• List of Articles


      • Open Access Article

        1 - Dual-Output Rectifier-Inverter System for Independently Supplying Two Three-Phase Loads
        M. Heydari A. Yazdian Varjani M. Mohamadian
        In this paper a rectifier-inverter system including a three phase diode rectifier and a dual output inverter is proposed for independently supplying two three-phase loads. This system employs less number of semiconductor devices compared to former dual output inverters Full Text
        In this paper a rectifier-inverter system including a three phase diode rectifier and a dual output inverter is proposed for independently supplying two three-phase loads. This system employs less number of semiconductor devices compared to former dual output inverters proposed in the literature and uses only six active switches for controlling two three-phase loads. Reducing the number of switches and hence drive and control circuits and also cooling system may result in a reduction in overall cost of the system, may reduce its semiconductor power loss and as a result increases efficiency and reliability especially in applications with low and medium voltage and power ratings. The new configuration is introduced and its carrier-based PWM schemes are developed. Analysis of sizing of the DC link capacitors is also performed so as to minimize the DC link voltage ripple, to reduce the value of DC link capacitors and to improve the grid current THD and the grid current balance. Furthermore, loss profile of the system is studied and the results are compared with counterpart topologies. Simulation and experimental results are presented to verify the authenticity of the theoretical model. Manuscript Document
      • Open Access Article

        2 - Optimal Location for Distributed Generation Based on Uuncertain Data
        H. Goodarzi  
        The purpose of this paper is optimal location of distributed generation in electric distribution networks. Load uncertainty and desired voltage range has been modeled using fuzzy data theory. The objective function includes loss reduction, improvement of profile index a Full Text
        The purpose of this paper is optimal location of distributed generation in electric distribution networks. Load uncertainty and desired voltage range has been modeled using fuzzy data theory. The objective function includes loss reduction, improvement of profile index and voltage stability index with their relevant constraints, voltage constraints and transmittable power from the line. Load variation has been shown for three different time durations (peak, off peak and average).PSO technique has been used to optimize the objective function while Max-Min method has been applied to select the answer. Results produced from the proposed model have been provided in 5 different scenarios on a 33 bus system of IEEE. Manuscript Document
      • Open Access Article

        3 - Designing a Self-Tuning Frequency Controller Based on ANNs for an Isolated Microgrid
        F. Habibi H. Bevrani J. Moshtag
        Increasing electrical energy demand, as well as fossil fuel shortages and environmental concerns have caused to use uncommon sources such as distributed generations (DGs) and renewable energy sources (RESs) into modern power systems. A microgrid (MG) system consists of Full Text
        Increasing electrical energy demand, as well as fossil fuel shortages and environmental concerns have caused to use uncommon sources such as distributed generations (DGs) and renewable energy sources (RESs) into modern power systems. A microgrid (MG) system consists of several DGs and RESs which is responsible to provide both electrical and heat powers for local loads. Due to the MGs nonlinearity/complexity which is imposed to the conventional power systems, classical and nonflexible control structures may not represent desirable performance over a wide range of operating conditions. Therefore, more flexible/intelligent control methods are needed most of the past. Hence, in this paper addresses to design an online/self-tuning PI-controller based on artificial neural networks (ANNs) for optimal regulating the MG systems frequency. Manuscript Document
      • Open Access Article

        4 - Wideband Spectrum Sensing in Cognitive Radio Networks by Using Improved Energy Detector
        Y. Eghbali M. Ahmadian Attari H. Hassani
        In cognitive radio networks, spectrum sensing is of a great importance in determining spectrum holes. In this paper, the impact of improved energy detector on the wideband spectrum sensing is considered for accurate detection of spectrum holes. For this end, wideband sp Full Text
        In cognitive radio networks, spectrum sensing is of a great importance in determining spectrum holes. In this paper, the impact of improved energy detector on the wideband spectrum sensing is considered for accurate detection of spectrum holes. For this end, wideband spectrum is sub channelized into equal non-overlapping sub-bands. Our main concern is to find the thresholds of the individual sub-bands simultaneously. By formulating the spectrum sensing problem, in terms of convex optimization one, we seek for maximizing the opportunistic aggregate throughput of cognitive users. In numerical simulation section, it is illustrated that using improved energy detector, the opportunistic aggregate throughput is improved significantly. Manuscript Document
      • Open Access Article

        5 - Joint Detection of Correlated OFDM Subchannels for Wideband Spectrum Sensing in Cognitive Radio Networks
        B. Rassouli A. Olfat
        In this paper, we consider the wideband spectrum sensing in which primary users use OFDM modulation. Pulse shape of each subchannel is non-ideal which results in the leakage of power among adjacent subchannels. This phenomenon makes the received energy of each subchanne Full Text
        In this paper, we consider the wideband spectrum sensing in which primary users use OFDM modulation. Pulse shape of each subchannel is non-ideal which results in the leakage of power among adjacent subchannels. This phenomenon makes the received energy of each subchannel (test statistic of energy detector) correlated with those of other subchannels. Therefore, in order to jointly detect the state of primary network subchannels, we propose a simple iterative method and we observe its performance improvements in comparison to the disjointed method (in which the detection of each subchannel state is independent of the detection of other s Manuscript Document
      • Open Access Article

        6 - Introducing a New Actuation Signal to Improve the Reliability of Capacitive RF MEMS Switch
        M. Zarghami Y. Mafinejad M. Zarghami Kh. Mafinezhad
        In this paper a modified novel dual pulse actuation signal has been proposed to reduce dielectric charging in microelectromechanical system switches. The waveform has a significant impact in reducing the dielectric charging; therefore the amount of charge density in the Full Text
        In this paper a modified novel dual pulse actuation signal has been proposed to reduce dielectric charging in microelectromechanical system switches. The waveform has a significant impact in reducing the dielectric charging; therefore the amount of charge density in the proposed waveform has decreased 7.2% than the dual pulse waveform, although the newest waveform (novel dual pulse) has shown a 5% reduction in dielectric charging. So, the proposed actuation signal waveform will increase the lifetime of switch. We utilized mathematical and transient circuit models to calculate the amount of charge density in the dielectric and finally, the new actuation signal waveform has shown better performance than the other prevalent actuation signal waveforms. Manuscript Document
      • Open Access Article

        7 - Designing an Optimal Proportional-Integral Sliding Surface for a Quarter Car Active Suspension System with Suspension Components Possessing Uncertain Constants and Nonlinear Characteristics
        S. A. Zahiripour A. A. Jalali
        In this paper, design of a controller for a quarter car active suspension system have been done with the focus on sliding mode strategy. Suspension components, including spring and shock-absorber have nonlinear characteristics with uncertain constants, but they have def Full Text
        In this paper, design of a controller for a quarter car active suspension system have been done with the focus on sliding mode strategy. Suspension components, including spring and shock-absorber have nonlinear characteristics with uncertain constants, but they have defined bound. To simplify the controller designing, feedback-linearization is proposed, then with using the optimal strategy, we obtain a proportional - integral sliding surface and a controller for meeting the sliding condition has been proposed. The design process is in a such way that not only, guarantees asymptotic stability of the suspension system in the presence of parametric uncertainties, but also the designer can supply his slightly trade-off between convenience of passengers and controllability of car, with setting some parameters. Manuscript Document