Abstract
The uneven current inside the press pack insulated gate bipolar transistor (PP-IGBT) is a key factor threatening its reliability. Although various existing methods could achieve non-invasive measurement of the current distribution in PP-IGBTs, the compact internal space of converter valves makes it difficult to install conventional sensors inside the valve. To address this challenge, a non-invasive monitoring method based on surface-mounted coils (SMCs) has been proposed in this paper. A surface-mounted layout for the coils has been designed, which has not only improved the magnetic field coupling efficiency but also enabled installation within the valve. The concept of a virtual current aggregation point (VCAP) has been introduced to conceptualize abstract current variations as changes in the VCAP's position. Furthermore, a localization method for the VCAP based on multi-dimensional vector synthesis has been proposed. This method extracts information characterizing current distribution changes from the mutual inductance variation of each coil and superposes them in space to achieve VCAP localization. Finally, a comprehensive experimental verification was conducted to rigorously evaluate the proposed method. Results from both the laboratory testbench and a commercial converter valve validate the high localization accuracy under various imbalance scenarios and confirm the feasibility of the method in practical industrial applications.