Novel multilevel inverter using Different pwm control techniques For grid connected hotovoltaic System

Abstract

A novel Multi-Level Inverter (MLI) is proposed to generate electrical power for high power applications with minimum Total Harmonic Distortion (THD) and improved power factor. Recently, there is a reduction of THD in three-phase Diode Clamped Multi-Level Inverter (DCMLI) for grid connected Photovoltaic (PV) system. Direct Current (DC) power is the input to the inverter circuit where the input is a solar photo voltaic array. Maximum power from the PV array can be achieved by Maximum Power Point Tracking (MPPT) algorithm. Fuzzy Logic Control (FLC) based MPPT algorithm is used to track maximum power from PV array. Fuzzy based MPPT is chosen because of nonlinear characteristics of the PV array. DC-DC converter is not needed because fuzzy MPPT is integrated with the multilevel inverter so that the output shows accurate and fast response. The absorbed and tracked DC power from the PV array is fed to three phase DCMLI circuit to convert into Alternating Current (AC). The three-phase DCMLI is controlled by two types of Pulse Width Modulation (PWM) techniques called Sinusoidal Pulse Width Modulation (SPWM) technique and Space Vector Pulse Width Modulation (SVPWM) technique. These techniques control the inverter circuit separately and THD rate which are compared between the levels of the three phase inverter circuit. The validity of the system is verified by MATLAB/Simulink environment. Simulation results of the three phase five level and seven-level inverter are compared for both SPWM and SVPWM techniques in terms of THD rate.The proposed topology also increases the level with only ten controlled switches for eleven-level inverter. It dramatically reduces the complexity of control circuit, cost, and lower order harmonic. Multi level inverter was controlled by SPWM technique, and this new model eleven level inverter simulated by the help of MATLAB/Simulink newline