Keywords

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Article

Shun Cai, Meng-Jia Jin, He Hao and Jian-Xin Shen

The purpose of this paper is to comparatively study a synchronous reluctance machine (SynRM) and a permanent magnet assisted synchronous reluctance machine (PMASynRM) as…

Abstract

Purpose

The purpose of this paper is to comparatively study a synchronous reluctance machine (SynRM) and a permanent magnet assisted synchronous reluctance machine (PMASynRM) as alternatives of the interior permanent magnet synchronous machine (IPMSM), and to investigate the performance and conclude both advantages and disadvantages.

Design/methodology/approach

A unified mathematical model is established for the IPMSM, SynRM and PMASynRM. Then finite element method (FEM) is used to compare the electromagnetic performance. Permeability-frozen method is utilized to distinguish basic electromagnetic torque and reluctance torque.

Findings

The PMASynRM can improve the power factor of the SynRM, overcome the drawback of the IPMSM in the high-speed flux-weakening region and is more proper to operate over a wide speed region. The SynRM is mechanically robust for lacking of the permanent magnets, and the PMASynRM can keep similar rotor stress as the SynRM by optimizing the magnets. Assembly of the SynRM is the simplest, and the economic performance of the SynRM and PMASynRM could be much better than the IPMSM which even uses ferrite magnets.

Practical/implications

The SynRM can produce identical torque and efficiency compared with the IPMSM except the poor power factor. The poor power factor could be improved by adopting the PMASynRM, which is proved to be able to act as an alternative of the IPMSM for low-cost high-performance application.

Originality/value

This paper provides the theoretical model of the IPMSM, SynRM and PMASynRM in a unified format. The electromagnetic, mechanical and economic performances of the three kinds of synchronous motors are compared comprehensively. Then, both the advantages and disadvantages are summarized.

Details

COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering, vol. 35 no. 2
Type: Research Article
ISSN: 0332-1649

Keywords

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Article

Luigi Alberti, Massimo Barcaro, Nicola Bianchi, Silverio Bolognani, Diego Bon, Mosè Castiello, Adriano Faggion, Emanuele Fornasiero and Luca Sgarbossa

The purpose of the paper is to present a complete design example of an interior permanent magnet integrated starter‐alternator (ISA).

Abstract

Purpose

The purpose of the paper is to present a complete design example of an interior permanent magnet integrated starter‐alternator (ISA).

Design/methodology/approach

After a preliminary design on the basis of an analytical model, finite element simulations are adopted to refine the design of the machine.

Findings

The designed ISA drive is able to satisfy all the requirements of modern cars, where the power of the electrical generators is increasing to deliver the on‐board power demand. The drive exhibits high torque, driving start, and a wide constant power speed range driving generation.

Originality/value

The entire system design is considered in the paper, both the electrical machine and the control strategy.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 30 no. 1
Type: Research Article
ISSN: 0332-1649

Keywords

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Article

Qinfen Lu, Liren Huang, Yunyue Ye, Xiaoyan Huang and Youtong Fang

Due to the merits of direct driven, high thrust density and high efficiency, PM linear synchronous motor (PMLSM) is pretty suitable for the long-stroke ropeless lifter…

Abstract

Purpose

Due to the merits of direct driven, high thrust density and high efficiency, PM linear synchronous motor (PMLSM) is pretty suitable for the long-stroke ropeless lifter. However, the vibration caused by detent force and difficulty of maintenance become the barriers that restrict its application. The paper aims to discuss these issues.

Design/methodology/approach

In order to simplify structure and improve driving performance, a novel PMLSM with segmented armature core and end non-overlapping windings is proposed. The analytical formula of detent force is derived based on energy method and harmonic analysis, which is validated by two-dimensional finite element analysis (FEA). Moreover, with erected parametric FEA calculation, the selection principles of slot-pole number combination and interval distance to this novel structure are obtained. Finally, the heat dissipation ability of conventional PMLSM and novel PMLSM are compared through thermal analysis.

Findings

In novel PMLSM, it is found that the (3m+1) and (3m+2) order harmonic components of thrust force are eliminated, which leads to a better driving performance in comparison with the conventional structure. Furthermore, the good heat dissipation ability of novel structure makes it possible for higher thrust density, which is crucial for ropeless lifter.

Originality/value

The novel PMLSM has excellent driving performance, simple structure for maintenance, possibility of modular production and high thrust density. It is a strong candidate for long-stroke ropeless lifter.

Details

COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering, vol. 35 no. 2
Type: Research Article
ISSN: 0332-1649

Keywords

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Article

Jiameng Shi, Hao Kong, Liren Huang, Qinfen Lu and Yunyue Ye

Nowadays, to simplify manufacture process and improve fault-tolerant capability, more and more modular electrical machines are being applied in industrial areas. The…

Abstract

Purpose

Nowadays, to simplify manufacture process and improve fault-tolerant capability, more and more modular electrical machines are being applied in industrial areas. The purpose of this paper is to investigate a novel modular single-sided flat permanent magnet linear synchronous motor (PMLSM), which adopts segmented armature with the required flux gaps between segments to enhance the performance.

Design/methodology/approach

Using 2D finite element analysis, the performances, such as open-flux linkage, back-EMF, average thrust force, thrust ripple, etc., are compared in different values of flux gaps, as well as different slot/pole number combinations (mainly odd numbers of poles). Finally, to show the difference of linear motor from rotary one, the detailed comparison is made between modular PMLSM and rotary PMSM.

Findings

Due to flux gaps, it is found the electromagnetic performances are worsened along with flux gap width increasing to modular PMLSMs having slot number higher than pole number, but some aspects of performances such as winding factor, open-circuit flux linkage, back-EMF and average thrust can be improved to those having slot number lower than pole number. Due to the end effect of linear format, the thrust ripple is not significantly improved.

Originality/value

It is concluded the proper flux gaps can be chosen to improve the performance of PMLSM with certain slot/pole combinations. A new structure of 12-slot-13-pole (hereinafter referred to as 12s/13p) PMLSM with fractional slot and alternative-teeth wound winding is designed.

Details

COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering, vol. 35 no. 2
Type: Research Article
ISSN: 0332-1649

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Article

Lidija Petkovska, Goga Cvetkovski and Paul Lefley

The purpose of this paper is to investigate the impact of the stator core design for a surface permanent magnet motor (SPMM) on the cogging torque profile. The objective…

Abstract

Purpose

The purpose of this paper is to investigate the impact of the stator core design for a surface permanent magnet motor (SPMM) on the cogging torque profile. The objective is to show how the cogging torque of this type of motor can be significantly reduced by implementing an original compound technique by skewing stator slots and inserting wedges in the slot openings.

Design/methodology/approach

At the beginning generic model of a SPMM is studied. By using FEA, for this idealised assembly, characteristics of cogging and electromagnetic torque are simulated and determined for one period of their change. Afterwards, actual stator design of the original SPMM is described. It is thoroughly investigated and the torque characteristics are compared with the generic ones. While the static torque is slightly decreased, the peak cogging torque is almost doubled and the curve exhibits an uneven profile. The first method for cogging torque reduction is skewing the stator stack. The second technique is to insert wedges of SMC in the slot openings. By using 2D and 2 1/2D numerical experiment cogging curves are calculated and compared. The best results are achieved by combining the two techniques. The comparative analyses of the motor models show the advantages of the proposed novel stator topology.

Findings

It is presented how the peak cogging torque can be substantially decreased due to changes in the stator topology. The constraint is to keep the same stator lamination. By skewing stator stack for one slot pitch 10° the peak cogging torque is threefold reduced. The SMC wedges in slot opening decrease the peak cogging almost four times. The novel stator topology, a combination of the former ones, leads to peak cogging of respectable 0.182 Nm, which is reduced for 7.45 times.

Originality/value

The paper presents an original compound technique for cogging torque reduction, by combining the stator stack skewing and inserting SMC wedges in the slot openings.

Details

COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering, vol. 34 no. 2
Type: Research Article
ISSN: 0332-1649

Keywords

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