Research And Design Of DC Current Sensor Based On Zero-Magnetic-Flux Principle

A large number of modern electronic power equipment requires real-time monitoring and measurement of current parameters,and the requirements for measuring equipment are getting higher and higher,not only requiring accuracy but also requiring resolution.The commonly used DC current sensor is mainly based on the principle of magnetic field detection.However,due to material properties or other reasons,the resolution and antiinterference ability are poor,and it is difficult to accurately measure,especially for weak current signals.Based on this,this paper makes an in-depth study on the principle of zero flux,and proposes a design of sensor,which has the ability to measure weak current and strong anti-interference ability.The specific research contents are as follows :Firstly,based on the comprehensive analysis of the zero-flux principle,the sensor model is established.In order to improve the accuracy of the sensor,the second harmonic measurement method is used to modulate the induction output waveform.At the same time,in order to improve the disadvantage of weak induced electromotive force at the induction end of single magnetic ring core,a double magnetic ring structure design with induced electromotive force twice that of single magnetic ring is designed.Secondly,in order to have better performance of the current sensor and the magnetic core can work in a saturated state,the permalloy with higher permeability is used as the magnetic core,and the most suitable excitation frequency and coil turns are calculated.At the same time,considering the magnetic field interference in the working environment of the sensor,a shielding shell is designed.In order to obtain the maximum shielding effect,1J85 is used as the shielding shell.At the same time,ANSYS is used to simulate the interference of the external magnetic field to verify the shielding ability of the shielding shell.At the same time,the whole sensor is simulated to ensure that the antiinterference ability of the sensor is improved to a certain extent.Finally,in order to verify the overall performance of the sensor,a test circuit board was designed for joint debugging.In the process of debugging,the whole is also optimized.The final results show that the sensor has a resolution of 1mAwhen measuring mA-level current,and can measure the current change from-200mAto +200mA,and the measurement error is less than 2%.When the μAcurrent variation is tested,the current variation of 0 to 900 μAcan be measured,the minimum resolution is 100μA,and the measurement error is less than 10 %.The experimental results show that the zero-flux current sensor can meet the requirements.