جستجوی مقالات مرتبط با کلیدواژه « مبدل های بهره بالا » در نشریات گروه « برق »

Because the traditional fossil energy is not renewable modern societies, are facing energy shortages. As a result, it is necessary to develop new energy that is clean and renewable to replace of fossil fuels. Solar energy, photovoltaic power generation, fuel cell and hydrogen energy are methods used to big - scale energy sources.
In a mono - phase system with two - step structure if the line voltage is 220 volts, bus inverter voltage that connected to network, should be about 380 volts. However, the output voltage of the photovoltaic cells and fuel cells are generally between 25 to 40 volts this voltage is much lower than the bus voltage. So a high efficiency DC-DC converter output voltage is required to boost fuel cells and photovoltaic cells. In this research, will be presented an improved structure as high efficiency voltage boost converter with a voltage multiplier circuit for solar cell applications. In the proposed structure for efficiency improvement, used voltage multiplier circuit techniques and coupled inductors. We have the proposed converter using the active clamp circuit to achieve soft switching conditions and reduce switching losses. generally, the advantages of the proposed converter are high step-up voltage and high efficiency, low voltage stress for switches and diodes, providing soft switching conditions, and ultimately reducing the number of magnetic elements and the circuit's size. In this paper, in addition to describing the operation of the circuit and provide theoretical analyzes, validity of circuit performance will be evaluated through simulation software

Recent developments in renewable energy sources has created demands for high step-up and high efficiency DC-DC converters. This demands are fulfilled basically through the use of high frequency transformer to achieve the required and desired gain. Power electronics solutions based on multi-converter structures provides economic methods for input and output power by combining a number of components. In this paper some of structures reviewed that have been proposed to achieve a high step-up converter and the advantages and disadvantages of these converters are discussed. The proposed converter is provided in order to reduce the voltage stress of high step-up converters based on coupled inductor and passive clamping circuit. The voltage stress of switches in the proposed converter is less than a simple boost converter also in this structure with using passive clamping circuit the oscillation of both sides of the switches is a little clamped and finally by using this technique it can achieve high gain by selecting the appropriate duty cycle. In this paper to review the principle of operation of the proposed converter theoretical analysis are provided and to verify the results of theoretical analysis of the proposed converter is given with its PSPICE simulation.

sun is of the clean and cheapest sources of energy. Charging slight energy to electricity is carried out by PV modules. Since most electric consumers need Ac input voltage, the PV modules output voltage should be changed into Ac form. But, the voltage level of PV modules is much lower than the voltage needed in input stage of inverters. Because of large voltage level. Difference it is not possible to use the basic boost and buck-boost converters. The basic boost and buck-boost converters definitely can not be used in this applications, for, they will face extreme drop in efficiency in duty cycles closer to unity.
In this paper The proposed converter is presented in order to decrease the voltage stress of coupled inductors based high step-up converters. The voltage stress in the proposed converter is lower than the high step-up boost converter with coupled inductors in identical condition. Also, soft switching condition for switches and diodes is realized by active clamp circuit, and with this technique and proper selection of duty cycle, large gain and high efficiency could be achieved ultimately. . In this paper theoretical analysis is used for analyzing the performance of the proposed converters, and in order to verify the theoretical analysis, simulated results from pspice software is provides.