In this study, two types of multilevel convertors, cascaded multilevel inverter with separate DC sources and diode clamped multilevel inverter with common DC source are modeled and compared in the case of feeding of an induction motor. Here, SHEPWM technique is used as the switching strategy. Also a new variable torque feedback control on modulation index is presented, to preserve the induction...

Multilevel inverters have been developed due to limitations of the conventional two-level voltage source inverters (VSIs). Most of the topologies of multilevel inverters that have been presented in the literature are based on the sharing of the rated voltage between the switches so that the switches with lower voltage ratings can be used. In these topologies, the current rating of all of the sw...

This study presents space vector-based quasi-two-level operation of a diode-clamped multilevel inverter which improves dc link utilisation and output voltage quality, and avoids the dc link capacitor voltage balancing problem experienced with standard multilevel operation. Beside a review of quasi-two-level operation and the capacitor voltage balancing method, the study presents a detailed disc...

The above concept brings out the method for the multilevel inverters for generation of space vector pulse width modulation (SVPWM) signals. The small triangles formed by the adjacent voltage space vectors are called sectors. Such six sectors around a voltage space vector forms a hexagon called sub hexagon. The space vector diagram of a multilevel inverter can be viewed as composed of a number o...

In this paper, an H-bridge inverter topology with reduced switch count technique is introduced. This technique reduces the number of controlled switches used in conventional multilevel inverter. To establish a single phase system, the proposed multilevel inverter requires one H-bridge and a multi conversion cell. A multi conversion cell consists of three equal voltage sources with three control...

Multilevel inverter technology has emerged recently as a very important alternative in the area of high-power medium-voltage energy control. This paper presents the most important topologies like diode-clamped inverter (neutral-point clamped), capacitor-clamped (flying capacitor), and cascaded multicell with separate dc sources. Emerging topologies like asymmetric hybrid cells and soft-switched...

This paper presents a micro controller based control of multilevel inverter for single phase Induction motor. IGBT is used as power element. Pulse width modulation techniques (PWM), introduced three decades ago, are the most used methods to control the voltage and frequency supplied to electrical AC machines. This work proposes a new switching scheme for the cascaded H-Bridge multilevel inverte...

The multilevel inverter power structure plays a vital role in the power industry. It is easier to produce a high-power, high-voltage inverter with the multilevel structure. The topologies of multilevel inverter have several advantages such as lower total harmonic distortion (THD), lower electromagnetic interference (EMI) generation, reduction of voltage ratings of the power semiconductor switch...

This project presents a three-level diode-clamped inverter feeding an asynchronous motor drive with direct torque control (DTC). The control method is based on DTC operating principles. The stator voltage vector reference is computed from the stator flux and torque errors imposed by the flux and torque controllers. This voltage reference is then generated using a diode-clamped inverter, where e...

A six-level inverter system for an open-end winding induction motor drive is presented in this paper. Multilevel inversion is achieved by feeding an open-end winding induction motor with a 3-level inverter from one end and a 2-level inverter from the other end of the motor. The 3level inverter used in the proposed drive, is realized by cascading two 2-level inverters. The combined inverter syst...