In order to meet the requirements of online DC measurement or detection

an open-close current sensor based on tunneling magnetoresistance (TMR) technology is designed using closed-loop zero-flux scheme.The magnetic core structure design

magnetic sensing components and signal processing circuits of the sensor are analyzed in detail

and the anti-interference design of the sensor is analyzed.Detailed tests are carried out on the sensor. The test results show that the designed sensor can meet the range of 0~50A

the measurement accuracy of the current sensor is better than ±1%

and the resolution is better than 50mA.The designed sensor has good linearity

high stability and strong anti-strong magnetic interference ability

which can effectively reduce the influence of harsh external environment on current measurement

and provide a feasible scheme for current online monitoring and accurate measurement of DC system.