Enes Ugur

A Bidirectional Nonisolated Multi-Input DC–DC Converter for Hybrid Energy Storage Systems in Electric Vehicles

To process the power in hybrid energy systems using a reduced part count, researchers have proposed several multiinput dc-dc power converter topologies to transfer power from different input voltage sources to the output. This paper proposes a novel bidirectional nonisolated multi-input converter (MIC) topology for hybrid systems to be used in electric vehicles composed of energy storage systems (ESSs) with different electrical characteristics. The proposed converter has the ability to control the power of ESSs by allowing active power sharing. The voltage levels of utilized ESSs can be higher or lower than the output voltage. The inductors of the converter are connected to a single switch; therefore, the converter requires only one extra active switch for each input, unlike its counterparts, hence resulting in reduced element count. The proposed MIC topology is compared with its counterparts concerning various parameters. It is analyzed in detail, and then, this analysis is validated by simulation and through a 1-kW prototype based on a battery/ultracapacitor hybrid ESS.

Fuel Consumption Comparison of Different Battery/Ultracapacitor Hybridization Topologies for Fuel-Cell Vehicles on a Test Bench

The power train of fuel-cell vehicles (FCVs) can be composed of onboard hybrid energy sources to reduce fuel consumption, extend driving range through regenerative braking energy recovery, and possibly increase the specific power density. One of the main issues significantly affecting the FCV performance is the chosen hybrid system topology along with system components, which requires research to find the best hybrid structure for the lowest fuel consumption. Although several hybridization topologies have been studied separately in the literature, an overall investigation and fuel consumption comparison of the most promising fuel-cell (FC) power-train topologies along with the experimental verification should be realized. In this regard, this paper demonstrates a detailed comparison of four different hybrid FC power-train configurations with feasible battery and ultracapacitor (UC) combinations, on a test bench using normalized ECE-15 drive cycle. The results demonstrate that the lowest equivalent fuel consumption can be achieved with FC/battery/UC hybrid combination.

Financial payback analysis of small wind turbines for a smart home application in Istanbul/Turkey

Small-scale wind turbines are promising renewable energy devices driven by the aim of carbon savings at energy generation. However, the use of small-scale wind turbines in residential areas is still very narrow because of low wind speeds, high turbulence intensity, and the perception of high aerodynamic noise produced by wind turbines. Furthermore, their high cost make it essential to assess the turbines carefully before deciding to purchase so that the optimum performance and costs can be obtained. In this study, power curves of bestselling small scale wind turbines in Turkey are compared using experimentally collected one year wind data for the use in a smart home environment at Davutpasa Campus, Istanbul. The total annual energy production of the wind turbines and financial payback periods are calculated. With the results of performed analysis, it is possible to define the most profitable small wind turbine to be used in related applications in Istanbul and in areas where wind speed is similar.

Carbon emission savings with a renewable energy supplied smart home operation

Recently, ideas like smart cities, smart buildings/homes has been widely used under smart grid concept, which is a new research area that combines power systems and information technology (IT). The basic building block of the smart grid can be considered as “smart home”. Smart grid infrastructure with smart homes will allow to monitor electrical demand of a city or a residential customer and to achieve better utilization of existing grid through the use of streaming demand data. In addition, it will be easier to integrate renewable energy sources into existing grid. Experimental demonstrations are important for promoting smart grid concept. Thus, a renewable energy supplied smart home project with a budget of

A New MPPT Algorithm for Vehicle Integrated Solar Energy System

0.5 million has been completed at Yıldız Technical University (YTU), Istanbul, Turkey. This paper first introduces the constructed smart home in detail. Then, the benefit of smart home operation on carbon emission reduction with appliance control through smart plugs is analysed by a simulation study in Matlab/Simulink.

Implementation of a reliable load sharing strategy between battery and ultra-capacitor on a prototype electric vehicle

Photovoltaic (PV) systems are considered as a support unit and eco-friendly energy source for the electric vehicles. If the surface of the electric vehicle is covered by PV cells, it is possible to store considerable amount of energy in the battery system. In this study, different maximum power point trackers (MPPT) with different maximum power point (MPP) tracking algorithms have been tested on a PV structure moving according to a predefined motion loop. Compatibility of each algorithm to moving systems, such as electric vehicles, is presented in a real experimental environment. As a result of these experiments, positive factors in each algorithm have been defined and a new MPP tracking algorithm convenient for moving vehicle has been proposed. The proposed MPPT algorithm shows a better performance than other MPPT algorithms under fast varying radiations. However, proposed algorithm brings slightly higher costs compared to usage of other MPPT algorithms since it requires the measurement of solar irradiance. The developed algorithm is described in detail and comparative analysis and performance evaluation with other algorithms are presented. Autor Nakir, Ismail; Durusu, Ali; Akca, Hakan; Ajder, Ali; Ayaz, Ramazan; Ugur, Enes; Tanrioven, Mugdesem Quelle Transactions of the ASME, Journal of Energy Resources Technology * Band 138 (2016) Heft 2, Seite 021601/1-9 (9 Seiten)

Power switch lifetime extension strategies for three-phase converters

In this study, a battery and ultra-capacitor (UC) hybrid electric vehicular system is proposed. The battery supplies the long term energy requirements of the vehicle while UC is employed for picking up the transient load variations that can seriously damage the electrochemical structure of the battery. An experimental assessment of the constructed vehicle prototype of such hybrid structure is realized under a real time drive cycle. The proposed system provides the advantages of eliminating of the supervisory control system necessity as well as realizing a more reliable local control approach based on voltage regulation compared to current based control approaches.

Small scale test bench based performance analysis of a fuel cell/ultra-capacitor hybrid vehicular power system with an improved power conditioning unit

The recent advances and reports on failure precursors of power switches have led to estimation of lifetime as well as developing secondary control schemes to increase the lifetime of the converters. In this study, a secondary control scheme to extend the lifetime of the converter based on the identified failure precursors such as the on-state resistance variation for power MOSFETs and collector emitter voltage variation for IGBTs is proposed for three-phase converters. The controller switches the modulation scheme from SVPWM to discontinuous PWM, and adjusts the switching frequency, once the tracked failure precursor reaches to the defined threshold value. The tradeoff between the total harmonic distortion and lifetime extension at different modulation techniques and switching frequencies are addressed.

Comparison of different small signal modeling methods for bidirectional DC-DC converter

For vehicular systems, fuel cells (FCs) are considered as a potential long term alternative to replace conventional combustion engines. However, high cost and slow dynamic response of FC are still the main challenges for wider applications. To overcome this problem, an auxiliary power system with adequate power capacity has to be incorporated. Ultra-capacitors (UCs) can provide an applicable solution in this aspect. Thus, a test bench of FC/UC hybrid configuration that can be suitable for vehicular systems is presented in this paper. In addition, an improved power conditioning unit (PCU) that can enhance fuel economy compared to conventional converter topologies is provided. Two different hybridization topologies are examined from different aspects. A test bench performance verification of a fuzzy logic based energy management strategy that was discussed in earlier simulation-based studies of the authors is investigated. Experimental results with small-scale devices, namely, a PEMFC (1200 W, 46 A) manufactured by the Ballard Power System Company, and four UC modules (58 F, 15 V) manufactured by the Maxwell Technologies Company, illustrate the performance analysis of both the applied PCUs and employed energy-management scheme during load cycles.

Sensorless control of BLDCs for all speed ranges with minimal components

Bidirectional dc-dc converters are widely used in applications requiring bidirectional power flow. Control of these converters in a more suitable way and modeling and analyzing of them in a simpler method is still a research topic. In this paper different small signal modeling methods for bidirectional dc-dc converters are compared. Mathematical averaged small signal modeling and ac sweep tool on PSIM simulation software are used to obtain ac response of the converter. These results are compared in terms of bode plots to evaluate accuracy and convenience of the modeling techniques. Step-by-step calculations and simulations are presented together with detailed comparison of simulation results.