Modified Discontinuous PWM Strategy for Three-Phase Grid-Connected PV Inverters With Hybrid Active–Passive Damping Scheme

摘要

This article proposes a modified discontinuous pulsewidth modulation (MDPWM) strategy for transformerless three-phase grid-connected photovoltaic (PV) inverters. MDPWM reduces the leakage current from PV inverter by reducing the magnitude of low-frequency harmonics presented in the common-mode voltage in comparison to classical discontinuous PWM technique. To enable the application of the MDPWM, a new hybrid active-passive damping scheme is proposed where common-mode and differential-mode dynamics are damped by passive and active schemes, respectively. Theoretical and experimental results show that the proposed scheme results in higher system efficiency in comparison to classic continuous PWM scheme keeping the leakage current reduced.