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In this article, an online condition monitoring (CM) method is proposed for the bond wire degradation of insulated-gate bipolar transistor (IGBT) modules in a single-phase or three-phase three-level neutral-point-clamped (3LNPC) dc–ac, ac–dc converter. The proposed method has the ability to detect the whole IGBTs in a 3LNPC converter, based on finding the idle on-state IGBTs under the specific load current direction and switching sequence of a leg. The detection time is short (0.2 ms) and the influence of online CM on load current can be completely neglected as long as the insertion areas for CM test are chosen reasonably. Meanwhile, an advanced bond wire CM module is designed to conduct the CM test. This module can generate and inject the current pulse trains into IGBT modules, with the high current for CM test and low current for temperature-sensitive electrical parameter measurement, and sample the collector–emitter on-state voltage (VCE ON) stably and precisely. Finally, the experimental work was carried out to verify the effectiveness of the proposed method and the practicality of the developed CM module. [ABSTRACT FROM AUTHOR]

The junction temperature fluctuation of an insulated-gate bipolar transistor (IGBT) is the most important factor of its aging failure, and smoothing the fluctuation is an effective way to improve the life of an IGBT. The existing methods for smoothing the fluctuation by active junction temperature control are not yet ready wide application, and exploring the different approaches to active junction temperature control is a hot topic. This paper presents a method of active junction temperature control that shifts the turn-off trajectory of an IGBT to adjust the IGBT turn-off loss for smoothing the junction temperature. The relationship between parameters of the adjusting circuit and turn-off loss is analyzed. On the basis of this analysis, a method of estimating the smoothing ability for the proposed active junction temperature control is deduced. Using an IGBT installed in a 1.2-MW direct-drive wind power converter as an example, the evaluation result shows that the proposed method can completely smooth the junction temperature fluctuation caused by a 40% rated load fluctuation. Finally, a low-power experiment is carried out. [ABSTRACT FROM PUBLISHER]

Potential defects inside an insulated gate bipolar transistor (IGBT) module can be seen as precursors of being about to wear out, and are important for health monitoring of the IGBT module which is used to enhance reliability. A method for detecting defects in the IGBT module by identifying dynamic changes of the gate current is presented in this paper. It is based on the fact that parasitic elements inside the IGBT module are affected by local damage induced by aging over time, and subsequently, these influences are easily distinguished by dynamic changes of the gate current. The proposed prognostic approach is based on relevance vector machine framework, which can give accurate predictions and allow operators to observe unhealthy IGBT modules inside a power converter, and then take appropriate measures timely to avoid breakdown. The parasitic elements involved in the gate circuit are extracted, and their contributions to dynamic changes of the gate current are also discussed. Finally, a confirmatory experiment is carried out, and the correctness of the proposed method is verified. [ABSTRACT FROM AUTHOR]