Closed-Loop Diamond Quantum Sensor for Large Range and High Precision Current Measurement

Magnetic field sensors based on quantum effects have shown superior performance in sensitivity, wherein the nitrogen-vacancy (NV) center in diamond has emerged as a microfabrication compatible solid-state platform for measuring magnetic fields at room temperature. Here, a closed-loop current sensor based on a compact diamond sensor is presented. Adapting dual-frequency driving mode and magnetic balance approach, a magnetic-temperature dual-loop architecture is established to extend the dynamic range and suppress the temperature drift, simultaneously. The proposed current sensor demonstrates an accuracy of 0.061% at a measuring range of ±1000 A. An isolation factor of 30.3 dB for temperature against magnetic field is obtained via the dual-loop calibration. The closed-loop strategy permits rapid adjustment of the output signal to align with fluctuations in the primary current and the response speed is achieved up to 107.6 kA
$\cdot \text{s}^{-{1}}$
. Our proposed closed-loop current sensor has potential applications in power grid and electric vehicle monitoring systems.