A fluxgate current sensor with a U-shaped magnetic gathering shell

This paper presents a current sensor based on fluxgate principle, which consists of a cylinder-shaped amorphous core with a U-shaped magnetic gathering shell. In the designed sensor, the exciting winding and secondary winding are arranged perpendicularly so that the magnetic fields produced are mutual orthogonally, that is, the exciting magnetic field and the feedback magnetic field is decoupled. Magnetic gathering effectiveness and magnetic coefficient of the shell are analyzed by finite element method (FEM) and some concerned parameters affecting the gathering effects are also discussed. Based on theoretical analysis and simulation results, a prototype was designed. The experiments show introducing of a magnetic gathering shell into the current sensor effectively concentrates the wanted signal and reduces the interference of external stray field, thus making the sensor have an excellent sensitivity and precision. The relative error of the measurement of the current sensor with and without magnetic gathering shell were tested and compared. The sensor we proposed with this design has an accuracy of 6⁰/₀₀ and a remarkable resolution of 8pT/√Hz for frequencies greater than 1 Hz.