A Segmented Rogowski Coils Based Noninvasive Monitoring Method of Current Imbalance in Press Pack IGBTs

Press pack insulated-gate bipolar transistor (PP IGBT) plays an essential role in high-capacity power electronic transmission equipment. Due to the influence of various factors, such as structural pressure and temperature in practical operation, the internal parallel chips of the IGBT may experience inevitable current imbalance, which cannot be detected by existing method. This letter proposes a segmented Rogowski coil (SRC) based noninvasive monitoring method of current imbalance in PP IGBT. By segmenting the standard Rogowski coils around the IGBT device and measuring them individually, the general distribution of the current inside the device can be perceived. After detailed analysis of the mutual inductance characteristics and transfer function, a prototype of SRC was developed. The theoretical model of SRC has been verified by measuring a single current-carrying wire, with an error of only 1.21%. The effectiveness of the proposed scheme was demonstrated by using it to monitor the current distribution in different directions for the same IGBT device.