Bio: H. Dogan is an academic researcher from Selçuk University. The author has contributed to research in topics: Combustion & Combustion chamber. The author has an hindex of 2, co-authored 2 publications receiving 54 citations.
01 Sep 2008
TL;DR: In this article, a fuzzy logic control (FLC) based novel compensation method is proposed, which performs close loop control of the output current to improve the output performance of the MC, and some results are presented to prove the effectiveness of the proposed compensation technique.
Abstract: Matrix converter (MC) is a direct energy conversation device without dc-link components. Therefore, the output of the converter is directly affected by the disturbances in the input voltages. Many researchers have made an effort to overcome this problem. In this paper, the behaviors of the MC have been investigated under the distorted input voltage conditions. A fuzzy logic control (FLC) based novel compensation method is proposed, which performs close loop control of the output current to improve the output performance of the MC. Some results are presented to prove the effectiveness of the proposed compensation technique.
01 Jan 2009
TL;DR: In this article, a simple control scheme of single-phase shunt active power filter for current harmonics and reactive power compensation of linear and non-linear loads, is proposed, which is based on uncomplicated reference source current generation and fuzzy logic based dc bus voltage regulation methods.
Abstract: In this paper, a simple control scheme of single-phase shunt active power filter for current harmonics and reactive power compensation of linear and non-linear loads, is proposed. Simplicity of the proposed control scheme is based on uncomplicated reference source current generation and fuzzy logic based dc bus voltage regulation methods. Thus, complex computations are not needed. To indicate reactive power and current harmonics compensation capability in both transient and steady state, leading and lagging power factor linear loads and uncontrolled rectifier and thyristor based ac regulator non-linear loads are connected to the system. The effectiveness of the proposed control technique is verified by the simulation results.
TL;DR: In this article , the effect of different chamber geometries on combustion parameters of a spark ignition engine operated at lean and stoichiometric mixtures was compared, and a new combustion chamber called MR type was designed and manufactured for accelerating flow motions through its sickle and bowl shape.
Abstract: The tightening of the exhaust emission limits and the desire to reduce fuel consumption determine the direction of research on internal combustion engines. As it is known, the leaning of the mixture in spark ignition engines generally decreases fuel consumption and NOX emission together. Due to this fact, many researchers are focusing on lean combustion. The main purpose of this study is to compare the effect of different chamber geometries on combustion parameters of a spark ignition engine operated at lean and stoichiometric mixtures. One of the most important parameters of the combustion process is cyclic variations. It defines the stability of a spark ignition engine in operating conditions. Cyclic variations are increased with the leaning of the mixture in spark ignition engines. For lean mixture, a new combustion chamber was designed and manufactured for accelerating flow motions through its sickle and bowl shape. This chamber called MR type decreased burn durations in the combustion process. While the start of the ignition for MR was later, the burn duration is shorter than the other two geometries. Therefore, MR type reduced the cyclic variations compared to other geometries in homogenous and lean mixtures. As a result, the combustion chamber must be designed to increase the turbulence intensity for a spark ignition engine to operate stably in lean mixtures, unlike the stoichiometric mixture.
TL;DR: In this article , the effect of different combustion chamber geometries on the turbulent burning speeds were investigated experimentally and theoretically, and a three-zone, quasi-dimensional thermodynamic model for a spark ignition engine was constructed.
Abstract: Combustion is the main parameter that affects efficiency and exhaust gas emissions. Recently, different studies have been carried out to increase the combustion rates due to the increasing of using the alternative fuels and lean mixture in spark ignition engines. In general, in the absence of systems such as an optical-access engine or ionization probes, combustion process evaluation is done on the basis of cylinder pressure. In this study, the effect of different combustion chamber geometries on the turbulent burning speeds were investigated experimentally and theoretically. A three-zone, quasi-dimensional thermodynamic model for a spark ignition engine was constructed. Measured cylinder pressure data were used to establish the transition between the zones of the model and determine turbulent burning speeds. Two different turbulent speeds were calculated in the model, these are flame propagation and consumption speeds. It was seen that combustion chamber geometry significantly affected turbulent burning speeds. In MR and cylindrical shapes, the turbulent burning speeds decreased after it reached a maximum value in the combustion period. In flat geometry, without any bowl, speed continuously decreased different from other two designs. By means of quasi-dimensional thermodynamic model, mean values of the turbulent burning and the flame propagation speeds can be calculated without having any optical observation.
TL;DR: In this paper , the diameter of the orifice and flow rate characteristics of the injector were investigated, and two types of injectors were selected: low speed and high speed.
Abstract: Direct injection on the Wankel engines has been practiced since the 1970’s. By applying direct injection in the Wankel engine, the specific fuel consumption and HC emissions, which are seen as disadvantages for this engine, might be reduced and the mixture formation is improved. In order to obtain a better mixture formation, the fuel injector must be located in a proper place and a correct direction. In addition, the most suitable injector for the engine structure should be selected. In this study, direct injection was applied for the RENESIS 13B Wankel engine and injector selection for the engine and the location of the injector on the housing were examined. In addition, the diameter of orifice and flow rate characteristics of the injector were investigated. According to the results, two types of injectors were selected. These injectors were called as low speed and high speed. An injector with a narrow nozzle angle (<30°) was used to deliver the fuel to the leading of the chamber, and the fuel injected after the intake ports closed. The orifice diameters of low-speed and high- speed injectors were measured 0.33 and 0.45 mm, respectively. In addition, both injectors have low speed rates when injection duration was below 2 ms. This flow rate was increased by providing high voltage.
TL;DR: It is concluded that the control strategy has a significant impact on the resonance of the MC input filter.
Abstract: This paper presents a review of the most popular control and modulation strategies studied for matrix converters (MCs) in the last decade. The purpose of most of these methods is to generate sinusoidal current on the input and output sides. These methods are compared considering theoretical complexity and performance. This paper concludes that the control strategy has a significant impact on the resonance of the MC input filter.
20 Mar 2009
TL;DR: A modified space vector modulation strategy for matrix converter can eliminate the influence of the abnormal input voltages on output side without an additional control circuit, and three-phase sinusoidal symmetrical voltages or currents can be obtained under normal and abnormal input-voltage conditions.
Abstract: The matrix converter is a single-stage ac-ac power conversion device without dc-link energy storage elements. Any disturbance in the input voltages will be immediately reflected to the output voltages. In this paper, a modified space vector modulation strategy for matrix converter has been presented under the abnormal input-voltage conditions, in terms of unbalance, nonsinusoid, and surge (sudden rising or sudden dropping). By using the instantaneous magnitude and phase of input-voltage vector to calculate the voltage modulation index and input-current phase angle, this modified modulation strategy can eliminate the influence of the abnormal input voltages on output side without an additional control circuit, and three-phase sinusoidal symmetrical voltages or currents can be obtained under normal and abnormal input-voltage conditions. The performance of the input currents is analyzed when the matrix converter uses different modulation strategies. Some numerical simulations are presented to confirm the analytical results. Tests are carried out on a 5.5-kW matrix converter prototype. Experimental results verify the validity of the proposed strategy.
TL;DR: In this article, a Z-source sparse matrix converter (ZSMC) and a compensation method based on a fuzzy logic controller are proposed to compensate unbalanced input voltages. But the compensation method is not suitable for low voltage transfer ratio of conventional matrix converters.
Abstract: In this paper, we present a novel Z-source sparse matrix converter (ZSMC) and a compensation method based on a fuzzy logic controller to compensate unbalanced input voltages. The ZSMC is developed based on the structure of an SMC to reduce the number of unipolar power semiconductor switches and employs a Z-source network to overcome the inherent limitation of the low voltage transfer ratio of conventional matrix converters. Although the ZSMC is a two-stage converter, it directly connects between a source and a load through a Z-source network, which is designed to have smaller passive components as the only purpose is voltage boosting. Therefore, the output of the ZSMC is directly affected by disturbances of the input-voltage source. The operational principle of the ZSMC is described and its modulation strategy is explained. Simulation and experimental results are shown to verify the feasibility of the ZSMC and its compensation method.
TL;DR: A comprehensive review of HVDC interconnections, asynchronous AC interConnections, synchronous AC Interconnections and different types of power flow controllers used in these interconnection technologies is presented.
Abstract: Energy security is one of the most crucial factor in the development of any nation. Interconnections among different power system networks are made to lower the overall price of power generation as well as enhance the reliability and the security of electric power supply. Different types of interconnection technologies are employed, such as AC interconnections, DC interconnections, synchronous interconnections, and asynchronous interconnections. It is necessary to control the power flow between the interconnected electric power networks. The power flow controllers are used to (i) enhance the operational flexibility and controllability of the electric power system networks, (ii) improve the system stability and (iii) accomplish better utilization of existing power transmission systems. These controllers can be built using power electronic devices, electromechanical devices or the hybrid of these devices. In this paper, control techniques for power system networks are discussed. It includes both centralized and decentralized control techniques for power system networks. This paper also presents a comprehensive review of HVDC interconnections, asynchronous AC interconnections, synchronous AC interconnections and different types of power flow controllers used in these interconnections. Moreover, some important and multivariable flexible AC transmission system (FACTS) devices such as UPFC and IPFC are also discussed with their merits and limitations. Finally, a new asynchronous AC link called flexible asynchronous AC link (FASAL) system is also described in detail. At last, a summary of the comparative analysis of power system link and power flow controllers is given based on recent publications. More than 400 research articles and papers on the topic of power transfer control are covered in this review and appended for a quick reference.