Browsing by Author "Tekgun, Burak"

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Core Loss Estimation in Electric Machines With Flux-Controlled Core Loss Tester
(IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 445 HOES LANE, PISCATAWAY, NJ 08855-4141 USA, 2019) Tekgun, Burak; Sozer, Yilmaz; Tsukerman, Igor; Upadhyay, Parag; Englebretson, Steven; 0000-0003-2720-8816; 0000-0003-3971-3967; AGÜ, Mühendislik Fakültesi, Elektrik - Elektronik Mühendisliği Bölümü
The complexity of core loss estimation is a serious challenge in the design of high-efficiency electric machines. Current estimation methods based on the Steinmetz equation and loss separation are not accurate enough, even at the rated conditions. This paper describes a loss estimation technique combining finite-element analysis (FEA) and actual core loss measurements. First, flux density waveforms in various parts of the electric machine are determined using FEA. Second, the same waveforms are generated in a wound toroidal core made of the same material as used in the machine. The loss is measured per unit mass, and then the total motor core loss is calculated by integrating the measured W/kg loss values for predefined sections of the motor. These estimation results are compared with those of the Bertotti method. The proposed procedure is shown to improve the accuracy of loss estimation.
Dalgıç Pompa Uygulamaları İçin Doğrudan Yol Vermeli Senkron Relüktans Motorunun Tasarım Optimizasyonu Ve Gerçeklemesi
(ELEKTRİK, ELEKTRONİK VE ENFORMATİK ARAŞTIRMA DESTEK GRUBU GRUBU: EEEAG, 2023) Tekgun, Burak; Alan, Irfan; Tekgun, Didem; 0000-0003-2720-8816; 0000-0001-7995-0540; AGÜ, Mühendislik Fakültesi, Elektrik - Elektronik Mühendisliği Bölümü; Tekgun, Burak; Alan, Irfan
Günümüzde doğal kaynakların korunması ve enerji maliyetlerinin düşürülmesi için enerji kayıplarının azaltılması ortak bir amaç olarak görülmektedir. Elektrik tahrik sistemlerinin küresel enerji tüketiminin yaklaşık %40?ını oluşturduğu düşünüldüğünde elektrik makinalarının verimlerinin artırılması ile sağlanacak avantajların hem ülke bazında hem de evrensel olarak büyük bir öneme sahip olduğu görülmektedir. Uygulama odaklı olarak bakıldığında yer altından su, petrol vb. çıkarmakta kullanılan pompa motorlarının endüstride kullanılmakta olan motorlar arasında oldukça büyük bir paya sahip olduğu görülmektedir. Özellikle dalgıç pompa uygulamalarında kullanılmakta olan pompa motorları gerek motor tasarım hatalarından, gerekse de yanlış motor-pompa konfigürasyonları seçiminden kaynaklanan hatalar nedeniyle çok düşük verimlerle çalışmaktadır. Sağlamlık, ucuzluk ve doğrudan yol verme gibi özelliklerinden dolayı pompa uygulamalarında genellikle indüksiyon motorları (İM) tercih edilmektedir. Fakat İM?lerin en büyük sorunu özellikle küçük ve orta güçte düşük enerji verimi ile çalışmalarıdır. Doğrudan yol vermeli sürekli mıknatıslı motorlar (DY-SMSM) yüksek güç yoğunluğuna sahip olmaları sebebiyle verimi yükseltmek adına İM?lere uygun bir alternatiftir. Fakat bu makinalarda doğrudan yol verme esnasında mıknatısların demagnetizasyonu ve en önemlisi doğada nadir bulunan mıknatısların kullanımından kaynaklı yüksek maliyet ve dışa bağımlılık sorunları araştırmacıları bu makinalara yeni bir alternatif arayışı içine itmektedir. Bu doğrultuda hem doğrudan yol verme özelliği hem de mıknatıs içermeyen yapısı ile doğrudan yol vermeli senkron relüktans motorlar (DY-SenRM) İM?lere uygun bir alternatif olarak karşımıza çıkmaktadır. En basit tanımla bu tip motorlar çalışma prensibi bakımından relüktans motor ve İM?nin bir kombinasyonudur. DY-SenRM?de makinanın rotoruna uygun şekilde gömülen rotor barları ile doğrudan yol verme özelliği kazandırılırken, İM?lerin aksine rotor bakır kayıpları sürekli rejimde sıfıra indirilmektedir. Dahası SenRM?ler İM?lere kıyasla daha yüksek güç ve moment yoğunluğuna sahiptir. SenRM?lerin dezavantajlarına bakıldığında düşük güç faktörü ile çalışma ve rotordaki açıklıklardan kaynaklı yapısal entegrasyon problemleri göze çarpmaktadır. Bu problemler tasarım aşamasında iyi incelenip gerekli önlemler alınmalıdır. Gerekli olduğu durumlarda nadir element bulundurmayan mıknatısların kullanımı güç faktörü sorununu ortadan kaldırdığı gibi verimi de artırmaktadır. Bu projede dalgıç pompaları için 4 kW gücünde DY-SenRM tasarımı üzerine çalışılacaktır. Özellikle sulama amaçlı üretilen yer altı pompa sistemlerinde en çok tercih edilen 6 inç çapındaki dalgıç pompalarına uygun, yüksek verimli 4 kW gücünde bir DY-SenRM?nin tasarım optimizasyonunun yapılması ve gerçeklemesi amaçlanmaktadır. Optimizasyon algoritması olarak çoklu amaç diferansiyel evrim algoritması, benzerlerine göre öne çıkan hızlı yakınsama ve doğru sonuçlara ulaşma özellikleri göz önüne alınarak seçilmiştir. Tasarlanacak DY-SenRM?nin geçici rejim performansı, senkronize olabilme yeteneği, senkron çalışma performansı ve boyutu optimizasyonda göz önüne alınacak metriklerdir. Bu çalışmanın başarıyla sonuçlanması ile DY-SenRM?nin sadece pompa uygulamaları değil, diğer sabit hız uygulamalarında da düşük verimli İM?lerin yerini alması; dolayısıyla düşük maliyetli, yüksek verimli motor teknolojisinin yaygın hale gelmesi ön görülmektedir.
Design and Optimization of an Outer Rotor Spoke Type PMSM with Improved Saliency for a Lightweight Racing Vehicle
(IEEE Xplore, 2024) Karatepe, Hasan Can; Tekgun, Burak; Tekgun, Didem; 0009-0009-8221-3141; 0000-0003-2720-8816; 0000-0003-4143-0720; AGÜ, Mühendislik Fakültesi, Elektrik - Elektronik Mühendisliği Bölümü; Karatepe, Hasan Can; Tekgun, Burak; Tekgun, Didem
This 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).
Design and real-time implementation of a sliding mode observer utilizing voltage signal injection and PLL for sensorless control of IPMSMs
(ELSEVIER, 2024) Ates, Ertugrul; Tekgun, Burak; Ablay, Gunyaz; Barut, Murat; 0000-0001-6628-5350; 0000-0003-2720-8816; 0000-0003-2862-6761; AGÜ, Mühendislik Fakültesi, Elektrik - Elektronik Mühendisliği Bölümü; Ates, Ertugrul; Tekgun, Burak; Ablay, Gunyaz
In this study, a sliding mode observer (SMO) based on high-frequency (HF) voltage signal injection and a phase-locked loop (PLL) is proposed for estimating the extended electromotive force (EEMF), rotor position, and rotor velocity of an interior permanent magnet synchronous machine (IPMSM). This approach addresses real-time estimation challenges associated with standard SMO and PLL at very low speeds and standstill. A reliable and accurate sensorless speed control system for IPMSM is then developed and implemented in real time using the proposed SMO and PLL, covering a wide range of speeds, including low-speed and standstill conditions. The SMO effectively estimates the EEMF, while the PLL extracts the rotor velocity and position based on these estimates. Compared to conventional SMO and PLL methods, real-time results from an 8-pole, 0.4 kW IPMSM demonstrate the superior efficiency of the proposed system.
Effect of the Stator Slot Indents on Fluid Damping Loss in Submersible Pump Applications
(IEEE, 2022) Tekgun, Didem; Cosdu, Muhammed Muhsin; Tekgun, Burak; Alan, Irfan; 0000-0003-2720-8816; 0000-0001-7995-0540; AGÜ, Mühendislik Fakültesi, Elektrik - Elektronik Mühendisliği Bölümü; Tekgun, Didem; Cosdu, Muhammed Muhsin; Tekgun, Burak; Alan, Irfan
In 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.
FEA based fast topology optimization method for switched reluctance machines
(SPRINGER, 2022) Tekgun, Didem; Tekgun, Burak; Alan, Irfan; 0000-0003-2720-8816; 0000-0001-7995-0540; AGÜ, Mühendislik Fakültesi, Elektrik - Elektronik Mühendisliği Bölümü; Tekgun, Didem; Tekgun, Burak; Alan, Irfan
In 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.
Four Switch Buck-Boost Quasi Single-Stage Inverter with Smooth Mode Transition Using Three-Mod Modulation Technique
(IEEE, 2024) Keskinkılıç, Ebubekir; Tekgun, Burak; 0000-0002-4913-6684; 0000-0003-2720-8816; AGÜ, Mühendislik Fakültesi, Elektrik - Elektronik Mühendisliği Bölümü; Keskinkılıç, Ebubekir; Tekgun, Burak
Quasi-single-stage inverters (QSSI) attract attention due to their simple structure and bidirectional operation capability. However, in the buck-boost DC-DC conversion stage, smooth transition, and efficient conversion cannot be achieved when the output voltage is close to the input voltage with the traditional two-mode control method. This is due to the pulse width ratio limitations, and non-idealities of the active and passive components. In this paper, a comparative analysis of the mode transition techniques in QSSIs is presented using methods available for DC/DC converters. The system efficiency and output voltage signal quality are selected as the performance metrics as they are important performance parameters in many applications. A 2kW QSSI is controlled using single-mode, two-mode, and three-mode modulation techniques. Simulation and experimental studies are conducted for validation. Based on these studies, it is concluded that the single-mode modulation technique performed the best in eliminating dead zone effects and reducing total harmonic distortion (THD), whereas the two-mode modulation technique achieved the highest system efficiency. The three-mode modulation has superior performance on dead zone elimination compared to the two-mode modulation and better system efficiency than the single-mode modulation method. Experimental results indicate that the three-mode modulation achieved an efficiency of 91.12% with a THD of 3.73%.
Instantaneous torque error compensation based online torque sharing function for Switched reluctance Machines
(ELSEVIER, 2023) Genc, Ufuk; Tekgun, Burak; 0000-0003-2720-8816; AGÜ, Mühendislik Fakültesi, Elektrik - Elektronik Mühendisliği Bölümü; Genc, Ufuk; Tekgun, Burak
An online torque sharing function (TSF) with instantaneous torque error compensation method for switched reluctance machines is proposed to maintain a minimized ripple operation. The proposed method adjusts the shared torque between the phases based on instantaneous torque error different than the existing TSF methods formulated with a mathematical expression. The objective of this approach is to benefit from the outgoing phase torque as it has slow current dynamics due to the high inductance. Also, the incoming phase is turned on as soon as it can generate positive torque. During this process, the total torque is estimated instantaneously using lookup tables, and a correction current is calculated and injected into the incoming phase reference current as the inductance is low and current dynamics are fast. This way, the torque ripple is reduced for a wide speed range. Compared to the conventional linear, sinusoidal, exponential, and cubic TSFs, better torque ripple performance is obtained.& COPY; 2023 THE AUTHORS. Published by Elsevier BV on behalf of Faculty of Engineering, Alexandria University. This is an open access article under the CC BY license
Instantaneous torque error compensation based online torque sharing function for Switched reluctance Machines
(ELSEVIER, 2023) Genc, Ufuk; Tekgun, Burak; 0000-0003-2720-8816; AGÜ, Mühendislik Fakültesi, Elektrik - Elektronik Mühendisliği Bölümü; Genc, Ufuk; Tekgun, Burak
An online torque sharing function (TSF) with instantaneous torque error compensation method for switched reluctance machines is proposed to maintain a minimized ripple operation. The proposed method adjusts the shared torque between the phases based on instantaneous torque error different than the existing TSF methods formulated with a mathematical expression. The objective of this approach is to benefit from the outgoing phase torque as it has slow current dynamics due to the high inductance. Also, the incoming phase is turned on as soon as it can generate positive torque. During this process, the total torque is estimated instantaneously using lookup tables, and a correction current is calculated and injected into the incoming phase reference current as the inductance is low and current dynamics are fast. This way, the torque ripple is reduced for a wide speed range. Compared to the conventional linear, sinusoidal, exponential, and cubic TSFs, better torque ripple performance is obtained
Investigating the Role of Stator Slot Indents in Minimizing Flooded Motor Fluid Damping Loss
(MDPI, 2023) Tekgun, Didem; Tekgun, Burak; 0000-0003-4143-0720; 0000-0003-2720-8816; AGÜ, Mühendislik Fakültesi, Elektrik - Elektronik Mühendisliği Bölümü; Tekgun, Didem; Tekgun, Burak
This 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.
Investigating the Tradeoff Between the MMF Distortion and End Turn Length of a 2-Pole Line Start SynRM Performance
(Institute for Ionics, 2023) Tekgun, Didem; Cosdu, Muhammed Muhsin; Tekgun, Burak; Alan, Irfan; 0000-0003-2720-8816; 0000-0001-7995-0540; AGÜ, Mühendislik Fakültesi, Elektrik - Elektronik Mühendisliği Bölümü; Tekgun, Didem; Cosdu, Muhammed Muhsin; Tekgun, Burak; Alan, Irfan
Conventional 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.
A multi-functional quasi-single stage bi-directional charger topology for electric vehicles
(ELSEVIER, 2024) Tekgun, Burak; Tekgun, Didem; Alan, Irfan; 0000-0003-2720-8816; 0000-0001-7995-0540; AGÜ, Mühendislik Fakültesi, Elektrik - Elektronik Mühendisliği Bölümü; Tekgun, Burak; Tekgun, Didem; Alan, Irfan
In this paper, a multi-functional quasi-single stage, bi-directional electric vehicle charger topology is proposed to realize high efficiency power conversion in all AC/DC, DC/DC, and DC/AC forms. The proposed circuitry includes a noninverting buck boost converter (NBB) and an H-bridge inverter. The NBB converter generates the desired output voltage waveform in the rectified form then the inverter unfolds the waveform to the AC waveform. The advantages of this circuit are the reduced losses due to the high frequency switching only occurring at the NBB converter and passive element sizes are smaller leading to reduced losses and cost. The proposed charger is designed for 2 kVA rating and simulated for all vehicle, grid, and another vehicle interaction modes. Then the circuit is experimentally tested and is validated that the proposed circuit can operate in all three modes at a wide range of loading and power factor conditions with over 92% efficiency.
Real-time energy management in an off-grid smart home: Flexible demand side control with electric vehicle and green hydrogen production
(PERGAMON-ELSEVIER SCIENCE LTD, 2023) Boynuegri, Ali Rifat; Tekgun, Burak; 0000-0003-2720-8816; AGÜ, Mühendislik Fakültesi, Elektrik - Elektronik Mühendisliği Bölümü; Tekgun, Burak
A real-time energy management system for an off-grid smart home is presented in this paper. The primary energy sources for the system are wind turbine and photovoltaics, with a fuel cell serving as a supporting energy source. Surplus power is used to generate hydrogen through an electrolyzer. Data on renewable energy and load demand is gathered from a real smart home located in the Yildiz Technical University Smart Home Laboratory. The aim of the study is to reduce hydrogen consumption and effectively utilize surplus renewable energy by managing controllable loads with fuzzy logic controller, all while maintaining the user's comfort level. Load shifting and tuning are used to increase the demand supplied by renewable energy sources by 10.8% and 13.65% from wind turbines and photovoltaics, respectively. As a result, annual hydrogen consumption is reduced by 7.03%, and the average annual efficiency of the fuel cell increases by 4.6%
Structural Integrity Analysis of a Two-Pole Synchronous Reluctance Machine with Non-circular Shaft
(Institute of Electrical and Electronics Engineers Inc., 2023) Tekgun, Didem; Tekgun, Burak; Alan, Irfan; 0000-0003-2720-8816; 0000-0001-7995-0540; AGÜ, Mühendislik Fakültesi, Elektrik - Elektronik Mühendisliği Bölümü; Tekgun, Didem; Tekgun, Burak; Alan, Irfan
This 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 noncircular 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