Research On High Precision Phase Difference Magnetic Modulation DC Sensor

In recent years,with the rapid development of new energy technology,DC systems such as electric vehicles and photovoltaic power generation have also been widely used.As one of the indispensable measurement and protection equipment in DC systems,DC sensors play an irreplaceable role in measuring DC leakage current and protecting DC electrical equipment.Therefore,the development and design of stable and reliable DC sensors have high engineering application significance.The existing magnetic cores of magnetic modulation sensors are mainly silicon steel sheets and ferrites,and these materials have low initial magnetic permeability,and they are not the best choice for magnetic core materials.In this paper,permalloy with strong magnetic permeability is selected as the core material of the magnetic modulation DC sensor,which greatly improves the accuracy and stability of the sensor.The sensor indirectly obtains the information of the DC leakage current by detecting the pulse width change of the output voltage,that is,the phase difference magnetic modulation principle of the DC leakage current sensor.Two coils of the same size but opposite directions are wound on the magnetic core,and the detection error caused by the zero drift in the sensor circuit is reduced by a differential method,so that the stability of the sensor can be greatly improved.Then,the single-coil and double-coil magnetic modulation DC leakage current sensor models were established in the simulation software Pspice.The simulation waveforms and pulse width data in the two cases are analyzed and compared.The results show that the magnetic modulation sensor with double coil structure has higher linearity,which proves that the previous solution using double coils to overcome zero drift is correct.Finally,the hardware and software parts of the magnetic modulation sensor are designed separately.The main control chip of the sensor adopts high-performance STM32 single-chip microcomputer and uses Keil ?Vision5 software to program the single-chip microcomputer.The test platform of the sensor system is built.The experimental results show that the sensor has good linearity in the DC current range of-50 m A ? + 50 m A,which meets the design requirements and has high engineering practical value.