Design of Heart-Shaped Current Sensor Based on Incomplete Magnetic Cancellation

High current measurement technology is of great importance in many fields, including power system protection and control, power metering, and power consumption reduction. Conventional electromagnetic current sensor has been widely used in power grid but cannot follow the trend of miniaturization and lightness of electrical equipment due to its large volume and poor heat dissipation performance. Heretofore, many methods have been tried to expand the measurement range by designing the compensation circuit, increasing the number of windings turns and the number of cascade levels, but they cannot avoid the problems of large volume and core saturation. Therefore, in this article, we proposed a heart-shaped core structure of current sensor based on the incomplete magnetic cancellation. Then, we conducted an analysis of the magnetic cancellation of heart-shaped core and the error calculation method, and we expanded its application in dc current measurement. Furthermore, we built a 3-D simulation model of the heart-shaped current sensor in COMSOL to verify the magnetic counteracting effect, and we investigated on the measurement range and error affected by the different cross-sectional areas. Finally, we built a proof-of-concept prototype of the heart-shaped current sensor and its sensor test system. We also conducted batches of experiments, and the results demonstrated that the heart-shaped current sensor can guarantee the measurement linearity with the same volume when the current is within 700 A, which implied that the performance of our proposed sensor is double of the conventional sensors (350 A); meanwhile, the core also has better anti-saturation capability through magnetic cancellation.