C. Dhanamjayulu

Bio: C. Dhanamjayulu is an academic researcher from VIT University. The author has contributed to research in topics: Inverter & Total harmonic distortion. The author has an hindex of 7, co-authored 24 publications receiving 177 citations.

Implementation and Comparison of Symmetric and Asymmetric Multilevel Inverters for Dynamic Loads

Abstract: This paper implements and compares a symmetric hybridized cascaded multilevel inverter and an asymmetric multilevel inverter utilizing a switched capacitor unit for 17 level inverters. The symmetric hybridized multilevel inverter topology consists of a modified H-bridge inverter, which results in an increase in the output voltage to five level from the three level by using a bi-directional switch at the midpoint of a dual-input dc source. In the proposed asymmetric multilevel inverter, dc sources are replaced with the switched capacitor unit, which in turn boosts the output voltage and produces twice the voltage levels at the loads. The proposed topology with the staircase modulation technique has been verified using MATLAB–SIMULINK, and the results are experimentally executed with prototype models, which are interfaced with dSPACE RTI 1104. The results of the proposed topologies are experimentally obtained for steady state, and the performance of the same is tested under different resistive and inductive load disturbance conditions. The results substantiate that these multilevel inverter topologies are better stabilized during load disturbance conditions with low total harmonic distortion, a lesser number of switches, and increased output voltage levels, and these topologies well suit for renewable energy applications.

Design and Implementation of Seventeen Level Inverter With Reduced Components

Abstract: The multilevel inverters (MLI) are resourceful in producing a voltage waveform with superior-quality staircase counterfeit sinusoidal and depressed harmonic distortion (THD). Several conventional topologies are proposed to realize the MLI however, the limitations of these topologies may involve more DC sources and power-switching devices, and less THD, which in turn, increases the cost and size of the inverter. These drawbacks can be eliminated with the proposed hybrid Cascaded H-Bridge Multilevel Inverter with reduced components topology. As compared with the established MLI topologies the recommended topology having a reduced number of DC sources, power-switching devices, component count level factor, lesser TSV, more efficient, lesser THD, and cost-effective. The proposed MLI is a blend of a single-phase T-Type inverter and an H-Bridge module made of sub switches. This article incorporates the design and simulation of the multilevel inverter with staircase PWM technique. Further, the 9-level and 17-level MLI is examined with different combinational loads. The proposed inverter is stable during nonlinear loads, and it is well suited for FACTS and renewable energy grid-connected applications. An operational guideline has been explained with correct figures and tables. The Output voltage wave is realized in numerical simulation. Finally, the experimental demonstrations were performed by implementing a hardware prototype setup for both linear and nonlinear loads using the dSPACE controller laboratory.

Design and Implementation of Multilevel Inverters for Fuel Cell Energy Conversion System

Abstract: Power converter plays a significant role in Proton Exchange Membrane Fuel Cell (PEMFC) energy generation systems, which is an alternative of distributed energy generation systems. So there creates a demand for high-quality power conditioning used in PEMFC systems. This article proposes a converter topology as a power interface and also introduced a multilevel inverter topology for various levels of operation. The converter steps up the input voltage to the rated voltage and transforms to the DC bus, the multilevel inverter converts the voltage to AC and feeds to AC loads. In this article, we develop an entire unit stack, which can produce an output with positive and zero sequences. The addition of H-bridge to the fundamental unit known to be an advance cascaded H-bridge multilevel inverter resulting in the formation of all sequences like positive, zero and negative levels. The conventional multilevel inverters are compared with the proposed inverters in terms of switch count, DC sources, diodes, through which the lesser requirement of components in a multilevel inverter is possible to observe, which results in the reduction in cost, dv/dt stress, component space of the driver circuit. With this implementation, the better possibility of control, increase the quality of output, reliability of the inverter with a reduced THD, and stress. The converter output is tested and verified in MATLAB, and the respective results of the different levels like five, seven and fifteen of a single-phase cascaded inverter are tested experimentally and in MATLAB Simulink.

Multi-level conversion : high voltage choppers and voltage-source inverters

Abstract: The authors discuss high-voltage power conversion. Conventional series connection and three-level voltage source inverter techniques are reviewed and compared. A novel versatile multilevel commutation cell is introduced: it is shown that this topology is safer and more simple to control, and delivers purer output waveforms. The authors show how this technique can be applied to either choppers or voltage-source inverters and generalized to any number of switches.<>

Annual European Union greenhouse gas inventory 1990-…2011 and inventory report 2013

Abstract: Annual European Union greenhouse gas inventory 1990-…2011 and inventory report 2013. Copenhagen : European Evironment Agency, 2013, 1159 p.(Technical report No 8/2013) http://www.eea.europa.eu/publications/european-union-greenhouse-gas-inventory-2013 This report is the annual submission of the greenhouse gas inventory of the European Union to the United Nations Framework Convention on Climate Change and the Kyoto Protocol. It presents greenhouse gas emissions between 1990 and 2011 for EU-27, ...

The Alternate Arm Converter: A New Hybrid Multilevel Converter with DC-Fault Blocking Capability

Abstract: This paper explains the working principles, sup- ported by simulation results, of a new converter topology intended for HVDC applications, called the alternate arm converter (AAC). It is a hybrid between the modular multilevel converter, because of the presence of H-bridge cells, and the two-level converter, in the form of director switches in each arm. This converter is able to generate a multilevel ac voltage and since its stacks of cells consist of H-bridge cells instead of half-bridge cells, they are able to gen- erate higher ac voltage than the dc terminal voltage. This allows the AAC to operate at an optimal point, called the “sweet spot,” where the ac and dc energy flows equal. The director switches in the AAC are responsible for alternating the conduction period of each arm, leading to a significant reduction in the number of cells in the stacks. Furthermore, the AAC can keep control of the current in the phase reactor even in case of a dc-side fault and support the ac grid, through a STATCOM mode. Simulation results and loss calculations are presented in this paper in order to support the claimed features of the AAC.

A New Multilevel Inverter Topology With Reduce Switch Count

Abstract: Multilevel inverters are a new family of converters for dc-ac conversion for the medium and high voltage and power applications. In this paper, two new topologies for the staircase output voltage generations have been proposed with a lesser number of switch requirement. The first topology requires three dc voltage sources and ten switches to synthesize 15 levels across the load. The extension of the first topology has been proposed as the second topology, which consists of four dc voltage sources and 12 switches to achieve 25 levels at the output. Both topologies, apart from having lesser switch count, exhibit the merits in terms of reduced voltage stresses across the switches. In addition, a detailed comparative study of both topologies has been presented in this paper to demonstrate the features of the proposed topologies. Several experimental results have been included in this paper to validate the performances of the proposed topologies with different loading condition and dynamic changes in load and modulation indexes.

A review on symmetric, asymmetric, hybrid and single DC sources based multilevel inverter topologies

Abstract: In recent past, multilevel inverters(MLIs) are treated as sophisticated power conversion systems demanded for high power medium voltage applications. The aim of this article is to review on recent examined multilevel inverter topologies which can be classified into four groups according to the DC voltage supplied to each fundamental unit and/or arrangement of non-identical fundamental units in an one configuration: Symmetric, Asymmetric, Hybrid and Single DC source topologies. In each group, several new versions have been constructed for last few decades. In this study the position (design and functionality) of each and every topology and also every group are reviewed. Further, a special attention is focused on Single DC source MLIs. Finally at the end of the review, merits, limitations and adequate applications are clearly mentioned. Thus, present review provides complete overview among newly developed multilevel inverters.