Design of electrical machines Research Papers (original) (raw)

Two original numerical techniques are developed for the finite element (FE) transient analysis of induction and permanent magnet motors operating in demanding aerospace applications. The first technique is the electromagnetic and thermal analysis weak coupling using a multiple slices 2D FE model. The advantage of the specific technique is the representation of complex actuator geometries including skewed magnets and winding ends, by using a low computational cost 2D model while taking into consideration temperature dependent material attributes. The second technique consists in the development of properly defined boundary conditions for the emulation of the cooling housing of actuators. Those boundary conditions are applied at the outer surface of the actuators in contact with the housing and eliminate the need of modeling complex 3D geometries of highly integrated actuator housings.

Selection of an industrial robot for a specific purpose is one of the most challenging problems in modern manufacturing atmosphere. The selection decisions become more multifaceted due to continuous incorporation of advanced features and facilities as the decision makers in the manufacturing environment are to asses a wide varieties of alternatives based on a set of conflicting criteria. To assist the selection procedure various Multiple Criteria Decision Making (MCDM) approaches are available. The present investigation endeavours to mitigate and unravel the robot selection dilemma employing the newly proposed Multiplicative Model of Multiple Criteria Analysis (MMMCA) approach. MMMCA is a novel model in which all performance ratings are converted into numerical values greater than and equal to unity and converting all non-benefit rating into benefit category. Each normalized weight is used as the index of corresponding normalized ratings those are multiplied to obtain the resultant ...

- by Balaram Dey
- •
- Languages, Information Retrieval, Artificial Intelligence, Image Processing

Starting from the first years of the proposed period right up to the 2000s, there were commercialization concerns of line start permanent magnet synchronous motors. This situation, which developed as a result of not developing methods to adequately explain the motor operating characteristics, and also because of the limitations associated with the non-high-performance manufacturing materials, took place widely until the 1970s. In subsequent years, the development of increasingly efficient materials, as well as the use of innovative methods, such as advanced magnetic circuit models and FEM analysis, which better reflect the performance of the motor, these motors became available for an increasing number of industries. In the past 10 years, research has paid off, and finally, line start permanent magnet synchronous motors have begun to be offered on the market as an alternative to AC induction motors. These motors, which are offered on the market with an IE4 efficiency class limits level that is currently tricky to achieve with traditional AC induction motors, are already included in the catalog of many major motor manufacturers.With this study, a detailed literature search was conducted and filtered on the development and improvement of line start permanent magnet synchronous motors. As a result of the study of numerous researches and more than 50 rotor topologies, design trends were identified that are important in the development of such motors. The development steps from the proposed years to the present have been discussed in terms of manufacturability, efficiency and performance.

- by Berkan ZÖHRA
- •
- Electrical Motors, Electric Motor, Design of electrical machines

The induction motors are widely used in industrial drives since of their low cost and flexibility. The control facet is very essential for any drive. This paper proposes an economical method of INDUCTION MOTOR speed control with efficient performance. The induction motor speed variation can be easily attained for a short range by stator voltage control. The terminal voltage across the stator winding of the motor can be varied to achieve the preferred speed control by controlling the firing angle of the semiconductor power devices (TRIAC in this paper). RASPBERRY PI 2(model B) plays an important in our project. Raspberry Pi is very small in size and it is a low cost device. Raspberry Pi has a Quadcore-broadcom BCM2836 900 MHz processor and 1GB RAM. It can perform all the work similar to a computer and can be referred as minicomputer. Python language must be used for this. It uses Raspbian operating system based on Debian distribution of LINUX.

- by jogendra sahoo
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- Power Electronics, Power System, Electric Power Systems, PLC Automation

—The design method of initial topology of interior permanent magnet synchronous machine (IPMSM) for hybrid electric vehicle (HEV) propulsion is described in this paper. Design constraints are selected on the basis of limitations imposed by machine's manufacturer and application (e.g. maximum copper slot fill factor, air gap length, permanent magnet material, limited space available in drive trains, etc.). Design variables are rotor radius, stator slot width and number of turns per phase winding. Parametric analysis is performed for various machine topologies. The cost function, which connects the distribution of operating points of HEV and the efficiency maps of various topologies of an electrical machine, is defined. Obtained parametric results are compared to find the result leading to the extreme value of the cost function. The initial design of IPMSM that corresponds to this result is considered as the best initial design.

—This paper deals with a sensitivity study of an outer rotor permanent magnet (PM) brushless DC (BLDC) motor design, concerning the effect of several parameters and factors on its corresponding performance. For the purposes of this study, several design features were considered regarding the type and size of the permanent magnets and the slot geometry. Moreover, the pole-arc to pole-pitch ratio variation was investigated. The primarily aim is to draw useful conclusions for the motor overall performance according to preset requirements, such as the rated speed, motor efficiency, output power, cogging torque, overall motor weight etc. The obtained results were validated through simulations using finite element method (FEM) analysis with the aid of commercial software. The concluded remarks reveal important considerations which have to be taken into account by the designer prior and through the design phase of a BLDC motor.

- by Yannis L Karnavas
- •
- Design of electrical machines
- by Spunei Elisabeta and +1
- •
- Design of electrical machines

An alternative to traditional low-speed/high-torque drive systems, which are currently used in industry, could be the use of a permanent magnet synchronous motor directly coupled to the load and running at low speed, instead of the induction motor along with its mechanical transmission parts. The paper—in this context—deals with the analytical design procedure, optimization, and evaluation of such a motor (5 kW/50 rpm) and focuses on 2 topologies, ie, with inner and outer rotor. Finite element method designs of the permanent magnet machines are implemented as solutions of a complex optimization problem and several goals (multiobjectives) are considered (ie, machine weight minimization or efficiency maximization) with respect to relevant constraints. Three optimization methods are adopted and applied and a weighted cost function is proposed. The effectiveness of our problem design formulation approach and the use of these methods, in finding alternative and competitive permanent magnet synchronous motor designs, are also evaluated. The results reveal satisfactory design solutions and present acceptable performance. Moreover, by means of simulations, the application of several commercially available ferromagnetic materials for the motors' stator and rotor cores is performed. Last but not least, the effect of pole-arc per pole-pitch ratio along with the magnets length variation is also investigated. KEYWORDS computer aided design, finite element method, modelling and optimization, permanent magnet synchronous motors

- by Yannis L Karnavas and +1
- •
- Electrical Machines, Design of electrical machines

In this paper a practical approach for the design and construction of a brushless DC motor (BLDCM) for a diver propulsion vehicle (DPV) is presented. After evaluating the corresponding vehicle's characteristics, a three step process is proposed and followed. For economical reasons and rapid prototyping, an appropriate motor stator found in the market is utilized. Thus, the required B-H curve of the material is extracted experimentally in the first step, whose knowledge is necessary for the motor design phase. Secondly, considering the DPV's thrust requirements, a suitable propeller is studied, designed and selected which in turn leads to the BLDCM requirements for torque and speed. Having the stator geometry known, the outer rotor BLDCM theory is followed in the third step where, with the help of a custom developed software code, the remaining variables are calculated pertaining to the windings, rotor and permanent magnet parts. Finally, relevant results are shown by studying the motor topology using FEM. Index Terms-Brushless DC motor, outer rotor, permanent magnet motor design, diver propulsion vehicle (DPV)

- by Yannis L Karnavas
- •
- Design of electrical machines
- by Spunei Elisabeta
- •
- Design of electrical machines
- by Harshad Jariwala
- •
- Design of electrical machines

In comparison to conventional power plants characterized by Synchronous Generators (GS), Distributed Generation units (DG) usually do not have damping or rotational inertia properties. With the increase of DG sources in the electrical system, the impact of low inertia and damping effect on the stability and dynamic performance of the grid increases. A solution to improve the stability of a power system is to provide virtual inertia by Virtual Synchronous Generators (VSG).
Using simulation in the PSCAD/EMTDC® software, this paper proves the efficiency of the virtual synchronous generator as a strategy to improve the static and dynamic stability of the frequency in power systems, by comparisons with the conventional control strategy, the PQ control, in a modeled scenario with characteristic conditions of the Sistema Interligado Nacional (SIN).

The slotless Permanent magnet Ind-syn
motor (SPMISM) have been developed in the recent
years and gained popularity in various industrial
applications. It is quite possible that this SPMISM will
become predominant in the near future .The SPMISM
has a slotless stator and cage rotor with permanent
magnets buried inside the rotor. Hence this work aims at
the design and development of SPMISM .This motor
starts as an induction motor, gets synchronized and runs
at synchronous speed. Attractive features of the
proportional model are compactness, energy efficient
operation, reduction in losses and active materials used
in motor. A prototype can be designed and developed.
Results validate the superior performance of this new
technology. The above feasible design and simulation of
motor has been done through the CAD/CAE software,
namely AUTOCAD2000 and MOTORPRO. Exercising
the energy conservation measures plays an important
role in the electricity, particularly in industrial and
agricultural sector. In this work a 2.2KW,415V,4 - pole
,delta connected 3-phase slotless permanent magnet
induction synchronous motor ( SPMISM) was designed.
The permanent magnets were fitted in rotor The
prototype motor has been run with load at speeds of up
to 6000 rpm and without load up to 10,000 rpm. It is
concluded that the slotless motor have substantially lower losses
DOI: 10.13140/2.1.3586.4641

The design of electrical machines is gaining more popularity in the last years especially in electrical engineering courses. However, commonly-used teaching techniques seem to limit students' understanding and prevent the attainment of the learning objectives. The competence of this subject can be significantly improved when a practical approach based on the use of computer-aided educational tools is followed. Thus, this paper proposes an effective and user-friendly educational tool, which has been developed and successfully implemented in postgraduate courses in order to facilitate the conception of brushless direct current (BLDC) machines design aspect. At first, a step-by-step design procedure is analytically described and then the main tool's characteristics and capabilities are also presented. Finally, its impact assessment has been conducted and the derived results revealed that its application could be extended to the design of various types of electrical motors and generators.

- by Yannis L Karnavas
- •
- Design of electrical machines

This paper presents design and analysis of Permanent Magnet Synchronous Motor (PMSM) used in industrial robot. Robotics is the applied science of motion control for multi-axis manipulators and is a large subset of the field of "mechatronics" (Mechanical, Electronic and Software engineering for product or systems development, particularly for motion control applications).Permanent Magnet Synchronous Motors have wide applications in industry, especially in AC servo drives such as industrial robots, and suitable when the application requires speed regulation. PMSM has gained interest due to several factors like reduced cost, ability to operate at near zero speed even at full load and flux weakening capability for spindle and traction applications. As the high field strength of neodymium-iron-boron (NdFeB) magnets become commercially available with affordable prices, PMSMs are receiving increasing attention due totheir high speed, high power density and high efficiency.

This paper presents the design of a Switched Reluctance Machine (SRM) for off-road hybrid electric vehicle applications. SRMs are ideally suited for this application for their low cost, fault tolerance and reliable operations. A multistage fast design methodology for SRM is presented in this paper. The process aims to determine the best speed at which the SRM would start single pulse mode operation. This ensures the best efficiencies over the specified operating range. The machine is initially designed at that operating point using analytical design tools and then further optimized through finite element analysis. The designed machine has been prototyped and then experimentally tested.

- by Ous Sama
- •
- Design of electrical machines

The losses in European Union distribution transformers are estimated at about 33 TW · h/year, whereas reactive power and harmonic losses add a further 5 TW · h/year. The reduction of distribution transformer no-load loss is particularly important as the ratio of no-load to load losses is nearly three. In this paper, the no load operation of wound-core transformers under sinusoidal and distorted supply-voltage conditions is investigated. For that purpose, a 2-D nonlinear transient finite-element analysis taking into account hysteresis has been developed. The hysteresis model is based on a modified Jiles–Atherton representation, and the proposed analysis is compared to experimental data.

- by Themistoklis D. Kefalas
- •
- Engineering, Electrical Engineering, Harmonic Analysis, Electromagnetism

This paper presents a new concept of Transverse Flux Machine (TFM) design that uses rotary transformers to replace the Permanent Magnet (PM) field excitation in the rotor. The rotary transformer has an inductive interface that allows for contactless transfer of energy to the field windings embedded in the rotor core. In order to achieve high magnetic coupling, a highly permeable ferrite core is selected for the transformer which is excited with high electrical frequency of 100 kHz. A field power converter is used to regulate the transformer secondary winding voltage to maintain constant DC field in the rotor. The proposed TFM has a modular structure that is free of PM, which makes it cost-effective, without sacrificing its peak torque and power when compared to a similar sized PM based TFM.

Nowadays, transformers are made of conventional magnetic cores which are constructed of a single grainoriented or amorphous, magnetic steel. Even though, the transformer is the most efficient of electrical machines, with efficiencies typically above 90%, it is possible to improve transformer performance by using composite magnetic cores. Patents related to this simple and effective technique can be traced back to 1929. The specific technique can be applied to wound core distribution transformers. By using wound cores constructed with a combination of conventional and high permeability grain-oriented steel the total owing cost (TOC) of the transformer can be reduced effectively. This paper presents a brief review of patents on wound and composite magnetic cores and introduces a generalized technique for the determination of the optimum design variables of a new composite wound core design.

Line start permanent magnet synchronous motors (LS-PMSM) are preferred more and more in industrial applications, because they can start on their own and because of their high efficiency. In this study, a new LS-PMSM rotor typology is suggested, which is modelled using surface mount permanent magnets, in which two different slot types have been used together. The rotor of an asynchronous motor on the industrial market in the IE2 efficiency segment has been remodeled in the study, resulting in an increase in motor efficiency from 85% to 91.8%. A finite elements software was used for determining motor design and performance, in addition to analytical methods.

For driving constant loads in industry, the use of direct-on-line-start permanent-magnet-assisted synchronous reluctance motors with ferrite magnets (DOL-Start-PMa-SynRM) is proposed. The bibliographic search demonstrated that this new motor has greater efficiency than one similar induction motor (IM). It was evidenced that the main element that is required for direct starting is to insert a squirrel cage into the rotor of a PMa-SynRM, which does not produce negative operational effects in a steady state. An economic evaluation was carried out in a sugar mill company, applying the differential net present value (NPV) method, and a sensitivity analysis, considering the four factors that present the most variation. It was demonstrated, by means of a Pareto diagram standardized for the NPV that the most significant factors are fuel factor, lifespan and the multiplication of both. With response surfaces that are obtained with a multilevel factorial experiment, it was determined that, by...

- by Enrique Ciro Quispe Oqueña
- •
- Electrical Engineering, Mathematics, Renewable Energy, Power Quality

Wind power generation facilities have been installed in the world. Recently offshore wind energy attracts greater attention, and development of wind turbine generators of higher power rating becomes more important. Superconducting technology is expected to be applied to over 10 MW class generators. We have studied 10 MW class large wind turbine generators using superconducting technologies. The paper presents fundamental structures of
large-scale wind turbine generators, paying attention to the reduction of superconducting wire length, and generator size and weight. Some design results of 10 MW wind turbine generators are shown and compared.

- by Hiroyuki Ohsaki and +2
- •
- Superconductivity, Applied Superconductivity, Wind turbine, Design of electrical machines

A new dual rotor mutually coupled switched reluctance machine (DR-MCSRM) is proposed. The proposed machine has a magnetic circuit similar to the full pitched mutual coupled switched reluctance machine (FP-MCSRM) without short end windings. FP-MCSRMs have higher torque and power density, but they have longer end windings leading to unwanted copper loss. The construction of the proposed machine is similar to the merging version of the outer rotor and inner rotor FP-MCSRMs. An example machine is designed to meet specifications developed for automotive applications. A finite element model is developed and the machine is optimized to meet the performance targets. The machine performance is compared with a FP-MCSRM designed for the similar specifications.

This paper develops a particular 2D FEM model for iron loss analysis in permanent magnet machines during rotor speed oscillations. Hysteresis and saturation effects in solid rotor iron parts are considered and rotor skew is accounted by using a particular special air-gap element combined with standard 2D finite elements. Internal and surface permanent magnet rotor topologies are compared. The results obtained have been validated by measurements of rotor speed damping, consisting an important phenomenon of the respective drive.

This paper investigates mechanical vibrations of an interior permanent magnet (IPM) synchronous electrical motor designed for a wide range of speeds by virtue of the modal and rotordynamic theory. Mechanical vibrations of the case study IPM motor components were detected and analyzed via numerical, analytical and experimental investigation. First, a finite element-based model of the stator assembly including windings was set up and validated with experimental and analytical results. Second, the influence of the presence of the motor housing on the natural frequencies of the stator and windings was investigated by virtue of numerical modal analysis. The experimental and numerical modal analyses were further carried out on the IPM rotor configuration. The results show that the natural frequencies of the IPM rotor increase due to the presence of the magnets. Finally, detailed numerical rotordynamic analysis was performed in order to investigate the most critical speeds of the IPM rotor with bearings. Based on the obtained results, the key parameters related to mechanical vibrations response phenomena, which are important when designing electrical motors with interior permanent magnets, are provided. The main findings reported here can be used for experimental and theoretical mechanical vibration analysis of other types of rotating electrical machines.

This paper describes finite element techniques that reduce the computational cost of the 3D transient thermal analysis. Based on those techniques a finite element package is assembled. The package is used for the transient thermal analysis, under different load conditions and ambient temperatures, of a surface mounted permanent magnet synchronous motor for aerospace actuation applications. Its validity is verified by measurements carried out in a thermal chamber.

This paper concerns the thermal investigation of a surface-mounted permanent-magnet synchronous motor designed for high-temperature aerospace actuation applications. A finite-element package was developed, enabling accurate 3-D transient thermal analysis by considering complex and unsymmetrical actuator housing configurations. Its validity was verified by measurements carried out at different duty cycles and operating conditions.

- by Ohiozua Ohijeagbon
- •
- Atmospheric Science, Renewable Energy, Meteorology, Renewable Energy Systems

This paper presents a methodology for the analytical computation of the slot leakage inductance of tooth-coil winding (TCW) permanent magnet synchronous machines (PMSMs). Generalized equations for the slot leakage inductance of the whole phase are derived, suitable for several slot-pole combinations, and meant to be used during the machine design stage. For simplicity, self-and mutual-inductance components are formulated using the classical method with detailed permeance determination for both horizontal and vertical distribution of coil sides in the slots, considering a straight-line path for the flux leakage. Several slot-pole combinations were simulated by means of Finite Element (FE) method in order to validate the analytical equations, both approaches, FE and analytical, showing adequate concordance.

- by Carlos Madariaga Cifuentes and +1
- •
- Electrical Machines, Design of electrical machines, Leakage inductance

Due to development in fields of materials and power electronics, use of high-speed electrical machines has boosted significantly in recent decades. They are widely used in number of applications, such as electrically assisted turbochargers, flywheel energy storage systems, spindle applications, turbo molecular pumps, micro gas turbines. In applications where high efficiency and high power density are required, the most suitable machine type for high-speed operations is a permanent magnet (PM) machine. In this paper the performance of several different topologies of high-speed PM machines required for use in a micro-gas turbine application are evaluated. Different winding topologies, retaining sleeve materials and magnetization patterns are considered, where the main criterion for the machine performance are eddy current losses in the rotor. Influence of time harmonics in stator currents caused by the inverter Pulse Width Modulation (PWM) is incorporated in the calculation.

- by Johannes J H Paulides
- •
- Electrical Engineering, Mechanical Engineering, Physics, Renewable Energy

— This paper investigates the effect of various rotor structures on the torque production capability of DC excited flux-switching motors. In these machines two set of windings, excited with DC and three-phase AC currents, are placed within the stator and the rotor structure should ensure that the applicable magnetic circuit is present to achieve both a high and smooth torque. As such, the rotor structure is an important factor that affects the performance of DC excited flux-switching motors. Results show that it is possible to increase the mean torque by varying the rotor tooth width or decreasing the torque ripple value by shaping the rotor tooth tip.

- by Johannes J H Paulides
- •
- Electrical Engineering, Mechanical Engineering, Physics, Power Electronics

This paper develops a model based on an original lumped-parameter network configuration for the thermal transient analysis of a permanent magnet synchronous motor (PMSM). The specific PMSM was designed and optimized for a demanding aerospace application. The validity of the proposed lumped-parameter model is verified by measurements carried out in a thermal chamber.

This paper presents a proposed hybrid system based on diesel generator and solar photovoltaic (PV) as an effective option to power a small remote community. The cost of running diesel generator speedily due to erratic power supply in a small remote community that is not grid connected is highly expensive and not environmentally friendly. A solar PV was used to reduce or augment the continuous diesel generator sets, resulting in reduced cost of operation and maintenance. A proper solar radiation data and sizing based on the specification of the PV system and battery bank was done. In addition, a comparative study was carried out considering two scenarios of the proposed model system. In the first scenario, the diesel generation, solar PV system was treated as autonomous (or standalone). In the second scenario, the proposed model system was connected to the grid system. It is discovered that powering the small remote community with the proposed hybrid system is much more beneficial and encourages competition with other conventional energy sources, because it minimizes both operating costs and pollutants emissions. Furthermore, analysis results obtain from HOMER software shows that is promising to implement the on-grid system.

- by Nathan Coppedge
- •
- Philosophy of Science, Statistical Modeling, Philosophy of Time, Archetypes

- by Enrique C . Quispe
- •
- Electrical Engineering, Renewable Energy, Power Quality, Sensitivity Analysis

This paper presents electromagnetic analysis of two permanent magnet transverse flux outer rotor machines with and without magnetic shunts. The research started with designing and analysing a permanent magnet transverse flux machine with inner rotor, previously patented by J. Giearas in 2010. However, the results obtained from the prototype test differed significantly from the estimated results. Applying 3D Finite Element Method tool main problem of the machine was detected. The problem was in high flux leakage which weakened magnetic flux density in the stator poles. Such observation led to designing two machines with outer rotor; with and without magnetic shunts. The role of the magnetic shunts is to minimize flux leakage in the stator in order to improve the performance of the machine. Electromechanical parameters of both outer rotor machines, with and without magnetic shunts, are compared in the paper. 3D Finite Element Method results are supported by laboratory analysis of the machines’ prototypes. Experimental measurements proved that the machine with magnetic shunts demonstrated better performance comparing to the machine without magnetic shunts. Presence of the magnetic shunts in the machine resulted in reducing of flux leakage and cogging torque.

- by Rupert Gouws
- •
- Energy Engineering, Machine Design, Pm Machines, Design of electrical machines

One of the still open issues within low-frequency magnetics is the inclusion of µ r in the calculations using the magnetic charge method. In this paper, a new iterative method to consider the relative permeability is investigated. This new method assumes a position-dependent surface charge distribution. Comparisons between model and finite element method results show that the model accurately accounts for the permeability of a magnet and a soft-magnet block within four iterations.

Helical windings (or zigzag windings) are used in a number of applications, however in electrical machines mainly employed in low-power, high-speed PM brushless DC machines due to the cost-effectiveness of the winding type while maintaining reasonable performance. Typically, helical winding are used for low voltage applications due to their spiral form, which makes them most suitable for a small number of turns. In high-speed electrical machines such a low number of turns is applicable. It is apparent that high-speed PM machines suffer from rotor eddy-current losses, which in some cases may lead to PM demagnetization due to overheating. The performance of the machine is compromised by these losses, hence they have to be taken into account during the design procedure. There are many papers analyzing the magnetic field of these machines employing helical windings, however none of them present a simple and precise electromagnetic model of a machine with the helical winding. This paper presents an analytical approach to model the resulting three-dimensional magnetic field of the helical winding, taking into account eddy currents in the conducting media of the rotor. The model is verified with 3D FEM by means of comparing magnetic field and rotor eddy-current losses.

- by Johannes J H Paulides
- •
- Electrical Engineering, Mechanical Engineering, Physics, Electrical Drives

This paper introduces a novel technique for iron loss minimization of wound core transformers. The proposed technique involves the evaluation of appropriate design variables of wound cores constructed by a combination of standard and high magnetization grade steel. The evaluation of the optimum design variables of the multiple grade lamination wound core is achieved by combining a permeability tensor finite-element model and simulated annealing with restarts.

- by Themistoklis D. Kefalas
- •
- Electrical Engineering, Electromagnetism, Numerical Simulations, Design

There are major challenges when using renewable energy for power supply. When it is cloudy usually after rain, solar production is low yet there is need to use power when the demand for power is required; weather conditions can be a problem at that period. An Automatic Transfer Switch (ATS) for a single-phase power generator has been designed to enable the automatic operation and transfer of power supply between a primary source of power supply and a secondary source (power generator). Clean and environmental energy sources campaign associated with their availability at almost zero cost have resulted in the increase of Renewable energy use throughout the world. In Nigeria and specifically in most parts of the country, Solar Energy constitutes a tremendous resource. When it is cloudy usually after rain, we usually experience low sunlight; hence there is need to maintain continuity of power supply switching automatically to the stand by source. The p rimary power source is the Solar PV system and the generator is the secondary. This research work provided the means to transfer power in a safe manner using relay logic technique. When solar production is low (below 200V), the system switches to the diese l or petrol system until it detects voltage within the allowable limits from the Inverter and switch back to Hybrid Renewable Energy System(HRES). The design is simulated using visual basic to validate the performance of this work. Contacts of HRES opened when voltage falls below 185V. Contacts of generator circuit closes when voltage is below normal 185-250Vac.

- by Engr.Dr.Ngang Bassey,FNSE ,MIEEE and +1
- •
- power system Automation, Power Electronics and Drives, Design of electrical machines

—The growing demand for electricity in developing countries calls for a continuous increase in the installed capacity. However, with installed capacity unable to meet the pace of increase in demand, increase in efficiency of energy conversion devices is a vital requirement. The present paper considers one such energy improvement method in the form of a Line Start Permanent Magnet Synchronous Motor (LSPMSM) which is intended as a substitute for induction motors in developing countries. The economic benefits due to the utilization of such machines, their commercial viability and their life cycle costing have all been considered here. The paper also presents theoretical results obtained for various rotor configurations of the LSPMSM and practical results for the selected spoke type rotor geometry.

Particle Swarm Optimization (PSO) and Genetic Algorithms (GA) are used to minimize the cost of a permanent magnet (PM) synchronous generator with concentrated windings for tidal power applications. With the use of MATLABs global optimization toolbox, it is possible to run several optimization algorithms on the same problem, and to combine the two stochastic solvers GA and PSO with the gradient based solver fmincon to produce two hybrid optimization solvers. It has been shown that a complex machine design problem with tight constraints and a narrow solution space is difficult to solve for both a GA and for PSO. Both GA and PSO were unable to find the optimal value on their own. Hybrid versions of GA and PSO gave better results. The average minimum costs found with hybrid PSO and hybrid GA were 1.07 and 1.11 times the global minimum. When the integer value was set to the optimal value, the hybrid GA found a mean cost only 1.01 times the global minimum. For both algorithms, it was necessary to increase the population size to improve the fitness functions and reduce the variance.

- by Erlend Engevik and +1
- •
- Genetic Algorithms, Particle Swarm Optimization, Electrical Machines, Design of electrical machines

This paper investigates the effects of rotor skew on the performance of permanent magnet synchronous generators. The main effects are concerning reduction of the electromotive force induced, stator current harmonics and torque ripple. The analysis performed is based on various 2D and 3D finite element techniques. Simulation results are compared to measurements.

- by Themistoklis D. Kefalas
- •
- Engineering, Electrical Engineering, Numerical Simulations, Design

—Transverse Flux Machines (TFM) exhibit 3-D flux patterns. Their analysis and design are generally based on 3-D Finite Element Methods (FEM). Previous analytical models were mostly limited to Magnetic Equivalent Circuits (MEC). The analytical model presented in this paper is used to perform extremely fast calculation of the flux linkage and EMF of a TFM. The analytical model uses a combination of the magnetic charge and magnetic imaging techniques to represent magnetic flux distribution within the air gap of a TFM. Furthermore, a suitable method to calculate the flux linkage of the TFM had to be determined to allow EMF calculation. This resulted in an analytical model which obtains a magnetic flux distribution with less than 10% error in the air gap. The calculated EMF, and therefore the flux linkage, is within 15% accuracy compared to the EMF measured for two prototypes.

The paper develops a special air-gap element based on the analytical solution of Laplace equation combined with standard finite elements, for analysis of electrical machines with rotor skew. It has been implemented for the analysis of a surface permanent magnet machine. The results obtained have been compared to the ones of a standard 3-D finite-element model and are in good agreement with the measured ones.

- by Themistoklis D. Kefalas
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- Engineering, Electrical Engineering, Numerical Simulations, Design

Elektrik motorları her gelişen ülkede olduğu gibi Türkiye’de de tüketilen elektrikte büyük paya sahiptir. Ayrıca mevcut verilere göre Türkiye elektriğinin %35’lik kısmı sanayide yoğun olarak tercih edilen asenkron motorlar tarafından tüketilmektedir. Bu nedenle bu motorların daha verimli hale getirilmesi ile elektrik tüketiminde de gözle görünür azalma sağlanabilmektedir. Ayrıca büyük oranda asenkron motorların kullanıldığı endüstriyel uygulamalarda daha verimli motorların tercih edilmesi durumunda, firma enerji giderlerinde de tasarruf sağlanabilmektedir. Günümüzde elektrik motorları pazarında çalışma koşullarına cevap verebilecek birçok ürün mevcuttur ve bu ürünler uluslararası standartlar ile karakterize edilmektedir. Elektrik motoru üreticileri tarafından kabul gören bu standartlar ile piyasaya sunulan elektrik motorlarının çerçeve boyutları ve çalışma şartları gibi birçok konuda düzenleme yapılmaktadır. Yoğun olarak kabul gören IEC 60034-30-1 elektrik motoru standartlarına göre 0.12 – 1000 kW mil gücü aralığındaki elektrik motorları verimliliklerine göre; IE1 - Standart Verimlilik, IE2 - Yüksek Verimlilik, IE3 - Premium Verimlilik ve IE4 - Süper Premium Verimlilik şeklinde sınıflandırılmaktadır. Asenkron motorlar teknolojik sınırlamalar ve malzeme limitleri neticesinde IE3 ve altı verimlikte piyasa sunulabilmektedir. Buna karşın asenkron motor rotorunun yüksek performanslı sabit mıknatıslar kullanılarak modellenmesi ile yüksek verim, güç faktörü ve güç yoğunluğu sunabilen elektrik motorları üretilebilmektedir. Rotorunda sincap kafesi ve sabit mıknatısların bir arada kullanılması neticesinde hibrit bir yapıya sahip olan bu motorlar literatürde “Şebeke Kalkışlı Sabit Mıknatıslı Senkron Motor” olarak yer almaktadır. Asenkron motorlar gibi sağlam ve az bakım gerektiren bu motorlar, rotorunda yer alan sabit mıknatıslar sayesinde IE3 üstü standartlarda verimlilik sunabilmektedir. Diğer bir yandan bu motorların üretim süreci sabit mıknatıs nedeni ile asenkron motorlara göre ile daha karmaşık ve maliyetli olmaktadır. Yapılan bu çalışma ile üretim maliyeti yüksek olan şebeke kalkışlı sabit mıknatıslı senkron motorların Türkiye pazarına giriş ücretleri ve yüksek verimli çalışma koşullarında motorun ne kadar zamanda alım maliyetini amorti edeceği tartışılmıştır. Ayrıca Türkiye’deki verimli motorlara geçiş sürecine ışık tutulmuştur.