T. Deepa

Bio: T. Deepa 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 4, co-authored 8 publications receiving 30 citations.

A guide to Nearest Level Modulation and Selective Harmonics Elimination modulation scheme for multilevel inverters

Abstract: Calculation of firing angles for the efficient operation of multilevel inverter is very important. This paper gives a simple guide to calculate the firing angles for the operation of multilevel inverter. The firing angles are calculated for Nearest Level Modulation and Selective Harmonics Elimination which are the two very popular low switching frequency modulation schemes. The modulation schemes are implemented on a Multilevel DC-link inverter to generate a nine level output. The simulation is carried out using Matlab/Simulink software. The Matlab code to calculate the THD is also presented. Hardware result is shown to validate the simulation results. The code to execute the firing pulse in Atmega32 AVR microcontroller is also presented.

A new asymmetric multilevel inverter with reduced number of switches and reduction of harmonics using Sine Property

Abstract: In this paper, a new topology named OTF (One-Two-Five) topology is proposed for an asymmetrical multilevel inverter. The OTF topology is implemented with less number of switches compared with other conventional and recently invented topologies. The reduction of switches leads to low cost of the inverter. The reduction of the switches is usually associated with more number of levels achieved and reduced harmonic content. Sine Property is reviewed with the proposed topology to reduce the harmonics content. Simulation is performed for a 17 level inverter of the proposed topology using MATLAB/SIMULINK. Fast Fourier Transformation (FFT) analysis is performed and the results are verified.

Multilevel Inverters: A Review of Recent Topologies and New Modulation Techniques

Abstract: The advent of high power and medium power appliances has given substantial importance to Multilevel Inverters (MLI) in recent times. The MLI is widely used in driving AC loads which requires to be operated with low harmonics. In this paper, the various MLI topologies and the modulation techniques implemented on MLIs are reviewed. While reviewing the various MLI topologies, they are categorized into symmetrical type and asymmetrical type. All the existing MLIs topologies and those that are developed in future can be categorized into one of these two categories. A comprehensive review is done of these topologies to examine the various performance parameters. The modulation techniques are also classified into fundamental switching frequency (FSF) modulation techniques and high switching frequency (HSF) modulation techniques. This classification provides an easy understanding of the concepts that are conveyed by MLI. This paper also gives a broad understanding of the various features of each modulation technique.

Simulation Analysis of a Nearest Level Modulation Scheme for Cross-Connected Sources based MLI

Abstract: This paper proposes a nearest level modulation (NLM) scheme for a Cross-Connected Sources (CCS) based MLI topology. The proposed modulation scheme is found to facilitate a reduction in the total harmonic distortion (THD) at the ac output of the inverter. The modulation scheme employs low switching frequency to operate the MLI. The paper presents an explanatory description of the NLM scheme in order to help the upcoming researchers for designing efficient MLI system. Simulation has been implemented using the MATLAB/Simulink 2015b software package. The simulation results indicate a significant reduction in the voltage THD and current THD. Improvement in the other output parameters of the inverter such as rms voltage, rms current and output power is also seen.

Simulation Analysis of Selective Harmonics Elimination scheme for a Symmetric CHB-Multilevel inverter

Abstract: A selective harmonics elimination (SHE) method for Cascaded H-Bridge (CHB) multilevel inverter (MLI) is proposed in this paper. The proposed modulation scheme is a low switching frequency modulation scheme and it is derived from the nearest level modulation scheme. The proposed modulation scheme reduces the total harmonic distortion (THD) at the ac output of the inverter. The SHE follows an algorithm presented in the paper in order to arrive at a set of switching angles for MLI which offers reduced THD. The Simulation is carried out using MATLAB / Simulink 2015b software and the results are presented which validates the simulation results. Results show that the lower order harmonics are eliminated in the THD content with the use of proposed modulation scheme. As a result of the improved THD content, improvement in the other inverter parameters such as rms voltage, rms current and output power is also observed.

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.<>

Electric power converter

Abstract: Provided is an electric power converter. A First and second series circuits of switching devices and a series circuit of capacitors are connected in parallel. Between the connection point in the first series circuit of switching devices and the connection point in the series circuit of capacitors, a first bidirectional switch is connected and, between the connection point in the second series circuit of switching devices and the connection point in the series circuit of capacitors, a second bidirectional switch is connected. The connection point in the first series circuit of switching devices is connected through a reactor to an input-output common connection line connected to one end of an AC power supply and the other end of the AC power supply is connected to the connection point in the series circuit of capacitors.

Extended Multilevel Inverter Topology With Reduced Switch Count and Voltage Stress

Abstract: For the applications related to the medium/high-power/voltage, Multilevel inverters (MLI) are widely accepted and commercially used. The performance of MLI compare to the conventional two-level inverters is significantly superior due to the insignificant amount of harmonic distortion, lower filter size, requirement of low voltage rating devices, lower electromagnetic interference, etc. However, there are a few disadvantages such as an increased number of components, a complex modulation and control strategy, and issues related to the voltage balancing of capacitors. The present paper proposes a new topology with a lower voltage rating component to improve the performance by remedying the mentioned disadvantages. Compared with existing inverter topologies, (especially higher levels), this topology requires fewer components, fewer dc sources, and gate drives. Further, voltage stress is also low. The overall costs and complexity are therefore greatly reduced, especially for higher voltage levels. The proposed topology has been compared with other similar topologies and the comparison proves the better structure of the proposed topology. To show the working of the proposed topology, a prototype has been developed and tested for a different operating condition with two different modulation techniques. All the results show the adequate performance of the inverter topology at the different real-time environment.

Multilevel Inverter: A Survey on Classical and Advanced Topologies, Control Schemes, Applications to Power System and Future Prospects

Abstract: In recent years, multilevel inverters (MLIs) have emerged to be the most empowered power transformation technology for numerous operations such as renewable energy resources (RERs), flexible AC transmission systems (FACTS), electric motor drives, etc. MLI has gained popularity in medium- to high-power operations because of numerous merits such as minimum harmonic contents, less dissipation of power from power electronic switches, and less electromagnetic interference (EMI) at the receiving end. The MLI possesses many essential advantages in comparison to a conventional two-level inverter, such as voltage profile enhancement, increased efficiency of the overall system, the capability of high-quality output generation with the reduced switching frequency, decreased total harmonic distortions (THD) without reducing the power of the inverter and use of very low ratings of the device. Although classical MLIs find their use in various vital key areas, newer MLI configurations have an expanding concern to the limited count of power electronic devices, gate drivers, and isolated DC sources. In this review article, an attempt has been made to focus on various aspects of MLIs such as different configurations, modulation techniques, the concept of new reduced switch count MLI topologies, applications regarding interface with renewable energy, motor drives, and FACTS controller. Further, deep insights for future prospective towards hassle-free addition of MLI technology towards more enhanced application for various fields of the power system have also been discussed. This article is believed to be extremely helpful for academics, researchers, and industrialists working in the direction of MLI technology.

A guide to Nearest Level Modulation and Selective Harmonics Elimination modulation scheme for multilevel inverters

Abstract: Calculation of firing angles for the efficient operation of multilevel inverter is very important. This paper gives a simple guide to calculate the firing angles for the operation of multilevel inverter. The firing angles are calculated for Nearest Level Modulation and Selective Harmonics Elimination which are the two very popular low switching frequency modulation schemes. The modulation schemes are implemented on a Multilevel DC-link inverter to generate a nine level output. The simulation is carried out using Matlab/Simulink software. The Matlab code to calculate the THD is also presented. Hardware result is shown to validate the simulation results. The code to execute the firing pulse in Atmega32 AVR microcontroller is also presented.