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A COMPUTATIONALLY EFFICIENT ENERGY MANAGEMENT STRATEGY FOR A PLUG-IN FUEL-CELL HYBRID ELECTRIC VEHICLE COMPOSED OF A MULTI-INPUT CONVERTER
(Muğla Sıtkı Koçman Üniversitesi, 2019) Akar, Furkan
Fuel cell vehicle technology has drawn wide attention because of the environmental and economic issues related to excessive usage of fossil fuels. Fuel cells are known for their unidirectional environmental friendly operation; however, they have low power density and suffer from slow dynamics. Therefore, a sole fuel cell system cannot meet the requirements of an electric vehicle whose power demand is quite dynamic. In a way of hybridizing a fuel cell with energy storage devices, it can be possible to overcome aforementioned problems. A plug-in fuel cell hybrid electric vehicle system, equipped with a battery and an ultra-capacitor, is proposed in this work. In this system, a single multi-input converter is utilized to control source energies. Moreover, this work develops a computationally efficient energy management strategy which is essentially a frequency decoupling method basically taking the advantage of easily applicable low pass filters. In this strategy, a polynomial scales the fuel cell and battery power levels to regulate ultra-capacitor voltage. The whole system is tested via a simulation model after the detailed analysis of the multi-input converter.
Analysis and experimental verification of a multi-input converter for DC microgrid applications
(Inst Engineering Technology-Iet, 2018) Akar, Furkan; Tavlaşoğlu, Yakup; Vural, Bülent
This work presents a multi-input converter (MIC) that can build a DC microgrid having renewable energy resources, balanced sources, and energy storage devices. After analysing its operation modes, a design procedure for the converter considering three different cases is provided. This procedure includes the semiconductor elements selection and design of the inductors. After this step, a detailed efficiency analysis is carried out for the studied cases. Finally, a 1kW prototype creating a photovoltaic-battery system is built. Through several experiments based on this set-up, it is shown that the theoretical analysis is accurate and the studied MIC can be successfully utilised to create DC microgrid.
Battery/UC Hybridization for Electric Vehicles via a Novel Double Input DC/DC Power Converter
(Ieee, 2013) Akar, Furkan; Vural, Bülent
In this work, for electric vehicles (EVs), a novel double input DC-DC power converter, that enables utilization of a battery and ultra-capacitor (UC) in parallel while increasing the overall performance of electric vehicles and recovering regenerative breaking energy, is introduced. Since UCs have higher power density when compared to batteries, by the use of a UC as a power input, DC bus voltage regulation at transients and peak loads is achieved easily, thus the life of the battery and efficiency of the system are increased. The average value model of the proposed converter is created in MA TLAB (R), Simulink (R) and SimPowerSystems (R) environment, then its dynamic performance is tested under the load determined from the ECE-15 drive cycle.
A Bidirectional Multi-Phase Multi-Input DC-DC Converter
(Ieee, 2017) Akar, Furkan
In this work, a bidirectional non-isolated multiphase multi-input dc-dc converter is proposed. This converter can easily construct hybrid power systems by means of utilizing different power sources and energy storage elements with different characteristics and voltage levels. The proposed converter can work in both buck and boost modes in both directions. Compared to the single phase version, the multi-phase structure helps to decrease the current ripples, thus the sizes of inductors, filter requirements, and semiconductor losses are essentially reduced. In this work, an analysis for the proposed converter concerned its operation modes is presented and details of a simulation study are given to test it for a hybrid energy system.
Comparative study of a bidirectional multi-phase multiinput converter for electric vehicles
(Scientific and Technological Research Council Turkey, 2022) Akar, Furkan; Kale, Murat; Yalçın, Sebahattin; Taş, Gözde
Multiinput converters allow to create hybrid energy systems in electric vehicles with a reduced part count. In addition, interleaved structures help to build efficient converters with several possible benefits, such as low current ripple and high power density. This paper proposes utilizing a multiphase multiinput converter (MPMIC), which concentrates the aforementioned advantages and presents a comprehensive comparison with its single-phase version, called singlephase multiinput converter (SPMIC). After analysing their steady-state characteristics, SPMIC and MPMIC are designed considering same conditions. Then, two laboratory prototypes rated at 2.5kW output power are implemented to validate the analysis. Finally, these prototypes are compared in terms of voltage-gain, input current ripple, efficiency, complexity, cost, and power density. The results show that MPMIC surpasses SPMIC in efficiency and in input current ripple at the expense of increments in the complexity and cost. Besides, MPMIC results in comparatively high voltage gain in low power region thanks to the discontinuous current mode operation. On the other hand, it is explored that SPMIC can reach higher power density in the event of effective cooling.
A COMPUTATIONALLY EFFICIENT ENERGY MANAGEMENT STRATEGY FOR A PLUG-IN FUEL-CELL HYBRID ELECTRIC VEHICLE COMPOSED OF A MULTIINPUT CONVERTER
(2019) Akar, Furkan
Fuel cell vehicle technology has drawn wide attention because of the environmental and economic issues related toexcessive usage of fossil fuels. Fuel cells are known for their unidirectional environmental friendly operation; however, theyhave low power density and suffer from slow dynamics. Therefore, a sole fuel cell system cannot meet the requirements ofan electric vehicle whose power demand is quite dynamic. In a way of hybridizing a fuel cell with energy storage devices, itcan be possible to overcome aforementioned problems. A plug-in fuel cell hybrid electric vehicle system, equipped with abattery and an ultra-capacitor, is proposed in this work. In this system, a single multi-input converter is utilized to controlsource energies. Moreover, this work develops a computationally efficient energy management strategy which is essentiallya frequency decoupling method basically taking the advantage of easily applicable low pass filters. In this strategy, apolynomial scales the fuel cell and battery power levels to regulate ultra-capacitor voltage. The whole system is tested viaa simulation model after the detailed analysis of the multi-input converter.
Current Ripple Minimization of a PEM Fuel Cell via an Interleaved Converter to Prolong the Stack Life
(Ieee, 2016) Yıldız, Emre; Vural, Bülent; Akar, Furkan
This paper focuses on to prolong the Proton Exchange Membrane (PEM) fuel cell stack life via an interleaved double switch buck-boost converter. PEM fuel cells are environmental friendly energy sources, and widely used in several applications such as electrical vehicles, power plants, back-up power units, thanks to their fast start-up ability, portability, and efficient operation. In the steady-state, the fuel cell current ripple may result in damage to the fuel cell chemical structure, so it is required to extract its power via a power converter that can overcome this issue. Therefore, in this work, a power converter topology and a control method are proposed in order to reduce the converter input current ripple in both buck and boost operation modes with the help of its two input inductors. In addition to that, sharing input current via these inductors decreases input capacitance voltage stresses and average current flowing through the interleaved inductors thus smaller input capacitance and inductors also increase the cost effectiveness of proposed converter. The simulation results indicate that the proposed interleaved buck-boost topology reduces the input current ripple, and leads less settling time hence better dynamic response owing to its interleaved structure.
Decoupled control of a high step-up multi-input converter for renewable energy applications
(Elsevier GmbH, 2023) Akar, Furkan
This paper focuses on the development and control of a non-isolated high step-up multi-input dc–dc converter for renewable energy applications. The converter has non-pulsed input currents and high voltage gain owing to the input inductors and a switched-capacitor (SC) network. In a two-input case, there are only two low-side switches controlled independently for adjusting individual input power levels and another low-side switch for operating the SC network. Steady-state analysis and dynamic modelling of the converter are provided. Design procedures regarding the hardware and decoupled control system dealing with the interactions of the control loops are given. After a benchmark study, a laboratory prototype rated at 200-W validates the analysis and tests the control system when subjected to step changes. © 2023 Elsevier GmbH
Elektrikli Araçlarda Hibrit Güç Sistemleri GeliştirilmesineYönelik Yüksek Verimli Çift Yönlü Çok Fazlı Çok Girişli Bir DC-DC Dönüştürücünün Geliştirilmesi
(2020) Akar, Furkan; Kale, Murat
Dengesiz petrol fiyatları, ekonomik kaygılar, küresel ısınma gibi sebepler elektrikli araçlara olan ilgiyi arttırmaktadır. Dinamik yük profilleri ile bilinen elektrikli araçların yüksek güç yoğunluğuna sahip bir enerji depolama sistemi ile beslenmesi gerekmektedir. Ayrıca, uzun menzil için enerji depolama sisteminin enerji yoğunluğunun da yüksek olması gerekmektedir. Bu iki ihtiyaca tek bir tür enerji depolama sistemi ile cevap verilmesi zor olduğundan, literatürde hibrit enerji depolama sistemlerinin kullanılması önerilmektedir. Örneğin, batarya ultrakapasitör hibrit sistemi ile yüksek güç ve yüksek enerji yoğunluğuna ulaşılabilirken aynı zamanda batarya ömrü de arttırılabilmektedir. Bu proje yukarıda örnekleri verilen hibrit güç sistemlerini oluşturabilecek, çift yönlü olarak giriş kaynakları arasında aktif güç paylaşımı yapabilen, her iki yönde de düşürücü ve yükseltici olarak çalışabilen çok fazlı çok girişli bir güç elektroniği dönüştürücüsü önermektedir. Önerilen bu dönüştürücü, çok fazlı yapısı yardımıyla benzer dönüştürücülerde karşılaşılan düşük verim ve yüksek giriş akımı dalgalanması gibi problemleri ortadan kaldırmayı amaçlamaktadır. Ayrıca verimi arttırmak amacıyla devreye bir bastırma hücresi eklenmesi önerilmektedir. Önerilen dönüştürücünün 1-fazlı, 2-fazlı ve 3-fazlı hallerinin bastırma hücresi içeren ve içermeyen durumları için analiz, tasarım ve benzetim çalışmaları yapılmıştır. Prototipler üretilmiş ve sistemler deneysel olarak test edilmiş, verim, güç yoğunluğu ve maliyet açılarından karşılaştırılmıştır. Son olarak detaylı bir maliyet analizi yapılmıştır.
An Energy Management Strategy for a Concept Battery/Ultracapacitor Electric Vehicle With Improved Battery Life
(Ieee-Inst Electrical Electronics Engineers Inc, 2017) Akar, Furkan; Tavlaşoğlu, Yakup; Vural, Bülent
Using multi-input converters (MICs) in hybrid energy storage systems (HESSs) presents several advantages, such as low component count, control simplicity, and fully control of source energies. The power levels of sources in these systems need to be determined wisely by an energy management strategy (EMS). This paper presents an EMS for a battery/ ultracapacitor (UC) HESS including a bidirectional MIC for electric vehicles (EVs). Thanks to the fact that energy flow between battery and UC is free in this MIC, the proposed EMS not only regulates the state-of-charge of UC but also smooths the battery power profile by using a fuzzy logic controller and a rate limiter. Therefore, it results in a sustainable HESS with longer battery life. Through a simulation study and an experimental setup including a real EV, the performance of the proposed system is evaluated comprehensively. Then, based on experimental results, battery cycle-life improvement due to the battery/UC hybridization is explored.
A fuel-cell/battery hybrid DC backup power system via a new high step-up three port converter
(Pergamon-Elsevier Science Ltd, 2021) Akar, Furkan
In this paper, a fuel-cell (FC)/battery hybrid direct-current (DC) backup power system is proposed for high step-up applications. This system is composed of a newly developed non-isolated three-port converter, which achieves a high voltage gain by taking the advantage of a quasi Z-source network and an energy transfer capacitor. After analyzing the converter, a comprehensive comparison study and a design procedure are provided. Moreover, the controllers regulating the source power levels while smoothing the FC power profile according to the proposed energy management strategy (EMS) are designed based on the developed small-signal model of the proposed converter. Both hardware and controller design procedures are validated through the PSIM model of the whole system. As a result, it is shown that the proposed system can effectively couple FC and battery while transferring their energies to a high voltage DC bus according to the offered EMS. (c) 2021 Published by Elsevier Ltd on behalf of Hydrogen Energy Publications LLC.
Fuzzy Logic Based Control of a Fuel Cell/Battery/Ultra-capacitor Hybrid Power System via a Multi-Phase Multi-Input Converter
(2022) Can, Aykut; Akar, Furkan
Fuel-cell (FC) based electric vehicles (EVs) are promising to reduce the carbon footprint due to the transportation sector. FCs are environmentally friendly systems that generate electricity from hydrogen and oxygen. Unfortunately, FCs solely fail to meet the high power density requirements of EVs. Therefore, this paper presents a FC/battery/ultra-capacitor (UC) hybrid power system (HPS) for electric vehicle applications. In this work, the power conversion is realized employing a single dc-dc converter which is a multi-phase multi- input converter to offer a compact and efficient HPS. After analyzing the converter, a fuzzy-logic-based energy management strategy (EMS) is developed to limit the rate of change of FC and battery power levels and regulate the voltage of UC. Finally, the offered EMS has been evaluated thanks to simulation models of the converter and sources.
A High Voltage Gain Multi-Input Converter
(Institute of Electrical and Electronics Engineers Inc., 2018) Akar, Furkan; Kale, Murat
This paper proposes a non-isolated unidirectional high step-up multi-input converter based on switched capacitor cells. The proposed structure specifically useful for hybrid power systems when energy sources with low output voltages, e.g., a photovoltaic system or a fuel cell, need to be connected to a dc bus with high voltage. Moreover, it is possible to store redundant energy into energy storage systems connected to the input of the converter, which is important for renewable energy systems. © 2018 IEEE.
A High Voltage Gain Multi-Input Converter
(Ieee, 2018) Akar, Furkan; Kale, Murat
This paper proposes a non-isolated unidirectional high step-up multi-input converter based on switched capacitor cells. The proposed structure specifically useful for hybrid power systems when energy sources with low output voltages, e.g., a photovoltaic system or a fuel cell, need to be connected to a dc bus with high voltage. Moreover, it is possible to store redundant energy into energy storage systems connected to the input of the converter, which is important for renewable energy systems.
A High-Efficiency Bidirectional Non-Isolated Multi-Input Converter
(Ieee, 2016) Akar, Furkan
A high-efficiency bidirectional non-isolated converter with multiple input sources is presented in this work. In the proposed converter, the energy from/to the input sources is transferred via the coupled inductors connecting to a switch pair. This topology does not only allow active power sharing, but also results in reduced component count. It also achieves zero-voltage-switching without any extra switching losses hence improving the cost-effectiveness, power density and efficiency.
A SOGI Based Band Stop Filter Approach for a Single-Phase Shunt Active Power Filter
(Institute of Electrical and Electronics Engineers Inc., 2018) Kale, Murat; Akar, Furkan; Karabacak, Murat
Control of shunt active power filter (SAPF) requires a cascaded control structure as inner current closed loop followed by outer voltage control loop. The inner current control loop is responsible for tracking of a reference current while the outer voltage loop regulates DC bus voltage to a fixed value. Dynamic performance of the DC bus voltage regulation suffers from the adverse effects such that harmonic currents produced by SAPFs lead to fluctuations in DC bus voltage at certain harmonic frequencies. This causes SAPF to produce additional harmonic components, since the outer voltage loop deals with only fundamental waves where the fluctuations should not appear. This study proposes a DC bus voltage regulation methodology based on a Second Order Generalized Integrator (SOGI) acting as a band-stop filter with the aim of increasing the voltage regulation performance in the steady state. The proposed filter does not affect the transient response thanks to that it only suppresses the harmonic-induced fluctuations in DC bus voltage. Through a simulation study, the proposed methodology is validated, and the results prove the performance and feasibility of the proposed filter. © 2018 IEEE.
A SOGI Based Band Stop Filter Approach for a Single-Phase Shunt Active Power Filter
(Ieee, 2018) Kale, Murat; Akar, Furkan; Karabacak, Murat
Control of shunt active power filter (SAPF) requires a cascaded control structure as inner current closed loop followed by outer voltage control loop. The inner current control loop is responsible for tracking of a reference current while the outer voltage loop regulates DC bus voltage to a fixed value. Dynamic performance of the DC bus voltage regulation suffers from the adverse effects such that harmonic currents produced by SAPFs lead to fluctuations in DC bus voltage at certain harmonic frequencies. This causes SAPF to produce additional harmonic components, since the outer voltage loop deals with only fundamental waves where the fluctuations should not appear. This study proposes a DC bus voltage regulation methodology based on a Second Order Generalized Integrator (SOGI) acting as a band-stop filter with the aim of increasing the voltage regulation performance in the steady state. The proposed filter does not affect the transient response thanks to that it only suppresses the harmonic-induced fluctuations in DC bus voltage. Through a simulation study, the proposed methodology is validated, and the results prove the performance and feasibility of the proposed filter.

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