A new approach for harmonic elimination in single-phase voltage source inverters

In this thesis firstly, modeling and simulation of a single-phase inverter has been performed by using two different modulation algorithms. Circuit structure of a single-phase voltage source inverter has been given and its operation has been analyzed for various load characteristics. Quasi square wave and pulse width modulation (PWM) algorithms which are used as voltage and frequency control methods in inverters have been demonstrated and applied to the single-phase inverter. The inverter has been modeled in Matlab/Simulink and simulation results have been taken for two modulation algorithms. Simulation results which are taken for various modulation indexes and output frequencies have been compared for the same operating conditions. In this thesis, a novel control technique which is a particular implementation of the quasi square wave method has been proposed for the single-phase voltage source inverter. This method produces V/f controlled voltage waveform at the output with low harmonic content comparing to the quasi square wave modulation technique. In addition the semiconductor devices in the inverter turns on and off only once in one output period resulting in minimum switching losses. Matlab/Simulink models of the proposed system and the inverter system with quasi square wave modulation technique have been obtained. The comparative simulation results for both techniques are given at various output frequencies. Open-loop V/f control has been applied to both inverters. Superiority of the proposed technique to the classical quasi square wave modulation technique has been shown with the output waveforms and their spectra.