PLECS-based thermal modelling and analysis of NPC three-level PV grid-connected inverters

Abstract

This study, based on the PLECS simulation platform, investigates the thermal characteristics and power loss mechanisms of a three-level neutral-point-clamped (NPC) photovoltaic grid-connected inverter. A comprehensive simulation model was developed integrating a photovoltaic arrays, an MPPT-controlled boost circuit, and a three-level inverter. Through dynamic environmental simulations (gradual irradiance variations and step changes), the switching losses, conduction losses of power devices, and their impacts on junction temperatures were systematically analysed. The research further proposes system loss optimization through simplified Space Vector Pulse Width Modulation (SVPWM) strategies, adaptive modulation techniques, and novel power devices (SiC MOSFETs), combined with an improved fuzzy incremental conductance MPPT algorithm to enhance dynamic response capabilities. These findings provide a theoretical foundation for thermal design, control strategy optimization, and high-reliability operation of photovoltaic grid-connected inverters, contributing significantly to advancing renewable energy systems toward enhanced efficiency and prolonged operational lifespan.