Three-level Gate Driving Method for Inrush Current Suppression in a Hybrid Si+SiC based Transformer-Less Medium Voltage PV Inverter

摘要

The transformer-less medium voltage (MV) photovoltaic (PV) inverter based on a five-level (5L) decoupled active neutral point clamped (DANPC) converter using hybrid “Si-IGBTs and SiC-MOSFETs” has benefits including low cost, high efficiency, simple control and improved thermal balance. However, it suffers the inrush current caused by the voltage difference on the dc-link capacitors. This paper proposes a three-level (3L) gate driving method to increase IGBT's damping to suppress the inrush current and improve the inrush energy loss distribution. Utilizing the gate loop's RC characteristic, proposed 3L gate driving method can be implemented on the conventional two-level (2L) gate driver hardware. Proposed 3L gate driving method is verified by simulation and experimental results.