Browsing by Author "Mese, E"

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    Computationally efficient predictive torque control strategies without weighting factors
    Zerdali, E; Altintas, M; Bakbak, A; Mese, E
    Predictive torque control (PTC) is a promising control method for electric machines due to its simplicity, fast dynamics, ability to handle nonlinearities, and easy inclusion of additional control objectives. The main challenge in conventional PTC design is to determine the weighting factors in the cost function. These weighting factors are generally chosen by the trial-and-error method or metaheuristic optimization algorithms, but these methods may not apply the optimum voltage vectors according to changing operating conditions. There are also several studies on the elimination of the weighting factors. This paper proposes two weighting factorless PTC strategies with lower computational complexities than the current literature. To demonstrate the superiority of the proposed methods, their performances are experimentally compared to those of the existing methods through a test bed equipped with an induction motor. Finally, two PTC strategies with a simple design and improved performance are introduced to the literature.
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    Maximizing Energy Extraction from Direct Grid Coupled PMSG For Wind Energy Conversion Systems
    Bakbak, A; Canseven, HT; Ayaz, M; Altintas, M; Mese, E
    Direct grid coupling of permanent magnet synchronous generators (PMSG) for wind energy conversion systems provides certain advantages with the penalties of maximum power point tracking (MPPT) and reactive power control. This article proposes a novel PMSG design philosophy such that optimizing PMSG design at the initial stage would compensate for the drawbacks arising from the lack of an MPPT algorithm. Also, the ability to maintain a high PF across a wide range of operating power levels is investigated by considering reactive power in the design process. In this article, optimization of slot/pole combination is described for direct grid coupled PMSGs to extract as much energy as possible according to wind data. A new benchmark, adequacy factor, is presented to determine the slot/pole combination. Variation of the reactive power is theoretically analyzed. A relationship is established between induced electromotive force, synchronous inductance values of machines, and the PF. Fixed and variable speed operations of PMSGs are compared in terms of annual energy yield. Finally, theoretical analyses are validated through laboratory testing of prototype generators.
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    Maintaining Synchronous Operation of a Damperless Dual-Port Tooth-Coil-Winding PMSG
    Canseven, HT; Altntas, M; Bakbak, A; Ayaz, M; Mese, E; Pyrhonen, J
    The stability of a wind turbine-rotated synchronous generator must be maintained during a sudden change in wind speed or direction. In integral slot winding machines this task is taken care of by rotor damper windings. Tooth-coil permanent magnet generators cannot, however, have a damper winding in the rotor because of the high harmonic content of the air gap. In this paper, we study a possibility to stabilize PMSG damperless synchronous operation by dividing the generator stator winding into two parts - power winding (PW) and control winding (CW). We call this machine a dual-port PMSG (DPPMSG). The PW is directly connected to the grid. Therefore, the generator rotates, in average, at a fixed speed. On the other hand, the CW is connected to the grid through a four-quadrant power converter. The CW has three different tasks: It is responsible for the startup process, damping of speed oscillations and, of course, power generation. Electrical and magnetic decoupling of the winding sets is ensured by concentrated wound coils. The number of stator coils allocated to a winding set determines its power level. Different power levels of winding sets are analytically analyzed for wind gust speeds according to the IEC 61 400 standard. The results are verified by experimental tests.
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    Comparison study on SMC and grain-oriented laminated steel core for small-size axial flux permanent-magnet synchronous machines
    Karabulut, Y; Mese, E; Ayaz, M; Aktas, S
    This study aims to compare the soft magnetic composite (SMC) and grain-oriented (GO) steel stator axial flux permanent-magnet synchronous machine (AFPMSM) in terms of performance and iron losses. Stator cores are manufactured using both materials to perform experimental performance tests. The produced machines are designed for pump propulsion systems in left ventricular assist devices as an application area. The machines are modeled with several analytical equations, and iron losses and performance tests are carried out with AFPMSMs, finite element methods, and experimental setups. Our findings show that the torque density is higher in the GO steel stator AFPMSMs that can produce 15.07 percent more torque. GO steel material experimentally has 20.33 percent less iron loss as SMC material since the loss value per kilogram for SMC material is higher than that for GO steel. In addition, the saturation value of the SMC material is lower than that of the GO material according to the magnetic flux density value.