No abstract

No abstract

No abstract

This paper presents a novel step-up DC to AC converter with only one power supply. These types of converters are suitable for renewable and sustainable energy applications with low input DC sources. The proposed topology has the ability of self-voltage balancing and does not apply end side H-bridge to produce a bipolar staircase waveform. Consequently, switching losses and voltage stress of semiconductor components are reduced to a great extent. A small DC voltage source can be used to achieve a high voltage high quality AC waveform through switching the pre-charged capacitors in series and in parallel. Circuit configuration and its operation principle, capacitors' charging process, thermal model, capacitances and losses calculations are discussed in details. Moreover, the comparison of the proposed circuit with the other single source multilevel converters shows that the proposed topology reduces the number of circuit elements. Finally, a laboratory 9-level prototype is built to verify the theoretical analyses and feasibility of the proposed topology. The experimental results show that the converter efficiency at 1 KW output power is 92.75 %.

This study presents a new topology of switched-capacitor (SC) multilevel inverter, which is able to step-up input DC voltage to a multilevel AC waveform. This single source inverter is designed based on series connection of the capacitors that charged by input DC sources through a SC network. The proposed modular inverter uses famous T and cross-connected modules that can be simply extended to higher output voltages without increasing the amount of total standing voltage and peak inverse voltage of switches. It generates positive and negative voltage levels inherently, which eliminates requirements of Hbridge inverters that are traditionally used to achieve a bipolar output voltage. Analysis shows that the voltage stress on components, cost, efficiency and losses are kept in acceptable range especially for higher-voltage levels. Capacitor's voltage self-balancing is another inherent advantage of this modular topology which leads to simplify control strategy and eliminate excess balancing circuit. Performance of a six-step proposed structure is evaluated by theoretical analysis, simulation and experimental results.

This study presents a new module for cascaded multilevel inverters (MLIs) based on switched-capacitor technique. Charging of the capacitors in the proposed switched-capacitor cell is performed in a self-balancing form. Voltage boosting capability and generating bipolar voltage levels without requiring an end-side H-bridge inverter are remarkable benefits of the proposed topology. Thereby, semiconductors with lower-voltage ratings are applied in its circuit. Comparison of the proposed inverter with traditional topologies and other recently introduced MLIs shows that the proposed topology reduces the number of circuit elements and also total blocking voltage by switches. Moreover, the proposed inverter configuration and its operating principle, capacitance, and power loss calculations, and also topology extension to achieve higher levels are investigated in depth. Finally, an experimental prototype is built to verify the theoretical analysis and feasibility of the proposed topology.

This study presents a new module for multilevel inverters with reduced components. Each module produces 25 levels using four asymmetrical DC voltage sources (two 1V DC and two 5V DC sources) and 10 semiconductor switches. A significant advantage of the suggested module is its potentiality in producing voltage levels with negative polarity without any end side Hbridge inverter. Therefore, switches with lower voltage ratings are used in its structure. Series connection of the proposed structure leads to a modular topology which produces more voltage levels using reasonable number of switches, gate driver circuits, power diodes and less DC voltage sources. These advantages are analysed by comparing this structure with other state-of-the-art topologies. Selective harmonic elimination pulse width modulation (SHE-PWM) scheme is used to achieve output voltage with high quality. To produce all voltage levels, two algorithms are proposed to determine DC voltage sources magnitude. The accuracy of the suggested module performance in producing all voltage levels is verified by simulation and experimental results.

No abstract