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Journal of international Conference on Electrical Machines and Systems
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Journal of International Conference on Electrical Machines and Systems
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Volume 1, Issue 4 - Dec 2012
Volume 1, Issue 3 - Sep 2012
Volume 1, Issue 2 - Jun 2012
Volume 1, Issue 1 - Mar 2012
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Comparative Study between Two Protection Schemes for DFIG-based Wind Generator Fault Ride Through
Okedu, K.E. ; Muyeen, S.M. ; Takahashi, R. ; Tamura, J. ;
Journal of international Conference on Electrical Machines and Systems , volume 1, issue 1, 2012, Pages 8~16
DOI : 10.11142/jicems.2012.1.1.008
Fixed speed wind turbine generators system that uses induction generator as a wind generator has the stability problem similar to a synchronous generator. On the other hand, doubly fed induction generator (DFIG) has the flexibility to control its real and reactive powers independently while being operated in variable speed mode. This paper focuses on a scheme where IG is stabilized by using DFIG during grid fault. In that case, DFIG will be heavily stressed and a remedy should be found out to protect the frequency converter as well as to allow the independent control of real and reactive powers without loosing the synchronism. For that purpose, a crowbar protection switch or DC-link protecting device can be considered. This paper presents a comparative study between two protective schemes, a crowbar circuit connected across the rotor of the DFIG and a protective device connected in the DC-link circuit of the frequency converter. Simulation analysis by using PSCAD/EMTDC shows that both schemes could effectively protect the DFIG, but the latter scheme is superior to the former, because of less circuitry involved.
Magnetic Characteristic Analysis of Permanent Magnet Motor with Complex E&S Modeling
Zeze, Shingo ; Todaka, Takashi ; Enokizono, Masato ;
Journal of international Conference on Electrical Machines and Systems , volume 1, issue 1, 2012, Pages 17~22
DOI : 10.11142/jicems.2012.1.1.017
This paper presents analyzed results of a permanent magnet motor by using complex E&S modeling. The calculated results are compared with ones from the conventional E&S modeling for verification. Combinations of the numbers of slots and poles are investigated to reduce total iron loss. The results demonstrate that the complex E&S modeling is very useful in design under consideration of rotational magnetic field and magnetic anisotropy.
Review of Variable-flux Permanent Magnet Machines
Owen, R.L. ; Zhu, Z.Q. ; Wang, J.B. ; Stone, D.A. ; Urquhart, I. ;
Journal of international Conference on Electrical Machines and Systems , volume 1, issue 1, 2012, Pages 23~31
DOI : 10.11142/jicems.2012.1.1.023
Variable-flux permanent-magnet machines (VFPM) are of great interest and many different machine topologies have been documented. This paper categorizes VFPM machine topologies with regard to the method of flux variation and further, in the case of hybrid excited machines with field coils, with regard to the location of the excitation sources. The different VFPM machines are reviewed and compared in terms of their torque density, complexity and their ability to vary the flux.
Individual and Global Optimization of Switched Flux Permanent Magnet Motors
Zhu, Z.Q. ; Liu, X. ;
Journal of international Conference on Electrical Machines and Systems , volume 1, issue 1, 2012, Pages 32~39
DOI : 10.11142/jicems.2012.1.1.032
With the aid of genetic algorithm (GA), global optimization with multiple geometry parameters is feasible in the design of switched flux permanent magnet (SFPM) machines. To investigate the advantages of global optimization over individual optimization, which has been used extensively for the design of SFPM machines, a comparison between the two approaches is carried out for the case of fixed copper loss and volume. In the case of individual parameter optimization, the sequence in which the individual parameters are optimized is very important. In the global optimization a better design can always be achieved although the corresponding torque density is found to be only slightly better than that of individually optimized with correct design sequence. By using the obtained global optimization results, the performance in machines having two types of stator and rotor pole combinations, i.e. 12/10 and 12/14, are compared, and it is shown that higher torque is exhibited in the 12/14 SFPM machine. Finally, this paper also demonstrates that global optimization, with the restriction of equal pole width, magnet thickness and slot opening, can maximize the torque density without significantly sacrificing other performance, such as cogging torque and overload capability.
Computer Model for Railway Inductive Power Supply Using the Valtchev Model
Dias, Joao Victor Pinon Pereira ; Kim, Hyung-Chul ; Jang, Dong-Uk ;
Journal of international Conference on Electrical Machines and Systems , volume 1, issue 1, 2012, Pages 40~46
DOI : 10.11142/jicems.2012.1.1.040
This paper presents contactless power supply systems using the Valtchev model in transportation systems. The major drawback of contactless systems is that the efficiency is lower than that of contact systems. The coupling coefficient of the contactless transformer is the most influential parameter on the system efficiency. Here, a new computer model for the contactless transfer system developed in the Korea Railroad Research Institute is presented. Also, simulations of the old model and the new model are compared with the prototype measurement to assure the model validity.
A Novel 6/5 Switched Reluctance Motor with Short Flux Path: Concept, Design and Analysis
Tanujaya, Marully ; Lee, Dong-Hee ; An, Young-Joo ; Ahn, Jin-Woo ;
Journal of international Conference on Electrical Machines and Systems , volume 1, issue 1, 2012, Pages 47~53
DOI : 10.11142/jicems.2012.1.1.047
A novel 6/5 switched reluctance motor (SRM) with short flux path is presented in this paper. The concept of this proposed motor is a novel SR motor with six stator and five rotor poles. The stator is constructed with three independent and physically separate C-core segments, and the rotor is composed of five poles. This motor, with a new selection for the number of stator/rotor poles, achieves a short flux path, which reduces the magnetomotive force required to drive the motor. To verify the performance of the proposed motor, a comparison with conventional SR motors with the same dimensions is executed. The comparison demonstrates that the proposed motor offers better performance in terms of maximum torque production. Furthermore, Finite Element Analysis (FEA) and Matlab/Simulink software are used to predict and simulate the performance of the proposed motor.
A Primary Permanent-Magnet Linear Motor for Urban Rail Transit
Cao, Ruiwu ; Cheng, Ming ; Mi, Chris ; Hua, Wei ; Zhao, Wenxiang ;
Journal of international Conference on Electrical Machines and Systems , volume 1, issue 1, 2012, Pages 54~60
DOI : 10.11142/jicems.2012.1.1.054
In this paper, a new permanent-magnet (PM) linear motor is proposed, in which both the magnets and armature windings are placed in the short mover, while the long stator consists of iron core only. Hence, this new PM linear motor can be called a primary permanent-magnet linear motor. It exhibits the advantages of robustness, low cost, high efficiency, high power factor, and high thrust force density. It is especially suitable for long stator applications such as urban rail transit. In this paper, the topology and operation principle of this motor are discussed in detail. The steady-state characteristics including field distributions, flux-linkage, back-EMF, phase inductance and thrust force are investigated. In addition, the technique of skewing stator teeth is adopted to improve the electromagnetic performance. Results from finite element method (FEM) verified the theoretical analysis results.
Novel Flexible Printed Circuit Windings for a Slotless Linear Motor Design
Hsu, Liang-Yi ; Yan, Guo-Jhih ; Tsai, Mi-Ching ;
Journal of international Conference on Electrical Machines and Systems , volume 1, issue 1, 2012, Pages 61~66
DOI : 10.11142/jicems.2012.1.1.061
Linear motors has been developed for factory automation, transportation applications, among other applications. As the trend toward compact sizes in micro electronic products progresses, the required motor drives in these applications need to be downsized with increased power densities. It appears that the winding of miniature linear motors is the most awkward part to be scaled down from conventional motor designs when miniaturizing. This paper presents an alternative design for slotless linear motors. A novel flexible printed circuit winding has been applied to obtain a simplified but qualified result. Having explained the prototyping and inspection, a discussion is given to examine the achievement of this study.
Switched Inductor Z-Source AC-DC Converter
Sedaghati, Farzad ; Hosseini, Seyed Hossein ; Sarhangzadeh, Mitra ;
Journal of international Conference on Electrical Machines and Systems , volume 1, issue 1, 2012, Pages 67~76
DOI : 10.11142/jicems.2012.1.1.067
Due to the increasing amount of applications of power electronic ac-dc converters, it is necessary to design a single-stage converter that can reliably perform both buck and boost operations. Traditionally, this can be achieved by double-stage conversion (ac/dc-dc/dc) which ultimately leads to less efficiency and a more complex control system. This paper discusses two types of modern ac-dc converters. First, the novel impedance-source ac-dc converter, abbreviated as custom Z-source rectifier, is analyzed; and then, switched inductor (SL) Z-source ac-dc converter is proposed. This paper describes the Z-source rectifiers' operating principles, the concepts behind them, and their superiorities. Analysis and simulation results show that the proposed custom Z-source rectifier can step up and step down voltage; and the main advantage of the SL Z-source ac-dc converter is its high step-up capability. Low ripple of the output dc voltage is the other advantage of the proposed converters. Finally, the SL Z-source ac-dc converter is compared with the custom Z-source ac-dc converter.
Harmonics Elimination in a Multilevel Inverter with Unequal DC Sources Using a Genetic Algorithm
Iranaq, Ali Reza Marami ; Kouhshahi, Mojtaba Bahrami ; Kouhshahi, Mehdi Bahrami ; Sharifian, Mohammad Bagher Bannae ; Sabahi, Mehran ;
Journal of international Conference on Electrical Machines and Systems , volume 1, issue 1, 2012, Pages 77~83
DOI : 10.11142/jicems.2012.1.1.077
In this paper, an optimal solution to the harmonic reduction problem in a cascaded multilevel inverter with non-equal DC sources using a genetic algorithm (GA) is presented. Switching angles are generated for different values of modulation index by the proposed algorithm, considering minimum voltage total harmonic distortion (THD) whereas selected harmonics are controlled within the allowable limits at all desired modulation indices including the point of discontinuity. Results are stored as a look-up table to be used to control the inverter for a certain operating point. The computed angles are used in a simulated circuit in Matlab\Simulink to validate the results.
Flux Position Estimation Method of IPMSM by Controlling Current Derivative at Zero Voltage Vector
Hosogaya, Yuji ; Kubota, Hisao ;
Journal of international Conference on Electrical Machines and Systems , volume 1, issue 1, 2012, Pages 84~90
DOI : 10.11142/jicems.2012.1.1.084
Various methods have been proposed to identify the flux position in an interior permanent magnet synchronous motor (IPMSM) without the use of mechanical sensors. To achieve this, a method that uses both the back electromotive force (EMF) and the saliency to identify the flux position in the IPMSM without the injection of high-frequency components at low speeds has been reported. This method was then extended in order to drive the motor with no load to a light load. We propose a combination of these methods with different proportional-integral (PI) controllers for controlling
/dt. We also introduce compensation values
to reduce the position error when the estimation rule is being selected.
A New Approach of BLDC Motor Using Unidirectional Current in the Driver Circuit and its Future Prospects
Yasuhiro, Komatsu ; Zawawi, Syed Abdul Kadir ;
Journal of international Conference on Electrical Machines and Systems , volume 1, issue 1, 2012, Pages 91~98
DOI : 10.11142/jicems.2012.1.1.091
Climate change and other pollutions make a huge demand of environment friendly and high efficient motors especially Brushless DC (BLDC) motors. Generally, bidirectional energized BLDC motors are used widely; however, inverter devices used in the driver put fear of being effected by noise. This paper proposes unidirectional energized BLDC motor which utilizes asymmetrical H-bridge circuit as the driver circuit. The Minato motor is one of the pioneers in unidirectional energized system. The use of bar magnets in the rotor is one of the biggest disadvantages of the motor. We proposed using tabular magnets. The paper compares the power consumption and efficiency of the Minato motor and the proposed motor. During high speed rotation, undesirable armature current is generated that has a deceleration characteristic. This current lowers the motor's efficiency. In this paper, we propose the solutions and show comparison through equations of the copper loss ratio for the Minato and our proposed motors. The third motor, which has the highest efficiency, was discovered during examination of the equations.
New Switch-Control Technique for Multiphase Interleaved Converters with Current Sharing and Voltage Regulation
Thongbuaban, Ponlawat ; Jantharamin, Niphat ;
Journal of international Conference on Electrical Machines and Systems , volume 1, issue 1, 2012, Pages 99~103
DOI : 10.11142/jicems.2012.1.1.099
This paper presents a new switch-control approach for multiphase interleaved converters. Development of the proposed technique is based on control-signal generation for multi-unit synchronization. Current sharing among the switching cells and voltage regulation are achieved by means of a multi-loop control scheme regardless of changes in input voltage and load. System stability is ensured by single-pole compensation. This proposed technique is straightforward, reliable and inexpensive, and can be applied to any higher number of cells without difficulty.
Augmentation of Wind Farms Ride Through by DFIG-based Variable Speed Wind Generators
Okedu, K.E. ; Muyeen, S.M. ; Takahashi, R. ; Tamura, J. ;
Journal of international Conference on Electrical Machines and Systems , volume 1, issue 1, 2012, Pages 104~113
DOI : 10.11142/jicems.2012.1.1.104
Wind farm grid codes require wind generators to ride through voltage sags, which means that normal power production should be re-initiated once the nominal grid voltage has been recovered. Doubly Fed Induction Generator (DFIG) based wind farm is gaining popularity these days because of its inherent advantages like variable speed operation and independent controllability of active and reactive power over conventional Induction Generator (IG). This paper proposes a new control strategy using DFIGs for stabilizing a wind farm composed of DFIGs and IGs. Simulation analysis by using PSCAD/EMTDC shows that the DFIGs can effectively stabilize the IGs and hence the entire wind farm through the proposed control scheme by providing sufficient reactive power to the system.
Theoretical Study on Eco-Driving Technique for an Electric Vehicle with Dynamic Programming
Kuriyama, Motoi ; Yamamoto, Sou ; Miyatake, Masafumi ;
Journal of international Conference on Electrical Machines and Systems , volume 1, issue 1, 2012, Pages 114~120
DOI : 10.11142/jicems.2012.1.1.114
Eco-driving technique for electric vehicles (EVs) is investigated in this paper. Many findings on EVs have been reported; however, they did not deal with eco-driving from the viewpoint of theoretical study. The authors have developed an energy-saving driving technique - the so-called "eco-driving" technique based on dynamic programming (DP). Optimal speed profile of an EV, which minimizes the amount of total energy consumption, was determined under fixed origin and destination, running time, and track conditions. DP algorithm can deal with such complicated conditions and can also derive the optimal solution. Using the proposed method, simulations were run for some cases. In particular, the author ran simulations for the case of a gradient road with a traffic signal. The optimization model was solved with MATLAB.
Steady-State Performance Analysis of an Integrated Wind Turbine Generating System in a DC Transmission System with Power Compensation System
Yamashita, Ken-Ichiro ; Nishikata, Shoji ;
Journal of international Conference on Electrical Machines and Systems , volume 1, issue 1, 2012, Pages 121~127
DOI : 10.11142/jicems.2012.1.1.121
An electric power compensation system for a DC transmission system with an integrated wind turbine generator is proposed. The proposed compensation system consists of a synchronous generator and a duplex reactor. This apparatus is connected to the sending-end circuit of the DC transmission system. A set of steady-state equations of the system is first derived. Then, the effect of the duplex reactor, which can eliminate the sending-end grid current distortion due to commutation of the converter, is explored. The relationships among power at the sending-end circuit are also revealed. It is shown that fluctuations in the sending-end grid power due to changes in wind velocities are compensated with the proposed system. Finally, the effects of the sending-end grid conditions on the steady-state characteristics of the system are studied.
Electrical Machines and Drives for Potentially Explosive Atmospheres
Grantham, Colin ;
Journal of international Conference on Electrical Machines and Systems , volume 1, issue 1, 2012, Pages 128~134
DOI : 10.11142/jicems.2012.1.1.128
This paper gives an overview of the requirements for electrical equipment in potentially explosive atmospheres and describes how these are applied to electrical machines and drives in hazardous areas. The method by which equipment can be shown to be safe in a whole range of gases, by testing in a single test gas, is covered. It is shown how the more recently introduced methods of protection for hazardous areas, increased safety and nonsparking, are ideally suited to AC machines and drives. A novel method of measuring the fullload temperature rise of electrical machines for hazardous, and other areas, without the need to connect a mechanical load to the machine's drive shaft is explained.
Power System Oscillations Damping Using UPFC Based on an Improved PSO and Genetic Algorithm
Babaei, Ebrahim ; Bolhasan, Amin Mokari ; Sadeghi, Meisam ; Khani, Saeid ;
Journal of international Conference on Electrical Machines and Systems , volume 1, issue 1, 2012, Pages 135~142
DOI : 10.11142/jicems.2012.1.1.135
In this paper, optimal selection of the unified power flow controller (UPFC) damping controller parameters in order to improve the power system dynamic response and its stability based on two modified intelligent algorithms have been proposed. These algorithms are based on a modified intelligent particle swarm optimization (PSO) and continuous genetic algorithm (GA). After extraction of UPFC dynamic model, intelligent PSO and genetic algorithms are used to select the effective feedback signal of the damping controller; then, to compare the performance of the proposed UPFC controller in damping the critical modes of a single-machine infinite-bus (SMIB) power system, the simulation results are presented. The comparison shows the good performance of both presented PSO and genetic algorithms in an optimal selection of UPFC damping controller parameters and damping oscillations.