Design and research of a high-precision TMR non-contact current sensor based on a dual-gap anti-interference structure

Purpose This paper aims to design and investigate a high-precision tunneling magnetoresistance (TMR) noncontact current sensor based on a dual-gap anti-interference structure, to address the susceptibility of traditional TMR current sensors to external interference in complex electromagnetic environments. Design/methodology/approach A systematic methodology integrating theoretical modeling, finite element simulation and experimental validation was used. A mathematical model of the dual-gap magnetic circuit was established based on magnetic Ohm’s law to analyze its differential output mechanism for suppressing common-mode magnetic field interference. Key parameters such as magnetic core cross-section and air gap dimensions (a = b = 7 mm) were optimized through finite element simulation, evaluating magnetic field uniformity and conductor displacement error. Thermal performance and anti-interference capability were experimentally validated under controlled conditions. Findings The optimized dual-gap structure improves magnetic field uniformity to 0.0010 and reduces measurement error caused by conductor displacement to below 0.08%. It also demonstrates superior thermal management, lowering temperature rise by 27.4% compared to a single-gap structure under high load. Under an external interference field of 10 Oe, the dual-gap sensor achieves an output voltage error of 0.014%, outperforming the single-gap design (0.017%). The sensor maintains a linearity of ± 0.5% and an accuracy of ± 1% across a temperature range of –50°C to 70°C. Originality/value This study proposes an innovative dual-gap magnetic circuit structure that effectively enhances anti-interference performance and thermal stability in TMR current sensors. The research provides a practical and reliable design pathway for developing high-precision, robust current sensors suitable for demanding electromagnetic environments.