As the core component of power electronic equipment for power transmission and transformation

IGBT undergoes package aging under long-term complex electrothermal stress

resulting in the degradation of the safety boundary. The existing safe operating area is unable to depict the aging process. Therefore

a life-cycle safe operating area calibration method considering package aging is proposed. Firstly

a “voltage-current-temperature” three-dimensional safe operating area is established. Next

the cumulative damage is quantified to reflect the fatigue degree of the solder layer

and the junction-case thermal resistance degradation model is established to reveal the shrinking law of the life-cycle safe operating area boundary

which is verified by power cycling experiments. Finally

the solid-state transformer is taken as an example

and a life-cycle safe operating area calibration process based on the linear cumulative damage of variable stress conditions is proposed. Results show that the fit goodness of the thermal resistance degradation model is 99.36%

the maximum power loss and current boundaries shrink by 33.3% and 23.6%

respectively

during the life cycle. When designing equipment

performing operation maintenance

and using aged components for downgrade

at least 1.5 times of power loss margin and 1.3 times of current margin should be reserved to ensure the safety of the IGBT module throughout its life cycle. This research can provide a reference for the safety design of new power system transmission and transformation equipment.