Closed-Loop Spin Valve Current Sensor Based on Magnetic Shunt Effect for Range Extension

Abstract

To address the wide-range and high-precision requirements of current sensors, this article proposes a design method for a current sensor based on the combination of magnetic shunt structure and closed-loop feedback technology. The system adopts a high-sensitivity spin valve chip to detect the magnetic field signal generated by the primary current. It utilizes the magnetic shunt effect of a soft magnetic ring to extend the detection range of the sensor. By integrating the signal processing techniques such as digital sampling, filtering, and signal feedback, the linearity, accuracy, and current measurement range of the sensor are enhanced. Using Ansys Maxwell 16.0, simulations and optimizations of the magnetic ring structure, magnetic shunt effect, and feedback coefficient are conducted. Simulation results show that the magnetic shunt effect can extend the current measurement range by about 20 times. The test results demonstrate that the sensor’s overall performance is excellent, with the sensitivity, linearity, and accuracy of 97 mV/A, 0.097%, and 0.324%, respectively. In addition, considering the uninterrupted power supply demand in practical applications, a detachable soft magnetic ring and a fixed structure are designed, enabling in situ current measurement. This design has potential applications in emerging energy fields such as electric vehicles and smart grids.