An integrated four-leg three-phase transformerless PV inverter with voltage boosting capability

Abstract

The leakage current minimization and voltage boosting are the two essential features for transformerless PV inverter configurations. In this paper, a conventional four-leg three-phase inverter is retrofitted with an inverting buck-boost converter to achieve the voltage boosting capability. The proposed power circuit configuration facilitates power transfer either directly from the PV source or through the buck-boost converter. Further, a new group of PWM schemes is introduced for the proposed power circuit configuration. These modulation strategies are capable of eliminating the switching frequency transitions from the common-mode voltage while maintaining the dc-link utilization for the inverter. The proposed modulation strategy results in a higher effective frequency for the fourth leg to optimize the design of the boosting inductor. The working principle of the proposed power converter is validated with simulation results.