Design and Optimization of a Three-coil Nested Inductive Sensor with Inner Sensing and Outer Excitation

This study designs and optimizes a three-coil nested inductive sensor suitable for 13mm inner diameter pipelines to enhance the detection capability of ferromagnetic debris. This paper proposes an inner sensing and outer excitation design to improve signal resolution and interference resistance. Through theoretical analysis and finite element simulation, the effects of coil turns, width, and radius on sensing voltage were evaluated. The results show that the number of turns in the excitation coil, the number of turns in the sensing coil, and the radius of the excitation coil have significant impacts. Experiments with the optimized sensor indicate effective detection of 300μm debris and stable performance at elevated temperatures, achieving a 90% detection rate for debris 500μm and above in oil pipeline tests.