Impacts of reactive power injections on thermal performances of PV inverters

This paper analyzes the impacts of reactive power injections by PV inverters on thermal performances of their components. The analysis is focus on three weakest components in PV inverters, namely, IGBTs, diodes and a DC link capacitor. Reactive power injections cause additional losses such as conduction losses and switching losses in IGBTs and diodes and conduction losses due to double frequency current ripples in a capacitor. These losses cause temperature rise in the devices. This paper simulates the thermal performances of PV inverters using PSIM software and verifies the results using analytical expression of conduction and switching losses. It is found that reactive power injections cause additional temperature rise in all the devices. Leading power factor operations result in a slightly higher temperature rise in IGBTs and diodes than lagging power factor operations.