Sensor for accumulated charge detection in packaged insulation layer of insulated gate bipolar transistor power devices

A compact system for detecting charge accumulation in the insulation layer of power electronic devices such as insulated gate bipolar transistor (IGBT) modules was developed. The amount of electric charge accumulated in IGBT modules at high dc voltages (100 to 5000 V) and in a wide temperature range (20 to 180 °C) was measured using the system consisting of two units. The battery-operated sensing and transmission unit (500 × 700 × 300 mm3) was connected in series to an IGBT module to which various dc voltages were applied at various temperatures. The collected data were transmitted to a data receiving unit for analysis, which is electrically isolated from the sensing and transmission unit. The data received as a function of time Q(t) were analyzed to obtain various parameter values that provide information on the insulation status of the IGBT module, such as the amount of initial charge, absorption current, and conduction current under various conditions. On the basis of the ratio Q(t)/Q0, where Q0 is the amount of initial charge, the amount of charge accumulated in the IGBT modules under high-stress conditions was obtained. The compact system for accumulated charge detection will be convenient for evaluating the insulation characteristics of IGBT modules, which operate under harsh conditions in real power electronic devices such as those used in electric vehicles.