Vol-1, Issue-1 PP. 36-45 ISSN: 2394-5788 36 | Page 30 November 2 0 1 4 www.gjar.org Development of High-Level Asymmetric Multilevel Inverter with Reduced Number of Switches for Fuel Cells S.Dharani PG Student, Department of EEE SSN College of Engineering, Chennai India. Dr.R. Seyezhai Associate Professor Renewable Energy Conversion Laboratory Department of EEE SSN College of Engineering, Chennai India. ABSTRACT Multilevel inverters have been an attractive topology for academia as well as industry in the recent decade for high power and medium voltage energy control. An asymmetric multilevel inverter, a new topology increases the level of output with reduced lower order harmonics and total harmonic distortion. In this topology, the output voltage and power increases with the number of level and increasing output voltage does not require an increase in voltage rating of individual commutated devices. In this paper, a fifteen-level asymmetric MLI with three DC sources and seven switches have been proposed which will be suited for fuel cell applications. For the proposed MLI, a new hybrid modulation technique combining the PWM and fundamental frequency switching technique is developed. The inverter structure is studied and simulated in MATLAB/SIMULINK for investigating the spectral quality of the output. Total Harmonic Distortion (THD) is analyzed for the various PWM techniques and the results are verified through simulation results. Keywords: Asymmetric Multilevel inverter, Total Harmonic Distortion, Sinusoidal Pulse Width Modulation, Fundamental frequency Pulse Width Modulation. 1. INTRODUCTION Multilevel inverters have the advantages like reduced EMI/RFI generation, minimum total harmonic distortion and can operate on several voltage levels compared with the conventional two-level inverter. Harmonics are reduced due to multi-switching and output is approximately a sine wave so the filter design and cost are reduced. The requirements of AC loads are fulfilled by controlling the output voltage of the inverters when such loads are fed by inverters. The MLI is used for high power ratings and for renewable energy sources such as fuel cell, wind and photovoltaic that can be interfaced easily for a high power application. The multilevel inverter can operate at both fundamental switching frequency and high switching frequency PWM. Multilevel inverter has two major classifications: Symmetric Multilevel Inverter and Asymmetric Multilevel Inverter (AMLI). AMLI is more advantageous than the symmetric one, because it produces more number of levels with same number of switches by having unequal voltage