Linearity Range Extension of Magnetostrictive Current Sensors Through Magnetic Circuit Optimization

The magnetic field distribution of magnetostrictive composites of magnetic circuits significantly affects the measurement range of magnetostrictive current sensors. A novel technique to extend the measurement range is proposed based on the optimization of the magnetic circuit gap and preparation of materials. First, the structure and working principle of magnetostrictive current sensors are analyzed. Second, a physical model is established to demonstrate the inverse relationship between the lengths of upper and lower gaps in the magnetic circuit of the magnetostrictive composite material. Finite element simulations are conducted to determine the optimal upper gap length of the magnetic circuit, and the magnetostrictive composite material is prepared accordingly. Furthermore, both finite element simulations and linear test experiments are conducted to investigate the magnetic field distribution with different lower gap lengths of magnetic circuits. The optimal lower gap length of the magnetic circuit is chosen, considering theoretical model and simulation analyses, as well as the optimal magnetic circuit and linear operating range. The simulation and experimental results confirm that the proposed magnetic circuit optimization method achieves the optimal gap lengths of the magnetic circuit to provide appropriate magnetic field distribution, thereby extending the specific sensor's measurement range from 100~1000 A to 0~1000 A.