Bond Wire Damage Detection and SOH Estimation of a Dual-Pack IGBT Power Module Using Active Power Cycling and Reflectometry

High thermal and electrical stress, over a period of time tends to deteriorate the health of power electronic switches. Being a key element in any high-power converter systems, power switches, such as insulated-gate bipolar junction transistors (IGBTs) and metal-oxide semiconductor field-effect transistors, are constantly monitored to predict when and how they might fail. A huge fraction of research efforts involves the study of power electronic device reliability and development of novel techniques with higher accuracy in the health estimation of such devices. Until today, no other existing technique can determine the number of lifted bond wires and their locations in a live IGBT module, although this information is extremely helpful to understand the overall state-of-health of an IGBT power module. Through this article, a new method for online condition monitoring of IGBTs and IGBT modules using spread spectrum time-domain reflectometry has been proposed. Unlike traditional methods, this research work concentrates at the gate terminals (low voltage) of the device instead of looking at the collector side. In addition, the RL-equivalent circuit to represent a bond wire has been developed for the device under test and simulated in CST Studio Suite to measure the reflection amplitudes. Experimental results were obtained using a prototype reflectometry hardware, and both the simulation and experimental results have been compared. These results prove that a single measurement is sufficient to predict the failure of the device instead of looking at the traditional precursor parameter (VCEON). With only two sets of measurements, it is possible to locate the aged device inside a module and detect the number of bond wire liftoffs associated with that device.