Power switch lifetime extension strategies for three-phase converters

The recent advances and reports on failure precursors of power switches have led to estimation of lifetime as well as developing secondary control schemes to increase the lifetime of the converters. In this study, a secondary control scheme to extend the lifetime of the converter based on the identified failure precursors such as the on-state resistance variation for power MOSFETs and collector emitter voltage variation for IGBTs is proposed for three-phase converters. The controller switches the modulation scheme from SVPWM to discontinuous PWM, and adjusts the switching frequency, once the tracked failure precursor reaches to the defined threshold value. The tradeoff between the total harmonic distortion and lifetime extension at different modulation techniques and switching frequencies are addressed.