WoS İndeksli Yayınlar Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12573/394
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Conference Object Structural Integrity Analysis of a Two-Pole Synchronous Reluctance Machine With Non-Circular Shaft(IEEE, 2023-06-14) Tekgun, Didem; Tekgun, Burak; Alan, IrfanThis paper investigates the structural strength of a 6-inch diameter, two-pole, 4 kW line start synchronous reluctance machine (LS-SynRM) designed with a new non-circular shaft structure that serves as a pump motor. Flux paths on the rotor are widened while narrowing down the shaft of the motor on the q- axis to improve the motor efficiency. By using this method, a wider path is created for the flux in the d-axis. As a result, the inductance in the d-axis, the ratio of inductance between the d-axis and q-axis (referred to as saliency ratio), and the difference in inductance between the d-axis and q-axis are all amplified. To evaluate the structural strength of the machine, a series of analyses are conducted, including modal, harmonic, and static examination on the rotor using ANSYS Structural. The findings indicate that to prevent redundant deformations and undesirable vibrations because of resonance, the maximum safe limit for shaft size reduction is determined as 8 mm.Article Citation - WoS: 1Citation - Scopus: 1Modified Induction Machine Equivalent Circuit Including Solid Shaft Eddy Currents(MDPI, 2023-12-15) Tekgun, DidemThe shaft eddy currents cause a significant saturation in two-pole induction machines (IMs) as they generate an opposing field and repulse the main flux, thus tightening the flux path. This results in inaccurate performance estimations with the magnetizing inductance measured in no-load conditions when the machine is loaded. This article presents a modified IM equivalent circuit considering the rotor back iron saturation effects caused by the solid shaft eddy currents using experimental measurements and recursive parameter estimation techniques. The classical equivalent circuit (CEC) parameters are determined with the standard test techniques followed by the parameter estimation of the newly introduced modified equivalent circuit (MEC) parameters. The proposed modified equivalent circuit is benchmarked with CEC and finite element analysis (FEA) simulations with and without considering eddy effects. The proposed MEC model and the FEA that consider eddy effects performed better than the other models and yielded a negligibly small error over a wide range of loading conditions. Compared to the FEA, the proposed MEC estimates the IM performance much faster, which makes it more appealing for IM performance estimations.Conference Object Citation - WoS: 5Citation - Scopus: 5Investigation of the Effects of Multi-Layer Winding Structures in Two Pole Synchronous Reluctance Machines(IEEE, 2021-10-05) Tekgun, Didem; Cosdu, Muhammed Muhsin; Tekgun, Burak; Alan, Irfan; Muhsin Cosdu, MuhammedIn this paper, a comparative study is performed between single, various double, and triple-layer winding structures to investigate the effects of the winding MMF harmonics and end winding length on the two-pole synchronous reluctance machines (SynRM). A two-step design approach is used including winding and geometry optimization using multi-objective differential evolution (MODE) algorithm. In the first stage, a Pareto front is obtained which determines the number of turns for each coil group for all winding configurations. Later in the second stage, three results are selected from the first stage to perform a geometric optimization to distinguish the effects of the THD and end winding length on the synchronous performance of a 4 kW two-pole SynRM. For the same average torque output, efficiency, mass, and the torque ripple of the selected designs are investigated and compared. Based on the analysis, it is concluded that rather than focusing on shortening the end winding length, reducing the MMF harmonics have a more positive effect on the machine performance as reduced harmonics resulted in efficiency improvement up to 2 points and torque ripple is reduced up to 8 points while having similar motor mass.Article Citation - WoS: 1Citation - Scopus: 1Investigating the Tradeoff Between the MMF Distortion and End Turn Length of a 2-Pole Line Start SynRM Performance(Springer int Publ Ag, 2023-07-19) Tekgun, Didem; Cosdu, Muhammed M.; Tekgun, Burak; Alan, IrfanConventional 2-pole AC machine windings have long end windings and generate harmonics, which increase losses and reduce torque density. This study investigates the performance tradeoff between the level of distortion (THD) in winding magneto-motive force (MMF) and end turn length on a 2-pole line start Synchronous Reluctance Machine (LS-SynRM) machine. A two-stage approach is used, winding and geometry optimization. Various multilayer winding configurations having unevenly distributed number of turns are investigated. First, the percentage of the turns in a coil group is optimized for minimum harmonics and end turn length for all structures. Second, geometric optimization is performed on selected winding configurations. Sixteen different configurations are optimized, and Pareto optimal solutions are obtained. Later, these solutions are graded with a new score-based assessment method to quantify the quality of the results. It is concluded that the designs having lower THD in winding MMF perform better than the designs with shorter end turns in terms of efficiency and torque density.Article Citation - WoS: 1Citation - Scopus: 3Investigating the Role of Stator Slot Indents in Minimizing Flooded Motor Fluid Damping Loss(MDPI, 2023-12-14) Tekgun, Didem; Tekgun, BurakThis research examines how fluid damping loss affects the operation of a two-pole, 5.5 HP (4 kW) induction machine (IM) within the context of different slot opening configurations developed for downhole water pump applications. Since these motors operate with their cavities filled with fluid, the variations in fluid viscosity and density, compared to air, result in the occurrence of damping losses. Furthermore, this loss can be attributed to the motor's stator and rotor surface geometry, as the liquid within the motor cavity moves unrestrictedly within the motor housing. This study involves the examination of the damping loss in a 24-slot IM under different stator slot indentations. The investigation utilizes computational fluid dynamics (CFD) finite element analysis (FEA) and is subsequently validated through experiments. The aim of this work is to emphasize the significance of fluid damping loss in submerged machines. Results reveal that the damping loss exceeds 8% of the motor output power when the stator surface has indentations, and it diminishes to 3.2% of the output power when a custom wedge structure is employed to eliminate these surface indentations.Article Citation - WoS: 10Citation - Scopus: 10FEA Based Fast Topology Optimization Method for Switched Reluctance Machines(Springer, 2022-01-04) Tekgun, Didem; Tekgun, Burak; Alan, IrfanIn this paper, a finite element analysis (FEA) based fast optimization method to optimize a lightweight in-wheel switched reluctance machine is presented. This method speeds up the switched reluctance machine optimization procedure by running the FEA simulations with single-phase constant current excitations for half electrical cycle and estimating the machine performance metrics using the gathered FEA data. Hence, the machine`s dynamic performance estimation process takes shorter for each design candidate. The optimization algorithm employs designs of experiments (DOE), response surface (RS) analysis method, and differential evolution algorithm (DE). Here, the DOE method is used to reduce the search space by narrowing down the upper and lower boundaries of each design variable based on the RS analysis. Although this process does not guarantee getting the Pareto front, it places the search space close to the actual one. Hence, the multi-objective DE optimization finds the Pareto optimal solution set without requiring a large number of iterations as well as a large number of candidate designs for each iteration. The method is applied to a 24/16 SRM that is intended to be used in a lightweight race car as a hub motor. Six dimensionless geometric variables are optimized to satisfy three objective functions, namely torque ripple, motor mass, and copper loss. While the conventional DE takes at least 3000 candidate designs, the proposed method considers only 559 designs to reach a similar Pareto front. It is observed that the proposed method takes about 6 h 30 min compared to the conventional method that takes 32 h 50 min using the same computer. Therefore, the computation time is reduced almost five times with the proposed method.Conference Object Citation - Scopus: 2Effect of the Stator Slot Indents on Fluid Damping Loss in Submersible Pump Applications(IEEE, 2022-06-14) Tekgun, Didem; Cosdu, Muhammed Muhsin; Tekgun, Burak; Alan, IrfanIn this study, the effect of fluid damping on the performance of a 2-pole, 4-kW line start synchronous reluctance machine (LS-SynRM) with different slot opening structures for submersible water pump applications is investigated. Since the submersible pump motors run inside a fluid-filled environment and the fluid viscosity and density differ from the air, it causes an increased damping effect comparing air-filled machines. Hence, a non-negligible damping loss occurs. In this study, the damping effects of the fluids in a 24 slot LS-SynRM for various stator slot indentations are investigated with computational fluid dynamics (CFD) finite element analysis (FEA) to highlight the importance of the fluid damping loss in flooded machines. Results show that the damping loss can go as high as 10% of the motor output power when the stator surface has indentations, and this loss can be cut down to 3.5 % when the surface indentations are eliminated with custom no-slotting wedge structures.Conference Object Citation - WoS: 1Citation - Scopus: 1Design and Optimization of an Outer Rotor Spoke Type PMSM With Improved Saliency for a Lightweight Racing Vehicle(IEEE, 2024-11-12) Karatepe, Hasan Can; Tekgun, Burak; Tekun, Diclem; Tekgun, DidemThis paper presents the design and optimization of an outer rotor spoke-type permanent magnet synchronous motor, aimed at achieving high torque density. The improvement is accomplished by enhancing the saliency through a center shift of the rotor arc, while simultaneously minimizing cogging torque and torque ripple. The proposed design is optimized for an electro-mobile that will participate in TEKNOFEST's "Efficiency Challenge". A vehicle dynamics simulation with the parameters of the designed vehicle was done under the "New European Driving Cycle" (NEDC) to determine the required torque and speed values using MATLAB's "Virtual Vehicle Composer" application. The multi-objective differential evolution (MODE) algorithm was chosen for optimization and further altered for maximum torque per ampere (MTPA) angle sweep, since each optimization individual would have a different MTPA angle. The optimization was conducted with 40 generations and 522 individual designs. An optimal solution from the Pareto-Front was selected and its performance was investigated using the 2D finite element analysis (FEA).Conference Object Citation - WoS: 5Citation - Scopus: 5Design and Control of a Single Phase DC/Rectified AC/AC Inverter for Low THD Applications(Institute of Electrical and Electronics Engineers Inc., 2018-10) Tekgun, Burak; Tekgun, Didem; Alan, İrfan; Badawy, Mohamed O.In this paper, a single phase DC/Rectified AC/AC (DC/RAC/AC) inverter is analyzed and compared to classical single phase PWM inverters. A traditional AC power supply (PS) system consists of a DC/DC converter, a cascaded H-bridge inverter, and a passive filter to generate the sinusoidal output voltage. The presented DC/RAC/AC inverter has a similar structure; however, the control of the cascaded units differ. The presented method generates rectified sine wave at the output of the DC/DC converter unit and the H-bridge inverter alternates the rectified sine wave to generate the full sine wave without having an additional output filter; hence, the switching losses at the H-bridge inverter is limited to the line frequency (50-60 Hz). Moreover, the bulk DC bus capacity at the output of the DC/DC converter is reduced significantly. Therefore, the power consumed by the passive elements are minimized. The circuit modes of operation are analyzed and the system is simulated in Matlab/Simulink environment for both traditional and proposed topologies. Results show that the proposed system is superior to the traditional one in terms of efficiency, generated THD with a simplified control structure, and it offers a reduced system size and cost. © 2019 Elsevier B.V., All rights reserved.Conference Object Citation - WoS: 3Citation - Scopus: 3A Modular Three-Phase Buck-Boost Motor Drive Topology(IEEE, 2020-10-05) Tekgun, Didem; Tekgun, Burak; Alan, IrfanThe voltage-source inverter (VSI) is a fundamental power electronic device to drive three-phase electrical machines with high performance. In this paper, a modular three-phase DC/Rectified AC/AC (DC/RAC/AC) inverter supplying a permanent-magnet synchronous machine (PMSM) is proposed. In this topology, the three-phase VSI is composed of three single-phase modules connected in parallel. Each single-phase inverter module consists of a non-inverting bidirectional buck-boost DC/DC converter and a cascaded H-bridge inverter. Here, the DC/DC converter generates rectified AC waveforms and the H-bridge inverter alternates these signals to create the intended AC voltage waveform. Therefore, the bulk DC Bus capacitor and boost converter inductor, which exist in a typical battery-powered voltage boosting topology can be eliminated which results in a smaller size and reduced cost. In addition, the switching losses only occur in the DC/DC converter unit and the H-bridge inverter switching losses are negligible due to the zero-voltage switching while in a conventional structure, high-frequency switching occurs both in the DC/DC converter and the six-switch inverter causing reduced overall system efficiency. The proposed inverter is controlled with a well-known field-oriented control (FOC). This paper presents the operating principle, design, and control structure of the proposed three-phase inverter. The functionality of the three-phase inverter is verified through PowerSim simulations. The proposed motor drive system is compared to the conventional one while driving a 4 kW PMSM with FOC and the whole system efficiency difference map is generated. The biggest difference is recorded as 3.8 points favoring the proposed system.