A Wide-Range IGCT Anode Current Detection Method Based on Tunnel Magnetoresistance Effect

The Integrated Gate-Commutated Thyristors (IGCT) have active turn-off capability and serves as a key component in modern power electronic equipment. However, its turn‑off capability is limited, and forced turn‑off beyond the safe turn‑off threshold will easily lead to device damage. Therefore, online monitoring of the current flowing through IGCTs is of great engineering significance. Current sensors based on the tunneling magnetoresistance (TMR) effect are widely employed in compact current sensing applications, but they are restricted by magnetic saturation and thus cannot accurately measure kA-level high currents. This paper first analyzes the magnetic saturation characteristics and hysteresis effects of the magnetic core. By establishing a mathematical model of the internal magnetic flux distribution inside the core, the factors influencing core saturation and hysteresis in strong magnetic field environment are clarified, and the effects of various structural designs on magnetic flux distribution are investigated through finite element analysis. Based on this investigation, a discrete core–air gap structure with enhanced resistance to localized saturation and excellent linearity is proposed. Finally, experimental results demonstrate that compared with the traditional structure, the proposed structure reduces the volume by 83% and extends the measurement range from 4.6 kA to 10 kA. The influence of hysteresis on the waveform delay time is significantly reduced, which validates the effectiveness of the proposed method.