Dr Pedram Asef


Staff
B.Sc.(Hons), M.Sc., Ph.D.(Cum Laude)
+44 (0)1483 684564
37 AA 03
09:00am-06:00pm

Biography

Areas of specialism

Transportation Electrification; Vehicle System Dynamics; Optimisation Methods; Electrical Machinery; Swarm Intelligence; Renewable Energy Systems; Machine learning; Electromagnetics; Power Systems

University roles and responsibilities

  • Member of Ethics Committee
  • Optimization of scalaBle rEaltime modeLs and functIonal testing for e-drive ConceptS (OBELICS), Funding Source: European Commission Horizon2020, Role: Researcher
  • Editor of the Frontier Energy System and Power Engineering Journal
  • Regional (R8) Lead of IEEE Power and Energy Society (PES)
  • Member of Electric Vehicle Technology and Control Group

Affiliations and memberships

Institute of Electrical and Electronics Engineers (IEEE)
Professional Member

Research

Research interests

My teaching

My publications

Publications

Pedram Asef, Ramon Bargallo, Ahu E. Hartavi Karci, P. Niknejad, M. R. Barzegaran, Andrew Lapthorn (2019). Correlation of solar power prediction considering the nominal operating cell temperature under partial shading effect
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The steadily rising efficiency together with the accuracy of prediction in solar photovoltaic (PV) energy requires a deterministic reliability in the realistic PV characteristic’s prediction subject to climatic changes. This empirical-based research validates IEC 61853 and improves output power prediction of a solar PV module with considering nominal operating cell temperature (NOCT) using online infrared thermal camera at short range outside. The impact of NOCT consideration is investigated, in which the error can be as high as 10.4 °C in comparison to non-NOCT. The objective is minimizing the power prediction error for the PV module, the significant parameters of the maximum power point tracking (MPPT) controller are used to evaluate the changes followed by the climatic-related parameters under partial shading condition. A set of non-parametric correlations are calculated using Spearman’s ρ and Kendall τ rank statistical methods to avoid experimental measurement difficulties and cost for an advanced output power prediction. Finally, the differences on the heat distribution of each cell, and its impact in the annual power prediction have been numerically and experimentally verified.
Pedram Asef, Ramon Bargallo, Andrew Lapthorn (2019). A Time Domain Computation of Rotational Iron Losses Considering the Bulk Conductivity for Permanent Magnet Synchronous Machines
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This study investigates an advanced finite-element (FE) technique for the evaluation of rotational iron losses based on a time-domain computation, where the bulk conductivity of the core materials is considered. The iron-loss characteristics are discussed for a radial flux permanent magnet synchronous machine (PMSM) for a wind generation application, with closed slots and outer rotor topology. The following factors are taken into account: (i) a real-time rotational iron-loss computation; (ii) the bulk conductivity of the steel laminations; and (iii) the influence of the controller harmonics on the system during transient conditions. The magnetic induction vector locus of each iron component is also discussed, where the magnetic induction is numerically modelled [three-dimensional (3D) finite element analysis (FEA)], computed using multiple magnetic antennae and is also experimentally verified. This comparative study shows a torque–frequency-loss computation that is presented from low to high frequencies (50–800) Hz. The FE model of the total iron losses for the PMSM using both pure sinusoidal and proportional–integral pulse-width modulation currents is studied and experimentally verified on a surface-mounted PMSM. The proposed method of iron losses prediction significantly reduced the rate of error between 3D FEA and experimental data to 1.7%.
Pedram Asef, Ramon Bargallo, Andrew Lapthorn (2016). Optimal Pole Number for Magnetic Noise Reduction in Variable Speed Permanent Magnet Synchronous Machines with Fractional-Slot Concentrated Windings
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Increasing the number of pole pairs leads to a lower electromagnetic yoke, and therefore, lower vibration and magnetic noise occur. In this paper, the influence of different numbers of pole pairs on the vibroacoustic design aspects of the machine is studied for the first time using a multislice subdomain method (MS-SDM) while considering the natural frequencies under a variable speed analysis. This paper aims to determine the optimal number of pole pairs for a low-speed, high-torque permanent magnet synchronous generator (PMSG) with double-layer, fractional-slot, nonoverlapping, concentrated windings (FSCWs) for wind turbine applications. First, all possible slots per pole per phase combinations, which offer the use of double-layer FSCW, are studied through a magnetomotive force (MMF) harmonic analysis. Second, the MS-SDM of the PMSG is studied to examine the vibroacoustic performance under a variable speed analysis. Finally, all affected major parameters are compared in order to find the optimal pole number of the PMSG. To verify the MS-SDM-based results, both 3-D finite element analysis and experimental investigations are employed.
Pedram Asef, Ramon Bargallo, Saeed Moazami, Andrew Lapthorn (2018). Rotor Shape Multi-Level Design Optimization for Double-Stator Permanent Magnet Synchronous Motors
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This research presents a rotor shape multi-level-objective optimization designed to reduce the mechanical stress distribution in the rotor core of a double-stator permanent magnet synchronous motor. The second objective is weight minimization performed via a response surface methodology (RSM) with a uniform precision central composite design (UP-CCD) function. The optimal operation point, with a substantial population size, is reached using a Monto Carlo algorithm on the fitted model. The goodness-of-fit for the model is evaluated based on the modified Akaike information criterion (AICc) and the Bayesian information criterion (BIC) with a linear regression approach. To achieve these goals, a multi-level design procedure is proposed for the first time in machine design engineering. All the electromagnetic forces of the machine such as normal, tangential, and centrifugal forces are calculated using 3-D transient finite element analysis (FEA). The outcome of the proposed rotor core optimization shows that the finalized shape of the studied core has significantly smaller weight and mechanical stress, while the electromagnetic performance of the machine has remained consistent with a pre-optimized machine.
Pedram Asef, Ramon Bargallo Perpina, Mohammadreza Barzegaran, Andrew Lapthorn (2018). A 3-D Pareto-Based Shading Analysis on Solar Photovoltaic System Design Optimization
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This paper utilizes a Pareto-based, three-dimensional (3-D) analysis to identify complete and partial shading of photovoltaic (PV) systems for a complicated urban environment, where unusual shape of PV and installation topology is studied. The Pareto optimization attempts to minimize losses in a certain area with an improved output energy and without compromising the overall efficiency of the system of which the nominal operating cell temperature (NOCT) for a glass/glass-module is considered as a significant parameter. The system is referenced to the environment based on IEC61215 via a closed-circuit and resistive load to ensure the module operates at the maximum power point. A maximum power point tracking controller is enhanced with an advanced perturb and observe algorithm to maintain the PV operating point at its maximum output under various working conditions. The most cost-effective design of the PV module is achieved via optimizing installation parameters such as tilt angle, pitch, and shading to improve the energy yield. The parameter settings and suitability of the design are also determined based on the reduced amount of CO 2 emissions. An experimental investigation has been carried out to verify the 3-D shading analysis and NOCT technique for both open-circuit and grid-connected PV modules.
Pedram Asef, Ramon Bargallo, M. R. Barzegaran, Andrew Lapthorn, Daniela Mewes (2018). Multiobjective Design Optimization Using Dual-Level Response Surface Methodology and Booth's Algorithm for Permanent Magnet Synchronous Generators
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This paper studies a dual-level response surface methodology (DRSM) coupled with Booth's algorithm using a simulated annealing (BA-SA) method as a multiobjective technique for parametric modeling and machine design optimization for the first time. The aim of the research is for power maximization and cost of manufacture minimization resulting in a highly optimized wind generator to improve small power generation performance. The DRSM is employed to determine the best set of design parameters for power maximization in a surface-mounted permanent magnet synchronous generator with an exterior-rotor topology. Additionally, the BA-SA method is investigated to minimize material cost while keeping the volume constant. DRSM by different design functions including mixed resolution robust design, full factorial design, central composite design, and box-behnken design are applied to optimize the power performance resulting in very small errors. An analysis of the variance via multilevel RSM plots is used to check the adequacy of fit in the design region and determines the parameter settings to manufacture a high-quality wind generator. The analytical and numerical calculations have been experimentally verified and have successfully validated the theoretical and multiobjective optimization design methods presented.
Pedram Asef, Ramon Bargallo, Mohammadreza Barzegaran (2018). Global Sizing Optimisation Using Dual-Level Response Surface Method based on Mixed-resolution Central Composite Design for Permanent Magnet Synchronous Generators
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This study presents a global sizing design optimisation of a permanent magnet synchronous generator (PMSG) using the three-dimensional finite-element analysis (3D FEA). To build an optimal parametric model structure, the efficiency improvement of the PMSG is taken as the main objective, where iron and copper losses were minimised. A dual-level response surface methodology (D-RSM) with a window-zoom-in approach for a variable-speed-range analysis as a global optimisation technique is employed to find out the optimal design variables of the objective function. The D-RSM using mixed-resolution central composite design (MR-CCD), full factorial design, central composite design (CCD), and box-Behnken design are applied to optimise the geometry with very small error. Analysis of variance and multi-level RSM plots are used to check the adequacy of fit. However, the MR-CCD exceeds the range of the boundary in the design region. Hence, a modified MR-CCD is used that improves the efficiency and proposes the parameter settings to manufacture the high-class quality wind generator. The validation of the analytical and numerical fashions is successfully achieved through rigorous FEA, and the experimental verifications perfectly marked the theoretical and significance optimisation design.
Pedram Asef, Ramon Bargallo, M. R. Barzegaran, Andrew Lapthorn, Jianning Dong, O. A. Mohammed (2018). A Comparative Study of Quasi-FEA Technique on Iron Losses Prediction for Permanent Magnet Synchronous Machines
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The paper presents an advanced quasi-FEA technique on the iron losses prediction using Bertotti’s iron loss separation models, in which a curve fitting is taken into account for coefficients calculation of each model. Moreover, the skin effect and saturation consideration are applied in order to check the accuracy through the relative error distribution in the frequency domain of each model from low up to high frequencies 50 to 700 (Hz). Additionally, this comparative study presents a torque-speed-flux density computation that is discussed and presented. The iron loss characteristics of a radial flux permanent magnet synchronous machine (PMSM) with closed-slots and outer rotor topology are also discussed. The quasi-finite-element (FE) analysis was performed using a 2-D and 3-D FEA, where the employed quasi-2-D FEA is proposed and compared with 3-D FEA, and along with experimental verifications. Finally, all the iron-loss models under realistic and non-ideal magnetization conditions are verified experimentally on a surface-mounted PMSG for wind generation application.
Pedram Asef, Ramon Bargallo Perpina, M. R. Barzegaran, Andrew Lapthorn, Daniela Mewes (2018). Load identification of different Halbach-array topologies on permanent magnet synchronous generators using the coupled field-circuit FE methodology
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In this paper, the influence of gap consideration on load identification under various Halbach-array-based topologies (HABOs) is investigated while the system is on-duty. The  of a radial flux generator with closed-slots and the exterior rotor topology is discussed, where the effect of eddy-currents are observed. This comparative study deals with the consideration of the combined  calculation that demonstrates how electromagnetic-based post processing calculations are estimated without the aid of nominal machine parameter values. The analysis was performed using a 2-D  of different HABOs with the gap consideration between the segments. Additionally, a comprehensive comparison with no gap is considered. Also, the using an uncontrolled conventional rectifier model is used to derive effected key output parameters such as torque, output power, power factor, and . The major objective of the study is to determine corresponding load results in order to employ the most suitable and capable magnetization topology from the load perspective in the PM  (PMSGs). Accordingly, the maximum power (MP) point was carried out to maximize the output DC power. With respect to the combined moment of inertia estimation, the load  is verified experimentally on a surface-mounted PMSG using different magnetization topologies. Furthermore, commercial and environmental issues of the project are considered to reduce CO2 emissions as part of green  development.
Pedram Asef, Ramon Bargallo, Andrew Lapthorn (2018). Iron Loss Prediction Using Modified IEM-Formula during the Field Weakening for Permanent Magnet Synchronous Machines
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During field weakening operation time (FWOT), the total iron loss rises and affects the accuracy of loss prediction and efficiency, especially if a large range of FWOT exists due to a large voltage drop that was rooted from the resistance of the used material. Iron loss prediction is widely employed in investigations for a fast electrical machine analysis using 2D finite element analysis (FEA). This paper proposes harmonic loss analytically by a steady-state equivalent circuit with a novel procedure. Consideration of skin effects and iron saturation are utilized in order to examine the accuracy through the relative error distribution in the frequency domain of each model from 50 to 700 Hz. Additionally, this comparative study presents a torque-frequency-field density calculation over each single term of the modified institute of electrical machines formula (IEM-Formula). The proposed analytical calculation is performed using 2D FEA for a classic and modified IEM-Formula along with experimental verifications on a surface-mounted permanent magnet synchronous generator (PMSG) for a wind generation application.
Pedram Asef, Ramon Bargallo Perpiñà, M. R Barzegaran (2017). An innovative natural air-cooling system technique for temperature-rise suppression on the permanent magnet synchronous machines
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This paper investigates a three-dimensional finite-element (3D-FEA) thermal analysis based on an embedded cooling system with various number of ducts for the outer-rotor permanent magnet synchronous machines (PMSMs). The segmented stator core due to closed-slot topology is the reason of a high temperature-rise at this core. The application-oriented study is aimed to reduce temperature-rise of the conventional model at the stator core via radial and circumferential airflow ducts. A temperature distribution, and heat transfer comparison among all FE models such as conventional, two and four ducts in-core natural cooling systems will be comprehensively presented through freezing the electromagnetic performance. The alternative models using FEA, and computational fluid dynamic (CFD) are experimentally verified the innovative technique, in which the generator is operated by a vertical axis twisted savonius type wind turbine (VAWT).
Pedram Asef, Ramon Bargallo Perpina, M. R. Barzegaran, Tanushree Agarwal (2017). Electromagnetic-based evaluation of different Halbach array topologies with gap consideration for the permanent magnet synchronous machines
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This paper investigates the influence of various Halbach arrays permanent magnets (PMs) on the electromagnetic performance of a radial flux machine with outer rotor topology. The static analysis is performed using a 2-D finite-element analysis (FEA) of six different machines with different Halbach array-based orientations. The gap consideration between PM segments is considered for the first time. The aim of the study is to find the most suitable magnetization topology determination for the PMSMs which brings maximum airgap flux density, coenergy, output torque turning, back-EMF, output electromagnetic power, and minimum corresponding harmonics, cogging torque and the likelihoods of saturation. Additionally, a comparative study of a continuous distribution that commercially is called polar anisotropic will be entirely discussed. The proposed model is verified by FEA, together with its experimental investigation for the small wind power generation application in the urban area. In addition, commercial and environmental issues of the project have been highly considered to reduce CO2 emissions as the part of green power generation mission.
Pedram Asef, Ramon Bargallo Perpina, Bereket T. Habte, Ali Babaeian (2017). An Alternative Organic growth through Acquisitions Investigation on Wind Energy
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In this paper, attention has been focused on continuous profitable growth which tends to the wind energy business worldwide, willing to go to consummate lengths in its pursuit with horizontal and vertical integration which bring speed, minimum risk to the development strategy at which enables experts to reach guaranteed growth. Organic growth through horizontal and vertical integration strategy in where Ansoff matrix was applied; a proposed management strategy through economic analysis verification has been shown and compared with typical organic strategy outcome. The return of investment with a lower rate of risk investment as objective of the work has been successfully achieved, in order to present a solution to following future challenge, considerable questions after recent Paris Climate Change Conference (PCCC) renowned as “how should EU manage such a big needed asset in order to build/ or buy possible renewable energy projects in the developing world countries?” as long as developed countries have been titled as notable share of greenhouses gases and “how should strong financial leadership make flawless scenarios for clean energy technologies?”. Nonetheless, acceptable financial methodology will be addressed as major study of the paper for only EU grant funding action. Besides, all advantages and disadvantages of the proposed strategy will be discussed.
Pedram Asef, Tianjie Zou, Haiyang Fang (2015). Optimal design of a direct-driven permanent magnet synchronous wind generator
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Low-speed high-torque direct-drive permanent magnet (LSHTPM) synchronous machines, which are characterized by large dimensions and weight, have huge potential for wind power generation. Despite to this fact, before the manufacture process of these machines, optimal design should be done to reduce the material costs and maximize power density and efficiency. In this paper, t he attention is focused on an optimal design of a 1.5MW direct-drive wind generator which is done in this research. The relationships between main dimensions of the machine and its power density, efficiency are investigated. In addition, a novel analytical optimization method is used to find optimal aspect ratio and split ratio to maximize power density and efficiency. The influences of electrical and magnetic load on the optimal aspect ratio and split ratio are also explored. Other parameters and results that may have major influence on the main dimensions such as pole number, slot width, and etc. are carried out and also discussed.
(2014). Design, characteristic analysis of PM wind generator based on SMC material for small direct-drive wind energy conversion system
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The objective of this paper is to provide a Design Of Low-Speed Permanent Magnet Synchronous Wind Generator (LSPMWG) by Conventional Inner-Rotor Radial-flux (CIRRF) topology to small direct-drive wind energy conversion system (SDWECS). Finite element analysis (FEM) was carried out to obtain magnetic flux density, Air-gap flux distribution versus Angles, Eddy-Current Loss, Hysteresis Loss, Anomalous Loss, Torque, and Electrical Energy Efficiency (EEE). Comparison of LSPMWG based on the latest Soft Magnet Powder Composite (SMC) with advantages and disadvantages are highlighted in comparison a conventional Steel laminated in this research paper. Besides, to ensure SMC-5P X-SOMALOY 700HR features of magnetic properties electrical the measurements must be done on standard geometry. the results present the best-suited materials to enhancing EEE of LSPMWG.