High Precision Closed-loop TMR Current Sensor for small Current Measurement

Low current monitoring is an important aspect of smart grid research. However, most of the studies focus only on certain indicators of current sensors such as sensitivity, linearity, and accuracy. ln this work, we have selected a high-precision TMR sensor chip and designed a two-step signal amplification current. We have also adopted the closed-loop feedback principle along with the magnetic toroid structure to make the sensor system less susceptible to interference. The designed current sensor was calibrated with several indicators under the condition of DC/AC 0~1A. The results showed that the current sensor has high accuracy, high linearity, and high sensitivity. Under AC O~100mA, the average relative error is as low as 0.31%, the R-squared value is 1, and the sensitivity is as high as 5279.1mV/A. The measured results demonstrate that the current sensor can be used on a large-scale smart grid upgrade.