Development Of Micro Current Sensor Based On Magnetoresistance Effect Principle

In the current spacecraft,there are two principles of the current sensor: direct resistance measurement(shunt),Hall current sensor,two kinds of sensors are mature.The direct resistance measurement method can not achieve electrical isolation,the resistance failure will break the current loop,and the accuracy of the sampling resistance directly affects the final accuracy of the measurement.Although the Hall effect principle is based on magnetic isolation measurement,but the current sensor is large.With the more and more applications of the current sensor,the volume and weight of the spacecraft are directly affected.For reducing the size,reducing the weight and reducing the cost,the micro current sensor is needed for the spacecraft.In view of the demand for small and low weight micro current sensors of spacecraft,Shandong Aerospace Electronic Technology Institute has developed a micro current sensor based on the principle of magnetoresistance effect.The micro current sensor developed by this project will be applied to the current measurement of spacecraft extensively.First,a design scheme of current sensor is presented,which is based on the principle of AMR magnetoresistance effect.The reliability and safety design of spacecraft application is carried out.Then,the design of the AMR probe chip is discussed.The design scheme of Barber electrode is studied,and the AMR Wheatstone bridge circuit is made,and the anti-jamming ability of the probe is improved by gradient measurement.After testing,the absolute value of the linearity of AMR chip is about 1%.It shows that the linearity of the whole sensor can reach about 1% even if it works in the open loop amplifier mode.The linear degree of the sensor can be further improved by using the closed loop feedback mode,and the probe meets the demand of the magnetic field detection in this subject.Next,this paper designs the circuit and ceramic substrate around the AMR probe chip,gives the detailed circuit of the closed loop reluctance current sensor,and selects the size and the geometric position of the carrier flow belt reasonably,and makes the product of the current sensor with the specified range.An automatic debugging platform is designed to realize automatic debugging of sensors.Finally,the platform of sensor testing system is built,and the sensor indexes are tested,and the results are recorded and analyzed.The results show that the absolute value of the linearity of the current sensor is better than 0.1%,the precisionis better than 0.8%,and the length and width of the sensor is 10mm*10mm*10mm.It meets the application requirements of the micro current sensor of the spacecraft,and is suitable for the satellite,spacecraft,rocket and other spacesuits.