Mehmet Onur Gulbahce

Prismatic radial slots machined into the aluminum rotor disk of an eddy current brake (ECB) increase the convective cooling area, but their effect on steady-state temperature has not been quantified systematically. This paper presents a two-dimensional polar finite difference thermal model, coupled with a one-dimensional pin-fin shaft model through an iterative energy balance loop, to evaluate 12 slotted disks for an axial-flux ECB with double-sided excitation, eight poles, and a rated speed of 3000 min⁻¹. Four slot counts (N = 12, 24, 36, 48) and three bridge subdivisions (single, double, triple) are compared with a solid disk under the same 400 W Joule heat load, which the excitation current holds constant for every disk; the effect of the slots on the loss distribution is not modeled. The model predicts a solid disk peak temperature of 165.5 °C, which the best slotted configuration (48 slots, triple subdivision) reduces to 130.8 °C, a 34.7 °C (21.0%) reduction. Slot count is the dominant design variable: increasing N from 12 to 48 lowers the peak temperature by 21.9 °C (14.2%), while bridge subdivisions contribute only 0.6–1.4 °C. At N = 48, slot-wall convection carries 37.0% of the heat. These are numerical predictions; the ranking survives variations in the face convection, slot width and heat load, and of the slot-wall convection down to one third of its estimate.

Flux-switching permanent-magnet (FSPM) generators are gaining prominence in renewable energy applications due to their robust rotor structure and high-power density. However, thermal management remains a critical challenge, as excessive heat can degrade insulation and permanent magnet (PM) properties. This study presents a comprehensive thermal analysis of a 12-slot/10-pole FSPM generator using 3D Computational Fluid Dynamics (CFD) via ANSYS Icepak. Electromagnetic losses, including copper, core, and eddy-current losses, were integrated into the finite-volume formulation to solve for conduction, convection, and radiation effects. Simulation results identify the primary hotspots in the central axial region of the armature windings, reaching a peak steady-state temperature of 78 °C. The rotor and PMs exhibit strong thermal coupling, stabilizing within a range of 69 °C to 78 °C. Transient analysis confirms that all components reach thermal stability after approximately 90 minutes. The findings demonstrate that peak temperatures remain well below the critical limits for NdFeB magnets and Class F insulation, validating the thermal reliability of the proposed design for long-term operation.

This paper presents a sustainability-oriented multi-objective design and optimization framework for a 4 kW LLC resonant converter intended for on-board charger applications. The proposed approach combines conventional electrical and thermal design procedures with life-cycle-based environmental modeling to achieve an optimal balance between efficiency, cost, volume, and carbon footprint. The methodology determines resonant parameters (L_r, L_m, and C_r) across a frequency range of 100–250 kHz and evaluates each configuration analytically, including magnetic component design, semiconductor loss estimation, and heatsink sizing. Environmental impacts are incorporated through cradle-to-gate and use-phase Global Warming Potential (GWP_man and GWP_usv) metrics for semiconductor, magnetic, and passive components. The optimization results reveal that SiC-based MOSFETs provide higher efficiency and lower operational emissions but at the expense of increased manufacturing footprint and cost, whereas Si-based diodes offer a more balanced trade-off between environmental and economic performance. A 4 kW prototype designed using the GWP_use-weighted optimal parameters achieved a peak efficiency of 98.1% within an input range of 325–375 V and an output range of 250–450 V, experimentally validating the proposed framework. Overall, the study demonstrates that integrating sustainability metrics into LLC converter design enables the development of high-performance, environmentally responsible, and cost-effective power conversion systems.

This study presents a comprehensive design and optimization framework that addresses both electromagnetic and thermal aspects of an interior permanent magnet synchronous motor (IPMSM) intended for use in midsize commercial EVs. A 60-slot/10-pole IPMSM with a V-shaped rotor, capable of delivering 125 kW peak power at 4500 rpm from a 400 VDC bus, has been developed using a systematic approach. The design process begins with analytical estimations to determine initial motor geometry and performance parameters, followed by a finite element-based validation. To enhance performance, a multiobjective optimization is conducted using the nondominated sorting genetic algorithm II (NSGA-II). The optimization targets three key objectives: maximizing average electromagnetic torque, maximizing torque-to-magnet volume ratio, and minimizing torque ripple. Sensitivity analysis is employed to identify the most influential design variables, enabling a more efficient and focused optimization process by narrowing the design space accordingly. Postoptimization, thermal validation is performed using a detailed lumped-parameter thermal model. A liquid-cooling system featuring an axial water jacket is implemented to ensure effective heat removal from the stator. The thermal analysis confirms that the optimized motor maintains safe operating temperatures, thereby validating the design’s robustness under high power density operation. The proposed methodology demonstrates a holistic design approach that integrates electromagnetic optimization with thermal feasibility, resulting in a high-performance IPMSM suitable for demanding EV traction applications.

Hyperloop technology, introduced in 2013, is a revolutionary transportation concept designed to achieve near-supersonic speeds of approximately 1220 km/h for long-distance travel. The key factor enabling the Hyperloop capsule to reach such high speeds is that the system is exposed to minimal friction. This study focuses on the design of an electrodynamic suspension disc for the levitation system of a Hyperloop capsule to be used in the Hyperloop Development Competition hosted by The Scientific and Technological Research Council of Türkiye (TUBITAK) Rail Transportation Technologies Institute (RUTE). The levitation system utilizes a high-speed rotating permanent magnet to generate magnetic forces that lift and stabilize the capsule above the rail. Following the completion of the analytical design, the system was simulated using the finite element method in ANSYS Electronics Desktop, and necessary geometric and electrical optimizations were performed based on the simulation results. Finally, the system was implemented, and the experimental results were analyzed to validate the design.

Flux-switching generators (FSGs) are widely used in wind turbine applications, particularly within microgrids, due to their unique structural and operational advantages. However, the salient pole structures of their stator and rotor teeth result in high torque ripple, elevated harmonic content, and increased magnetic flux density in the stator and rotor teeth. These issues necessitate optimization of the machine’s design parameters. This study investigates the effects of rotor pole skew (delta) and coil-pole pitch ratio (embrace) on the performance of a 260 W FSG operating at 1200 rpm and 200 Hz. A multi-slice skewing method was applied to the rotor to analyze its impact on average torque, torque ripple, and efficiency. The results reveal that variations in pole skew and coil-pole pitch ratio significantly affect torque, flux linkage, and induced voltage while also reducing magnetic stresses. Despite these improvements, the prominence of the second harmonic limits the effectiveness of the skewing angle on generator output parameters. Additionally, the influence of the number of rotor slices on output performance and manufacturing complexity was examined.Cite this article as: T. Ozmen, T. Isıkelekoglu, S. Tunahan Durmaz, B. Eren Ergun, and N. Onat, "Comprehensive analysis of rotor geometric parameters and skewing methods in flux-switching generators," Turk J Electr Power Energy Syst., Published online April 21, 2025. doi 10.5152/tepes.2025.25003.

This paper presents a systematic approach to selecting lithium iron phosphate (LFP) battery cells for electric vehicle (EV) applications, considering cost, volume, aging characteristics, and overall performance. A battery selection algorithm is developed to evaluate four different LFP battery cell models based on their long-term behavior in a 40 kWh battery pack. The algorithm integrates a vehicle energy consumption model, where battery performance is analyzed based on the Worldwide Harmonised Light Vehicles Test Procedure (WLTP) over a 10-year simulated period, considering five driving cycles per day. In order to ensure a fair assessment, the model accounts for variations in battery pack weight as the sole influencing factor on vehicle dynamics. The results compare vehicle range, battery pack mass, cost, cell degradation, and volume for each battery option. The findings indicate that the A123 Systems ANR 26650m1 battery cell offers the best trade-off between longevity and cost-effectiveness, making it a highly suitable choice for durable and efficient EV battery packs. This study underscores the importance of the most suitable battery selection in designing cost-effective, long-lasting EV energy storage solutions.