A Chip Open-Circuit Failure Monitoring Method in Multichip IGBT Modules Based on the Fall Time of Gate Voltage

In high-power converters, multichip insulated gate bipolar transistor (mIGBT) modules, consisting of multiple parallel chips, are widely used to obtain the desired large current capacity. For evaluating the reliability of power converters, it is significant to monitor chip open-circuit failure of mIGBT modules caused by bond-wires lift off. This article proposes that the fall time of gate-voltage ( $t_{\text {gf}}$ ) is adopted to monitor chip open-circuit failure. Because the gate input capacitance of mIGBT modules suddenly decreases when the chip open-circuit fails, resulting in a remarkable decrease of $t_{\text {gf}}$ . A double-pulse experimental platform is developed to verify the feasibility and sensitivity of the proposed method. Experimental results show that $t_{\text {gf}}$ jumps and decreases immediately when the chip open-circuit failure occurs, and the proposed method has a strong immunity to variations in operating conditions. In addition, the proposed method only requires measuring variations in gate voltage, and the monitoring circuit can be integrated into the gate drive circuit or used as a plug-and-play device. Thus, the proposed method is safe, less invasive, and easy to implement, which can provide a way for the reliability evaluation of mIGBT modules.