부산대학교 도서관

The application of current sensing technology in power system has achieved remarkable results under the rapid development of smart grid and ubiquitous power Internet of Things. A non-invasive weak current sensor based on tunneling magnetoresistive effect is studied in order to meet the application requirements of detecting the grounding current of 110kV single-core power cable safely and reliably. A two-lobe square fillet magnetic core structure is designed, and a voltage stabilizing circuit with isolated power supply and an instrument amplifier circuit with floating common-mode bootstrap structure are designed based on the closed-loop principle. By analyzing the test data of the sensor, the non-invasive weak current sensor based on tunneling magnetoresistive effect designed in this paper has a range of 0-20mA, and has a sensitivity of 20m V/mA and a linearity of 0.52% in this range. Compared with the closed magnetic core structure, the open-close magnetic core structure meets the needs of easy disassembly of the sensor and broadens the application scenarios of the sensor. TMR current sensor has a wider range and higher linearity, which can meet the accurate detection of grounding current.