Novel control technique for quasi Z-source with improved voltage gain and reduced THD

Abstract

A novel control technique for step-up DC/AC renewable energy converter to improve the voltage gain, efficiency and reduce total harmonic distortion (THD) is investigated. The main drawback of the conventional control techniques for DC/AC conversion is drawn from the multistage energy conversion structure which implies complicated control, protection algorithms and reduced reliability due to the increased number of switching devices. To overcome this problem, combination of quasi impedance voltage fed source inverter with a modified double carrier based SPWM in simple operation condition for maximum constant boost control with 3 rd harmonic injection is proposed. This is achieved by voltage-fed quasi impedance source inverter with continuous input current implemented at the converter input side and it can boost the input voltage by utilizing extra switching state with the help of shoot-through state technique. The proposed strategy gives a significantly high voltage gain compared to the traditional PWM techniques since all the zero states are converted into shootthrough states.