Active thermal control for improved reliability of power electronics systems

As previously discussed, the thermal stress of power electronics components is intimately associated with some significant wear-out failure mechanisms observed in converter systems. In many emerging applications of power electronics, including renewable energy, electric vehicles, and power transmission, the operating conditions of the converter are often complicated, resulting in adverse thermal behaviors in the power electronics components with various time constants. This can lead to a significant risk of reliability issues. This chapter introduces the active control methods that are designed to relieve the critical thermal stress in power electronics components. As one of the most vulnerable and expensive components, power semiconductor devices will be the primary focus, with case studies of a few selected converter applications. It can be concluded that the thermal stress, especially the thermal cycling in the power semiconductor devices, can be significantly relieved by proper controls, modulation strategies, and the activation of energy storage systems. Further studies on this topic are still underway, with promising results.