Aging monitoring method for IGBT module based on conduction voltage drop in bridge-arm short-circuit

Abstract

Insulated gate bipolar transistors (IGBTs) serve as the pivotal components within power conversion systems, and given the harsh conditions they endure, evaluating their aging is of paramount importance. Traditional offline aging monitoring method are relatively complex. Based on the conduction voltage drop as the characteristic quantity of IGBT aging, a simpler technique for extracting this parameter is presented, facilitating the assessment of IGBT aging status. Incorporating the working principle of the IGBT bridge-arm short-circuit, a conduction voltage drop model has been established. A composite aging electrical parameter is used to eliminate the impact of degradation in the bond wire of the current source device. By engineering a closed-loop gate drive circuit with adjustable voltage, the short-circuit current is maintained constant, thereby facilitating the acquisition of a consistent conduction voltage drop. A conduction voltage extraction circuit is proposed, in which a resistance-capacitance discharging time is equivalent to the conduction voltage drop to replace the analogue-to-digital circuit. By decreasing the amount of active zone of the chip in IGBT module for increased conduction voltage drop to simulate aging state, the proposed method with the driving circuit is experimentally validated as feasible and reliable.