Anti-Interference Current Sensing With Enhanced Sensitivity Based on Magnetoresistive Sensors

Medium-voltage (MV) power converts have various intended applications in renewable energy resources integration, power substations, and electrical mobility. The high power and high switching frequency of MV power converters have necessitated the development of a contactless current sensing technique based on magnetoresistive (MR) sensors to provide galvanic isolation, wide bandwidth, and minimum stray inductive on the current path. The prevailing solution involves placing the MR sensor under a straight printed circuit board (PCB) trace. However, this setup suffers reduced sensitivity due to sensor installation errors and inaccurate measurement owing to the nearby interfering conductors. To address these two issues, a double circular PCB trace is proposed to replace the traditional straight PCB trace. In the proposal, two MR sensors are encircled by a circular PCB trace separately. The interference impact is mitigated by subtracting the differential output from the sensors. Additionally, the double circular trace (DC trace) is optimally designed to enhance the position tolerance of sensor installation by providing a uniform magnetic field within the sensing area. The experiment measurement under a 2 mm position error shows that the proposed method improves the sensitivity from 0.1736 V/A in the conventional straight trace to 0.5902 V/A. Moreover, the sensitivity remains consistent even in the presence of interfering conductors.