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In this study, it is aimed to design an external rotor permanent magnet synchronous reluctance motor (PMSynRM) for an electric vehicle (EV). In recent years, developments in EV technology have increased the need for electric motor design. Electric motors designed to be used in EVs are considered to have high efficiency, high torque and high power density in a wide speed range. Considering these situations, one of the recently designed electric motors is the synchronous reluctance motor (SynRM). However, the disadvantage of a synchronous reluctance motor is the torque ripple. In this study, a 2-kW, three-phase, eight-pole, 24-slots hub motor with an external rotor (PM-SynRM) with a rotational speed of 750 rpm is designed. The design was modeled using the finite element method (FEM) and the necessary analysis was performed. When designing the flux barrier Ld/Lq rate was considered. By using permanent magnets in the design of electric motors, torque and efficiency values have been increased. For this reason, in our PMSynRM design, Neodymium Iron Boron (NdFeB) permanent magnet material is placed in the rotor flux barriers to increase torque. In addition, it is aimed to reduce the torque ripples at low speeds by selecting the distributed winding in the stator windings. Simulation results show that high torque is obtained with low torque ripple. In addition, good results were obtained in terms of efficiency, current, speed and power density. © 2021, The Author(s), under exclusive license to Springer Nature Switzerland AG.

This paper deals with an energy management issue for the grid-connected renewable energy sources connected with unbalanced loads. In the gridconnected energy systems, conventional energy management methods are used to manage balanced active power supplied from energy units to grids/ loads. However, unbalanced load groups, like single-phase loads, parallel rectifiers, and three-winding transformers tied to the electric networks, cause zero-sequence currents and impair the power stability at the gridside. For this purpose, in this study, an improved power flow controller method with zero-sequence current injection is proposed in order to compensate zero-sequence currents and ensure phase equilibrium at grid-side. Therefore, it is tested in a photovoltaic/fuel cell-based hybrid energy system with unbalanced loads, including zero-sequence. Instead of the conventional abc/dq frame used in energy management control, the proposed method makes use of triple αβ transforms and implemented in each phase to be controlled separately under designed unbalanced load groups. Hence, it abolishes the weakness of the conventional abc/dq frame method that generates the undesirable mean reference for zero-sequence situations. In addition, the designed system cannot only mitigate the grid-side zerosequence currents but also supply active powers to three-phase loads/ grids. The optimization of energy systems is also provided through a maximum power point tracking algorithm. In the performance testing, the energy generation units are performed under three states, which produce different supplied currents at the output. In the performance section, it is obvious that zero-sequence components at grid-side currents are significantly reduced via the proposed power flow controller-based system. Also, the results are compared to the conventional method in order to verify the validity of the proposed approach under the designed load groups.

The use of aluminum (Al) alloy substances is analyzed in this paper in order to obtain a lighter and less costly winding design without dimensional changes in electrical machines. The determination of aluminum alloy winding material, which has an electrical conductivity close to that of copper (Cu) but has a lower density, is the basis of this study. In this context, various aluminum alloy substances have been investigated. Windings with these aluminum alloy materials for a 300 kVA synchronous alternator have been modeled with the Ansys Maxwell 2D software program. The performances of tempered and annealed alloy windings have been analyzed with respect to that of a copper winding. The analysis results show that the aluminum winding losses are close to copper winding losses under nominal operating current values. Among the aluminum alloy winding models, aluminum 1350 and aluminum 2041 have the closest loss values. On the other hand, there is very little difference between aluminum alloy windings in terms of winding weight, while the weight of the aluminum winding is 70% lower compared with that of the copper winding. It is suggested to wind turbine manufacturers that windings be formed with the aluminum 1350 and aluminum 2041 series to provide performance comparable with that of copper windings. © 2020 ICE Publishing: All rights reserved., Kocaeli Üniversitesi: 2019/089, This work was supported by the Scientific Research Projects Coordination Unit of Kocaeli University under contract number 2019/089.

Aging of high voltage generators and motors lead to changes in the dielectric properties of the stator winding insulation system. Research on the relation between aging and dielectric response has been going on for decades. A particular challenge is that the coil insulation consists of several materials: two that strongly affect the dielectric response are the ground-wall insulation and the stress grading shield (end-corona protection, ECP), which exhibit quite different properties. The influence of the ECP on the overall dielectric response of the insulation system might dwarf the condition change of the ground-wall insulation. In this paper, we introduce a test system that can measure the dielectric response in both time and frequency domain from low to rated voltage. Measurement results of two types of custom-designed, commercial standard stator winding coils are presented, and the influence of the ECP can be observed. The validity of time-frequency domain transformation of this nonlinear system is discussed. This paper acts as a basis for the application of dielectric diagnostic testing in the field. QC 20211005

Modern technology for the processing of spent fuel assemblies (SFA) and radioactive waste (RW) is utilized in radiation protection cells. Under the conditions of exposure to high radiation fields, there is an intense destruction of various assemblies of actuators made of organic materials, including insulation of motor windings, which leads to frequent equipment failures requiring repair or replacement. Within the limits of the existing need, a project is being developed, with the purpose of creation of a radiation-resistant asynchronous electric motor with ceramic insulation for operation in. The proposed technical solutions make possible to increase the service life of the engine operating under the influence of radiation fields in radiation protection chambers by 4-5 times. Operation under an extreme condition requires an assessment of the engine itself. Considering a non-standard cooling system is of crucial importance for such projects.

3rd International Symposium on Multidisciplinary Studies and Innovative Technologies, ISMSIT 2019 -- 11 October 2019 through 13 October 2019 -- -- 156063, Lightning strike is a very important phenomenon for all electrical power systems because of over voltage impulse. Thus, lightning analysis is equally important for power issue. In this paper, lightning electric field analysis of an oil type distribution transformer with a 25-kVA power capacity using ANSYS Maxwell simulation program are proposed. Lightning impulse voltage applied to transformer, electric field and voltage distribution of the transformer during lightning are presented with simulation results. Critical regions that can cause breakdown on insulation materials between primary and secondary windings are shown as three dimensionally. Electric field distribution on critical regions on insulation material of two-dimensional model is also shown. The comparison of three and two-dimensional analyses are compared for insulation breakdown during lightning analyses. This paper provides advantage researchers and engineers whom design/produce/choose the transformer bushings/isolators and other insulation materials on a simulation program such as ANSYS. In future, optimization study for insulation materials and partial discharge localization will be done. © 2019 IEEE., FDK-2018-9906, ACKNOWLEDGMENT The authors would like to acknowledge the Scientific Project Unit of Cukurova University (Project ID: FDK-2018-9906) for the support during this work.

We report the fabrication of Ni2.7Mn0.9Ga0.4/InGaAs bilayers on GaAs (001)/InGaAs substrates by molecular beam epitaxy. To form freestanding microtubes the bilayers have been released from the substrate by strain engineering. Microtubes with up to three windings have been successfully realized by tailoring the size and strain of the bilayer. The structure and magnetic properties of both, the initial films and the rolled-up microtubes, are investigated by electron microscopy, X-ray techniques and magnetization measurements. A tetragonal lattice with c/a = 2.03 (film) and c/a = 2.01 (tube) is identified for the Ni2.7Mn0.9Ga0.4 alloy. Furthermore, a significant influence of the cylindrical geometry and strain relaxation induced by roll-up on the magnetic properties of the tube is found. Dieser Beitrag ist aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.

This paper investigates the influence of the slot/pole (S/P) combination on inter-turn short-circuit (SC) current in fault-tolerant permanent magnet (FT-PM) machines. A 2-D sub-domain field computational model with multi-objective genetic algorithm is used for the design and performance prediction of the considered FT-PM machines. The electromagnetic losses of machines, including iron, magnet, and winding losses are systematically computed using analytical tools. During the postprocessing stage, a 1-D analysis is employed for turn-turn fault analysis. The method calculates self-and mutual inductances of both the faulty and healthy turns under an SC fault condition with respect to the fault locations, and thus SC fault current, considering its location. Eight FT-PM machines with different S/P combinations are analyzed. Both the performance of the machine during normal operation and induced currents during a turn-turn SC fault are investigated. To evaluate the thermal impact of each S/P combination under an inter-turn fault condition, a thermal analysis is performed using finite element computation. It is shown that low-rotor-pole-number machines have a better fault tolerance capability, while high-rotor-pole-number machines are lighter and provide higher efficiency. Results show that the influence of the S/P selection on inter-turn fault SC current needs to be considered during the design process to balance the efficiency and power density against fault-tolerant criteria of the application at hand.

This paper deals with new procedures based on vibro-acoustic techniques to diagnose power medium-voltage/low-voltage (MV/LV) transformers. The normal operating machines can be monitored and checked from a remote, dedicated diagnostic center where information is received directly from the field. The diagnostic method adopted and the experimental test results are reported. Tests have been performed either in the laboratory or directly in the field on transformers in normal operating conditions. The laboratory tests related the transformer vibrations to internal anomalies. The suggested monitoring and diagnostic system allows one to usefully schedule preventative maintenance, reduce costs, and improve the quality of power distribution.

Exploiting the rich switching redundancies of the dual inverter, new hybrid pulsewidth-modulation (PWM) switching methods are proposed in this paper using the degree of freedom of operating the individual inverters independently, in addition to exercising the degree of freedom of controlling the switching action of the individual legs independently. Two voltage entities, namely, common-mode voltage (CMV) and differential-mode voltage are identified in the dual inverter, and all hybrid PWMs are envisaged aimed at reducing and also eliminating the CMV in it. The effects of such attempts on motor shaft voltage and also the motor bearing currents are presented in detail. Furthermore, bearing current profiles of an open-end winding induction motor are also presented with both conventional and hybrid PWMs proposed in this paper. Electric discharge machining discharge currents are completely eliminated with the use of all hybrid PWM methods proposed in this paper. In addition, implications of completely eliminating the CMV are also presented in this paper. All hybrid PWMs proposed in this paper are first simulated using MATLAB and are experimentally verified on a dual two-level inverter feeding a 1.1-kW 415-V 3-? open-end winding induction motor drive. � 2014 IEEE.

The space utilization of linear switched reluctance machine is relatively low, which unavoidably constrains the improvement of system output performance. The objective of this paper is to propose a novel tubular linear switched reluctance motor with double excitation windings. The employment of double excitation helps to increase the electromagnetic force of the system. Furthermore, the installation of windings on both stator and mover can make the structure more compact and increase the system force density. The design concept and operating principle are presented. Following that, the major structure parameters of the system are determined. Subsequently, electromagnetic force and reluctance are formulated analytically based on equivalent magnetic circuits, and the result is validated with numerical computation. Then, a research prototype is developed, and experiments are conducted on the system output performance. It shows that the proposed design of electric linear machine can achieve higher thrust force compared with conventional linear switched reluctance machines. Published version

A novel active soft switched phase-shifted full-bridge (PSFB) dc-dc converter is presented in this paper. An auxiliary circuit is added to the pulse width modulation counterpart to achieve the soft switching. The proposed circuit achieves soft switching for both main and auxiliary switches, without increasing the main device current/voltage rating. The auxiliary circuit is gated appropriately in order to achieve zero voltage switching for lagging leg. Tapping in the primary winding of power transformer is added for the purpose of commutation. The proposed circuit is capable of operating at elevated switching frequencies of several hundreds of kilohertz in a range of line and load variations. Steady-state analysis and evaluation of losses for the proposed circuit is presented. Analytical models valid for steady state and dynamic performance are proposed. A 350-W, 100-kHz active soft switched PSFB dc-dc converter prototype is implemented. The proposed analytical models are validated experimentally on 350-W prototype. Experimental results verifying steady state and dynamic models are presented. � 1986-2012 IEEE.

The development of a computer-controlled current-comparator-based calibration system to determine the current ratio errors of high-voltage conventional and nonconventional current transformers (CTs) under actual operating conditions of high-voltage and distorted current waveforms up to 100 kV and 2000 A is described. The ratio errors of a CT are affected by the applied high voltage due to capacitive currents flowing in its winding. The errors are also affected by the phase angle of the primary currents with respect to the operating high voltage. Therefore, the new calibration system allows the phase angle of the test primary currents to be adjusted at power factors of zero lag through unity to zero lead. The uncertainty k = 2 of the new calibration system is estimated to be not more than 20 × 10-6 for both the in-phase and quadrature components of the measured ratio errors. © 2006 IEEE.

The field regulated reluctance machine is perspective for automotive transport electric drives. In this machine, the switching of a stator current is done in function of a rotor position. The massive salient rotor of the electric machine does not contain windings. The stator is fulfilled in the body and iron of serial ac induction motor. The stator winding sections, which conductors lay above between rotor poles intervals, serve as a excitation winding, and others sections, which conductors lay above rotor poles, the role of a armature winding. In most cases, the optimal winding current waveform is distinct from the sine waveform. For a case of use separate current sources for each phase, the ideal is rectangular waveform. At the rotation of the motor, the each stator section winding pass from a zone of "excitation" to a zone of "armature". The stator has finite number of phases. At switching stator currents, the part of a phase, in which there is a switching of an armature current, is in a zone of excitation, and another - in a zone of an armature. It causes additional losses in the rotor, because the rotor is fabricated massive (not laminated). For calculation of the losses first of all it is necessary to determine the factors, which influence on their value, and then, to estimate a degree of influence of each of them on value of switching losses. As such factors are taken: the form of the stator core, the form of a current in phase windings, and the number of stator winding phases. The calculation of losses is executed by the method of winding functions. The experimental data are received on a breadboard model of the 20 kW drive. Copyright © 2010 SAE International.

Stator end windings of large turbogenerators are subjected to static and harmonic forces due to electromagnetic interaction of the electric currents in them. In this paper the free vibration characteristics of these end winding coils are analyzed by using a transfer matrix approach, with account taken of the flexural and torsional rigidities of the composite coil section. An analytical method in which Prandtl's stress function and Roth's double infinite series are used is developed for determining the effective torsional rigidity of the composite rectangular sections with jump non-homogeneity along the principal directions of the section. The necessary equations for the space curve representing the end winding coils are developed. The natural frequencies of a single coil have been experimentally determined by an impact hammer test. The theoretical and experimental values are in good agreement.

The electric drive with the synchronous electrical machine of independent excitation differs by high specific parameters, adaptability to manufacture, simplicity of a design, and reliability. These properties of the electric drive allow using it in heavy conditions of operation. In particular, it can be recommended to use in electrical vehicles. The electric motor for this electric drive can be executed with two separate stator windings. Therefore, there are additional benefits connected to an opportunity of change of geometry of an iron stator stamp of the given type motor. In this report, the principle of operation of the electric drive with control system is considered. The different variants of a stator design of the electrical machine are discussed. The stator design allows improve of the mass and weight parameters of the electric machine. For the offered stator designs, the comparison of specific parameters (relationship of the nominal torque to load current) is carried out. The received results of analysis are discussed. Copyright © 2009 SAE International.

A method is proposed for recognizing PD events within a winding during impulse tests using a lock-in amplifier technique. The resonant frequencies of the winding serve as the basis of selection of the lock-in amplifier reference frequencies. It is implemented with a virtual instrument and validated with an independent stand-alone lock-in amplifier. A physical model of a winding with discrete elements is used to demonstrate the results. A theoretical basis for the instrument is established using an 'abc' model of PD along with a linear discrete winding model. The influence of location of PD is also addressed. The method will provide online recognition of PD during the impulse test and can be adapted for onsite measurements. � 2007 IEEE.

A correlation method is proposed for the location of partial discharge within a winding. Theoretical simulations and experimental results on a lumped parameter model of a winding are shown to prove the feasibility of the method. � 2006 IEEE.

In the literature on EM launcher research, number of proposals have been made to suppress the negative influence of the velocity skin effect on the performance of solid armatures during electromagnetic launch. In this paper, the results of a study of two of these methods, i.e. the application of multi-fibre solid brush armatures and the use of accelerator rails with a resistive layer, are presented. This study is performed by means of two-dimensional finite element computer simulation of the electrothermal behaviour of the armature and the rails during the launch process. A description of the electrothermal mode used in the simulation is given. Here, the fibre armatures are regarded as made of materials with an anisotropic electrical and thermal conductivity. The results for the current distribution in a rectangular multi-fibre solid brush armature obtained from the simulations agree with the results of an analytical method. It is shown that fibre armatures have a more homogeneous current distribution during the acceleration process than monobloc armatures. U-shaped molybdenum multi-fibre solid brush armatures are good candidates for arc erosion-free launching if the electrical insulation of the fibres can be maintained at increasing temperature. Simulations also show that the skin depth in monobloc and fibre armatures can be increased by using rails with resistive layer with suitable material properties. >