Smooth adjustment of switching frequency of triple PWM inverters of transformer-based PV system

Abstract

This paper presents a comparative analysis of the operation of a photovoltaic (PV) inverter unit consisting of three voltage source inverters with synchronous pulse-width modulation (PWM). The inverters are controlled by flexibly adjusting their switching frequency based on the current magnitude of the dc voltage of the corresponding PV strings. Such smooth adjustment of the switching frequency of inverters allows for a reduction in harmonic distortion of the winding voltage of the power transformer. Continuous and discontinuous schemes of synchronous space-vector PWM for smooth regulation of inverters are investigated. Simulation results are provided to verify the analyzed control and modulation strategy.