An Online Condition Monitor Method for IGBT Independent of Collector Current

Junction temperature monitoring and fault diagnosis of power semiconductor devices can provide critical information to ensure the reliable operation of power electronic systems. In this article, an online condition monitoring method for insulated gate bipolar transistors (IGBTs), which is not affected by the collector current, is proposed based on the Miller voltage plateau of the conduction process. The relationship between the Miller voltage plateau and the junction temperature is analyzed, and an analytical model of the Miller voltage against junction temperature is established. By using this model and the conducting-state characteristics of the device, a reverse current phase measuring strategy is proposed to decouple the influence of the collector current on the junction temperature estimation, and an online measurement circuit of the Miller voltage is designed. In addition, the characteristics of the trigger voltage under different faults are analyzed to recognize fault types. The experimental results show that the proposed method has high sensitivity and good linearity. It is proven that the proposed measurement strategy is independent of the collector current, which can accurately distinguish the fault forms of IGBTs.