Research On GMR Current Sensor Based On Magnetic Shunt Structure

High-performance wide-range current sensor components are widely used in instrumentation,automotive electronics,and smart grids.The current wide-range current sensor technology mainly includes flux gate type,fiber type,Hall type,shunt type,etc.Flux-gate current sensors have the advantages of high detection accuracy and good temperature stability,but their disadvantages are that they are large and their bandwidth is difficult to improve;Although the fiber-optic current sensor has high accuracy,it is easy to be interfered by the environment and caused measurement errors.The Hall-type current sensor has a large measurement range,but its signal-to-noise ratio is low,resulting in low measurement accuracy and severe temperature drift;The shunt has the characteristics of high measurement accuracy,but it is directly connected to the circuit tested,which has a great impact on the circuit tested.Large contact resistance and shunt resistance will cause a large amount of heat,and direct contact between the device and the circuit under test exists a safety risk.The above types of current sensors are difficult to meet the measurement requirements of high stability and wide range.The new design scheme based on GMR technology proposed in this thesis uses soft magnetic shunt technology combined with multi-sensor fusion technology to measure signal current magnetic field.It has the advantages of advanced technology,strong feasibility,strong anti-interference,good temperature stability,low power consumption and wide range.The advantages of wideness can be widely used in current standard devices,high-precision energy metering devices,high-voltage power distribution systems,and electronic instrumentation.The specific content and technical route of this thesis are as follows.Research on GMR spin sensing technology,analyze the linearity,sensitivity,linear detection range and magnetic field detection limit of the sensor chip.Design and simulation of soft magnetic shunt structure,ansoft Maxwell software is used to model and simulate the soft magnetic shunt structure.Through structural optimization,the magnetic field generated by the measured current is within the linear detection range of the sensor;The design of multi-sensor fusion improves the anti-interference ability,detection accuracy and stability of the entire sensing system.This paper designs two kinds of current sensors,one is a wide-range current sensor,which can theoretically achieve a measurement range of zero to ten thousand amps,which mainly verifies the feasibility of a wide-range current sensor.The other is a small-range current sensor,which can achieve zero to five amps measurement.It is mainly used to verify the detection accuracy and stability of the GMR current sensor.Afterexperimental measurement,the sensitivity of the small-range current sensor is 61.6m V/V/A,the linearity is 0.55%,and the accuracy is about 0.6%.