Evaluation of Cycling Stress Imposed on IGBT Modules in PV Central Inverters in Sunbelt Regions

Frequent temperature variations imposed on power electronic modules may lead to ageing of the internal connections of the module and may thus limit the module's lifetime. The temperature cycles occurring at the power electronics modules of a photovoltaic central inverter are analysed using mission profiles for a number of locations in the earth's sunbelt. A comparison of the predicted cycling stresses with cycling capability data from the power electronic module manufacturer is undertaken to evaluate if the temperature cycles limit the lifetime of the power electronic modules in the inverter. Additionally, the effect of different cooling system control strategies on the cycling stress is investigated.