Pallavee Bhatnagar

Multilevel Inverter Topologies With Reduced Device Count: A Review

Multilevel inverters have created a new wave of interest in industry and research. While the classical topologies have proved to be a viable alternative in a wide range of high-power medium-voltage applications, there has been an active interest in the evolution of newer topologies. Reduction in overall part count as compared to the classical topologies has been an important objective in the recently introduced topologies. In this paper, some of the recently proposed multilevel inverter topologies with reduced power switch count are reviewed and analyzed. The paper will serve as an introduction and an update to these topologies, both in terms of the qualitative and quantitative parameters. Also, it takes into account the challenges which arise when an attempt is made to reduce the device count. Based on a detailed comparison of these topologies as presented in this paper, appropriate multilevel solution can be arrived at for a given application.

Control techniques analysis of DC-DC converter for photovoltaic application using SIMSCAPE

This paper presents design and simulation of a dc -dc boost converter for photovoltaic solar system, using two different control techniques, using SIMSCAPE. SIMSCAPE is software used for simulation of PV cell and panel. A photovoltaic solar system exhibits nonlinear voltage-current characteristic and it varies with solar insolation and temperature. Also maximum power output of PV array varies with the change in temperature and insolation conditions. A DC-DC boost converter efficiently converts DC voltage to a higher voltage, and is also used for PV maximum power tracking purpose to obtain maximum power possible from PV solar system. This paper proposes step by step process of designing and simulation of DC to DC boost converter for a Solar panel of 12 Volts open circuit voltage, 50 Ampere short circuit current and a load of 120 ohms. The DC to DC converter is first simulated at a switching frequency of 100 kHz using PWM controller and then the same converter is simulated using hysteresis controller.

Basics of Multilevel Inverters

This chapter introduces you to the “concept” of multilevel inverters. This concept is best understood with the example of so-called cascaded H-bridge topology. In addition, other conventional topologies are also discussed in this chapter, along with the respective modulation schemes employed for these topologies.

Basics of Inverters

In this chapter, fundamental concepts related to power electronics and inverters are discussed. Popular terminology is defined so that understanding multilevel inverters becomes much easier.

Comparison of Multilevel Inverter Topologies

In this chapter, a paradigm is presented to compare multilevel inverter topologies. As an example of the paradigm, topologies discussed in this book are compared with conventional topologies and also compared with one another for their advantages and disadvantages.

Cross-Connected Sources-Based Multilevel Inverter

In contrast to the BCS-MLI discussed in Chapter 5, Multilevel Inverter Based on Bridge-Type Connected Sources, a novel topology for multilevel DC-to-AC conversion is discussed in this chapter which requires only bidirectional-conducting-unidirectional-blocking switches and can operate effectively with symmetric and asymmetric sources. It consists of isolated input DC sources alternately connected in opposite polarities through power switches. The structure allows the synthesis of a multilevel waveform using a reduced number of power switches as compared to the classical topologies. The working principle of the proposed topology is explained and important mathematical formulations are presented. Also, an algorithm for asymmetric source configuration is presented since the popular configurations cannot be used with the topology. In addition, an alternative generalization of CCS-MLI is also presented in which “cells” with two input sources are series-connected so as to form a cascaded structure. The primary objective of this structure is to retain the salient features of the CCS-MLI structure with two input sources; namely, fundamental switching operation of higher voltage-rated switches and possibility of equal load sharing amongst the equal input DC sources. Separate accounts of symmetric and asymmetric source configurations are presented along with appropriate switching procedures.

Multilevel Inverter Based on Bridge-Type Connected Sources

Abstract This chapter introduces a new multilevel converter topology which can synthesize all possible additive and subtractive combinations of input DC levels in the output voltage waveform. The input voltage levels are obtained from floating DC sources such that the consecutive sources are connected in a “bridge” fashion through controlled power switches. The operation and performance of the topology has been ascertained through simulations and experimentation with the example of a single-phase nine-level inverter. In addition, a 15-level inverter with asymmetric source configuration is presented to demonstrate charge balance control using state selection procedure.

Advent of New Topologies

Abstract This chapter discusses the background to the evolution of new topologies of multilevel inverters. A detailed discussion is presented with a description of topologies that have been conceptualized with the objective of reducing the device count for an increased number of output levels.

Universal Control Scheme with Voltage-Level-Based Methods

Abstract The process of switching the semiconductor devices in a power electronic converter from one state to another is called modulation. For a given family of converters, the development of modulation strategies and control schemes must take into consideration parameters such as: switching frequency, distortion, losses, harmonic generation, and speed of response. To date, many topologies for multilevel inverters (MLIs) have been introduced and various modulation schemes have been studied. In this chapter a so-called universal control scheme for MLIs is developed so as to modulate any topology with voltage-level-based modulation techniques. Practical implementation of such a scheme is facilitated by modern tools to interface computer-based models (e.g., using MATLAB/Simulink) with advanced digital processors (e.g., a dSPACE DS1103 real-time controller).