A Double PS-PWM Strategy for Improving Total Output Current Quality in Parallel Converters

This article proposes a double phase shifted pulsewidth modulation (PWM) strategy to improve the quality of total output current in multiple parallel converters for the photovoltaic application with the advantage of being easy to implement/extend. Different from phase shifted PWM (PS-PWM), the additional modified angles are deduced and added in the initial phase shifted angles of carriers. The better total output current with lower total harmonic distortion can be achieved by modifying the phase shifted angles of carriers in each converter twice. The harmonic spectrum analysis shows that the proposed method could provide superior total output line voltage and total output current quality than conventional PS-PWM. The correctness and effectiveness of the proposed method are verified by the experiments in parallel three-phase two-level and three-level converters.