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Article
Publication date: 3 July 2017

Ping Yang, Yawei Wang, T. Chang, H. Ma, Zhuyong Li, Zhijian Jin and Zhiyong Hong

The purpose of this paper is to propose a hybrid driving system that couples a motor and flywheel energy storage (FES) for a megawatt-scale superconducting direct current…

Abstract

Purpose

The purpose of this paper is to propose a hybrid driving system that couples a motor and flywheel energy storage (FES) for a megawatt-scale superconducting direct current (DC) induction heater. Previous studies have proven that a superconducting DC induction heater has great advantages in relation to its energy efficiency and heating quality. In this heater, a motor rotates an aluminium billet in a DC magnetic field and the induced eddy current causes it to be heated. When the aluminium billet begins to rotate, a high peak load torque appears at a low rotation speed. Therefore, driving the billet economically has been a great challenge when designing the driving system, which is the focus of this paper.

Design/methodology/approach

A hybrid driving system based on FES is designed to provide extra torque when the peak load torque occurs at a low rotation speed, which allows the successful start-up of the aluminium billet and the operation of the motor at its rated capacity. The mechanical structure of this hybrid driving system is introduced. A simulation model was constructed using Matlab/Simulink and the dynamic start-up process is analysed. The influence of the flywheel’s inertia and required minimum engagement speed are investigated.

Findings

The results of this paper show that the hybrid driving system that couples FES and a motor can successfully be used to start the aluminium billet rotating. The flywheel’s inertia and engagement speed are the most important parameters. The inertia of the flywheel decreases with an increase in its engagement speed.

Practical implications

The cost of the driving system is significantly reduced, which is very important in relation to the commercial potential of this apparatus.

Originality/value

A novel start-up strategy for driving the aluminium billet of a superconducting DC induction heater at low speed is proposed based on FES.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 36 no. 4
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 20 August 2018

Athanasios Sarigiannidis, Minos Beniakar and Antonios Kladas

This paper aims to introduce a computationally efficient hybrid analytical–finite element (FE) methodology for loss evaluation in electric vehicle (EV) permanent magnet…

Abstract

Purpose

This paper aims to introduce a computationally efficient hybrid analytical–finite element (FE) methodology for loss evaluation in electric vehicle (EV) permanent magnet (PM) traction motor applications. In this class of problems, eddy current losses in PMs and iron laminations constitute an important part of overall drive losses, representing a key design target.

Design/methodology/approach

Both surface mounted permanent magnet (SMPM) and double-layer interior permanent magnet (IPM) motor topologies are considered. The PM eddy losses are calculated by using analytical solutions and Fourier harmonic decomposition. The boundary conditions are based on slot opening magnetic field strength tangential component in the air gap in the SMPM topology case, whereas the numerically evaluated normal flux density variation on the surface of the outer PM is implemented in the IPM case. Combined analytical–loss evaluation technique has been verified by comparing its results to a transient magnetodynamic two-dimensional FE model ones.

Findings

The proposed loss evaluation technique calculated the total power losses for various operating conditions with low computational cost, illustrating the relative advantages and drawbacks of each motor topology along a typical EV operating cycle. The accuracy of the method was comparable to transient FE loss evaluation models, particularly around nominal speed.

Originality/value

The originality of this paper is based on the development of a fast and accurate PM eddy loss model for both SMPM and IPM motor topologies for traction applications, combining effectively both analytical and FE techniques.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 37 no. 6
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 2 March 2015

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

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Article
Publication date: 4 May 2020

Lidija Petkovska, Paul Lefley and Goga Vladimir Cvetkovski

This paper presents the design techniques applied to a novel fractional-slot 6/4 pole permanent magnet brushless direct current (PMBLDC) motor, for cogging torque

Abstract

Purpose

This paper presents the design techniques applied to a novel fractional-slot 6/4 pole permanent magnet brushless direct current (PMBLDC) motor, for cogging torque reduction. The notable feature of this motor is the simplicity of the design and low production cost. The purpose of this paper is to reduce the peak cogging torque of the motor. The focus is put on the stator topology tuning, and a new design for the stator poles is proposed. By determining the optimum stator pole arc length and the best pole shoe thickness, the cogging torque is significantly reduced. This new optimised motor design has been analysed in detail. The validation of the results is documented with respective figures and charts.

Design/methodology/approach

At the beginning, the design data for the 6/4 pole PMBLDC motor with concentrated three phase windings and asymmetric stator pole arcs is presented. In the study, this motor is taken as a reference model (A0, T0). A full performance finite element analysis of the reference motor has been carried out, and the weak points in the motor design have been identified. By simple design techniques, tuning the stator pole geometry, a two-stage design optimisation for cogging torque minimisation has been performed and the solution array has been derived. The optimised model is selected and proposed (Aopt, Topt). The comparative analysis of the reference and optimised motors show the advantages of the proposed novel design and prove the methodology.

Findings

The results of the work demonstrate how simple design techniques can minimise the peak of the cogging torque profile, while maintaining the specified electromagnetic torque value. The sensitivity of the cogging torque profile because of changes of the stator pole design inside the prescribed constraints is apparent. The stator poles of the reference motor have an arc length of 85° and pole shoe thickness of 6 mm. The newly shaped stator poles have an arc length of 78.5° and pole shoe thickness 4.8 mm. The peak-cogging torque has been reduced from 0.158 Nm to a respectable value of 0.066 Nm. However, to reduce electromagnetic torque ripple and pulsations, further investigations are required.

Originality/value

The paper presents an approach to cogging torque reduction for a 6/4 PMBLDC motor. A two-step original design procedure is introduced and an optimised stator pole geometry is defined. The minimised cogging torque has been demonstrated with improved usage of the active materials. This work could serve as a good basis for further optimisation of the motor design.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering , vol. 39 no. 5
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 5 January 2015

Murat Caner, Chris Gerada and Greg Asher

The purpose of this paper is to introduce a new design optimization technique for a surface mounted permanent magnet (SMPM) machine to increase sensorless performance at…

Abstract

Purpose

The purpose of this paper is to introduce a new design optimization technique for a surface mounted permanent magnet (SMPM) machine to increase sensorless performance at high loadings by compromising with torque capability.

Design/methodology/approach

An SMPM parametric machine model was created and analysed by finite element analysis (FEA) software by means of the Matlab environment. Eight geometric parameters of the machine were optimized using genetic algorithms (GAs). The outer volume of the machine, namely copper loss per volume, was kept constant. In order to prevent sensorless performance loss at high loading, an optimization process was realized using two loading stages: maximum torque with minimum ripple at nominal load and maximum self-sensing capability at twice load. In order to show the effectiveness of the proposed technique, the obtained results were compared with the classical one-stage optimization realized for each loading condition separately.

Findings

With the proposed technique, fairly good performance results of the optimization were obtained when compared with the one-stage optimizations. Using the proposed technique, sensorless performance of the motor was highly increased by compromising torque capability for high loading. Additionally, this paper shows that the self-sensing properties of a SMPM machine should be considered at the design stage of the machine.

Originality/value

In related literature, design optimization studies for the sensorless capability of SMPM motor are very few. By increasing optimization performance, new proposed technique provides to achieve good result at high load for sensorless performance compromising torque capability.

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
Publication date: 11 May 2010

Drago Dolinar, Petar Ljušev, Gorazd Štumberger, Matjaž Dolinar and Daniel Roger

The purpose of this paper is to analyze the impact of magnetic saturation on the steady‐state operation of the induction motor (IM) drive in regard to rotor field‐oriented…

Abstract

Purpose

The purpose of this paper is to analyze the impact of magnetic saturation on the steady‐state operation of the induction motor (IM) drive in regard to rotor field‐oriented control (RFOC). The aim of the presented two methods is to obtain the required steady‐state torque with minimal stator current, which thus reduces stator coper losses considerably.

Design/methodology/approach

The first method is based on an analytic calculation of the peak torque‐per‐ampere ratio curve of saturated IM. The torque characteristics obtained at a constant stator current are used to calculate that value of magnetizing current which gives the minimal stator current for the required load torque. The second method directly searches the minimal stator current for the required load torque. Experiments completely confirm the efficiency of the proposed selection of a magnetizing current reference.

Findings

Operation of the IM drive strongly depends on a proper selection of the rotor flux linkage reference value, the selection of which represents an additional degree of freedom in control design. Therefore, it can be used to optimize some of those drive features subjected to voltage and current constraints. The proposed calculation procedure is simple so that can be easily implemented in practically application. However, some additional IM data like magnetizing curve, inertia moment, and coefficient of viscous friction are necessary.

Originality/value

The substantial impact of saturation on the stead‐state torque characteristics of IM, determined for the constant stator current and the constant d‐axis stator current, is determined analytically and numerically.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 29 no. 3
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 7 March 2016

Y. Guan, Z.Q. Zhu, I.A.A. Afinowi, J.C. Mipo and P. Farah

The purpose of this paper is to make a quantitative comparison between induction machine (IM) and interior permanent magnet machine (IPM) for electric vehicle…

Abstract

Purpose

The purpose of this paper is to make a quantitative comparison between induction machine (IM) and interior permanent magnet machine (IPM) for electric vehicle applications, in terms of electromagnetic performance and material cost.

Design/methodology/approach

The analysis of IM is based on an analytical method, which has been validated by test. The analysis of IPM is based on finite element analysis. The popular Toyota Prius 2010 IPM is adopted directly, and the IM is designed with the same stator outer diameter and stack length as Prius 2010 IPM for a fair comparison.

Findings

The torque capability of IM is lower than IPM for low electric loading and competitive to IPM for high electric loading. The maximum torque/power-speed characteristic of IM is competitive to IPM; while the rated torque/power-speed characteristic of IM is poorer than IPM. The power factor of IM is competitive and even better than IPM for high electric loading in low-speed region. The torque ripple of IM is comparable to IPM for high electric loading and much lower than IPM for low electric loading. The overall efficiency of IM is lower than IPM, and the maximum efficiency of copper squirrel cage IM is approximately 2-3 percent lower than IPM. The material cost of IM is about half of IPM when IM and IPM are designed with the same stator outer diameter and stack length.

Originality/value

The electromagnetic performances and material costs of IM and IPM are quantitatively compared and discussed.

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
Publication date: 1 June 2000

K. Wiak

Discusses the 27 papers in ISEF 1999 Proceedings on the subject of electromagnetisms. States the groups of papers cover such subjects within the discipline as: induction…

Abstract

Discusses the 27 papers in ISEF 1999 Proceedings on the subject of electromagnetisms. States the groups of papers cover such subjects within the discipline as: induction machines; reluctance motors; PM motors; transformers and reactors; and special problems and applications. Debates all of these in great detail and itemizes each with greater in‐depth discussion of the various technical applications and areas. Concludes that the recommendations made should be adhered to.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 19 no. 2
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 1 January 2013

Luigi Alberti, Elisabetta Tedeschi, Nicola Bianchi, Maider Santos and Alessandro Fasolo

The purpose of this paper is to investigate the impact of control strategy selection on the power performance of wave energy converters for different ratings of the Power…

Abstract

Purpose

The purpose of this paper is to investigate the impact of control strategy selection on the power performance of wave energy converters for different ratings of the Power Take‐Off (PTO) system.

Design/methodology/approach

The case of a point absorber equipped with an all‐electric PTO is considered. The effect of control techniques and electrical generator design is analyzed from a theoretical standpoint and then verified through integrated hydrodynamic‐electric simulations.

Findings

It has been proved that control parameters that maximize the power extraction from the waves can be derived based on the power and torque constraints imposed by the electrical machine.

Originality/value

An optimized and integrated approach to the control strategy selection and generator design for point absorbers has been presented, which maximizes the electric power generation from sea waves under real conditions and represents a good trade‐off for the PTO from both the technical and the economic standpoint.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 32 no. 1
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 26 March 2019

Mahmoud M. Elkholy and Fathi Abd-Elkader

This paper aims to present an optimal variable speed drive of a doubly fed induction motor (DFIM) with minimum losses and reduced inverter capacity. The operation with…

Abstract

Purpose

This paper aims to present an optimal variable speed drive of a doubly fed induction motor (DFIM) with minimum losses and reduced inverter capacity. The operation with minimum losses ensures that the DFIM develops the required load torque at desired speed with maximum energy saving. Moreover, the control of rotor voltage ensures the reduced inverter capacity. The water cycle algorithm (WCA) as one of meta-heuristic optimization techniques is used to estimate the optimal rotor voltages to drive the DFIM with minimum losses. The results of WCA are confirmed with other well-known and reliable optimization method such as particle swarm optimization along with classical method.

Design/methodology/approach

The DFIM is an efficient alternative solution of synchronous motor (SM) because of its speed is synchronized with both stator and rotor frequencies regardless the load torque. As a result, the speed of variable speed drive associated with DFIM can be controlled through a rotor inverter with reduced capacity rather than SM. The output voltage of rotor inverter is controlled to develop the demanded output power with minimum motor losses.

Findings

A complete DFIM drive model is developed under MATLAB/SIMULINK environment using d-q dynamic model to verify the strength and significance of the proposed controller. An experimental setup using a 300 W three-phase wound rotor induction motor is established to validate the mathematical models and theoretical results. The motor performances with proposed rotor voltage control (minimum losses) are compared with conventional method of constant voltage to frequency ratio (V/f constant). It is found that the proposed WCA based on controller achieves significant reductions in motor losses, input power and rotor inverter power.

Originality/value

The paper presents an efficient method to maximize the energy saving of DFIM with a reduced inverter capacity using WCA.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering , vol. 38 no. 2
Type: Research Article
ISSN: 0332-1649

Keywords

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