Hakan Polat

Mr. Hakan Polat

orcid

Research Focus & Metrics

Academic Career Length

34Years (1993-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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8 February 2023 in Batteries
Verified
Journal Article
Open access
PDF file
HPHakan Polat
Hakan Polat
FHFarzad Hosseinabadi
Farzad Hosseinabadi
MHMd. Mahamudul Hasan
Md. Mahamudul Hasan
Sajib ChakrabortySajib Chakraborty
Sajib Chakraborty
Thomas GeuryThomas Geury
Thomas Geury
Omar HegazyOmar Hegazy
Omar Hegazy
The global promotion of electric vehicles (EVs) through various incentives has led to a significant increase in their sales. However, the prolonged charging duration remains a significant hindrance to the widespread adoption of these vehicles and the broader electrification of transportation. While DC-fast chargers have the potential to significantly reduce charging time, they also result in high power demands on the grid, which can lead to power quality issues and congestion. One solution to this problem is the integration of a battery energy storage system (BESS) to decrease peak power demand on the grid. This paper presents a review of the state-of-the-art use of DC-fast chargers coupled with a BESS. The focus of the paper is on industrial charger architectures and topologies. Additionally, this paper presents various reliability-oriented design methods, prognostic health monitoring techniques, and low-level/system-level control methods. Special emphasis is placed on strategies that can increase the lifetime of these systems. Finally, the paper concludes by discussing various cooling methods for power electronics and stationary/EV batteries.

23 March 2023 in Energies
Verified
Journal Article
Open access
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TTTRAN MANH TUAN
TRAN MANH TUAN
STsarath THEKKAN
sarath THEKKAN
HPHakan Polat
Hakan Polat
DTDuong Tran
Duong Tran
MBMohamed El Baghdadi
Mohamed El Baghdadi
Omar HegazyOmar Hegazy
Omar Hegazy
Along with the technology boom regarding electric vehicles such as lithium-ion batteries, electric motors, and plug-in charging systems, inductive power transfer (IPT) systems have gained more attention from academia and industry in recent years. This article presents a review of the state-of-the-art development of IPT systems, with a focus on low-voltage and high-current electric mobility applications. The fundamental theory, compensation topologies, magnetic coupling structures, power electronic architectures, and control methods are discussed and further considered in terms of several aspects, including efficiency, coil misalignments, and output regulation capability. A 3D finite element software (Ansys Maxwell) is used to validate the magnetic coupler performance. In addition, a 2.5 kW 400/48 V IPT system is proposed to address the challenges of low-voltage and high-current wireless charging systems. In this design, an asymmetrical double-sided LCC compensation topology and a passive current balancing method are proposed to provide excellent current sharing capability in the dual-receiver structures under both resonant component mismatch and misalignment conditions. Finally, the performance of the proposed method is verified by MATLAB/PSIM simulation results.

14 June 2022 in IEEE Journal of Emerging and Selected Topics in Industrial Electronics
Verified
Journal Article
Closed access
EAEnes Ayaz
Enes Ayaz
OAOgun Altun
Ogun Altun
HPHakan Polat
Hakan Polat
FKFurkan Karakaya
Furkan Karakaya
Ozan KeysanOzan Keysan
Ozan Keysan
This article presents a novel system to utilize conventional motor drives for wireless power transfer (WPT) to supply auxiliary systems, such as Internet-of-Things devices or sensors in rotating systems. The conventional method is to use a slip ring, which reduces reliability, or to use an extra high-frequency converter next to the motor drive, which increases the system cost. The development of wide-bandgap devices such as gallium nitride and silicon carbide transistors has increased the switching frequencies of motor drives with lower switching losses. The voltage harmonics of these high switching frequencies can be utilized to excite a WPT system while the low-frequency modulated current can still be used to drive the motor. In this article, the relation between the motor drive and the WPT system is investigated under different operating conditions, and the proposed method is experimentally verified with a GaN-based full-bridge converter, a series–series WPT system at 50 W, and a dc motor at 500 W. Thereby, a cost-reduced contactless slip ring was obtained using the concurrent conventional motor drive and inductive power transfer systems.

22 April 2021 in IEEE Journal of Emerging and Selected Topics in Power Electronics
Verified
Journal Article
Closed access
HPHakan Polat
Hakan Polat
EAEnes Ayaz
Enes Ayaz
OAOgun Altun
Ogun Altun
Ozan KeysanOzan Keysan
Ozan Keysan
The aim of this paper is to design a modular, fault tolerant multi-transmitter(Tx)/multi-receiver(Rx) parallel connected common DC bus inductive power transfer(IPT) system to replace slip rings in wind turbines or brushless exciters. In parallel connected common DC bus systems, current unbalance is a major issue that results in thermal stresses and over current or voltages. In this paper, two different new current balancing methods are proposed: Cross-coupled Rx modules and intentional de-tuning of Rx side resonant frequency. These methods are investigated both analytically and experimentally for a single Tx and two Rx system for a 500 W prototype. The proposed methods are tested independently, and then the combined current balancing method is also investigated. For the same misalignment case, cross-coupled/de-tuned has a 55.8% current balancing improvement compared to de-coupled/fully-tuned topology.

25 March 2024 in IEEE Access
Verified
Journal Article
Open access
HPHakan Polat
Hakan Polat
EUEneko Unamuno
Eneko Unamuno
DRDavid Cabezuelo Romero
David Cabezuelo Romero
Thomas GeuryThomas Geury
Thomas Geury
Omar HegazyOmar Hegazy
Omar Hegazy
In this paper, a smart machine-learning-based energy management system (MLBEMS) is developed for a hybrid energy storage system (HESS). This HBESS consists of batteries with high-energy (HE) and high-power (HP) characteristics, to provide grid-supporting services. The aim of the MLBEMS is to improve the overall battery lifetime and achieve state-of-charge (SoC) balancing for two different use cases (UC). UC1 involves enhanced frequency regulation for the Pan-European grid, while UC2 pertains to an electric vehicle (EV) charging station with photovoltaic (PV) generation. The designed MLBEMS is compared with a rule-based energy management system (RBEMS) from the literature with similar use cases. To ensure optimal power sharing between the battery modules, an optimization model is created using real battery aging data. Using a genetic algorithm, optimal power sharing is achieved for various initial SoC conditions. The generated dataset is subsequently utilized to train a machine-learning regression model, and the resulting prediction function is imported into MATLAB/Simulink. In UC1, MLBEMS achieved a 39.3% better SoC balancing compared to RBEMS, along with 36.5% and 22.6% higher battery lifetimes for HE and HP batteries, respectively. Similarly, for UC2, MLBEMS achieved a 68.5% improvement in SoC balancing, along with 53.6% and 45.8% higher battery lifetimes for HE and HP batteries, respectively.

1 January 1993 in Energy Sources
Verified
Journal Article
Closed access
HPHakan Polat
Hakan Polat
NSNevin Selçuk
Nevin Selçuk
SSSelçuk Soyupak
Selçuk Soyupak
Data for semicontinuous anaerobic digestion of sunflower heads were obtained in fermentors of 1 l of effective volume, maintained at 55°C. Experiments were carried out with a 2%percnt; sunflower head-water mixture for hydraulic retention times of 15, 10, and 8 days. Biogas quantities and compositions were measured each day until steady state was achieved. The steady state was achieved after three times of each hydraulic retention time (HRT). Gas productions of 0.180 m3 /m3 dig. day with 62%percnt; CH4, 0.280 m3/m3 dig. day with 58%percnt; CH4, and 0.375 m3/m3 dig. day with 48%percnt; CH4 were obtained, for 15, 10, and 8 days of HRT, respectively.