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Yilmaz Sozer

Bio: Yilmaz Sozer is an academic researcher from University of Akron. The author has contributed to research in topics: Switched reluctance motor & Stator. The author has an hindex of 35, co-authored 312 publications receiving 4056 citations. Previous affiliations of Yilmaz Sozer include Dana Corporation & Qatar Airways.


Papers
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Journal ArticleDOI
TL;DR: In this article, the phase currents of a switched reluctance machine are profiled to minimize the torque ripple of the phase current of the machine, which is achieved in three steps: the first step is to design a machine that has symmetric torque characteristics with an extended flat portion, the second step was to find the required current profile through simulation, and the third step is the fine tuning of the profile.
Abstract: This paper presents a novel method of profiling the phase currents to minimize the torque ripple of a switched reluctance machine. The method is a combination of machine design and control algorithm. The minimization is accomplished in three steps: The first step is to design a machine that has symmetric torque characteristics with an extended flat portion, the second step is to find the required current profile through simulation, and the third step is the fine tuning of the profile. The simulation is done to verify the method through a coupling of the finite-element-based machine model and the Matlab/Simulink-based dynamic controller model. The coupled simulation considers the nonlinearities, electrical loss, magnetic loss, and mutual coupling. Experimental verification validated the torque-ripple minimization procedure.

160 citations

Journal ArticleDOI
TL;DR: In this paper, an optimal power flow technique of a PV-battery powered fast EV charging station is presented to continuously minimize the operation cost, along with the required constraints and the operating cost function is chosen as a combination of electricity grid prices and the battery degradation cost.
Abstract: The prospective spread of electric vehicles (EV) and plug-in hybrid EV raises the need for fast charging rates. High required charging rates lead to high power demands, which may not be supported by the grid. In this paper, an optimal power flow technique of a PV-battery powered fast EV charging station is presented to continuously minimize the operation cost. The objective is to help the penetration of PV-battery systems into the grid and to support the growing need of fast EV charging. An optimization problem is formulated along with the required constraints and the operating cost function is chosen as a combination of electricity grid prices and the battery degradation cost. In the first stage of the proposed optimization procedure, an offline particle swarm optimization (PSO) is performed as a prediction layer. In the second stage, dynamic programming (DP) is performed as an online reactive management layer. Forecasted system data is utilized in both stages to find the optimal power management solution. In the reactive management layer, the outputs of the PSO are used to limit the available state trajectories used in the DP and, accordingly, improve the system computation time and efficiency. Online error compensation is implemented into the DP and fed back to the prediction layer for necessary prediction adjustments. Simulation and 1 kW prototype experimental results are successfully implemented to validate the system effectiveness and to demonstrate the benefits of using a hybrid grid tied system of PV-battery for fast EVs charging stations.

136 citations

Journal ArticleDOI
TL;DR: In this article, an overview of modeling and control of the inverter system that interfaces with the utility grid is presented along with practical implementations. Algorithms are given in general form for application to single and three-phase inverters with any number of levels.
Abstract: As alternative energy sources become more competitive with traditional energy sources, the proliferation of distributed generation sources that interface to the electric utility grid continues. Most of the alternative energy sources either produce dc directly (solar photovoltaics or fuel cells) or create dc before inversion to the utility (wind or hydroelectric turbines). The dc electric energy is injected into the ac utility through an inverter. The resulting ac electric energy has to be compatible with the energy within the ac utility system at the point where the inverter is connected to the utility system. The control, design, and operation of the inverter must meet the applicable standards. This paper provides an overview of modeling and control of the inverter system that interfaces with the utility grid. Recent advancements in the state of the art are presented along with practical implementations. Simulation and experimental test results are provided to emphasize concepts and illustrate issues. Embedded control of the inverter is assumed to be implemented through digital control techniques. Algorithms are given in general form for application to single- and three-phase inverters with any number of levels.

133 citations

Journal ArticleDOI
TL;DR: This paper presents the performance analysis and comparison of two types of bidirectional dc-dc converters-cascaded buck-boost capacitor in the middle and cascaded Buck-boost inductor in themiddle for use in plug-in electric and hybrid electric vehicles.
Abstract: This paper presents the performance analysis and comparison of two types of bidirectional dc–dc converters—cascaded buck–boost capacitor in the middle and cascaded buck–boost inductor in the middle for use in plug-in electric and hybrid electric vehicles. The comparison of the two converters is based on device requirements, rating of switches and components, control strategy, and performance. Each of the converter topologies has some advantages over the other in certain aspects. Efficiency analysis has been carried out for specific scenarios in vehicle applications. The simulation and experimental results are provided for both converter types.

114 citations

Journal ArticleDOI
TL;DR: In this article, a deadbeat predictive current controller is proposed to accurately predict the required duty ratio for the PWM pulse for a given reference current in each digital time step over the entire speed range of operation.
Abstract: The paper presents a novel fixed switching frequency predictive current control method for switched reluctancemachines (SRM). The proposed deadbeat predictive current controller accurately predicts the required duty ratio for thePWM pulse for a given reference current in each digital time step over the entire speed range of operation. The pulsewidth depends on the operating conditions, machine parameters and the rotor position. The controller utilizes themachine inductance profile as a function of current and rotor position to accurately predict the required voltage. Thecontrol method is studied through computer simulation and followed by experimental validation. The method is suitablefor torque ripple sensitive applications requiring accurate tracking of a given current profile and mitigating theaudible noise due to the switching of the inverter.

111 citations


Cited by
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[...]

08 Dec 2001-BMJ
TL;DR: There is, I think, something ethereal about i —the square root of minus one, which seems an odd beast at that time—an intruder hovering on the edge of reality.
Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

33,785 citations

01 Sep 2010

2,148 citations

Journal ArticleDOI
TL;DR: A hybrid ac/dc micro grid is proposed to reduce the processes of multiple dc-ac-dc or ac-dc-ac conversions in an individual ac or dc grid to maintain stable operation under the proposed coordination control schemes.
Abstract: This paper proposes a hybrid ac/dc micro grid to reduce the processes of multiple dc-ac-dc or ac-dc-ac conversions in an individual ac or dc grid. The hybrid grid consists of both ac and dc networks connected together by multi-bidirectional converters. AC sources and loads are connected to the ac network whereas dc sources and loads are tied to the dc network. Energy storage systems can be connected to dc or ac links. The proposed hybrid grid can operate in a grid-tied or autonomous mode. The coordination control algorithms are proposed for smooth power transfer between ac and dc links and for stable system operation under various generation and load conditions. Uncertainty and intermittent characteristics of wind speed, solar irradiation level, ambient temperature, and load are also considered in system control and operation. A small hybrid grid has been modeled and simulated using the Simulink in the MATLAB. The simulation results show that the system can maintain stable operation under the proposed coordination control schemes when the grid is switched from one operating condition to another.

1,058 citations

Journal ArticleDOI
TL;DR: This paper presents a review of issues concerning microgrid issues and provides an account of research in areas related to microgrids, including distributed generation, microgrid value propositions, applications of power electronics, economic issues, micro grid operation and control, micro grids clusters, and protection and communications issues.
Abstract: The significant benefits associated with microgrids have led to vast efforts to expand their penetration in electric power systems. Although their deployment is rapidly growing, there are still many challenges to efficiently design, control, and operate microgrids when connected to the grid, and also when in islanded mode, where extensive research activities are underway to tackle these issues. It is necessary to have an across-the-board view of the microgrid integration in power systems. This paper presents a review of issues concerning microgrids and provides an account of research in areas related to microgrids, including distributed generation, microgrid value propositions, applications of power electronics, economic issues, microgrid operation and control, microgrid clusters, and protection and communications issues.

875 citations

Journal ArticleDOI
TL;DR: In this article, the authors present a review of the history of power converter control with an emphasis on the more recent introduction of predictive control, and give a glimpse on the challenges and possibilities ahead.
Abstract: The evolution of power electronics and its control has been mainly driven by industry applications and influenced by the development achieved in several technologies, such as power semiconductors, converter topologies, automatic control, and analog and digital electronics. Digital signal processors (DSPs), in particular, have experienced an exponential development in processing power, which until now has not been fully exploited for control purposes in power converters and drive applications. Presently, the control system technology finds itself in a paradigm-changing tipping point, in which more demanding control goals, system flexibility, and functionalities required by emerging applications are driving the control system technology development, in addition to stabilization and robustness, which was the main focus in the past. This article walks briefly through the history of the mainstream power converter control scene, with an emphasis on the more recent introduction of predictive control, and gives a glimpse on the challenges and possibilities ahead. Special attention is given to finite control set (FCS)-model predictive control (MPC), because of its simplicity, flexibility, inherent adaptation to power electronic circuits and their discrete nature, both in the finite amount of switching states and the digital implementation with microprocessors.

383 citations