Analysis and Optimization of Current Sensors for Detecting Shoot-Through Currents in High-Power Inverters

Electric current sensors have become a crucial component in power electronics applications, especially when it comes to measuring currents in inverters. In a specific case, in direct-link inverters, sensors detecting shoot-through events in the inverter sides are utilized, which possess a wide bandwidth and a large DC amplitude amount. In a common current transformer, the magnetic core is saturated by a DC component in the primary current. Consequently, in these kinds of applications, an appropriate current sensor must have the capability to withstand high current levels and also sense high-frequency currents. This paper analyzes the limitations of conventional current transformers in such applications, particularly their susceptibility to core saturation under high DC currents. We propose an optimized design featuring an air gap in the transformer’s core, which mitigates saturation while maintaining sensitivity to high-frequency currents. The effectiveness of the proposed design is validated through finite element simulations, demonstrating its capability to detect shoot-through events accurately. The analysis aims to optimize current transformer performance for robust current sensing in high-power electronic systems. The functionality of the proposed current sensing method is confirmed using finite element simulation for a 140 A case study.