In Situ Junction Temperature Monitoring and Bond Wire Detecting Method Based on IGBT and FWD on-State Voltage Drops

Junction temperature monitoring and bond wire detection are crucial for the condition monitoring and protection of insulated gate bipolar transistor (IGBT) and freewheeling diode (FWD). on-state voltage drop is one of the most popular parameters for junction temperature estimation and bond wire detection. However, there is still a lack of cost-effective on-state voltage drop measuring techniques for both IGBT and FWD with a fast response. This article proposes an in situ junction temperature monitoring and bond wire detecting method based on IGBT and FWD on-state voltage drops. The proposed technique can measure the on-state voltage drops of IGBT and FWD online with high accuracy and fast response. The on-state voltage drops of IGBT and FWD under low load current are linearly dependent on their junction temperatures. Besides, the on-state voltage drops under high load current are closely related to the bond wire degradation. Therefore, the junction temperatures and bond wire conditions of both IGBT and FWD can be monitored based on the on-state voltage drops during a period of alternating current. The experiment results validate the feasibility of the proposed on-state voltage drop-based method for junction temperature monitoring and bond wire detecting. The proposed method has characteristics of high response speed, noninvasiveness for normal converter operating, and simple structure.