فهرست مطالب

  • Volume:8 Issue: 4, 2020
  • تاریخ انتشار: 1399/02/10
  • تعداد عناوین: 6
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  • Bahman Taheri*, Gholamreza Aghajani, Mahsa Sedaghat, Shokoufeh Sharifi, Milad Teimourian Pages 1-6

    Renewable energy resources such as photovoltaic systems are a promising way to meet the nowadays energy demand. In this paper, a novel non-isolated DC-DC boost converter is proposed to be used in photovoltaic systems. Since photovoltaic systems have low voltage gain, it is required to utilize a converter with high gain, low cost, and high efficiency. Thus, the proposed converter is of an additive boost converter with a switched inductor. With an appropriate duty cycle and low-voltage pressure in power switch, this converter obtains high voltage gain. Additional stored energy in the inductor may be eliminated in the output capacitor. Renewable energy resources such as photovoltaic systems are a promising way to meet the nowadays energy demand. In this paper, a novel non-isolated DC-DC boost converter is proposed to be used in photovoltaic systems. Since photovoltaic systems have low voltage gain, it is required to utilize a converter with high gain, low cost, and high efficiency. Thus, the proposed converter is of an additive boost converter with a switched inductor. With an appropriate duty cycle and low-voltage pressure in power switch, this converter obtains high voltage gain. Additional stored energy in the inductor may be eliminated in the output capacitor.

    Keywords: DC-DC Boost Converter, Switched Capacitor, High Gain, High Efficiency, Low Cost, PhotovoltaicSystem
  • Fatemeh Rezaei*, Mostafa Mahmoudi Pages 7-15

    Today, increasing environmental pollution due to the use of fossil fuels to provide thermal comfort is one of the problems of this area. The amount of these contaminants in residential buildings are more tangible. By referring to the traditional architecture, it can be seen that natural ventilation was provided by using natural forces (in this article: wind). Therefore, it can be concluded that the proper use of effective elements on natural ventilation can solve the problems created by air conditioning in new buildings. This article was identified different models of locating of openings in buildings (city of Gorgan) and analyzed the wind behavior in each of these models in terms of natural ventilation and finally, the optimal model for natural ventilation was selected. In this article, qualitative research methodology to identify and study the methods of using wind in vernacular habitats was used firstly. Then by CFD modeling and choosing selected models in terms of location of openings in order to improve the natural ventilation, Wind behavior analysis in these models was performed by the simulation research method (Gambit 2.4.6 software for making model geometry and creating grid mesh and ANSYS FLUENT 15 for wind behavior analysis). As a result of analyzes, models that had northeastern-southwest direction, more openings in the southwest elevation and the suction window in the opposite direction were selected as the optimal model for residential buildings in city of Gorgan.

    Keywords: Natural Ventilation, Residential Building, Gorgan, CFD, Moderate, Humid
  • Sajad Saberi*, Behrooz Rezaie Pages 17-25

    Full range speed and position estimation of permanent magnet synchronous motors is a challenging task. In this paper, a nonsingular terminal sliding mode observer is proposed for fast and precise estimation of speed and position. It is shown that adaptive gain in proposed method not only helps to reduce chattering problem in low speed range considerably but also decreases estimation error in nominal speed. Furthermore, in order to accurately estimate the rotor position in the reverse speed, a quadrature-component-based phase lock loop is utilized instead of arctan function. Finally, to illustrate effectiveness of proposed method, simulation results using MATLAB/SIMULINK is provided.

    Keywords: Position, Speed Estimation, Fast Terminal Sliding Mode Observer, Permanent Magnet SynchronousMotor, Quadrature-Component-Based Phase Lock Loop
  • Nima Norouzi* Pages 27-40

    Iran holding 153.8 billion barrels of crude oil with a share of 9.3 percent and 33.5 billion cubic meters of gas with 18 percent share of oil and gas reservoirs are among the world's most important oil and gas producing countries. Hydrocarbon reservoirs are one of the most important competitive advantages of Iran, along with a specific geographic location. In the social and economic structure of Iran, the oil has a special place. In a context where dynamic and permanent variables are changing and uncertainty is high, the use of scenarios for long-term horizons is beneficial and useful for strategic planning and policymaking. In this study, the future of Iranian oil and gas industries is being studied in four scenarios using the hybrid foresight methodology and the Iranian seventh progress plan strategies to enhance their accuracy. the noted scenarios are the most probable future pathway for the Iranian oil and gas industry.

    Keywords: Oil, gas, policymaking, scenario planning, Energy Governance
  • A. Teimori*, Majid Delshad Pages 41-45

    Incremental converters are nowadays widely used in new energy systems because new energy systems such as photovoltaic, fuel cell, etc have low output voltage and need to be increased to the desired level to connect these systems to the global electricity grid; DC-DC converter converters have played a prominent role, but these converters have to incur significant losses to the system and, on the other hand, operate under the input-to-output variations, so the switchers were considered soft switches. In this study, a non-isolated booster converter with soft switching voltage gain-raising technique was designed. This converter has a switch that is controlled by the Pwm signal. The benefits of this converter include reduced switching losses, simplicity of operation, provision of soft switching and low voltage stress; an active clamp is used to provide soft switching for multiple voltage elements and back cells to maximize gain and input. The converter used an auxiliary branch to increase the gain instead of using the output inductor at the input, and in addition an inductor was used as a filter inductor to reduce the input ripple. This converter has six states. The switches are switched on under zvzcs and switched off under zvc conditions.

    Keywords: Converter, Highly Increasing, Soft Switch, High Efficiency, Coupled Inductor
  • Habib Benbouhenni* Pages 47-55

    This research work presents a new seven-level space vector pulse width modulation (SVPWM) based on fuzzy logic (FL) of the doubly fed induction generator (DFIG) integrated in a wind turbine system is presented. The classical direct vector control (DVC) using conventional proportional-integral (PI) controller presents considerable active and reactive power ripples. In order to ensure a robust DVC control scheme for the DFIG-rotor side converter and reduces reactive power ripple, harmonic distortion of rotor current, electromagnetic torque ripples and active power ripples, a DVC based on seven-level fuzzy space vector modulation (FSVPWM) technique is used in this article. Simulation results show the efficiency of the proposed method of control especially on the quality of the provided power comparatively to a DVC with classical SVPWM strategy of seven-level inverter.

    Keywords: DFIG, SVPWM, FSVPWM, WTS, PI, DVC, Seven-level Inverter