A cascaded h-bridge multilevel inverter based on switched-capacitor for high frequency ac applications

Abstract

High frequency ac applications with a reduced component of a cascaded multilevel inverter using switched capacitor are proposed in this project. Here switched capacitor and H-Bridges are constructed in front end and back end through the connections of series and parallel conversions. An increasing the voltage level by switched capacitor, output harmonics can be reduced. High Frequency AC Applications (HFAC) is alternative to DC distribution due to lower cost. These are most commonly used to apply for small scale and closed electrical network in electric vehicles due to moderate size and reduction of weight for distribution network. The type of multilevel inverter used in this project is cascaded H-Bridge and they built by the series connection of H-Bridges. It is similar to dc-dc converters. The cascaded H-Bridges needs individual input and four power switches for construction in order to increase number of voltage levels with their staircase output. However control strategy is difficult because of input current will be in discontinuous; therefore Electromagnetic Interference (EMI) becomes worst. The advantages for this topology at rated output frequency of about 20 kHz are feasible to operate, increasing reliability and high efficiency. By increasing number of voltage levels, the total harmonic distortion (THD) content of staircase output can be decreased and further in such a way that, has a particular meaning to simplifying the filter design. This topology will be analyzed by symmetrical modulation for 13–level inverter, which is based on switched capacitor of a cascaded multilevel inverter for HFAC PDS. The entire system is simulated in MATLAB/SIMULINK TOOL.