A cascaded hybrid phase shift-PWM and asymmetric selective harmonic mitigation-PWM modulation technique for grid-tied converter to reduce the switching frequency and meet the grid current harmonic requirement

Abstract

In this paper, a low frequency hybrid cascaded phase shift-PWM (PSPWM) and asymmetric selective harmonic mitigation-PWM (ASHM-PWM) modulation technique is proposed to meet limits of power quality standard with the low number of switching frequency. For this aim, the low order harmonics of PSPWM technique are reduced by the ASHM-PWM technique. The equations of both modulation techniques are included in the optimization process to meet standard for all of the low order current harmonics of grid-tied cascaded h-bridge (CHB) converter. The proposed technique has advantages of both PSPWM and ASHM-PWM modulation techniques. Furthermore, the critical parameters of grid-tied CHB converter such as inductance and switching frequency of converter are derived based on the equations of proposed hybrid PSPWM and ASHM-PWM technique. The simulation and experimental results were conducted on 7-level CHB converter to validate the proposed modulation technique.