Since the insulated gate bipolar transistor (IGBT) is the core component of grid-connected inverters

improving its reliability is crucial. Current thermal control research mainly focuses on the steady-state thermal stress of IGBTs during long-term operation or examines the impact of short-term overstress on IGBTs in motor drive applications

particularly under motor stall conditions. However

due to the complexity and short duration of transient faults in grid-connected converters

few studies have addressed the thermal control of IGBTs during these transient periods. Nevertheless

the transient overstress is equally critical and should not be overlooked. Therefore

this paper proposes an active thermal control method for IGBTs in grid-connected inverter during transient faults. A grid-connected inverter model based on virtual synchronous generator (VSG) control is developed

along with a corresponding electrothermal model for the internal IGBT. Then

by analyzing the relationship between the junction temperature of the IGBT and electrical parameters

an active thermal control method is proposed that integrates virtual impedance

adaptive power adjustment

and switching frequency variation. This approach aims to alleviate internal overstress during transient faults while enhancing the stability of the inverter. Finally

the feasibility and accuracy of the proposed method are validated through simulations and experiments.