Shaik Reddi Khasim

Bio: Shaik Reddi Khasim is an academic researcher from VIT University. The author has contributed to research in topics: Inverter & Topology (electrical circuits). The author has an hindex of 3, co-authored 4 publications receiving 27 citations.

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.

A Novel Asymmetrical 21-Level Inverter for Solar PV Energy System With Reduced Switch Count

Abstract: This article presents a novel asymmetrical 21-level multilevel inverter topology for solar PV application. The proposed topology achieves 21-level output voltage without H-bridge using asymmetric DC sources. This reduces the devices, cost and size. The PV standalone system needs a constant DC voltage magnitude from the solar panels, maximum power point tracking (MPPT) technique used for getting a stable output by using perturb and observe (P&O) algorithm. The PV voltage is boosted over the DC link voltage using a three-level DC-DC boost converter interfaced in between the solar panels and the inverter. The inverter is tested experimentally with various combinational loads and under dynamic load variations with sudden load disturbances. Total standing voltage with a cost function for the proposed MLI is calculated and compared with multiple topologies published recently and found to be cost-effective. A detailed comparison is made in terms of switches count, and sources count, gate driver boards, the number of diodes and capacitor count and component count level factor with the same and other levels of multilevel inverter and found to be the proposed topology is helpful in terms of its less TSV value, devices count, efficient and cost-effective. In both simulation and experimental results, total harmonic distortion (THD) is observed to be the same and is lower than 5% which is under IEEE standards. A hardware prototype is implemented in the laboratory and verified experimentally under dynamic load variations, whereas the simulations are done in MATLAB/Simulink.

Design and Implementation of 31-Level Asymmetrical Inverter With Reduced Components

Abstract: This paper presents a novel topology for the single-phase 31-level asymmetrical multilevel inverter accomplished with reduced components count. The proposed topology generates maximum 31-level output voltage with asymmetric DC sources with an H-bridge. The fundamental 13-level multilevel inverter (MLI) topology is realized, and further, the topology is developed for 31-level can be used for renewable energy applications. This reduces the overall components count, cost and size of the system. Rather than the many advantages of MLIs, reliability issues play a significant role due to higher components count to reduce THD. This is a vital challenge for the researchers to increase the reliability with less THD. Several parameters are analyzed for both fundamental 13-level and developed 31-level MLIs such as total standing voltage (TSV), cost function (CF) and power loss. The inverter is tested experimentally with various combinational loads and under dynamic load variations with sudden load disturbances. Total standing voltage with the cost function for the proposed MLI is compared with various topologies published recently and is cost-effective. A detailed comparison of several parameters with graphical representation is made. Less TSV and components requirement is observed for the proposed MLI. The obtained total harmonic distortion (THD) is under IEEE standards. The topology is simulated in MATLAB/Simulink and verified experimentally with a hardware prototype under various conditions.

Selection parameters and synthesis of multi-input converters for electric vehicles: An overview

Abstract: The effect of pollution on the planet earth and the rapid use of fossil fuels provides a strong impulse for the growth and evolution of electric vehicles (EVs). The advancements in Hybrid electric vehicles (HEV) proving the best quick fix towards the severity of the problem on the planet. HEVs not only reduce the emissions but also decreases the fuel cost for the consumer with their improved driving range and dynamic characteristics satisfying environmental regulations. For the extension of the driving range in EVs, multiple energy sources like ultra-capacitor, fuel cells, solar PV are to be interfaced with a battery. This in turn reduces the charging time, which is a significant drawback of EVs. To handle the multiple sources with distinct V–I characteristics, an efficient power electronic circuitry is needed, which can able to provide an efficient power transfer capability between sources and load for the vehicle propulsion. In handling the energy from multiple sources stabilizing at DC bus, the DC-DC converter plays a crucial role. Due to this, in the recent past, the transformation of DC-DC converters from a single input to a multi-input (MIC) has been noticed. The several combinations of integrating sources let on to the new topologies and even more complicated with the configurations. The topology selection imposes more challenges in choosing the best fit for the specific applications. This paper produces a detailed review of the types of EVs, their architectures, merits and demerits. MIC topologies used in EVs with a detailed comparison. A comprehensive study on design rules of MICs, structures and selection procedures of MICs for various applications in detail. This study categorizes MICs based on their characteristics. The significant findings, merits and demerits are also discussed in detail with their suitability.

Design and Implementation of Asymmetrical Multilevel Inverter With Reduced Components and Low Voltage Stress

Abstract: Multilevel inverters with a high device count, low boosting and DC voltage imbalance are all common problems exists in the traditional topologies. In this article, a new single-phase asymmetrical multilevel inverter (MLI) that can generate 33 levels at the output with fewer components and lower total standing voltage (TSV) at the switches is presented. The multiple input sources of the proposed inverter make it suited for the use in renewable energy generating systems which have a variety of DC sources. The stress distribution among the switches is investigated that reduces the use of high rated devices with which overall cost of the inverter gets reduced. The topology can be extended by adding the circuits in series for higher levels. The performance of the inverter is calculated considering a variety of critical parameters such as TSV, cost function (CF), power loss, and efficiency calculations. The MLI is tested under dynamic load conditions with sudden load disturbances with a range of combinational loads and it has been determined to be stable throughout its operation. A detailed comparison is made based on stress across the switches, stress distribution, switches count, DC sources count, gate driver circuits, component count factor, TSV, CF, and other existing topologies using graphical representations and shown to be cost-effective and superior in all aspects. The total harmonic distortion (THD) derived from simulation and experiment complies with IEEE standards. The proposed framework has been developed in MATLAB/Simulink and tested in a laboratory environment with hardware.

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, ...

A Survey on Reduced Switch Count Multilevel Inverters

Abstract: An efficient and cost-effective power converter is a pre-requisite for the modern power applications. With the evolvement of matured medium power self-commutated switching devices, multilevel inverters (MLIs) are emerged as a promising solution for high-power medium-voltage applications. Though, MLIs are performing a promising role in industrial applications, their high device count, size, cost and control complexities have restricted their market penetration. To address the disadvantages of MLIs, researchers are continuously contributing to new generation topologies under the name of reduced switch count (RSC) MLIs. From the past decade, numerous RSC-MLIs topologies have been reported for various applications. Therefore, this paper presents a comprehensive review and classification of RSC-MLI topologies, in terms of their structure, features, limitations, suitability and selection for specific 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.

Dynamic modelling and experimental analysis of PEMFCs: a comparative study

Abstract: Different Fuel Cell (FC) stacks or system models must be developed relevance to a specified main objective,either an accurate electro-chemical behavior descriptionoroptimization procedure at a system level. In this paper,the characteristics of cell polarization V-I curves arestudied for three different dynamicmodels (Dicks, impedance and electrical equivalent circuit). Thesimulation results, usingMATLAB-SimulinkTM,provideanadequateevaluation of each modelunder different load conditions.Although the different models provide acceptable results and are suitable for many applications particularlyembedded systems, the electrical equivalent circuit model offers accuracy four times better than the Dicks model.The experimental validation of the FC voltage-current characteristic obtained by the different models at steady-state and transient conditions is performed. The agreement between the simulation and the experimental results is adequate.

A Novel Asymmetrical 21-Level Inverter for Solar PV Energy System With Reduced Switch Count

Abstract: This article presents a novel asymmetrical 21-level multilevel inverter topology for solar PV application. The proposed topology achieves 21-level output voltage without H-bridge using asymmetric DC sources. This reduces the devices, cost and size. The PV standalone system needs a constant DC voltage magnitude from the solar panels, maximum power point tracking (MPPT) technique used for getting a stable output by using perturb and observe (P&O) algorithm. The PV voltage is boosted over the DC link voltage using a three-level DC-DC boost converter interfaced in between the solar panels and the inverter. The inverter is tested experimentally with various combinational loads and under dynamic load variations with sudden load disturbances. Total standing voltage with a cost function for the proposed MLI is calculated and compared with multiple topologies published recently and found to be cost-effective. A detailed comparison is made in terms of switches count, and sources count, gate driver boards, the number of diodes and capacitor count and component count level factor with the same and other levels of multilevel inverter and found to be the proposed topology is helpful in terms of its less TSV value, devices count, efficient and cost-effective. In both simulation and experimental results, total harmonic distortion (THD) is observed to be the same and is lower than 5% which is under IEEE standards. A hardware prototype is implemented in the laboratory and verified experimentally under dynamic load variations, whereas the simulations are done in MATLAB/Simulink.