Sinusoidal Current through Seven-Level Inverter using Solar Power Generation System

Abstract: This paper proposes a new seven level inverter with a solar power generation system, which is composed of a dc-dc power converter and a new seven level inverter. The dc-dc power converter integrates a boost converter and a transformer to convert the output voltage of the solar cell array into independent voltage sources with multiple relationships. The most commonly used solar cell model is introduced and the generalized PV model using Matlab/simulink is developed. Taking the effect of solar intensity and cell temperature, the characteristics of PV model is simulated. This model can be used for analysis of PV characteristics and for simulation with Maximum power point tracking algorithms. This new seven level inverter is configured using a capacitor selection circuit and a full bridge power converter. The capacitor selection circuit converts the two output voltage sources of dc/dc power converter into a three level dc voltage, and the full bridge converter further converts this three level dc voltage into seven level ac voltage. The proposed system generates a sinusoidal output current that is in phase with the utility voltage and is fed into the utility. Some of the advantages are that the output waveform were improved since new seven level produced nearly sinusoidal output voltage waveforms, hence the total harmonic distortion also low. The switching losses also become less. And, the filter needed to smooth the output voltage is small; hence, the system is compact, lighter and much cheaper.

Keywords: Grid-connected, multilevel inverter, pulse-width modulated (PWM) inverter.