www.ijsetr.com ISSN 2319-8885 Vol.04,Issue.20, June-2015, Pages:3771-3777 Copyright @ 2015 IJSETR. All rights reserved. A Higher Voltage Multilevel Inverter with Reduced Number of Power Electronic Switches TEKI VAMSEE KRISHNA 1 , DARA SUBRAHMANYAM 2 , A. VENKAR RAO 3 1 PG Scholar, Dept of Power Electronics, St.Mary’s Engineering College, Hyderabad, TS, India,E-mail: amsi.teki239@gmail.com. 2 Assistant Professor, Dept of EEE, St.Mary’s Engineering College, Hyderabad, TS, India, E-mail: 214mani@gmail.com. 3 HOD, Dept of EEE, St.Mary’s Engineering College, Hyderabad, TS, India, E-mail: Hodeeesmec@stmarysgroup.com. Abstract: Power electronic inverter become popular for various industrial drives applications. The multi-level inverter system is very promising in ac drives. Large electrical drives and utility application require advanced power electronics converter to meet the high power demands. As a result, multilevel power converter structure has been introduced as an alternative in high power and medium voltage situations. A multilevel converter not only achieves high power rating but also improves the performance of the whole system in terms of harmonics. The inverter output with more numbers of voltage levels with reduced number of switches as compared to cascade H-bridge inverter, which results in reduction of installation cost and have simplicity of control system. In this paper, a new configuration of a three-phase seven-level multilevel voltage source inverter is introduced. The proposed topology constitutes the conventional three-phase five-level bridge with three bidirectional switches. A multilevel dc link using fixed dc voltage supply and cascaded half-bridge is connected in such a way that the proposed inverter outputs the required output voltage levels. For the purpose of increasing the number of voltage levels with fewer number of power electronic components, the structure of the proposed inverter is extended and different methods to determine the magnitudes of utilized dc voltage supplies are suggested by using MAT Lab/Simulink. Keywords: Bidirectional Switch, Fundamental Frequency Staircase Modulation, Multilevel Inverter . I. INTRODUCTION Multilevel inverters are composed of a number of power electronic switches and DC voltage sources that produce a stepped voltage waveform in its output. Generally, multilevel inverters are divided into three categories as follows: neutral-point clamped inverter (NPC), flying capacitor inverter (FC), and cascaded H- bridge inverter (CHB). These inverters can surrender higher power with lower dv/dt and di/dt in output waveform which is to reduce EMI noise and Size of the output filter. Therefore, using these inverters is very common nowadays. In recent years, several architectures have been proposed for cascade multilevel inverters. This kind of inverters can produce more voltage levels and also provide higher quality of power in its output. As a result, this kind of inverter is considered more than other kinds of inverters. Cascade inverters are made of series separate single phase inverters with separate dc voltage sources. On the other hand, this inverter consists of a number of basic blocks (sub multilevel inverter) that each of these blocks has similar control system. One of the major advantages of this type of inverters is the ability of its modulation. So, if an error occurs in one of the blocks, it can replace or fix by using a control system, but there are some disadvantages such as high number of dc voltage sources and power electronic switches. Increasing the number of power electronic switches leads to increase the number of driver circuits too. Both of these issues caused to increase in complexity, size, and cost of the circuit. Thus, reducing the number of power electronic switches is very vital and should be considered. Some applications for these new converters include industrial drives, flexible ac transmission systems (FACTS), and vehicle propulsion. One area where multilevel converters are particularly suitable is that of renewable photovoltaic energy that efficiency and power quality are of great concerns for the researchers. Some new approaches have been recently suggested such as the topology utilizing low switching-frequency high-power devices. Although the topology has some modification to reduce output voltage distortion, the general disadvantage of this method is that it has significant low-order current harmonics. The purpose of improving the performance of the conventional single- and three-phase inverters, different topologies employing different types of bidirectional switches. Comparing to the unidirectional one, bidirectional switch is able to conduct the current and withstanding the voltage in both directions. Bidirectional switches with an appropriate control technique can improve the performance of multilevel inverters in terms of reducing the number of