935 research outputs found

    A generalized multilevel inverter based on T-Type switched capacitor module with reduced devices

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    Conventional multilevel inverters have problems in terms of their complicated expansion and large number of devices. This paper proposes a modular expanded multilevel inverter, which can effectively simplify the expansion and reduce the number of devices. The proposed inverter can ensure the voltage balancing of the voltage-dividing capacitors. The cascading of the T-type switched capacitor module and the step-by-step charging method of the switched capacitors enable the inverter to achieve high output voltage levels and voltage gain. In addition, the inversion can be achieved without the H-bridge, which greatly reduces the total standing voltage of the switches. The nine-level inverter of the proposed topology can be realized with only ten switches, obtaining a voltage gain that is two times larger. The above merits were validated through theoretical analysis and experiments. The proposed inverter has good application prospects in medium- and low-voltage photovoltaic power generation

    Reduced switch multilevel inverter topologies for renewable energy sources

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    This article proposes two generalized multilevel inverter configurations that reduce the number of switching devices, isolated DC sources, and total standing voltage on power switches, making them suitable for renewable energy sources. The main topology is a multilevel inverter that handles two isolated DC sources with ten power switches to create 25 voltage levels. Based on the main proposed topology, two generalized multilevel inverters are introduced to provide flexibility in the design and to minimize the number of elements. The optimal topologies for both extensive multilevel inverters are derived from different design objectives such as minimizing the number of elements (gate drivers, DC sources), achieving a large number of levels, and minimizing the total standing voltage. The main advantages of the proposed topologies are a reduced number of elements compared to those required by other existing multilevel inverter topologies. The power loss analysis and standalone PV application of the proposed topologies are discussed. Experimental results are presented for the proposed topology to demonstrate its correct operation. © 2013 IEEE

    Design, Optimization and Implementation of a High Frequency Link Multilevel Cascaded Inverter

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    This thesis presents a new concept of cascaded MLI (CMLI) device reduction by utilizing low and high frequency transformer link. Two CMLI topologies, symmetric and asymmetric are proposed. Compared with counterpart CMLI topologies available in the literatures, the proposed two inverter topologies in this thesis have the advantages of utilizing least number of electronic components without compromising overall performance particularly when a high number of levels is required in the output voltage waveform

    Development of a multilevel converter topology for transformer-less connection of renewable energy systems

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    The global need to reduce dependence on fossil fuels for electricity production has become an ongoing research theme in the last decade. Clean energy sources (such as wind energy and solar energy) have considerable potential to reduce reliance on fossil fuels and mitigate climate change. However, wind energy is going to become more mainstream due to technological advancement and geographical availability. Therefore, various technologies exist to maximize the inherent advantages of using wind energy conversion systems (WECSs) to generate electrical power. One important technology is the power electronics interface that enables the transfer and effective control of electrical power from the renewable energy source to the grid through the filter and isolation transformer. However, the transformer is bulky, generates losses, and is also very costly. Therefore, the term "transformer-less connection" refers to eliminating a step-up transformer from the WECS, while the power conversion stage performs the conventional functions of a transformer. Existing power converter configurations for transformer-less connection of a WECS are either based on the generator-converter configuration or three-stage power converter configuration. These configurations consist of conventional multilevel converter topologies and two-stage power conversion between the generator-side converter topology and the high-order filter connected to the collection point of the wind power plant (WPP). Thus, the complexity and cost of these existing configurations are significant at higher voltage and power ratings. Therefore, a single-stage multilevel converter topology is proposed to simplify the power conversion stage of a transformer-less WECS. Furthermore, the primary design challenges – such as multiple clamping devices, multiple dc-link capacitors, and series-connected power semiconductor devices – have been mitigated by the proposed converter topology. The proposed converter topology, known as the "tapped inductor quasi-Z-source nested neutral-point-clamped (NNPC) converter," has been analyzed, and designed, and a prototype of the topology developed for experimental verification. A field-programmable gate array (FPGA)-based modulation technique and voltage balancing control technique for maintaining the clamping capacitor voltages was developed. Hence, the proposed converter topology presents a single-stage power conversion configuration. Efficiency analysis of the proposed converter topology has been studied and compared to the intermediate and grid-side converter topology of a three-stage power converter configuration. A direct current (DC) component minimization technique to minimize the dc component generated by the proposed converter topology was investigated, developed, and verified experimentally. The proposed dc component minimization technique consists of a sensing and measurement circuitry with a digital notch filter. This thesis presents a detailed and comprehensive overview of the existing power converter configurations developed for transformer-less WECS applications. Based on the developed 2 comparative benchmark factor (CBF), the merits and demerits of each power converter configuration in terms of the component counts and grid compliance have been presented. In terms of cost comparison, the three-stage power converter configuration is more cost-effective than the generatorconverter configuration. Furthermore, the cost-benefit analysis of deploying a transformer-less WECSs in a WPP is evaluated and compared with conventional WECS in a WPP based on power converter configurations and collection system. Overall, the total cost of the collection system of WPP with transformer-less WECSs is about 23% less than the total cost of WPP with conventional WECs. The derivation and theoretical analysis of the proposed five-level tapped inductor quasi-Z-source NNPC converter topology have been presented, emphasizing its operating principles, steady-state analysis, and deriving equations to calculate its inductance and capacitance values. Furthermore, the FPGA implementation of the proposed converter topology was verified experimentally with a developed prototype of the topology. The efficiency of the proposed converter topology has been evaluated by varying the switching frequency and loads. Furthermore, the proposed converter topology is more efficient than the five-level DC-DC converter with a five-level diode-clamped converter (DCC) topology under the three-stage power converter configuration. Also, the cost analysis of the proposed converter topology and the conventional converter topology shows that it is more economical to deploy the proposed converter topology at the grid side of a transformer-less WECS

    A Flexible Rung Ladder Structured Multilevel Inverter

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    The tenet of the multilevel inverter (MLI) is a peculiar kind in the voltage source inverter (VSI) family, which offers a prudent solution to prevailing issues of conventional two levels VSI, higher dv/dt and harmonic distortion, through a staircase/stepped output voltage from multiple separate dc sources (SDCs). The incessant research effort in the last four decades has bestowed a host of MLI topologies with different concepts, structures, component requirements and application appropriateness. The main issue with the MLI structures is the objectionable component count while upping the number of levels in the output staircase waveform. This paper suggests a new MLI structure, a flexible rung ladder structured multilevel inverter (FRLSMLI), with a savvy to operate both in symmetrical and asymmetrical modes involving only fewer component counts. The proposed FRLSMLI is basically a ladder structured bridge (H-bridge with additional rungs) and the rungs comprise either source inclusion-bypass cell (SIBC) or four level creator cell (FLCC). The FRLSMLI can synthesize fifteen levels with three SDCs. The simulation and experimental results are projected to validate the viability of proposed MLI in real time applications

    Multilevel Converters: An Enabling Technology for High-Power Applications

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    | Multilevel converters are considered today as the state-of-the-art power-conversion systems for high-power and power-quality demanding applications. This paper presents a tutorial on this technology, covering the operating principle and the different power circuit topologies, modulation methods, technical issues and industry applications. Special attention is given to established technology already found in industry with more in-depth and self-contained information, while recent advances and state-of-the-art contributions are addressed with useful references. This paper serves as an introduction to the subject for the not-familiarized reader, as well as an update or reference for academics and practicing engineers working in the field of industrial and power electronics.Ministerio de Ciencia y Tecnología DPI2001-3089Ministerio de Eduación y Ciencia d TEC2006-0386
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