An Investigation on Diagnosis-Based Power Switch Lifetime Extension Strategies for Three-Phase Inverters

Fault diagnosis and failure prognosis of power electronics systems are essential for various mission critical applications, where safety, continuity, and survivability of the system are of paramount importance. With the recent advances in power device failure precursor identification and lifetime estimation, it is possible to extend the lifetime of the power devices, and thereby converters through secondary control schemes. The essence of the lifetime extension strategies relies on either reducing the power loss on the degraded device(s) and shifting it to other parts, or decreasing the total power loss of the converter. As the power converters are optimized for efficiency and total harmonic distortion (THD) requirements, these secondary control strategies can result in operations above the design limits. This paper proposes a hybrid secondary lifetime extension control scheme for three-phase inverters based on the identified failure precursors, which dynamically changes the modulation scheme and adjusts the switching frequency. In the content of this paper, the tradeoff between the THD and achievable lifetime extension is addressed, and a control algorithm is proposed, which maximizes the lifetime with feasible lowest THD.