جستجوی مقالات مرتبط با کلیدواژه « Voltage Multiplier » در نشریات گروه « فنی و مهندسی »

This paper investigates the connection of a single-phase multilevel inverter structure to an existing power grid. The applied voltage source inverter is able to generate a near sinusoidal voltage waveform with an amplitude six times the input voltage by using a single DC input power supply. A proportional-resonant (PR) controller regulates the injected current into the grid. While the EPLL is used to ensure the synchronization of the phase and frequency of the output voltage with the grid. The performance of the grid-connected inverter under different loading conditions was simulated in MATLAB software. Finally, the simulation results were compared with the experimental ones. In addition, the behavior of the inverter in standalone operating mode supplying a local load as well as its performance in the grid-tied with a constant and variable current reference was evaluated. The correct operation of the inverter in all operating modes an achieving 96.9% efficiency along with the self-voltage balancing of the capacitors, makes it suitable for grid-integration of the low voltage renewable energy sources’ applications.

This paper presents a new Switched-Capacitor Multilevel Inverter (SCMLI) structure. The presented configuration generates a staircase almost sinusoidal AC voltage by using a single DC source and a few capacitors which its amplitude is several times the input voltage. The operation of the converter is controlled by the help of NLC modulation strategy to choose the best switching states in a way that they always ensure the self-balancing capability of the capacitors voltages. Low switching frequency, simple control and inherent bipolar output are some of the advantages of the presented SCMLI. In comparison with other existing topologies, to reach a specific voltage level, the structure requires less circuit elements since the capacitors in follower modules can be charged up to 3 times the input voltage. Having a modular structure, facilitates the expansion of the circuit to attain higher voltage levels. In order to investigate the performance of the presented topology, MATLAB software was used. Furthermore, a 13-level laboratory prototype was performed to affirm the efficacy of the circuit under different loads using AVR ATMEGA 16A microcontroller. Both simulation and experimental results accredit the appropriate performance of the converter. Finally, after calculating losses, a theoretical efficiency of 92.72% is reached.

Due to the energy storage cells low voltage, such as batteries and super-capacitors, it is often necessary to connect them in series to form a string. Generally, these components are sensitive to over-voltage. Also, due to the inevitable differences in these devices, their charging and discharging processes cause their voltages to be different. This problem leads to inappropriate use of capacity, short life time, and even explosion. To overcome these problems and also to achieve safe and economic operation of these storage devices, employing voltage equalizer converters is necessary, in practice. The proposed converter can overcome the above-mentioned problems and it has less components than the conventional voltage equalizers, smaller dimensions, and lower cost. It operates at a fixed switching frequency under soft switching conditions without any feedback circuit and transformer. Therefore, it is more economic than the conventional voltage equalizers. Here, simulations and analysis of the different operating modes of the converter are given for four series connected lithium-ion batteries. To verify the given analysis and simulations, its prototype has been tested under different conditions. The experimental results are in good agreement with the analysis and simulation results, as well. The batteries voltages maximum differences in simulations and in practice are less than 5 and 10 mV, respectively, which indicate proper circuit operation.

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

Requests for production of high voltage pulses have increased recently. Traditional pulsed power converters suffer from high number of switching components and high amplitude of input voltage. Voltage multipliers are introduced as alternative to generate high voltage pulses with lower input voltage sources. This paper presents a pulsed power inverter based on switched-capacitors multiplier technology with low input voltage sources. The high output voltage can be achieved at a bipolar waveform with a flexible switching frequency. This topology consists of a voltage multiplier based on H-bridge cells and a bipolar Marx topology. Due to application of voltage multiplier at this converter, input DC voltage is boosted to a certain amount and then it will be converted to a high voltage pulse and therefore, number of circuit components decrease to a certain amount in comparison with other power electronics-based topologies. As the main constraint of this circuit is using two switches with high voltage stress, the main application of proposed pulse generator is in the applications with low voltage DC sources. Proposed structure can generate narrow pulses combined with wide pulses as well. Experimental results with TMS320F28335 processor are obtained to verify the analysis.