Performance limitations and reliability of power devices: A thermal insight

An investigation of the power performance limitations or power devices due to thermal failure has been performed under steady-state and transient conditions. The maximum thermal resistance Rθthat prevents thermal runaway under various blocking conditions was computed as a function of applied voltage VAand of leakage current Io. The dependences Rθ=f (VA,Io) were computed for the worst cases and their validity had been proved by experimental data on diodes, transistors and thyristors. The reliability and performance limitations of devices under transient conditions had been investigated for the most complex case, i.e. the transient thermal response of an amplifying gate thyristor (a.g.t.) during its firing. The analytical model and basic computer procedure are described in detail. A good agreement was found between computed values and experimental data for maximum temperature Tm.