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Gate-oxide degradation has been one of the critical reliability concerns of silicon carbide (SiC) metal–oxide–semiconductor-field-effect transistors (mosfets), which could be monitored through aging-sensitive parameters. In this article, an online gate-oxide degradation monitoring method for planar SiC mosfets is proposed by extracting gate charge time at a specific range of gate voltage. It is based on the findings that the input capacitances of planar SiC mosfets change significantly over gate-oxide degradation, which is theoretically analyzed and experimentally verified. The capacitance variations are converted into the gate charge time as the new aging-sensitive parameter. The new parameter measurement circuit is proposed and integrated into the gate driver module. The article results indicate that the new parameter varies noticeably with gate-oxide degradation and the difference of this parameter caused by junction temperature is much smaller than that caused by degradation. Besides, the parameter is immune to package degradation and load current. The condition monitoring method can be implemented online since the parameter is extracted during the off-state of SiC mosfet devices, which does not affect normal operation. The confirmatory experiment is carried out to verify the correctness of the proposed method. [ABSTRACT FROM AUTHOR]

Monitoring the defective multichip insulated gate bipolar transistor (IGBT) module is a cost-effective approach to improve the quality of customer service. A method using time duration of the gate charge is proposed to monitor bond wires fatigue of the multichip IGBT modules when the modules are in the off-state. It is based on the fact that failure of the chip branch due to bond wires fatigue changes the gate input capacitance of the multichip IGBT module. The health state of bond wires can be converted into the change of time duration of gate charge under the constant gate current. A driver containing the constant current source is proposed. The study results indicate that the time duration of the gate charge decreases significantly when the failure of the chip branch occurs, and the effect of junction temperature can be ignored within the special range of gate voltage. Condition monitoring can be implemented during the off-state of the multichip module and without considering the effects of junction temperature. The confirmatory experiment is carried out to verify the correctness of the proposed method. [ABSTRACT FROM AUTHOR]

Wide bandgap (WBG) devices offer the advantages of high frequency, high efficiency, and high power density to power converters due to their excellent performance. However, their low parasitic capacitance and fast switching speed also make them more susceptible to switching oscillations. The switching oscillations can cause voltage and current overshoots, shoot-through, electromagnetic interference, additional power loss, and even device damage, which can seriously affect the performance of power converters and systems. However, a comprehensive and in-depth overview is lacking on this topic. This article reviews the types, the causes and negative effects, the effects of parasitic parameters and suppression methods of these switching oscillations, which is helpful for practical engineering. First, the switching oscillations are divided into different types, and their causes and negative effects are reviewed. Then, the effects of different parasitic parameters on the switching oscillations are overviewed. It is found that due to the different physical structures of silicon carbide metal-oxide-semiconductor field-effect transistors, enhancement-mode gallium nitride high-electron mobility transistors (eGaN HEMTs), and cascode GaN HEMTs, the effects are also different. Finally, the main methods of suppressing the switching oscillations are summarized, and the advantages and disadvantages of these methods are presented. Furthermore, future research works on this topic and the conclusion of this paper are drawn, which will help readers deepen their understanding of the switching oscillations of WBG devices, and inspire readers to better use WBG devices for high-frequency and high-efficient power conversion. [ABSTRACT FROM AUTHOR]

Finding and replacing the defective insulated-gate bipolar transistor (IGBT) module timely by monitoring the ageing state of IGBT can improve the reliability of a power converter and reduce the loss caused by IGBT failure. A method for detecting the condition of bond wires in IGBT module by identifying the short-circuit current of IGBT module is presented in this paper. It is based on the fact that parasitic parameters of IGBT module are affected by the local damage induced by ageing over time, and these changes can be easily detected by monitoring the difference of short-circuit current. The study results indicate that short-circuit current of IGBT module decreases with module ageing over time, and the difference of short-circuit current caused by junction temperature is much smaller than that caused by bond wires fatigue on a specific gate driving voltage. Therefore, the IGBT module in the power converter can be diagnosed by detecting the difference of short-circuit current without considering the effects of junction temperature. Finally, a confirmatory experiment is carried out, and the correctness of the method proposed in this paper is verified. [ABSTRACT FROM AUTHOR]

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]